zika fever

File:Zika.Virus.Rash.Arm.2014.jpg

Most people who are infected have no or few symptoms.{{cite web|title=Symptoms, Diagnosis, & Treatment of Zika Virus|url=https://www.cdc.gov/zika/symptoms/index.html|website=Zika Virus Home|publisher=Centers for Disease Control and Prevention|access-date=29 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160430170339/http://www.cdc.gov/zika/symptoms/index.html|archive-date=30 April 2016|df=dmy-all|date=2014-11-05}} Otherwise the most common signs and symptoms of Zika fever are fever, rash, conjunctivitis (red eyes), muscle and joint pain, and headache, which are similar to signs and symptoms of dengue and chikungunya fever.{{cite journal | first1=Vireak | last1=Heang | title=Zika Virus Infection, Cambodia, 2010 | display-authors=3 | last2=Yasuda | first2=Chadwick Y. | last3=Sovann | first3=Ly | last4=Haddow | first4=Andrew D. | last5=Travassos da Rosa | first5=Amelia P | last6=Tesh | first6=Robert B. | last7=Kasper | first7=Matthew R. | journal=Emerging Infectious Diseases | year=2012 | volume=18 | issue=2 | pages=349–351 | issn=1080-6040 | doi=10.3201/eid1802.111224 | pmc=3310457 | pmid=22305269 | df=dmy-all }} The time from a mosquito bite to developing symptoms is not yet known, but is probably a few days to a week.{{cite web | url=https://www.cdc.gov/zika/symptoms/ | title=Signs and Symptoms | publisher=Centers for Disease Control and Prevention | website=Zika virus home | access-date=30 January 2016 | url-status=live | archive-url=https://web.archive.org/web/20160129165646/http://www.cdc.gov/zika/symptoms/ | archive-date=29 January 2016 | df=dmy-all | date=2014-11-05 }} The disease lasts for several days to a week. It is usually mild enough for people not to go to a hospital.{{cite journal | title=The emergence of Zika virus as a global health security threat: A review and a consensus statement of the INDUSEM Joint Working Group (JWG) | date=11 February 2016 | display-authors=3 | last1=Sikka | first1=Veronica | last2=Chattu | first2=Vijay Kumar | last3=Popli | first3=Raaj K. | last4=Galwankar | first4=Sagar C. | last5=Kelkar | first5=Dhanashree | last6=Sawicki | first6=Stanley G. | last7=Stawicki | first7=Stanislaw P. | last8=Papadimos | first8=Thomas J. | journal=Journal of Global Infectious Diseases | volume=8 | issue=1 | pages=3–15 | language=en | issn=0974-8245 | doi=10.4103/0974-777X.176140 | pmid=27013839 | pmc=4785754 | doi-access=free }}

Due to being in the same family as dengue, there has been concern that it could cause similar bleeding disorders. However that has only been documented in one case, with blood seen in semen, also known as hematospermia.{{cite journal | first1=Brian D. | display-authors=3 | first2=K.C. | first4=B.J. | first8=R.B. | journal=Emerging Infectious Diseases | last1=Foy | title=Probable Non–Vector-borne Transmission of Zika Virus, Colorado, USA | last2=Kobylinski | last3=Foy | first3=J.L.C. | last4=Blitvich | last5=Travassos da Rosa | first5=A. | last6=Haddow | first6=A.D. | last7=Lanciotti | first7=R.S. | last8=Tesh | year=2011 | volume=17 | issue=5 | pages=880–882 | issn=1080-6040 | doi=10.3201/eid1705.101939 | pmid=21529401 | pmc=3321795 | df=dmy-all }}

Zika virus infections have been strongly associated with Guillain–Barré syndrome (GBS), which is a rapid onset of muscle weakness caused by the immune system damaging the peripheral nervous system, and which can progress to paralysis.{{Cite journal|last1=Frontera|first1=Jennifer A.|last2=Silva|first2=Ivan R.F. da|date=2016-10-05|title=Zika Getting on Your Nerves? The Association with the Guillain–Barré Syndrome |journal=New England Journal of Medicine|language=EN|volume=375|issue=16|pages=1581–1582|doi=10.1056/nejme1611840|pmid=27705077 |s2cid=42198417|doi-access=free}} While both GBS and Zika infection can simultaneously occur in the same individual, it is difficult to definitively identify Zika virus as the cause of GBS.{{cite web | url=https://www.cdc.gov/zika/qa/gbs-qa.html | title=Guillain–Barré syndrome Q & A | publisher=Centers for Disease Control and Prevention | date=8 February 2016 | access-date=10 March 2016 | url-status=live | archive-url=https://web.archive.org/web/20160311013537/http://www.cdc.gov/zika/qa/gbs-qa.html | archive-date=11 March 2016 | df=dmy-all }} Though Zika virus has been shown to infect human Schwann cells.{{Cite journal|last1=Dhiman|first1=Gaurav.|last2=Abraham|first2=R.|last3=Griffin|first3=D. |date=2019|title=Human Schwann cells are susceptible to infection with Zika and yellow fever viruses, but not dengue virus|pmid=31289325 |pmc=6616448|journal=Scientific Reports|volume=9|issue=1|pages=9951|doi=10.1038/s41598-019-46389-0|bibcode=2019NatSR...9.9951D}} Several countries affected by Zika outbreaks have reported increases in the rate of new cases of GBS. During the 2013–2014 outbreak in French Polynesia there were 42 reported cases of GBS over three months, compared to between 3 and 10 annually before the outbreak.{{cite journal | first1=Van-Mai | first10=Philippe | first11=Anne-Laure | first12=Christophe | first13=Valérie | first14=Susan K | first15=Hugh J | first16=Lucile | first17=Jean-Claude | first18=Philippe | first19=Emmanuel | first20=Henri-Pierre | first21=Didier | first22=Arnaud | first23=Jean | first24=Frédéric | last1=Cao-Lormeau | last10=Larre | last11=Vial | last12=Decam | last13=Choumet | last14=Halstead | last15=Willison | last16=Musset | last17=Manuguerra | last18=Despres | last19=Fournier | last2=Blake | first2=Alexandre | last20=Mallet | last21=Musso | last22=Fontanet | last23=Neil | last24=Ghawché | title=Guillain–Barré Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study | last3=Mons | first3=Sandrine | last4=Lastère | first4=Stéphane | last5=Roche | first5=Claudine | last6=Vanhomwegen | first6=Jessica | last7=Dub | first7=Timothée | last8=Baudouin | first8=Laure | last9=Teissier | first9=Anita | journal=The Lancet | year=2016 | issn=0140-6736 | doi=10.1016/S0140-6736(16)00562-6 | display-authors=3 | volume=387 | issue=10027 | pages=1531–1539 | pmid=26948433| pmc=5444521 }}

File:Microcephaly-comparison-500px.jpg]]

{{See also|#Microcephaly}}

The disease spreads from mother to child in the womb and can cause multiple problems, most notably microcephaly, in the baby. The full range of birth defects caused by infection during pregnancy is not known, but they appear to be common, with large-scale abnormalities seen in up to 42% of live births.{{Cite journal|last1=Brasil|first1=Patrícia|last2=Pereira|first2=José P.|last3=Moreira|first3=M. Elisabeth|last4=Nogueira|first4=Rita M. Ribeiro|last5=Damasceno|first5=Luana|last6=Wakimoto|first6=Mayumi|last7=Rabello|first7=Renata S.|last8=Valderramos|first8=Stephanie G.|last9=Halai|first9=Umme-Aiman|date=2016-03-04|title=Zika Virus Infection in Pregnant Women in Rio de Janeiro |journal=New England Journal of Medicine|language=EN|volume=375|issue=24|pages=2321–2334|doi=10.1056/nejmoa1602412 |pmid=26943629|pmc=5323261}} The most common observed associations have been abnormalities with brain and eye development such as microcephaly and chorioretinal scarring.{{Cite journal|last1=de Paula Freitas B|last2=de Oliveira Dias J|last3=Prazeres J|date=9 February 2016|title=Ocular findings in infants with microcephaly associated with presumed zika virus congenital infection in salvador, brazil |journal=JAMA Ophthalmology|volume=134|issue=5|pages=529–535|doi=10.1001/jamaophthalmol.2016.0267|pmid=26865554|pmc=5444996|issn=2168-6165|display-authors=etal}} Less commonly there have been systemic abnormalities such as hydrops fetalis, where there is abnormal accumulation of fluid in the fetus.{{Cite journal|last1=Sarno|first1=Manoel|last2=Sacramento|first2=Gielson A.|last3=Khouri|first3=Ricardo|last4=Rosário|first4=Mateus S. do|last5=Costa|first5=Federico|last6=Archanjo|first6=Gracinda|last7=Santos|first7=Luciane A. Jr.|last8=Nery|first8=Nivison Jr.|last9=Vasilakis|first9=Nikos|last10=Ko|first10=Albert I.|last11=de Almeida|first11=Antonio R. P.|date=25 February 2016|title=Zika Virus Infection and Stillbirths: A Case of Hydrops Fetalis, Hydranencephaly and Fetal Demise|journal=PLOS Negl Trop Dis|volume=10|issue=2|pages=e0004517|doi=10.1371/journal.pntd.0004517|issn=1935-2735|pmc=4767410|pmid=26914330|df=dmy-all |doi-access=free }} These abnormalities can lead to intellectual problems, seizures, vision problems, hearing problems, problems feeding and slow development.{{Cite journal|last1=Boeuf|first1=Phillipe|last2=Drummer|first2=Heidi E.|last3=Richards|first3=Jack S.|last4=Scoullar|first4=Michelle J. L.|last5=Beeson|first5=James G.|date=2016-01-01|title=The global threat of Zika virus to pregnancy: epidemiology, clinical perspectives, mechanisms, and impact |journal=BMC Medicine|volume=14|issue=1|pages=112|doi=10.1186/s12916-016-0660-0|issn=1741-7015|pmc=4973112|pmid=27487767 |doi-access=free }}

Whether the stage of pregnancy at which the mother becomes infected affects the risk to the fetus is not well understood, nor is whether other risk factors affect outcomes. One group has estimated the risk of a baby developing microcephaly at about 1% when the mother is infected during the first trimester, with the risk of developing microcephaly becoming uncertain beyond the first trimester.{{cite bioRxiv|title=Risk estimates for microcephaly related to Zika virus infection – from French Polynesia to Bahia, Brazil|date=May 2, 2016|biorxiv=10.1101/051060}} Affected babies might appear normal but actually have brain abnormalities; infection in newborns could also lead to brain damage.{{cite journal |doi=10.1016/S0140-6736(16)30902-3 |pmid=27372398 |title=Congenital Zika virus syndrome in Brazil: A case series of the first 1501 livebirths with complete investigation |journal=The Lancet |volume=388 |issue=10047 |pages=891–7 |year=2016 |last1=França |first1=Giovanny V A |last2=Schuler-Faccini |first2=Lavinia |last3=Oliveira |first3=Wanderson K |last4=Henriques |first4=Claudio M P |last5=Carmo |first5=Eduardo H |last6=Pedi |first6=Vaneide D |last7=Nunes |first7=Marília L |last8=Castro |first8=Marcia C |last9=Serruya |first9=Suzanne |last10=Silveira |first10=Mariângela F |last11=Barros |first11=Fernando C |last12=Victora |first12=Cesar G |doi-access=free }}

Zika virus is a mosquito-borne flavivirus closely related to the dengue and yellow fever viruses. While mosquitoes are the vector, the main reservoir species remains unknown, though serological evidence has been found in both West African monkeys and rodents.{{cite journal | title=Zika Virus Outside Africa | last=Hayes | first=Edward B. | journal=Emerging Infectious Diseases | pmc=2819875 | year=2009 | volume=15 | issue=9 | pages=1347–50 | doi=10.3201/eid1509.090442 | pmid=19788800 | df=dmy-all }}{{cite book|last=Brack|first=Manfred|title=Agents Transmissible from Simians to Man|url=https://books.google.com/books?id=gbDtCAAAQBAJ|date=6 December 2012|publisher=Springer Science & Business Media|isbn=978-3-642-71911-0|url-status=live|archive-url=https://web.archive.org/web/20160617124521/https://books.google.com/books?id=gbDtCAAAQBAJ|archive-date=17 June 2016|df=dmy-all}}

Transmission is via the bite of mosquitoes from the genus Aedes, primarily Aedes aegypti in tropical regions. It has also been isolated from Ae. africanus, Ae. apicoargenteus, Ae. luteocephalus,{{cite web | url=http://www.wrbu.org/SpeciesPages_non-ANO/non-ANO_A-hab/AElut_hab.html | title=Aedes luteocephala | publisher=Walter Reed Biosystematics Unit | work=Medically Important Mosquitoes | access-date=1 February 2016 | url-status=dead | archive-url=https://web.archive.org/web/20160128210229/http://www.wrbu.org/SpeciesPages_non-ANO/non-ANO_A-hab/AElut_hab.html | archive-date=28 January 2016 | df=dmy-all }} Ae. albopictus,{{Cite journal|last1=Grard|first1=G|last2=Caron|first2=M|last3=Mombo|first3=I M|last4=Nkoghe|first4=D|last5=Ondo|first5=S M|last6=Jiolle|first6=D|last7=Fontenille|first7=D|last8=Paupy|first8=C|last9=Leroy|first9=E M|date=2014|title=Zika Virus in Gabon (Central Africa) – 2007: A New Threat from Aedes albopictus ?|journal=PLOS Negl Trop Dis|volume=8|issue=2|pages=e2681|doi=10.1371/journal.pntd.0002681|issn=1935-2735|pmc=3916288|pmid=24516683|df=dmy-all|doi-access=free}}{{Cite journal|last1=Wong|first1=PJ|last2=Li|first2=M I|last3=Chong|first3=C|last4=Ng|first4=L|last5=Tan|first5=C|date=2013|title=Aedes ( Stegomyia ) albopictus (Skuse): A Potential Vector of Zika Virus in Singapore|journal=PLOS Negl Trop Dis|volume=7|issue=8|pages=e2348|doi=10.1371/journal.pntd.0002348|issn=1935-2735|pmc=3731215|pmid=23936579|df=dmy-all |doi-access=free }} Ae. vittatus and Ae. furcifer. During the 2007 outbreak on Yap Island in the South Pacific, Aedes hensilli was the vector, while Aedes polynesiensis spread the virus in French Polynesia in 2013.

Zika virus can also spread by sexual transmission from infected men to their partners.{{cite journal | display-authors=3 | first1=Alexandra M. | first2=John T. | first3=Jo Ellen | last4=Kachur | first4=Rachel E. | journal=MMWR. Morbidity and Mortality Weekly Report | last1=Oster | title=Interim Guidelines for Prevention of Sexual Transmission of Zika Virus — United States, 2016 | last2=Brooks | last3=Stryker | last5=Mead | first5=Paul | last6=Pesik | first6=Nicki T. | last7=Petersen | first7=Lyle R. | year=2016 | volume=65 | issue=5 | pages=120–121 | issn=0149-2195 | doi=10.15585/mmwr.mm6505e1 | pmid=26866485 | df=dmy-all | doi-access=free }}{{cite web | url=https://www.cdc.gov/media/releases/2016/s0223-zika-guidance.html | title=CDC encourages following guidance to prevent sexual transmission of Zika virus | publisher=Centers for Disease Control and Prevention | work=CDC Newsroom Releases | date=23 February 2016 | url-status=live | archive-url=https://web.archive.org/web/20160227052140/http://www.cdc.gov/media/releases/2016/s0223-zika-guidance.html | archive-date=27 February 2016 | df=dmy-all }}{{cite journal | first1=Susan L. | last1=Hills | url=https://www.cdc.gov/mmwr/volumes/65/wr/mm6508e2.htm | title=Transmission of Zika Virus Through Sexual Contact with Travelers to Areas of Ongoing Transmission — Continental United States, 2016 | display-authors=3 | last2=Russell | first2=Kate | last3=Hennessey | first3=Morgan | last4=Williams | first4=Charnetta | last5=Oster | first5=Alexandra M. | last6=Fischer | first6=Marc | last7=Mead | first7=Paul | journal=MMWR. Morbidity and Mortality Weekly Report | year=2016 | volume=65 | issue=8 | issn=0149-2195 | doi=10.15585/mmwr.mm6508e2er | url-status=live | archive-url=https://web.archive.org/web/20160315234550/http://www.cdc.gov/mmwr/volumes/65/wr/mm6508e2.htm | archive-date=15 March 2016 | df=dmy-all }} Zika virus has been isolated from semen samples, with one person having 100,000 times more virus in semen than blood or urine, two weeks after being infected.{{cite journal | first1=Jean Michel | last1=Mansuy | title=Zika virus: high infectious viral load in semen, a new sexually transmitted pathogen? | last2=Dutertre | first2=Marine | last3=Mengelle | first3=Catherine | last4=Fourcade | first4=Camille | last5=Marchou | first5=Bruno | last6=Delobel | first6=Pierre | last7=Izopet | first7=Jacques | last8=Martin-Blondel | first8=Guillaume | journal=The Lancet Infectious Diseases | year=2016 | issn=1473-3099 | doi=10.1016/S1473-3099(16)00138-9 | pmid=26949027 | display-authors=3 | volume=16 | issue=4 | pages=405| doi-access=free }} It is unclear why levels in semen can be higher than other body fluids, and it is also unclear how long infectious virus can remain in semen. There have also been cases of men with no symptoms of Zika virus infection transmitting the disease.{{Cite journal|last1=Brooks|first1=Richard B.|last2=Carlos|first2=Maria Paz|last3=Myers|first3=Robert A.|last4=White|first4=Mary Grace|last5=Bobo-Lenoci|first5=Tanya|last6=Aplan|first6=Debra|last7=Blythe|first7=David|last8=Feldman|first8=Katherine A.|date=2016-01-01|title=Likely Sexual Transmission of Zika Virus from a Man with No Symptoms of Infection — Maryland, 2016|journal=MMWR. Morbidity and Mortality Weekly Report|volume=65|issue=34|pages=915–916|doi=10.15585/mmwr.mm6534e2|pmid=27585037|issn=0149-2195|df=dmy-all|doi-access=free}} The CDC has recommended that all men who have travelled to affected areas should wait at least 6 months before trying to attempt conception, regardless of whether they were ill.{{Cite journal|last1=Petersen|first1=Emily E.|last2=Meaney-Delman|first2=Dana|last3=Neblett-Fanfair|first3=Robyn|last4=Havers|first4=Fiona|last5=Oduyebo|first5=Titilope|last6=Hills|first6=Susan L.|last7=Rabe|first7=Ingrid B.|last8=Lambert|first8=Amy|last9=Abercrombie|first9=Julia|date=2016-01-01|title=Update: Interim Guidance for Preconception Counseling and Prevention of Sexual Transmission of Zika Virus for Persons with Possible Zika Virus Exposure — United States, September 2016|journal=MMWR. Morbidity and Mortality Weekly Report|volume=65|issue=39|doi=10.15585/mmwr.mm6539e1|pmid=27711033|issn=0149-2195|pages=1077–1081|df=dmy-all|doi-access=free}} To date there have been no reported sexual transmissions from women to their sexual partners. Oral, anal, or vaginal sex can spread the disease.{{cite news |url=https://www.nytimes.com/2016/04/15/health/zika-virus-can-be-transmitted-through-anal-sex-cdc-says.html |title=Zika Virus Can be Transmitted Through Anal Sex, C.D.C. Says |access-date=2017-03-03 |url-status=live |archive-url=https://web.archive.org/web/20161221154558/http://www.nytimes.com/2016/04/15/health/zika-virus-can-be-transmitted-through-anal-sex-cdc-says.html |archive-date=21 December 2016 |df=dmy-all |newspaper=The New York Times |date=2016-04-14 |last1=McNeil |first1=Donald G. Jr. }} Zika Virus Can Be Transmitted Through Anal Sex, C.D.C. Says{{Cite journal|last1=D’Ortenzio|first1=Eric|last2=Matheron|first2=Sophie|last3=de Lamballerie|first3=Xavier|last4=Hubert|first4=Bruno|last5=Piorkowski|first5=Géraldine|last6=Maquart|first6=Marianne|last7=Descamps|first7=Diane|last8=Damond|first8=Florence|last9=Yazdanpanah|first9=Yazdan|date=2016-06-02|title=Evidence of Sexual Transmission of Zika Virus |journal=New England Journal of Medicine|volume=374|issue=22|pages=2195–2198|doi=10.1056/NEJMc1604449|issn=0028-4793|pmid=27074370|doi-access=free}}

Cases of vertical perinatal transmission have been reported. The CDC recommends that women with Zika fever should wait at least 8 weeks after they start having symptoms of the disease before attempting to conceive.{{cite journal|last2=Polen|first2=Kara N.D.|last3=Meaney-Delman|first3=Dana|last4=Ellington|first4=Sascha R.|last5=Oduyebo|first5=Titilope|last6=Cohn|first6=Amanda|last7=Oster|first7=Alexandra M.|last8=Russell|first8=Kate|last9=Kawwass|first9=Jennifer F.|year=2016|title=Update: Interim Guidance for Health Care Providers Caring for Women of Reproductive Age with Possible Zika Virus Exposure — United States, 2016|url=https://www.cdc.gov/mmwr/volumes/65/wr/mm6512e2er.htm|journal=MMWR. Morbidity and Mortality Weekly Report|volume=65|issue=12|pages=315–322|doi=10.15585/mmwr.mm6512e2|pmid=27031943|issn=0149-2195|first1=Emily E.|first10=Mateusz P.|first11=Ann M.|first12=Jeanne|first13=John T.|first14=Dmitry|first15=Julie|first16=Jorge|first17=Matthew|first18=Christine K.|first19=Margaret A.|first20=Maria|first21=Denise J.|first22=Sonja A.|last1=Petersen|last10=Karwowski|last11=Powers|last12=Bertolli|last13=Brooks|last14=Kissin|last15=Villanueva|last16=Muñoz-Jordan|last17=Kuehnert|last18=Olson|last19=Honein|last20=Rivera|last21=Jamieson|last22=Rasmussen|display-authors=3|url-status=live|archive-url=https://web.archive.org/web/20160328161610/http://www.cdc.gov/mmwr/volumes/65/wr/mm6512e2er.htm|archive-date=28 March 2016|df=dmy-all|doi-access=free}} There have been no reported cases of transmission from breastfeeding, but infectious virus has been found in breast milk.{{cite journal | display-authors=3 | title=Infectious Zika viral particles in breastmilk | last1=Dupont-Rouzeyrol | first1=Myrielle | last2=Biron | first2=Antoine | last3=O'Connor | first3=Olivia | last4=Huguon | first4=Emilie | last5=Descloux | first5=Elodie | journal=The Lancet | doi=10.1016/s0140-6736(16)00624-3 | volume=387 | issue=10023 | pages=1051 | pmid=26944028| year=2016 | doi-access=free }}

Like other flaviviruses it could potentially be transmitted by blood transfusion and several affected countries have developed strategies to screen blood donors.{{cite journal | title=Blood safety and zoonotic emerging pathogens: now it's the turn of Zika virus! | last1=Franchini | first1=M. | last2=Velati | first2=C. | journal=Blood Transfusion | volume=14 | year=2016 | issue=2 | pages=93–94 | doi=10.2450/2015.0187-15 | pmid=26674809 | pmc=4781775 | df=dmy-all }} The U.S. FDA has recommended universal screening of blood products for Zika.{{Cite web|url=https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm518218.htm|title=FDA advises testing for Zika virus in all donated blood and blood components in the US|website=Food and Drug Administration|date=August 26, 2016|url-status=live|archive-url=https://web.archive.org/web/20160902092708/https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm518218.htm|archive-date=2 September 2016|df=dmy-all}} The virus is detected in 3% of asymptomatic blood donors in French Polynesia.{{cite journal|last1=Guillaume|first1=Theiry|title=Zika virus-associated Guillain–Barré syndrome: a warning for critical care physicians|journal=Intensive Care Medicine|volume=42|issue=9|date=27 April 2016|pages=1485–1486|doi=10.1007/s00134-016-4364-x|pmid=27118575|doi-access=free}}

In fruit flies microcephaly appears to be caused by the flavivirid virus protein NS4A, which can disrupt brain growth by hijacking a pathway that regulates the growth of new neurons.{{cite news|last=Chiu|first=Molly|date=14 November 2019|title=How Maternal Zika Virus Infection Results In Newborn Microcephaly|url=https://scienmag.com/how-maternal-zika-virus-infection-results-in-newborn-microcephaly/|work=Scienmag|access-date=7 January 2020}}

It is difficult to diagnose Zika virus infection based on clinical signs and symptoms alone due to overlaps with other arboviruses that are endemic to similar areas.{{cite journal | title=Zika Virus in the Americas – Yet Another Arbovirus Threat | date=18 February 2016 | last1=Fauci | first1=Anthony S. | last2=Morens | first2=David M. | journal=New England Journal of Medicine | volume=374 | issue=7 | pages=601–604 | doi=10.1056/NEJMp1600297 | pmid=26761185 | s2cid=4377569 | doi-access=free }} The US Centers for Disease Control and Prevention (CDC) advises that "based on the typical clinical features, the differential diagnosis for Zika virus infection is broad. In addition to dengue, other considerations include leptospirosis, malaria, rickettsia, group A streptococcus, rubella, measles, and parvovirus, enterovirus, adenovirus, and alphavirus infections (e.g., chikungunya, Mayaro, Ross River, Barmah Forest, O'nyong'nyong, and Sindbis viruses)."{{cite web | url=https://www.cdc.gov/zika/hc-providers/clinicalevaluation.html | title=Clinical Evaluation & Disease | publisher=Centers for Disease Control and Prevention | work=For Health Care Providers | access-date=24 December 2015 | url-status=live | archive-url=https://web.archive.org/web/20151225051517/http://www.cdc.gov/zika/hc-providers/clinicalevaluation.html | archive-date=25 December 2015 | df=dmy-all }}

In small case series, routine chemistry and complete blood counts have been normal in most patients. A few have been reported to have mild leukopenia, thrombocytopenia, and elevated liver transaminases.{{cite journal | title=Zika Virus: Diagnostics for an Emerging Pandemic Threat | date=17 February 2016 | last1=Waggoner | first1=Jesse J. | last2=Pinsky | first2=Benjamin A. | journal=Journal of Clinical Microbiology | pages=JCM.00279–16 | issn=0095-1137 | doi=10.1128/JCM.00279-16 | pmid=26888897 | pmc=4809954 | volume=54 | issue=4 | df=dmy-all }}

Zika virus can be identified by reverse transcriptase PCR (RT-PCR) in acutely ill patients. However, the period of viremia can be short and the World Health Organization (WHO) recommends RT-PCR testing be done on serum collected within 1 to 3 days of symptom onset or on saliva samples collected during the first 3 to 5 days.{{cite web |url=http://www.wpro.who.int/mediacentre/factsheets/fs_05182015_zika/en |title=Zika virus |access-date=24 December 2015 |url-status=dead |archive-url=https://web.archive.org/web/20151225035504/http://www.wpro.who.int/mediacentre/factsheets/fs_05182015_zika/en/ |archive-date=25 December 2015 |df=dmy-all }} When evaluating paired samples, Zika virus was detected more frequently in saliva than serum. Urine samples can be collected and tested up to 14 days after the onset of symptoms, as the virus has been seen to survive longer in the urine than either saliva or serum.{{cite journal|title=Interim Guidance for Zika Virus Testing of Urine – United States, 2016.|journal=MMWR. Morbidity and Mortality Weekly Report|date=13 May 2016|volume=65|issue=18|pages=474|pmid=27171368|doi=10.15585/mmwr.mm6518e1|doi-access=free}} The longest period of having a detectable level of the virus has been 11 days and the Zika virus does not appear to establish latency.

Later on, serology for the detection of specific IgM and IgG antibodies to the Zika virus can be used. IgM antibodies can be detectable within 3 days of the onset of illness. Serological cross-reactions with closely related flaviviruses such as dengue and West Nile virus as well as vaccines to flaviviruses are possible.{{cite journal | display-authors=3 | first1=Oumar | url=http://journalofclinicalvirology.com/article/S1386-6532(08)00184-4/abstract | first2=Ousmane | first3=Anne | last4=Weidmann | first4=Manfred | last1=Faye | title=One-step RT-PCR for detection of Zika virus | last2=Faye | last3=Dupressoir | last5=Ndiaye | first5=Mady | last6=Alpha Sall | first6=Amadou | journal=Journal of Clinical Virology | year=2008 | volume=43 | issue=1 | pages=96–101 | issn=1386-6532 | doi=10.1016/j.jcv.2008.05.005 | pmid=18674965}}{{cite journal | first1=Robert S. | last1=Lanciotti | title=Genetic and Serologic Properties of Zika Virus Associated with an Epidemic, Yap State, Micronesia, 2007 | last2=Kosoy | first2=Olga L. | last3=Laven | first3=Janeen J. | last4=Velez | first4=Jason O. | last5=Lambert | first5=Amy J. | last6=Johnson | first6=Alison J. | last7=Stanfield | first7=Stephanie M. | last8=Duffy | first8=Mark R. | journal=Emerging Infectious Diseases | year=2008 | volume=14 | issue=8 | pages=1232–1239 | issn=1080-6040 | doi=10.3201/eid1408.080287 | display-authors=3 | pmid=18680646 | pmc=2600394 | df=dmy-all }} As of 2019, the FDA has authorized two tests to detect Zika virus antibodies.{{cite web |last1=Commissioner |first1=Office of the |title=Zika Virus Response Updates from FDA |url=https://www.fda.gov/emergency-preparedness-and-response/mcm-issues/zika-virus-response-updates-fda |website=FDA |access-date=18 July 2019 |language=en |date=18 July 2019}}

The CDC recommends screening some pregnant women even if they do not have symptoms of infection. Pregnant women who have traveled to affected areas should be tested between two and twelve weeks after their return from travel.{{cite journal | first1=Titilope | first10=Ann M. | first11=Julie | first12=Romeo R. | first13=Ada | first14=Jorge L. | first15=Margaret A. | first16=Denise J. | last1=Oduyebo | last10=Powers | last11=Villanueva | last12=Galang | last13=Dieke | last14=Muñoz | last15=Honein | last16=Jamieson | title=Update: Interim Guidelines for Health Care Providers Caring for Pregnant Women and Women of Reproductive Age with Possible Zika Virus Exposure — United States, 2016 | last2=Petersen | first2=Emily E. | last3=Rasmussen | first3=Sonja A. | last4=Mead | first4=Paul S. | last5=Meaney-Delman | first5=Dana | last6=Renquist | first6=Christina M. | last7=Ellington | first7=Sascha R. | last8=Fischer | first8=Marc | last9=Staples | first9=J. Erin | journal=MMWR. Morbidity and Mortality Weekly Report | year=2016 | volume=65 | issue=5 | pages=1–6 | issn=0149-2195 | doi=10.15585/mmwr.mm6505e2er | pmid=26866840 | display-authors=3 | df=dmy-all }} Due to the difficulties with ordering and interpreting tests for Zika virus, the CDC also recommends that healthcare providers contact their local health department for assistance. For women living in affected areas, the CDC has recommended testing at the first prenatal visit with a doctor as well as in the mid-second trimester, though this may be adjusted based on local resources and the local burden of Zika virus. Additional testing should be done for any signs of Zika virus disease. Women with positive test results for Zika virus infection should have their fetus monitored by ultrasound every three to four weeks to monitor fetal anatomy and growth.

For infants with suspected congenital Zika virus disease, the CDC recommends testing with both serologic and molecular assays such as RT-PCR, IgM ELISA and plaque reduction neutralization test (PRNT).{{Cite journal|last1=Russell|first1=Kate|last2=Oliver|first2=Sara E.|last3=Lewis|first3=Lillianne|last4=Barfield|first4=Wanda D.|last5=Cragan|first5=Janet|last6=Meaney-Delman|first6=Dana|last7=Staples|first7=J. Erin|last8=Fischer|first8=Marc|last9=Peacock|first9=Georgina|date=2016-01-01|title=Update: Interim Guidance for the Evaluation and Management of Infants with Possible Congenital Zika Virus Infection — United States, August 2016|journal=MMWR. Morbidity and Mortality Weekly Report|volume=65|issue=33|pages=870–878|doi=10.15585/mmwr.mm6533e2|pmid=27559830|issn=0149-2195|df=dmy-all|doi-access=free}} RT-PCR of the infants serum and urine should be performed in the first two days of life. Newborns with a mother who was potentially exposed and who have positive blood tests, microcephaly or intracranial calcifications {{Cite journal|last1=Aguilar Ticona|first1=Juan P.|last2=Nery|first2=Nivison|last3=Doss-Gollin|first3=Simon|last4=Gambrah|first4=Claudia|last5=Lessa|first5=Millani|last6=Rastely-Júnior|first6=Valmir|last7=Matos|first7=Adriana|last8=de Paula Freitas|first8=Bruno|last9=Borja|first9=Ana|last10=Wunder|first10=Elsio A.|last11=Ballalai|first11=Verena|date=2021-09-15|editor-last=Isgum|editor-first=Ivana|title=Heterogeneous development of children with Congenital Zika Syndrome-associated microcephaly|journal=PLOS ONE|language=en|volume=16|issue=9|pages=e0256444|doi=10.1371/journal.pone.0256444|issn=1932-6203|pmc=8443077|pmid=34525107|bibcode=2021PLoSO..1656444A|doi-access=free}} should have further testing including a thorough physical investigation for neurologic abnormalities, dysmorphic features, splenomegaly, hepatomegaly, and rash or other skin lesions. Other recommended tests are cranial ultrasound, hearing evaluation,{{cite journal |doi=10.15585/mmwr.mm6534e3 |pmid=27585248 |title=Hearing Loss in Infants with Microcephaly and Evidence of Congenital Zika Virus Infection — Brazil, November 2015–May 2016 |journal=Morbidity and Mortality Weekly Report |volume=65 |issue=34 |pages=917–9 |year=2016 |last1=Leal |first1=Mariana C |last2=Muniz |first2=Lilian F |last3=Ferreira |first3=Tamires S.A |last4=Santos |first4=Cristiane M |last5=Almeida |first5=Luciana C |last6=Van Der Linden |first6=Vanessa |last7=Ramos |first7=Regina C.F |last8=Rodrigues |first8=Laura C |last9=Neto |first9=Silvio S. Caldas |doi-access=free }} and eye examination. Testing should be done for any abnormalities encountered as well as for other congenital infections such as syphilis, toxoplasmosis, rubella, cytomegalovirus infection, lymphocytic choriomeningitis virus infection, and herpes simplex virus. Some tests should be repeated up to 6 months later as there can be delayed effects, particularly with hearing.

In response to the widespread transmission of the Zika virus during the 2016 outbreak and concerns about viral genetic material detected in breast milk the World Health Organization (WHO) released a Guideline for infant feeding in areas of Zika virus transmission, first in 2016 and updated in 2021, where the evidence showed that despite the detection of Zika virus in breast milk, there is unclear evidence of transmission to the infant, and considering that Zika virus infection among infants is mild, the balance between desirable and undesirable effects favors breastfeeding versus not breastfeeding.{{Cite web|title=Guideline: infant feeding in areas of Zika virus transmission, 2nd edition|url=https://www.who.int/publications-detail-redirect/9789240029187|access-date=2021-11-19|website=www.who.int|language=en}} According to the 2021WHO guidelines:

• Infants born to mothers with suspected, probable, or confirmed Zika virus infection or who reside in or have traveled to areas of ongoing Zika virus transmission should be fed according to normal infant feeding guidelines. They should start breastfeeding within one hour of birth, be exclusively breastfed for six months, and have timely introduction of adequate, safe, and properly fed complementary foods while continuing breastfeeding up to two years of age or beyond.
• Infants fed with expressed breast milk from mothers with suspected, probable, or confirmed Zika virus infection or who reside in or have traveled to areas of ongoing Zika virus transmission should be fed according to normal infant feeding guidelines (strong recommendation, very-low certainty of evidence).
• Among infants (0–12 months) affected by complications associated with Zika virus infection, infant feeding practices should be modified (such as adjusting the environment, postural correction, or thickening feeds) to achieve and maintain optimal possible infant growth and development (strong recommendation, very- low certainty of evidence).
• Mothers and caregivers of infants affected by complications associated with Zika virus (such as feeding difficulties) should receive skilled support from health-care workers to initiate and sustain optimal infant feeding practices

The virus is spread by mosquitoes, making mosquito avoidance an important element of disease control. The CDC recommends that individuals:{{cite web | url=http://wwwnc.cdc.gov/travel/page/avoid-bug-bites | title=Avoid bug bites | publisher=Centers for Disease Control and Prevention | work=Travelers' Health | access-date=15 March 2016 | url-status=live | archive-url=https://web.archive.org/web/20160313104044/http://wwwnc.cdc.gov/travel/page/avoid-bug-bites | archive-date=13 March 2016 | df=dmy-all }}

• Cover exposed skin by wearing long-sleeved shirts and long pants treated with permethrin.{{cite web |url=https://www.cdc.gov/zika/prevention/prevent-mosquito-bites.html |title=Zika Virus – Protect Yourself from Mosquito Bites |access-date=2016-10-01 |url-status=live |archive-url=https://web.archive.org/web/20161001202644/https://www.cdc.gov/zika/prevention/prevent-mosquito-bites.html |archive-date=1 October 2016 |df=dmy-all |date=2014-11-05 }} Permethrin-treated clothing will protect you after multiple washings
• Use an insect repellent containing DEET,{{cite news |url=https://www.nytimes.com/2016/04/05/health/zika-virus-deet-pregant-women-safety.html |title=DEET Seen as Safe for Pregnant Women to Avoid Zika Despite Few Studies |access-date=2017-03-03 |url-status=live |archive-url=https://web.archive.org/web/20160917011028/http://www.nytimes.com/2016/04/05/health/zika-virus-deet-pregant-women-safety.html |archive-date=17 September 2016 |df=dmy-all |newspaper=The New York Times |date=2016-04-04 |last1=Louis |first1=Catherine Saint }} DEET Seen as Safe for Pregnant Women to Avoid Zika Despite Few Studies picaridin, oil of lemon eucalyptus (OLE), or ethyl butylacetylaminopropionate (IR3535)
• Always follow product directions and reapply as directed
• If you are also using sunscreen, apply sunscreen first, let it dry, then apply insect repellent
• Follow package directions when applying repellent on children. Avoid applying repellent to their hands, eyes, or mouth
• Stay and sleep in screened-in or air-conditioned rooms
• Use a bed net if the area where you are sleeping is exposed to the outdoors
• Cover cribs, strollers, and carriers with mosquito netting for babies under 2 months old.

The CDC also recommends strategies for controlling mosquitoes such as eliminating standing water, repairing septic tanks, and using screens on doors and windows.{{cite web | url=https://www.cdc.gov/chikungunya/resources/vector-control.html | title=Surveillance and Control of Aedes aegypti and Aedes albopictus in the United States | publisher=Centers for Disease Control and Prevention | work=Chikungunya Virus Home: Resources | date=10 March 2016 | url-status=live | archive-url=https://web.archive.org/web/20160206004720/http://www.cdc.gov/chikungunya/resources/vector-control.html | archive-date=6 February 2016 | df=dmy-all }}{{cite web | url=https://www.cdc.gov/chikungunya/pdfs/control_mosquitoes_chikv_denv_zika.pdf | title=Help Control Mosquitoes that Spread Dengue, Chikungunya, and Zika Viruses | publisher=Centers for Disease Control and Prevention | work=Chikungunya Virus Home: Fact Sheets and Posters | date=August 2015 | url-status=live | archive-url=https://web.archive.org/web/20160201150616/http://www.cdc.gov/chikungunya/pdfs/control_mosquitoes_chikv_denv_zika.pdf | archive-date=1 February 2016 | df=dmy-all }} Spraying insecticide is used to kill flying mosquitoes and larvicide can be used in water containers.

Because Zika virus can be sexually transmitted, men who have gone to an area where Zika fever is occurring should be counseled to either abstain from sex or use condoms for 6 months after travel if their partner is pregnant or could potentially become pregnant. Breastfeeding is still recommended by the WHO, even by women who have had Zika fever. There have been no recorded cases of Zika transmission to infants through breastfeeding, though the replicative virus has been detected in breast milk.{{cite web | url=http://apps.who.int/iris/bitstream/10665/204473/1/WHO_ZIKV_MOC_16.5_eng.pdf | title=Breastfeeding in the context of Zika virus | publisher=World Health Organization | work=Institutional Repository for Information Sharing | date=25 February 2016 | access-date=28 February 2016 | url-status=live | archive-url=https://web.archive.org/web/20160305025404/http://apps.who.int/iris/bitstream/10665/204473/1/WHO_ZIKV_MOC_16.5_eng.pdf | archive-date=5 March 2016 | df=dmy-all }}

When returning from travel, with or without symptoms, it is suggested that prevention of mosquito bites continue for 3 weeks in order to reduce the risk of virus transmission to uninfected mosquitos.

Because of the "growing evidence of a link between Zika and microcephaly", in January 2016, the CDC issued a travel alert advising pregnant women to consider postponing travel to countries and territories with ongoing local transmission of Zika virus.{{cite news|url=http://www.medscape.com/viewarticle/857389?nlid=97363_3901&src=wnl_newsalrt_160115_MSCPEDIT&uac=28013DZ&impID=957011&faf=1|title=CDC Issues Zika Travel Alert|last=Lowes|first=R.|date=15 January 2016|work=Medscape Medical News|access-date=16 January 2016|url-status=live|archive-url=https://web.archive.org/web/20160126092814/http://www.medscape.com/viewarticle/857389?nlid=97363_3901&src=wnl_newsalrt_160115_MSCPEDIT&uac=28013DZ&impID=957011&faf=1|archive-date=26 January 2016|df=dmy-all}} Later, the advice was updated to caution pregnant women to avoid these areas entirely if possible and, if travel is unavoidable, to protect themselves from mosquito bites.{{cite web|url=https://www.cdc.gov/zika/pregnancy/protect-yourself.html#one|title=How to Protect Yourself|date=4 March 2016|publisher=Centers for Disease Control and Prevention|access-date=16 March 2016|url-status=live|archive-url=https://web.archive.org/web/20160312044518/http://www.cdc.gov/zika/pregnancy/protect-yourself.html#one|archive-date=12 March 2016|df=dmy-all}} Male partners of pregnant women and couples contemplating pregnancy who must travel to areas where Zika is active are advised to use condoms or abstain from sex. The agency also suggested that women thinking about becoming pregnant should consult with their physicians before traveling.{{cite web|url=https://www.cdc.gov/media/releases/2016/s0315-zika-virus-travel.html|title=CDC issues interim travel guidance related to Zika virus for 14 Countries and Territories in Central and South America and the Caribbean|date=15 January 2016|publisher=Centers for Disease Control and Prevention|work=CDC Newsroom Releases|url-status=live|archive-url=https://web.archive.org/web/20160118024439/http://www.cdc.gov/media/releases/2016/s0315-zika-virus-travel.html|archive-date=18 January 2016|df=dmy-all}}

In September 2016, the CDC travel advisories included:{{Cite web|url=http://wwwnc.cdc.gov/travel/page/zika-information|title=Zika Travel Information {{!}} Travelers' Health {{!}} CDC|website=wwwnc.cdc.gov|access-date=2016-09-02|url-status=live|archive-url=https://web.archive.org/web/20160907045947/http://wwwnc.cdc.gov/travel/page/zika-information|archive-date=7 September 2016|df=dmy-all}}

• Cape Verde
• Many parts of the Caribbean: Anguilla, Antigua and Barbuda, Aruba, The Bahamas, Barbados, Bonaire, British Virgin Islands, Cayman Islands, Cuba, Curaçao, Dominica, Dominican Republic, Grenada, Guadeloupe, Haiti, Jamaica, Martinique, Puerto Rico, Saba, Saint Saint Barthélemy, Saint Lucia, Saint Martin, Saint Vincent and the Grenadines, Sint Eustatius, Sint Maarten, Trinidad and Tobago, and the U.S. Virgin Islands
• Central America: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama
• Mexico
• Most of South America: Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, and Venezuela
• Several Pacific Islands: American Samoa, Fiji, Marshall Islands, Micronesia, New Caledonia, Papua New Guinea, Samoa, and Tonga
• In Asia: Singapore, Malaysia, Brunei

In December 2020, no active Zika outbreaks were reported by the CDC.{{cite web|url=https://wwwnc.cdc.gov/travel/page/zika-information |title=Zika Travel Information |publisher=CDC |date=December 10, 2020 |accessdate=21 February 2021}}

Both the regional Pan American Health Organization (PAHO) as well as the WHO have issued statements of concern about the widespread public health impact of the Zika virus and its links to GBS and microcephaly.{{cite web|url=http://www.paho.org/hq/index.php?option=com_content&view=category&layout=blog&id=1218&Itemid=2291|title=Neurological syndrome, congenital malformations, and Zika virus infection – Epidemiological Update|date=17 January 2016|publisher=Pan American Health Organization|work=Epidemiological Alerts and Updates CHA.01.04b Epidemic Alert and Response|url-status=live|archive-url=https://web.archive.org/web/20160126083239/http://www.paho.org/hq/index.php?option=com_content&view=category&layout=blog&id=1218&Itemid=2291|archive-date=26 January 2016|df=dmy-all}}{{Cite web|url=http://www.nbcnews.com/storyline/zika-virus-outbreak/who-declares-zika-public-health-emergency-n508761|title=WHO Declares Zika a Public Health Emergency|website=NBC News|date=February 2016 |access-date=8 February 2016|url-status=live|archive-url=https://web.archive.org/web/20160207220721/http://www.nbcnews.com/storyline/zika-virus-outbreak/who-declares-zika-public-health-emergency-n508761|archive-date=7 February 2016|df=dmy-all}} The WHO Director-General, Margaret Chan, issued a statement in February 2016 "declaring that the recent cluster of microcephaly cases and other neurological disorders reported in Brazil, following a similar cluster in French Polynesia in 2014, constitutes a Public Health Emergency of International Concern." The declaration allowed the WHO to coordinate international response to the virus as well as gave its guidance the force of international law under the International Health Regulations.{{cite news|url=https://www.nytimes.com/2016/02/02/health/zika-virus-world-health-organization.html|title=Zika Virus a Global Health Emergency, W.H.O. Says|last1=Tavernise|first1=Sabrina|date=1 February 2016|work=The New York Times|last2=McNeil |first2=Donald G. Jr.|issn=0362-4331|access-date=8 February 2016|url-status=live|archive-url=https://web.archive.org/web/20160208085615/http://www.nytimes.com/2016/02/02/health/zika-virus-world-health-organization.html|archive-date=8 February 2016|df=dmy-all}}{{cite web|url=https://www.who.int/ihr/procedures/pheic/en/|title=IHR Procedures concerning public health emergencies of international concern (PHEIC)|publisher=World Health Organization|access-date=8 February 2016|url-status=dead|archive-url=https://web.archive.org/web/20160203074335/http://www.who.int/ihr/procedures/pheic/en/|archive-date=3 February 2016|df=dmy-all}} The declaration was ended in November 2016.{{Cite web|url=http://www.cnn.com/2016/11/18/health/who-ends-zika-public-health-emergency/index.html|title=WHO ends Zika public health emergency|author=Debra Goldschmidt|website=CNN|date=18 November 2016|access-date=2016-12-24|url-status=live|archive-url=https://web.archive.org/web/20161223122134/http://www.cnn.com/2016/11/18/health/who-ends-zika-public-health-emergency/index.html|archive-date=23 December 2016|df=dmy-all}}

{{Main|Zika virus vaccine}}

As of 2016, there was no available vaccine. Development was a priority of the US National Institutes of Health (NIH), but officials stated that development of a vaccine could take years.{{cite news | url=https://time.com/4188973/zika-virus-vaccine-nih/ | title=U.S. Launches 'Full-court Press' for a Zika Vaccine | magazine=Time | date=21 January 2016 | access-date=23 January 2016 | author=Sifferlin, Alexandra | url-status=live | archive-url=https://web.archive.org/web/20160122154151/http://time.com/4188973/zika-virus-vaccine-nih/ | archive-date=22 January 2016 | df=dmy-all }} To speed new drug development regulatory strategies were proposed by the WHO and NIH.{{Cite journal|last1=J.|first1=Thomas, Stephen|last2=Maïna|first2=L’Azou|last3=D.T.|first3=Barrett, Alan|last4=A.C.|first4=Jackson, Nicholas|date=2016-09-28|title=Fast-Track Zika Vaccine Development — Is It Possible? |language=EN|doi=10.1056/nejmp1609300|volume=375|issue=13|journal=New England Journal of Medicine|pages=1212–1216|pmid=27682032 |doi-access=free}}{{Cite journal|last1=D.|first1=Marston, Hilary|last2=Nicole|first2=Lurie|last3=L.|first3=Borio, Luciana|last4=S.|first4=Fauci, Anthony|date=2016-09-28|title=Considerations for Developing a Zika Virus Vaccine |language=EN|doi=10.1056/nejmp1607762|volume=375|issue=13|journal=New England Journal of Medicine|pages=1209–1212|pmid=27682031|doi-access=free}} Animal and early human studies were underway as of September 2016.{{Cite journal|last1=Barzon|first1=Luisa|last2=Trevisan|first2=Marta|last3=Sinigaglia|first3=Alessandro|last4=Lavezzo|first4=Enrico|last5=Palù|first5=Giorgio|date=2016-09-01|title=Zika virus: from pathogenesis to disease control |journal=FEMS Microbiology Letters|language=en|volume=363|issue=18|pages=fnw202|doi=10.1093/femsle/fnw202|issn=1574-6968|pmid=27549304|doi-access=free}}{{Cite journal|last=Morrison|first=Chris|date=2016-08-01|title=DNA vaccines against Zika virus speed into clinical trials|journal=Nature Reviews Drug Discovery|language=en|volume=15|issue=8|pages=521–522|doi=10.1038/nrd.2016.159|issn=1474-1776|pmid=27469223|df=dmy-all|doi-access=free}} As of December 2019, there were several vaccine candidates in various stages of development.{{cite journal|last1=Poland|first1=Gregory A.|last2=Ovsyannikova|first2=Inna G.|last3=Kennedy|first3=Richard B.|title=Zika Vaccine Development: Current Status|journal=Mayo Clinic Proceedings|volume=94|issue=12|year=2019|pages=2572–2586|issn=0025-6196|doi=10.1016/j.mayocp.2019.05.016|pmid=31806107|doi-access=free|pmc=7094556}}

Disease control in the affected countries currently centers around mosquito control. Several approaches are available for the management of Aedes aegypti mosquito populations, including the destruction of larval breeding sites (the aquatic pools in which eggs are laid and larvae hatch before mosquito development into flying adults); and, insecticides targeting either the larval stages, adult mosquitoes or both. Additionally, a whole host of novel technologies are under current development for mosquito control and the World Health Organization has recently lent its support for the accelerated development of modern methods for mosquito control such as the use of Wolbachia bacteria to render mosquitoes resistant to the virus, and, the release of sterilized male mosquitoes that breed with wild female mosquitoes to give rise to non-viable offspring (offspring that do not survive to the biting, adult stage).{{cite journal|last1=Yakob|first1=Laith|last2=Walker|first2=Thomas|title=Zika virus outbreak in the Americas: the need for novel mosquito control methods|journal=The Lancet Global Health|date=March 2016|volume=4|issue=3|pages=e148–e149|doi=10.1016/S2214-109X(16)00048-6|pmid=26848089|doi-access=free}}

Oxitec's genetically modified OX513A mosquito was approved by Brazil's National Biosecurity Technical Commission (CTNBio) in April 2014Tracy Thompson: [http://www.oxitec.com/press-release-high-tech-solution-for-controlling-the-dengue-mosquito-is-approved-by-ctnbio/ Oxitec's solution for controlling the dengue mosquito is approved by CTNBio.] {{webarchive|url=https://web.archive.org/web/20160301083503/http://www.oxitec.com/press-release-high-tech-solution-for-controlling-the-dengue-mosquito-is-approved-by-ctnbio/ |date=1 March 2016 }} Oxitech, 11 April 2014 and it was being used to try to combat mosquitoes carrying the Zika virus in the town of Piracicaba, São Paulo in 2016.{{cite news|last1=Pollack|first1=Andrew|title=New Weapon to Fight Zika: The Mosquito|url=https://www.nytimes.com/2016/01/31/business/new-weapon-to-fight-zika-the-mosquito.html?_r=0|access-date=16 March 2016|work=New York Times|date=30 January 2016|url-status=live|archive-url=https://web.archive.org/web/20160203154347/http://www.nytimes.com/2016/01/31/business/new-weapon-to-fight-zika-the-mosquito.html?_r=0|archive-date=3 February 2016|df=dmy-all}}

In the 1940s and 1950s, the Aedes aegypti mosquito was eradicated on some Caribbean islands and in at least eighteen Latin American countries. Decreasing political will and presumably available money, mosquito resistance to insecticide, and a pace of urbanization that exceeded eradication efforts led to this mosquito's comeback.{{cite news|last1=Dennis|first1=Brady|title=How a tiny mosquito became one of the world's 'most efficient killers'|url=https://www.washingtonpost.com/national/health-science/mosquito-spreading-zika-has-long-been-one-of-the-worlds-most-efficient-killers/2016/02/19/b4ace548-d5a9-11e5-9823-02b905009f99_story.html|access-date=20 January 2018|newspaper=Washington Post|date=19 February 2016}}

Due to the difficulty of diagnosing the Zika virus early, as many cases are asymptomatic, machine learning techniques have emerged as a potentially promising solution for improving the prediction and surveillance of virus outbreaks. This approach would track the virus’s spread by analyzing genetic data, media, and climate history to identify environmental changes that allow Aedes mosquitoes to thrive. Such insights could aid in early warning and preventative efforts. However, challenges remain in integrating these methods into healthcare systems and ensuring the data quality used for accurate predictions.El-Sayed, E., Eid, M., & Abualigah, L. (2024). Machine Learning in Public Health Forecasting and Monitoring the Zika Virus. Metaheuristic Optimization Review. https://doi.org/10.54216/mor.010201.

There is currently no specific treatment for Zika virus infection. Care is supportive with the treatment of pain, fever, and itching. Some authorities have recommended against using aspirin and other NSAIDs as these have been associated with hemorrhagic syndrome when used for other flaviviruses. Additionally, aspirin use is generally avoided in children when possible due to the risk of Reye syndrome.{{cite journal | url=http://pediatrics.aappublications.org/cgi/pmidlookup?view=long&pmid=7079050 | title=Aspirin and Reye Syndrome | date=June 1982 | access-date=11 March 2016 | last1=Fulginiti | first1=Vincent A. | last2=Brunell | first2=Philip A. | last3=Cherry | first3=James D. | last4=Ector | first4=Walton L | last5=Gershon | first5=Anne A. | last6=Gotoff | first6=Samuel P. | last7=Hughes | first7=Walter T. Jr.| last8=Mortimer | first8=Edward A Jr. | last9=Peter | first9=Georges | journal=Pediatrics | volume=69 | issue=6 | pages=810–812 | doi=10.1542/peds.69.6.810 | issn=1098-4275 | pmid=7079050 | s2cid=57918899 | display-authors=3}}

Zika virus was poorly studied until the major outbreak in 2015, and no specific antiviral treatments are available as yet. Advice to pregnant women is to avoid any risk of infection so far as possible, as once infected there is little that can be done beyond supportive treatment.{{cite journal | first1=Emily E. | display-authors=3 | first2=J. Erin | first4=Marc | last1=Petersen | title=Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016 | last2=Staples | last3=Meaney-Delman | first3=Dana | last4=Fischer | last5=Ellington | first5=Sascha R. | last6=Callaghan | first6=William M. | last7=Jamieson | first7=Denise J. | journal=Morbidity and Mortality Weekly Report | year=2016 | volume=65 | issue=2 | pages=30–33 | issn=0149-2195 | doi=10.15585/mmwr.mm6502e1 | pmid=26796813| doi-access=free }}

Most of the time, Zika fever resolves on its own in two to seven days, but rarely, some people develop Guillain–Barré syndrome.CDC [https://www.cdc.gov/zika/healtheffects/index.html Zika Virus: Health Effects & Risks] {{webarchive|url=https://web.archive.org/web/20160820203326/http://www.cdc.gov/zika/healtheffects/index.html |date=20 August 2016 }} Page last reviewed: August 9, 2016; Page last updated: August 9, 2016 The fetus of a pregnant woman who has Zika fever may die or be born with congenital central nervous system malformations, like microcephaly.

Some individuals have reported experiencing symptoms similar to those they had during their initial Zika virus infection, such as arthralgia, muscle aches, and fatigue, months after recovery. Although these symptoms are not typical, they can persist for months, though they tend to be less severe than during the acute phase of infection. This underscores the importance of ongoing research to understand better the long-term health effects of contracting the Zika virus.

File:CDC Zika active transmission map Sept 2016.jpg

In April 1947, as part of studies sponsored by the Rockefeller Foundation into yellow fever, 6 caged rhesus monkeys were placed in the canopy of the Zika Forest of Uganda.{{Cite journal|last1=Musso|first1=Didier|last2=Gubler|first2=Duane J.|date=2016-07-01|title=Zika Virus|journal=Clinical Microbiology Reviews|language=en|volume=29|issue=3|pages=487–524|doi=10.1128/CMR.00072-15|issn=0893-8512|pmc=4861986|pmid=27029595|df=dmy-all}} On April 18 one of the monkeys (no. 776) developed a fever and blood samples revealed the first known case of Zika fever. Population surveys at the time in Uganda found 6.1% of individuals to be seropositive for Zika.{{Cite journal |title = Zika virus: a previously slow pandemic spreads rapidly through the Americas |journal = Journal of General Virology |volume = 97 |issue = 2 |pages = 269–273 |date = 18 December 2015 |doi = 10.1099/jgv.0.000381 |first1 = Derek |last1 = Gatherer |first2 = Alain |last2 = Kohl |pmid=26684466|url = http://eprints.gla.ac.uk/113711/1/113711.pdf |doi-access = free }} The first human cases were reported in Nigeria in 1954.{{cite journal | first1=F.N. | last1=MacNamara | url=http://trstmh.oxfordjournals.org/content/48/2/139 | title=Zika virus: A report on three cases of human infection during an epidemic of jaundice in Nigeria | journal=Transactions of the Royal Society of Tropical Medicine and Hygiene | year=1954 | volume=48 | issue=2 | pages=139–145 | issn=0035-9203 | doi=10.1016/0035-9203(54)90006-1 | pmid=13157159 | url-status=live | archive-url=https://web.archive.org/web/20160401045454/http://trstmh.oxfordjournals.org/content/48/2/139 | archive-date=1 April 2016 | df=dmy-all }} A few outbreaks have been reported in tropical Africa and some areas in Southeast Asia.{{cite journal | first1=D.I.H. | last1=Simpson | url=http://trstmh.oxfordjournals.org/content/58/4/335.abstract | title=Zika virus infection in man | journal=Transactions of the Royal Society of Tropical Medicine and Hygiene | year=1964 | volume=58 | issue=4 | pages=339–348 | issn=0035-9203 | doi=10.1016/0035-9203(64)90201-9 | url-status=live | archive-url=https://web.archive.org/web/20160206035738/http://trstmh.oxfordjournals.org/content/58/4/335.abstract | archive-date=6 February 2016 | df=dmy-all | pmid=14175744 }} Until recently there were no documented cases of Zika virus in the Indian subcontinent, however, the first cases were reported in 2017 from Gujarat state and Tamil Nadu,{{Cite journal|last1=Sapkal|first1=Gajanan N.|last2=Yadav|first2=Pragya D.|last3=Vegad|first3=Mahendra M.|last4=Viswanathan|first4=Rajlakshmi|last5=Gupta|first5=Nivedita|last6=Mourya|first6=Devendra T.|date=2018-03-01|title=First laboratory confirmation on the existence of Zika virus disease in India|url=https://www.journalofinfection.com/article/S0163-4453(17)30312-2/abstract|journal=Journal of Infection|language=English|volume=76|issue=3|pages=314–317|doi=10.1016/j.jinf.2017.09.020|issn=0163-4453|pmid=28988896}} more cases were reported in Rajasthan state involving an outbreak of 153 reported cases{{Cite journal|last1=Malhotra|first1=Bharti|last2=Gupta|first2=Veenu|last3=Sharma|first3=Pratibha|last4=Singh|first4=Ruchi|last5=Sharma|first5=Himanshu|last6=Vyas|first6=Madhavi|last7=Mathur|first7=Ravi P.|last8=Mathur|first8=Virender K.|last9=Meena|first9=Deepa|last10=Malhotra|first10=Hemant|last11=Yadav|first11=Pragya D.|date=2020-12-01|title=Clinico-epidemiological and genomic profile of first Zika Virus outbreak in India at Jaipur city of Rajasthan state|journal=Journal of Infection and Public Health|language=en|volume=13|issue=12|pages=1920–1926|doi=10.1016/j.jiph.2020.10.006|pmid=33172818|s2cid=226303046|issn=1876-0341|doi-access=free}} and in a pregnant women living in Kerala state.{{Cite web|title=Zika Virus Disease – India|url=https://www.who.int/emergencies/disease-outbreak-news/item/zika-virus-disease-india|access-date=2021-11-19|website=www.who.int|language=en}} A 1954 study assessing blood samples from several people from different states found antibodies to Zika in healthy people in India which could indicate past exposure, though it could also be due to cross-reaction with other flaviviruses.{{cite journal | title=Neutralizing antibodies against certain viruses in the sera of residents of India | date=1 April 1954 | last1=Smithburn | first1=K. C. | last2=Kerr | first2=J. A. | last3=Gatne | first3=P. B. | journal=Journal of Immunology | volume=72 | issue=4 | pages=248–257 | doi=10.4049/jimmunol.72.4.248 | pmid=13163397| doi-access=free }}

By using phylogenetic analysis of Asian strains, it was estimated that Zika virus had moved to Southeast Asia by 1945. In 1977–1978, Zika virus infection was described as a cause of fever in Indonesia.{{cite journal | url=http://trstmh.oxfordjournals.org/content/75/3/389 | title=Zika virus, a cause of fever in Central Java, Indonesia | date=1 January 1981 | last1=Olson | first1=J. G. | last2=Ksiazek | first2=T. G. | journal=Transactions of the Royal Society of Tropical Medicine and Hygiene | volume=75 | issue=3 | pages=389–393 | doi=10.1016/0035-9203(81)90100-0 | pmid=6275577 | url-status=live | archive-url=https://web.archive.org/web/20160206035743/http://trstmh.oxfordjournals.org/content/75/3/389 | archive-date=6 February 2016 | df=dmy-all }} Before 2007, there were only 13 reported natural infections with Zika virus, all with a mild, self-limited febrile illness.{{Cite journal|last1=Baden|first1=Lindsey R.|last2=Petersen|first2=Lyle R.|last3=Jamieson|first3=Denise J.|last4=Powers|first4=Ann M.|last5=Honein|first5=Margaret A.|date=30 March 2016|title=Zika Virus |journal=New England Journal of Medicine|language=EN|volume=374|issue=16|pages=1552–1563|doi=10.1056/nejmra1602113|pmid=27028561 |doi-access=free}} As of July 2019, evidence of local transmission from mosquitoes to humans has been reported in a total of 87 countries from four of six WHO Regions; African, Americas, South-East Asia and Western Pacific.{{Cite web|last=WHO|date=2019|title=Zika Epidemiology Update|url=https://cdn.who.int/media/docs/default-source/documents/emergencies/zika/zika-epidemiology-update-july-2019.pdf?sfvrsn=14a1b3a7_2|access-date=November 19, 2021}}

Since the previous epidemiological update in 2019, Kenya and India have been added to the list of countries with confirmed local Zika virus transmission. World Health Organization. (2022, February). Countries and territories with current or previous Zika virus transmission. World Health Organization. https://cdn.who.int/media/docs/default-source/documents/emergencies/zika/map-of-countries_with_zika_transmission_feb2022.pdf?sfvrsn=802a352a_5.

{{Main|2007 Yap Islands Zika virus outbreak}}The first major outbreak, with 185 confirmed cases, was reported in 2007 in the Yap Islands of the Federated States of Micronesia.{{cite journal | first1=M.R. | first10=C. | first11=L. | first12=A. | first13=M. | first14=A.J. | first15=J. | first16=O. | first17=A. | first18=B.J. | first19=M. | first20=E.B. | last1=Duffy | last10=Dubray | last11=Guillaumot | last12=Griggs | last13=Bel | last14=Lambert | last15=Laven | last16=Kosoy | last17=Panella | last18=Biggerstaff | last19=Fischer | title=Zika Virus Outbreak on Yap Island, Federated States of Micronesia | display-authors=3 | last2=Chen | first2=T.H. | first3=W.T. | first5=J.L. | last20=Hayes | last3=Hancock | last4=Powers | first4=A.M. | last5=Kool | last6=Lanciotti | first6=R.S. | last7=Pretrick | first7=M. | last8=Marfel | first8=M. | last9=Holzbauer | first9=S. | journal=New England Journal of Medicine | year=2009 | volume=360 | issue=24 | pages=2536–43 | doi=10.1056/NEJMoa0805715 | pmid=19516034 | doi-access=free }} A total of 108 cases were confirmed by PCR or serology and 72 additional cases were suspected. The most common symptoms were rash, fever, arthralgia, and conjunctivitis, and no deaths were reported. The mosquito Aedes hensilli, which was the predominant species identified in Yap during the outbreak, was probably the main transmission vector. While the way of introduction of the virus on Yap Island remains uncertain, it is likely to have happened through the introduction of infected mosquitoes or a human infected with a strain related to those in Southeast Asia. This was also the first time Zika fever had been reported outside Africa and Asia. Before the Yap Island outbreak, only 14 human cases had ever been reported.{{cite journal | first1=Oumar | last1=Faye | title=Molecular Evolution of Zika Virus during Its Emergence in the 20th Century | date=9 January 2014 | last2=Freire | first2=Caio C. M. | last3=Iamarino | first3=Atila | last4=Faye | first4=Ousmane | last5=de Oliveira | first5=Juliana Velasco C. | last6=Diallo | first6=Mawlouth | last7=Zanotto | first7=Paolo M. A. | last8=Sall | first8=Amadou Alpha | last9=Bird | first9=Brian | journal=PLOS Neglected Tropical Diseases | volume=8 | issue=1 | pages=e2636 | doi=10.1371/journal.pntd.0002636 | pmc=3888466 | pmid=24421913 | display-authors=3 | doi-access=free }}

{{Main|2013–2014 Zika virus outbreaks in Oceania}}

In 2013–2014, several outbreaks of Zika were reported in French Polynesia, New Caledonia, Easter Island and the Cook Islands. The source of the virus was thought to be an independent introduction of the virus from Southeast Asia, unrelated to the Yap Islands outbreak.

{{Further|2015–16 Zika virus epidemic}}

File:CDC map of active Zika virus transmission.jpg

Genetic analyses of Zika virus strains suggest that Zika first entered the Americas between May and December 2013.{{Cite journal|last1=Faria|first1=Nuno Rodrigues|last2=Azevedo|first2=Raimunda do Socorro da Silva|last3=Kraemer|first3=Moritz U.G.|last4=Souza|first4=Renato|last5=Cunha|first5=Mariana Sequetin|last6=Hill|first6=Sarah C.|last7=Thézé|first7=Julien|last8=Bonsall|first8=Michael B.|last9=Bowden|first9=Thomas A.|date=2016-04-15|title=Zika virus in the Americas: Early epidemiological and genetic findings|journal=Science|volume=352|issue=6283|pages=345–349|doi=10.1126/science.aaf5036|issn=0036-8075|pmc=4918795|pmid=27013429|bibcode=2016Sci...352..345F}} It was first detected in the Western Hemisphere in February 2014, and rapidly spread throughout South and Central America, reaching Mexico in November 2015.{{Cite journal|title = Zika virus spreads across Americas as concerns mount over birth defects|url = http://www.bmj.com/content/351/bmj.h6983|journal = BMJ|date = 23 December 2015|pmid = 26698165|pages = h6983|volume = 351|doi = 10.1136/bmj.h6983|first = Owen|last = Dyer|url-status = live|archive-url = https://web.archive.org/web/20151230150617/http://www.bmj.com/content/351/bmj.h6983|archive-date = 30 December 2015|df = dmy-all|doi-access = free}} In 2016 it established local transmission in Florida and Texas.{{Cite news|url=https://www.nytimes.com/2016/11/28/health/zika-case-texas.html|title=Local Transmission of Zika Virus Is Reported in Texas|last1=McNeil|first1=Donald G. Jr.|date=2016-11-28|last2=Fernandez|first2=Manny|newspaper=The New York Times|issn=0362-4331|access-date=2016-12-09|url-status=live|archive-url=https://web.archive.org/web/20161211070723/http://www.nytimes.com/2016/11/28/health/zika-case-texas.html|archive-date=11 December 2016|df=dmy-all}}{{Cite journal|last1=Likos|first1=Anna|last2=Griffin|first2=Isabel|last3=Bingham|first3=Andrea M.|last4=Stanek|first4=Danielle|last5=Fischer|first5=Marc|last6=White|first6=Stephen|last7=Hamilton|first7=Janet|last8=Eisenstein|first8=Leah|last9=Atrubin|first9=David|date=2016-01-01|title=Local Mosquito-Borne Transmission of Zika Virus — Miami-Dade and Broward Counties, Florida, June–August 2016|journal=MMWR. Morbidity and Mortality Weekly Report|volume=65|issue=38|pages=1032–1038|doi=10.15585/mmwr.mm6538e1|pmid=27684886|issn=0149-2195|df=dmy-all|doi-access=free}} The first death in the United States due to Zika occurred in February 2016.{{Cite news|url=https://www.washingtonpost.com/news/to-your-health/wp/2016/04/29/first-zika-virus-related-death-reported-in-u-s-in-puerto-rico/|title=First Zika virus-related death reported in U.S. in Puerto Rico|newspaper=Washington Post|access-date=29 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160601183923/https://www.washingtonpost.com/news/to-your-health/wp/2016/04/29/first-zika-virus-related-death-reported-in-u-s-in-puerto-rico/|archive-date=1 June 2016|df=dmy-all}}

In May 2015, Brazil officially reported its first 16 cases of the illness.{{cite news |url=http://g1.globo.com/bemestar/noticia/2015/05/ministerio-da-saude-confirma-16-casos-de-zika-virus-no-brasil.html |title=Ministério da Saúde confirma 8 casos de zika vírus no RN e 8 na BA |language=pt |trans-title=Ministry of Health confirms 8 cases of zika virus in infants and 8 in BA |work=Ben Estar |date=14 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20150518005419/http://g1.globo.com/bemestar/noticia/2015/05/ministerio-da-saude-confirma-16-casos-de-zika-virus-no-brasil.html |archive-date=18 May 2015 |df=dmy-all }} Although, a case of illness was reported in March 2015 in a returning traveller.{{cite journal |last1=Zammarchi |first1=L |last2=Tappe |first2=D |last3=Fortuna |first3=C |last4=Remoli |first4=M |last5=Günther |first5=S |last6=Venturi |first6=G |last7=Bartoloni |first7=A |last8=Schmidt-Chanasit |first8=J |title=Zika virus infection in a traveller returning to Europe from Brazil, March 2015 |journal=Eurosurveillance |date=11 June 2015 |volume=20 |issue=23 |pages=21153 |doi=10.2807/1560-7917.ES2015.20.23.21153|pmid=26084316 |url=https://flore.unifi.it/bitstream/2158/1015991/2/8.%20Pubmed%20Zammarchi%20Zika%20virus%20infection%20in%20a%20traveller%20returning%20to%20Europe%202015.pdf |doi-access=free }} According to the Brazilian Health Ministry, as of November 2015 there was no official count of the number of people infected with the virus in Brazil, since the disease is not subject to compulsory notification. Even so, cases were reported in 14 states of the country. Mosquito-borne Zika virus is suspected to be the cause of 2,400 possible cases of microcephaly and 29 infant deaths in Brazil in 2015 (of the 2400 or so notified cases in 2015, 2165 were under investigation in December 2015, 134 were confirmed and 102 were ruled out for microcephaly).

The Brazilian Health Ministry has reported at least 2,400 suspected cases of microcephaly in the country in 2015 as of 12 December, and 29 fatalities.{{cite web | url=http://portalsaude.saude.gov.br/images/pdf/2015/dezembro/15/COES-Microcefalias---Informe-Epidemiol--gico---SE-49---15dez2015---10h.pdf | title=Monitoramento dos casos de microcefalias no Brasil | publisher=Centro de Operações de Emergências em Saúde Pública sobre Microcefalias | date=12 December 2015 | access-date=24 December 2015 | language=pt | trans-title=Monitoring cases of microcephaly in Brazil}}{{cite news | url=http://www.bbc.com/portuguese/noticias/2015/11/151127_confirma_zika_microcefalia_mdb | title=Governo confirma relação entre zika vírus e epidemia de microcefalia | trans-title=Government confirms relationship between zika virus and epidemic microcephaly | work=BBC Brasil | date=28 November 2015 | access-date=10 March 2016 | language=pt | url-status=live | archive-url=https://web.archive.org/web/20160131072310/http://www.bbc.com/portuguese/noticias/2015/11/151127_confirma_zika_microcefalia_mdb | archive-date=31 January 2016 | df=dmy-all }}{{cite news | url=https://www.reuters.com/article/brazil-health-zica-idUSL1N13N0NH20151128#x4sFsU0kCzW0J1Uk.97 | title=Brazil confirms zica virus link to fetal brain-damage outbreak | work=Reuters | date=28 November 2015 | access-date=4 February 2016 | last=Blount | first=Jeb | url-status=live | archive-url=https://web.archive.org/web/20160305045848/http://www.reuters.com/article/brazil-health-zica-idUSL1N13N0NH20151128#x4sFsU0kCzW0J1Uk.97 | archive-date=5 March 2016 | df=dmy-all }}{{cite news | url=http://noticias.uol.com.br/saude/ultimas-noticias/redacao/2015/11/30/pais-tem-1248-casos-de-microcefalia-ligacao-com-virus-zika-e-confirmada.htm | title=País registra 1.248 casos de microcefalia e sete mortes; maioria em PE | work=UOL Notícias | date=30 November 2015 | access-date=4 February 2016 | language=pt | trans-title=The country has recorded 1,248 cases of microcephaly and seven deaths; most are in PE | url-status=live | archive-url=https://web.archive.org/web/20160204001420/http://noticias.uol.com.br/saude/ultimas-noticias/redacao/2015/11/30/pais-tem-1248-casos-de-microcefalia-ligacao-com-virus-zika-e-confirmada.htm | archive-date=4 February 2016 | df=dmy-all }} Before the Zika outbreak, only an average of 150 to 200 cases per year were reported in Brazil.{{cite web | access-date=11 February 2016 | url=http://ecdc.europa.eu/en/publications/Publications/zika-virus-americas-association-with-microcephaly-rapid-risk-assessment.pdf | title=Rapid risk assessment: Zika virus epidemic in the Americas: potential association with microcephaly and Guillain–Barré syndrome | publisher=European Centre for Disease Prevention and Control | date=10 December 2015 | url-status=dead | archive-url=https://web.archive.org/web/20160212164036/http://ecdc.europa.eu/en/publications/Publications/zika-virus-americas-association-with-microcephaly-rapid-risk-assessment.pdf | archive-date=12 February 2016 | df=dmy-all }} In the state of Pernambuco the reported rates of microcephaly in 2015 are 77 times higher than in the previous 5 years. A model using data from a Zika outbreak in French Polynesia estimated the risk of microcephaly in children born to mothers who acquired Zika virus in the first trimester to be 1%.{{Cite journal|last1=Cauchemez|first1=Simon|last2=Besnard|first2=Marianne|last3=Bompard|first3=Priscillia|last4=Dub|first4=Timothée|last5=Guillemette-Artur|first5=Prisca|last6=Eyrolle-Guignot|first6=Dominique|last7=Salje|first7=Henrik|last8=Kerkhove|first8=Maria D Van|last9=Abadie|first9=Véronique|title=Association between Zika virus and microcephaly in French Polynesia, 2013–15: a retrospective study |journal=The Lancet|doi=10.1016/s0140-6736(16)00651-6|volume=387|issue=10033|pages=2125–2132|year=2016|pmid=26993883|pmc=4909533}}

On 24 January 2016, the WHO warned that the virus is likely to spread to nearly all countries of the Americas, since its vector, the mosquito Aedes aegypti, is found in all countries in the region, except for Canada and continental Chile.{{cite news | url=https://www.theguardian.com/world/2016/jan/25/zika-virus-likely-spread-throughout-americas-says-who | title=Zika Virus likely to spread throughout the Americas, says WHO | work=The Guardian | date=25 January 2016 | url-status=live | archive-url=https://web.archive.org/web/20160824014625/https://www.theguardian.com/world/2016/jan/25/zika-virus-likely-spread-throughout-americas-says-who | archive-date=24 August 2016 | df=dmy-all }}{{cite web|title=PAHO Statement on Zika Virus Transmission and Prevention|date=24 January 2016|publisher=Pan American Health Organization|url=http://www.paho.org/hq/index.php?option=com_content&view=article&id=11605&Itemid=0&lang=en|url-status=live|archive-url=https://web.archive.org/web/20160126055104/http://www.paho.org/hq/index.php?option=com_content&view=article&id=11605&Itemid=0&lang=en|archive-date=26 January 2016|df=dmy-all}} The mosquito and dengue fever have been detected in Chile's Easter Island, some {{convert|3500|km|abbr=on}} away from its closest point in mainland Chile, since 2002.{{cite journal | title=Detection of flavivirus in mosquitoes (Diptera: Culicidae) from Easter Island-Chile | date=February 2015 | display-authors=3 | last1=Collao | first1=X. | last2=Prado | first2=L. | last3=González | first3=C. | last4=Vásquez | first4=A. | last5=Araki | first5=R. | last6=Henríquez | first6=T. | last7=Peña | first7=C.M. | journal=Revista Chilena de Infectología | volume=32 | issue=1 | pages=113–6 | language=es | doi=10.4067/S0716-10182015000200021 | pmid=25860055 | df=dmy-all | doi-access=free }}

In February 2016, WHO declared the outbreak a Public Health Emergency of International Concern as evidence grew that Zika is a cause of birth defects and neurological problems.{{cite web |url=https://www.who.int/mediacentre/news/statements/2016/emergency-committee-zika-microcephaly/en/ |title=WHO Director-General summarizes the outcome of the Emergency Committee regarding clusters of microcephaly and Guillain–Barré syndrome |publisher=World Health Organization |date=1 February 2016 |access-date=2 February 2016 |url-status=live |archive-url=https://web.archive.org/web/20160202010842/http://www.who.int/mediacentre/news/statements/2016/emergency-committee-zika-microcephaly/en/ |archive-date=2 February 2016 |df=dmy-all }}{{cite web |access-date=1 February 2016 |url=https://www.bbc.com/news/health-35459797 |title=Zika-linked condition: WHO declares global emergency |work=BBC News Online |date=1 February 2016 |author=Roberts, Michelle |url-status=live |archive-url=https://web.archive.org/web/20160201194729/http://www.bbc.com/news/health-35459797 |archive-date=1 February 2016 |df=dmy-all }}{{cite news |access-date=2 February 2016 |url=http://www.cnn.com/2016/02/01/health/zika-virus-public-health-emergency/index.html |title=Zika virus sparks 'public health emergency' |work=CNN |date=2 February 2016 |author=Pearson, Michael |url-status=live |archive-url=https://web.archive.org/web/20160202004724/http://www.cnn.com/2016/02/01/health/zika-virus-public-health-emergency/index.html |archive-date=2 February 2016 |df=dmy-all }} In April 2016, WHO stated there is a scientific consensus, based on preliminary evidence, that Zika is a cause of microcephaly in infants and Guillain–Barré syndrome in adults. Studies of this and prior outbreaks have found Zika infection during pregnancy to be associated with early pregnancy loss and other pregnancy problems.{{cite web |url=https://www.cdc.gov/zika/index.html |title=Zika Fever |publisher=Centers for Disease Control and Prevention |date=1 February 2016 |access-date=1 February 2016 |url-status=live |archive-url=https://web.archive.org/web/20160131102957/http://www.cdc.gov/zika/index.html |archive-date=31 January 2016 |df=dmy-all }}{{cite journal |title=Rapid spread of Zika virus in the Americas raises alarm |journal=Science News |date=22 January 2016 |last=Rosen |first=Meghan |volume=189 |issue=4 |page=16 |url=https://www.sciencenews.org/article/rapid-spread-zika-virus-americas-raises-alarm?mode=magazine&context=191494 |access-date=16 February 2016 |url-status=live |archive-url=https://web.archive.org/web/20160223234450/https://www.sciencenews.org/article/rapid-spread-zika-virus-americas-raises-alarm?mode=magazine&context=191494 |archive-date=23 February 2016 |df=dmy-all }} In the Americas the number of cases peaked during the first half of 2016 and declined through 2017–2018, with a total of 31,587 suspected, probable, and confirmed cases of ZIKV disease were reported in the Region of the Americas. Of these, 3,473 (11%) were laboratory-confirmed. Transmission persists at low levels in some areas and is not uniformly distributed within countries.

In 2016 imported or locally transmitted Zika was reported in all the countries of Asia except Brunei, Hong Kong, Myanmar and Nepal.{{Cite journal|last1=Duong|first1=Veasna|last2=Dussart|first2=Philippe|last3=Buchy|first3=Philippe|title=Zika virus in Asia |journal=International Journal of Infectious Diseases|volume=54|pages=121–128|doi=10.1016/j.ijid.2016.11.420|pmid=27939768|year=2017|doi-access=free}} Serological surveys have indicated that Zika virus is endemic in most areas of Asia, though at a low level. While there was a sharp rise in the number of cases of Zika detected in Singapore after the 2016 Summer Olympics in Brazil, genetic analysis revealed that the strains were more closely related to strains from Thailand than from those causing the epidemic in the Americas.{{Cite journal|last1=de Bernardi Schneider|first1=Adriano|last2=Malone|first2=Robert W.|last3=Guo|first3=Jun-Tao|last4=Homan|first4=Jane|last5=Linchangco|first5=Gregorio|last6=Witter|first6=Zachary L.|last7=Vinesett|first7=Dylan|last8=Damodaran|first8=Lambodhar|last9=Janies|first9=Daniel A.|date=2016-12-01|title=Molecular evolution of Zika virus as it crossed the Pacific to the Americas |journal=Cladistics|language=en|pages=1–20|doi=10.1111/cla.12178|issn=1096-0031|volume=33 |issue=1|pmid=34724757|doi-access=free}}{{Cite journal|last1=Maurer-Stroh|first1=Sebastian|last2=Mak|first2=Tze-Minn|last3=Ng|first3=Yi-Kai|last4=Phuah|first4=Shiau-Pheng|last5=Huber|first5=Roland G|last6=Marzinek|first6=Jan K|last7=Holdbrook|first7=Daniel A|last8=Lee|first8=Raphael TC|last9=Cui|first9=Lin|title=South-east Asian Zika virus strain linked to cluster of cases in Singapore, August 2016|journal=Eurosurveillance|volume=21|issue=38|doi=10.2807/1560-7917.es.2016.21.38.30347|pmid=27684526|pmc=5073200|df=dmy-all|year=2016}}{{Cite journal|last1=Fisher|first1=Dale|last2=Cutter|first2=Jeffery|date=2016-01-01|title=The inevitable colonisation of Singapore by Zika virus |journal=BMC Medicine|volume=14|issue=1|pages=188|doi=10.1186/s12916-016-0737-9|issn=1741-7015|pmc=5116805|pmid=27866470 |doi-access=free }}

It is named after the Zika Forest near Entebbe, Uganda, where the Zika virus was first identified.{{cite journal | title=The emergence of zika virus as a global health security threat: A review and a consensus statement of the INDUSEM Joint Working Group (JWG) | date=11 February 2016 | last1=Sikka | first1=Veronica | last2=Chattu | first2=Vijay Kumar | last3=Popli | first3=Raaj K. | last4=Galwankar | first4=Sagar C. | last5=Kelkar | first5=Dhanashree | last6=Sawicki | first6=Stanley G. | last7=Stawicki | first7=Stanislaw P. | last8=Papadimos | first8=Thomas J. | journal=Journal of Global Infectious Diseases | volume=8 | issue=1 | pages=3–15 | issn=0974-8245 | doi=10.4103/0974-777X.176140 | pmc=4785754 | pmid=27013839 | doi-access=free }}

Zika virus was first identified in the late 1940s in Kampala, Uganda, Africa but was first confirmed in Brazil. Since it was first identified, Zika has been found in more than 27 countries and territories.{{cite journal|last1=Basarab|first1=Marina|last2=Bowman|first2=Conor|last3=Aarons|first3=Emma J|last4=Cropley|first4=Ian|title=Zika virus|journal=BMJ|volume=352|date=26 February 2016|pages=i1049|doi=10.1136/bmj.i1049|pmid=26921241|doi-access=free}} Following the initial Zika outbreak in Northeastern Brazil in May 2015, physicians observed a tremendous surge of reports of infants born with microcephaly, with 20 times the number of expected cases.{{cite news |last1=Romero |url=https://www.nytimes.com/2015/12/31/world/americas/alarm-spreads-in-brazil-over-a-virus-and-a-surge-in-malformed-infants.html?_r=0 |title=Alarm Spreads in Brazil Over a Virus and a Surge in Malformed Infants |work=The New York Times |date=30 December 2015 |access-date=24 January 2016 |first1=Simon |url-status=live |archive-url=https://web.archive.org/web/20160103094246/http://www.nytimes.com/2015/12/31/world/americas/alarm-spreads-in-brazil-over-a-virus-and-a-surge-in-malformed-infants.html?_r=0 |archive-date=3 January 2016 |df=dmy-all }}{{cite news |first1=Simon |last1=Romero |url=https://www.nytimes.com/2016/01/22/world/americas/zika-virus-may-be-linked-to-surge-in-rare-syndrome-in-brazil.html |title=Zika Virus May be Linked to Surge in Rare Syndrome in Brazil |work=The New York Times |date=21 January 2016 |access-date=13 March 2016 |last2=McNeil |first2=Donald G. Jr. |url-status=live |archive-url=https://web.archive.org/web/20160221183051/http://www.nytimes.com/2016/01/22/world/americas/zika-virus-may-be-linked-to-surge-in-rare-syndrome-in-brazil.html |archive-date=21 February 2016 |df=dmy-all }} Many of these cases have since been confirmed, leading WHO officials to project that approximately 2,500 infants will be found to have been born in Brazil with Zika-related microcephaly.{{cite news | url=https://www.washingtonpost.com/news/to-your-health/wp/2016/03/22/zika-in-brazil-more-than-2500-births-with-microcephaly-who-predicts/ | title=Zika: More than 2,500 babies born with microcephaly in Brazil, WHO predicts | newspaper=Washington Post | date=22 March 2016 | access-date=23 March 2016 | author=Sun, Lena H. | url-status=live | archive-url=https://web.archive.org/web/20160322181334/https://www.washingtonpost.com/news/to-your-health/wp/2016/03/22/zika-in-brazil-more-than-2500-births-with-microcephaly-who-predicts/ | archive-date=22 March 2016 | df=dmy-all }}{{cite news | url=https://www.nytimes.com/2016/03/23/health/zika-colombia-microcephaly-world-health-organization.html | title=Birth Defects Tied to Zika in Panama | work=New York Times | date=22 March 2016 | access-date=23 March 2016 | author=Tavernise, Sabrina | url-status=live | archive-url=https://web.archive.org/web/20160323021008/http://www.nytimes.com/2016/03/23/health/zika-colombia-microcephaly-world-health-organization.html | archive-date=23 March 2016 | df=dmy-all }}

Proving that Zika causes these effects was difficult and complex for several reasons.{{cite news|last1=Fine Maron|first1=Dina|title=Zika–Microcephaly Link: Public health officials are not yet ready to say the connection is causal|url=http://www.scientificamerican.com/article/what-would-it-take-to-prove-the-zika-microcephaly-link1/|access-date=13 March 2016|work=Scientific American|date=28 January 2016|url-status=live|archive-url=https://web.archive.org/web/20160320050439/http://www.scientificamerican.com/article/what-would-it-take-to-prove-the-zika-microcephaly-link1/|archive-date=20 March 2016|df=dmy-all}}{{cite news|last1=McNeil |first1=Donald G. Jr.|title=Proof of Zika's Role in Birth Defects Still Months Away, W.H.O. Says|url=https://www.nytimes.com/2016/02/20/health/zika-virus-microcephaly-birth-defects-proof-who.html|access-date=13 March 2016|work=New York Times|date=19 February 2016|url-status=live|archive-url=https://web.archive.org/web/20160312162917/http://www.nytimes.com/2016/02/20/health/zika-virus-microcephaly-birth-defects-proof-who.html|archive-date=12 March 2016|df=dmy-all}} For example, the effects on an infant might not be seen until months after the mother's initial infection, long after the time when Zika is easily detected in the body. In addition, research was needed to determine the mechanism by which Zika produced these effects.{{cite web|title=WHO statement on the 2nd meeting of IHR Emergency Committee on Zika virus and observed increase in neurological disorders and neonatal malformations|url=https://www.who.int/mediacentre/news/statements/2016/2nd-emergency-committee-zika/en/|website=World Health Organization|access-date=13 March 2016|date=8 March 2016|url-status=live|archive-url=https://web.archive.org/web/20160312083659/http://who.int/mediacentre/news/statements/2016/2nd-emergency-committee-zika/en/|archive-date=12 March 2016|df=dmy-all}}

Since the initial outbreak, studies that use several different methods found evidence of a link, leading public health officials to conclude that it appears increasingly likely the virus is linked to microcephaly and miscarriage.{{cite news|last1=McNeil|first1=Donald G. Jr. |last2=Saint Louis|first2=Catherine|title=Two Studies Strengthen Links Between the Zika Virus and Serious Birth Defects|url=https://www.nytimes.com/2016/03/05/health/zika-virus-microcephaly-fetus-birth-defects.html|access-date=13 March 2016|work=New York Times|date=4 March 2016|url-status=live|archive-url=https://web.archive.org/web/20160312162856/http://www.nytimes.com/2016/03/05/health/zika-virus-microcephaly-fetus-birth-defects.html|archive-date=12 March 2016|df=dmy-all}} On 1 February 2016, the World Health Organization declared recently reported clusters of microcephaly and other neurological disorders a Public Health Emergency of International Concern (PHEIC).{{cite journal |display-authors=3 |first1=David L |first10=Pedro F C |first11=Silvia |first12=K U |title=Zika virus and microcephaly: why is this situation a PHEIC? |date=20 February 2016 |last2=Hodgson |first2=Abraham |last3=Sall |first3=Amadou Alpha |last4=Freedman |first4=David O |last5=Staples |first5=J Erin |last6=Althabe |first6=Fernando |last7=Baruah |first7=Kalpana |last8=Mahmud |first8=Ghazala |last1=Heymann |last10=Vasconcelos |last11=Bino |last12=Meno |last9=Kandun |first9=Nyoman |journal=The Lancet |volume=387 |issue=10020 |pages=719–721 |doi=10.1016/S0140-6736(16)00320-2 |pmid=26876373|pmc=7134564 |doi-access=free }} On 8 March 2016, the WHO Committee reconfirmed that the association between Zika and neurological disorders is of global concern.

The Zika virus was first linked with newborn microcephaly during the Brazil Zika virus outbreak. In 2015, there were 2,782 suspected cases of microcephaly compared with 147 in 2014 and 167 in 2013. Confirmation of many of the recent cases is pending,{{cite news |url=https://www.washingtonpost.com/news/worldviews/wp/2016/01/29/brazil-may-have-fewer-zika-related-microcephaly-cases-than-previously-reported/ |title=Brazil may have fewer Zika-related microcephaly cases than previously reported |newspaper=The Washington Post |url-status=live |archive-url=https://web.archive.org/web/20160316105654/https://www.washingtonpost.com/news/worldviews/wp/2016/01/29/brazil-may-have-fewer-zika-related-microcephaly-cases-than-previously-reported/ |archive-date=16 March 2016 |df=dmy-all }} and it is difficult to estimate how many cases went unreported before the recent awareness of the risk of virus infections.{{cite web |url=http://www.the-scientist.com/?articles.view/articleNo/45297/title/Brazil-s-Pre-Zika-Microcephaly-Cases/ |title=Brazil's Pre-Zika Microcephaly Cases |url-status=live |archive-url=https://web.archive.org/web/20160314013616/http://www.the-scientist.com/?articles.view%2FarticleNo%2F45297%2Ftitle%2FBrazil-s-Pre-Zika-Microcephaly-Cases%2F |archive-date=14 March 2016 |df=dmy-all }}

File:Videoconferência na Sala Nacional de Coordenação e Controle para Enfrentamento da dengue, chikungunya e Zika vírus, em Brasília. (24576476372).jpg in a videoconference about the Zika virus at the National Center for Disaster Management.]]

In November 2015, the Zika virus was isolated in a newborn baby from the northeastern state of Ceará, Brazil, with microcephaly and other congenital disorders. The Lancet medical journal reported in January 2016 that the Brazilian Ministry of Health had confirmed 134 cases of microcephaly "believed to be associated with Zika virus infection" with an additional 2,165 cases in 549 counties in 20 states remaining under investigation.{{cite journal |first1=Marcia |last1=Triunfol |title=A new mosquito-borne threat to pregnant women in Brazil |journal=The Lancet Infectious Diseases |year=2016 |volume=16 |issue=2 |pages=156–157 |issn=1473-3099 |doi=10.1016/S1473-3099(15)00548-4 |pmid=26723756|s2cid=29688849 }} An analysis of 574 cases of microcephaly in Brazil during 2015 and the first week of 2016, reported in March 2016, found an association with maternal illness involving rash and fever during the first trimester of pregnancy. During this period, 12 Brazilian states reported increases of at least 3 standard deviations (SDs) in cases of microcephaly compared with 2000–14, with the northeastern states of Bahia, Paraíba and Pernambuco reporting increases of more than 20 SDs.{{cite journal |first1=Wanderson |last1=Kleber de Oliveira |title=Increase in Reported Prevalence of Microcephaly in Infants Born to Women Living in Areas with Confirmed Zika Virus Transmission During the First Trimester of Pregnancy – Brazil, 2015 |last2=Cortez-Escalante |first2=Juan |last3=De Oliveira |first3=Wanessa Tenório Gonçalves Holanda |last4=do Carmo |first4=Greice Madeleine Ikeda |last5=Henriques |first5=Cláudio Maierovitch Pessanha |last6=Coelho |first6=Giovanini Evelim |last7=Araújo de França |first7=Giovanny Vinícius |journal=MMWR. Morbidity and Mortality Weekly Report |year=2016 |volume=65 |issue=9 |pages=242–247 |issn=0149-2195 |doi=10.15585/mmwr.mm6509e2 |pmid=26963593 |display-authors=3 |df=dmy-all |doi-access=free }}

In January 2016, a baby in Oahu, Hawaii, was born with microcephaly, the first case in the United States of brain damage linked to the virus. The baby and mother tested positive for a past Zika virus infection. The mother, who had probably acquired the virus while traveling in Brazil in May 2015 during the early stages of her pregnancy, had reported her bout of Zika. She recovered before relocating to Hawaii. Her pregnancy had progressed normally, and the baby's condition was not known until birth.{{cite news |first1=Donald G. |last1=McNeil Jr. |url=https://www.nytimes.com/2016/01/17/health/hawaii-reports-baby-born-with-brain-damage-linked-to-zika-virus.html?_r=0 |title=Hawaii Baby With Brain Damage Is First U.S. Case Tied to Zika Virus |work=The New York Times |date=16 January 2016 |url-status=live |archive-url=https://web.archive.org/web/20170223073750/https://www.nytimes.com/2016/01/17/health/hawaii-reports-baby-born-with-brain-damage-linked-to-zika-virus.html?_r=0 |archive-date=23 February 2017 |df=dmy-all }}

In February 2016, ocular disorders in newborns have been linked to Zika virus infection.{{cite journal |first1=Camila V |last1=Ventura |title=Zika virus in Brazil and macular atrophy in a child with microcephaly |date=January 2016 |last2=Maia |first2=Mauricio |last3=Bravo-Filho |first3=Vasco |last4=Góis |first4=Adriana L |last5=Belfort |first5=Rubens |journal=The Lancet |volume=387 |issue=10015 |page=228 |doi=10.1016/S0140-6736(16)00006-4 |pmid=26775125 |display-authors=1|doi-access=free }} In one study in Pernambuco state in Brazil, about 40 percent of babies with Zika-related microcephaly also had scarring of the retina with spots, or pigment alteration.{{cite web |url=http://www.promedmail.org/direct.php?id=3974426 |title=Zika virus: Americas, Asia |publisher=International Society for Infectious Diseases |website=ProMED-mail |date=28 January 2016 |access-date=8 February 2016 |url-status=live |archive-url=https://web.archive.org/web/20160202133759/http://www.promedmail.org/direct.php?id=3974426 |archive-date=2 February 2016 |df=dmy-all }} On 20 February 2016, Brazilian scientists announced that they had successfully sequenced the Zika virus genome and expressed hope that this would help in both developing a vaccine and in determining the nature of any link to birth defects.{{cite news |last=Martinez |first=Michael |url=http://www.cnn.com/2016/02/20/health/zika-virus-genome-brazil/index.html |title=Zika virus: Brazilian scientists decipher its genome, agency says |work=CNN |date=20 February 2016 |url-status=live |archive-url=https://web.archive.org/web/20160221111329/http://www.cnn.com/2016/02/20/health/zika-virus-genome-brazil/index.html |archive-date=21 February 2016 |df=dmy-all }}

Also in February 2016, rumors that microcephaly is caused by the use of the larvicide pyriproxyfen in drinking water were refuted by scientists.{{cite news |last=Szabo |first=Liz |url=https://www.usatoday.com/story/news/2016/02/16/experts-dismiss-claims-pesticide-not-zika-causes-birth-defects/80451116/ |title=Scientists debunk theory linking pesticide, not Zika, to birth defects |work=USA Today |date=16 February 2016 |url-status=live |archive-url=https://web.archive.org/web/20160218212943/http://www.usatoday.com/story/news/2016/02/16/experts-dismiss-claims-pesticide-not-zika-causes-birth-defects/80451116/ |archive-date=18 February 2016 |df=dmy-all }}{{cite news |url=http://www.sciencealert.com/argentinian-report-says-monsanto-linked-pesticide-is-to-blame-for-microcephaly-outbreak-not-zika |title=Report says Monsanto-linked pesticide is to blame for microcephaly outbreak – not Zika |work=Science Alert |location=Australia |date=16 February 2016 |quote=But let's be clear – there is no scientific evidence to support that link. |url-status=live |archive-url=https://web.archive.org/web/20160216204117/http://www.sciencealert.com/argentinian-report-says-monsanto-linked-pesticide-is-to-blame-for-microcephaly-outbreak-not-zika |archive-date=16 February 2016 |df=dmy-all }}{{cite news |url=https://www.nytimes.com/2016/02/17/world/americas/conspiracy-theories-about-zika-spread-along-with-the-virus.html |title=Conspiracy Theories About Zika Spread Along With the Virus |date=16 February 2016 |access-date=16 February 2016 |work=The New York Times |first=Andrew |last=Jacobs |url-status=live |archive-url=https://web.archive.org/web/20160217022402/http://www.nytimes.com/2016/02/17/world/americas/conspiracy-theories-about-zika-spread-along-with-the-virus.html |archive-date=17 February 2016 |df=dmy-all }} "It's important to state that some localities that do not use pyriproxyfen also had reported cases of microcephaly", read a Brazilian government statement.{{cite news |url=https://www.telegraph.co.uk/news/worldnews/zika/12157747/Zika-virus-Brazil-dismisses-link-between-larvicide-and-microcephaly.html |title=Zika virus: Brazil dismisses link between larvicide and microcephaly |work=Daily Telegraph |date=15 February 2016 |last=Bowater |first=Donna |url-status=live |archive-url=https://web.archive.org/web/20160217081038/http://www.telegraph.co.uk/news/worldnews/zika/12157747/Zika-virus-Brazil-dismisses-link-between-larvicide-and-microcephaly.html |archive-date=17 February 2016 |df=dmy-all }} The Brazilian government also refuted conspiracy theories that chickenpox and rubella vaccinations or genetically modified mosquitoes were causing increases in microcephaly.

Researchers also suspected that the Zika virus could be transmitted by a pregnant woman to her baby ("vertical transmission"). This remained unproven until February 2016, when a paper by Calvet et al. was published, showing not only the Zika virus genome found in the amniotic fluid but also IgM antibodies against the virus.{{cite journal | display-authors=3 | first1=Guilherme | first10=Louisi | first11=Diogo A | first12=Carlos G | first13=Fabiano L | first14=Patricia | first15=Flavia B | first16=Rita M R | first17=Amilcar | first18=Ana M B | first2=Renato S | first6=Allison | last1=Calvet | last10=de Oliveira | last11=Tschoeke | last12=Schrago | last13=Thompson | last14=Brasil | last15=dos Santos | last16=Nogueira | last17=Tanuri | last18=de Filippis | title=Detection and sequencing of Zika virus from amniotic fluid of fetuses with microcephaly in Brazil: a case study | date=February 2016 | last2=Aguiar | last3=Melo | first3=Adriana S O | last4=Sampaio | first4=Simone A | last5=de Filippis | first5=Ivano | last6=Fabri | last7=Araujo | first7=Eliane S M | last8=de Sequeira | first8=Patricia C | last9=de Mendonça | first9=Marcos C L | journal=The Lancet Infectious Diseases | volume=16 | issue=6 | pages=653–660 | doi=10.1016/S1473-3099(16)00095-5 | pmid=26897108 | issn=1473-3099| url=https://www.arca.fiocruz.br/handle/icict/13666 | doi-access=free }} This means that not only can the virus cross the placental barrier, but also the antibodies produced by the mother can reach the fetus, which suggests that vertical transmission is plausible in these cases. One other study published in March 2016 by Mlakar and colleagues analyzed autopsy tissues from a fetus with microcephaly that was probably related to Zika virus; researchers found ZIKV in the brain tissue and suggested that the brain injuries were probably associated with the virus, which also shed a light on the vertical transmission theory.{{cite journal | title=Zika Virus Associated with Microcephaly | date=10 March 2016 | last1=Mlakar | first1=Jernej | last2=Korva | first2=Misa | last3=Tul | first3=Nataša | last4=Popović | first4=Mara | last5=Poljšak-Prijatelj | first5=Mateja | last6=Mraz | first6=Jerica | last7=Kolenc | first7=Marko | last8=Resman Rus | first8=Katarina | last9=Vesnaver Vipotnik | first9=Tina | journal=New England Journal of Medicine | volume=374 | issue=10 | pages=951–958 | issn=0028-4793 | doi=10.1056/NEJMoa1600651 | pmid=26862926 | display-authors=3 | doi-access=free }} Also in March 2016, first solid evidence was reported on how the virus affects the development of the brain, indicating that it appears to preferentially kill developing brain cells.{{cite news |first1=Gretchen |last1=Vogel |url=https://www.science.org/content/article/zika-virus-kills-developing-brain-cells |title=Zika virus kills developing brain cells |work=Science |date=4 March 2016 |url-status=live |archive-url=https://web.archive.org/web/20160306183536/http://www.sciencemag.org/news/2016/03/zika-virus-kills-developing-brain-cells |archive-date=6 March 2016 |df=dmy-all }}

The first cases of birth defects linked to Zika in Colombia{{cite journal | title=First Zika-linked birth defects detected in Colombia | date=4 March 2016 | author=Butler, Declan | journal=Nature | volume=531 | issue=7593 | doi=10.1038/nature.2016.19502 | pmid=26961637 | page=153 | issn=0028-0836 | df=dmy-all | bibcode=2016Natur.531..153B | s2cid=4470808 | doi-access=free }} and in Panama were reported in March 2016.{{cite news | url=https://www.bbc.co.uk/news/world-latin-america-35850696 | title=Zika: Panama has 'first microcephaly case outside Brazil' | publisher=BBC | work=BBC News Latin America | date=19 March 2016 | access-date=20 March 2016 | url-status=live | archive-url=https://web.archive.org/web/20160320235739/http://www.bbc.co.uk/news/world-latin-america-35850696 | archive-date=20 March 2016 | df=dmy-all }} In the same month, researchers published a prospective cohort study that found profound impacts in 29 percent of infants of mothers infected with Zika, some of whom were infected late in pregnancy.{{cite journal | first1=Patrícia | first10=Denise | first11=Guilherme A. | first12=Elizabeth S. | first13=Maria E. | first14=Ana E. | first15=Paulo R. | first16=Carla | first17=Stephanie G. | first18=James D. | first19=Ana M. | first20=Karin | first4=Luana | last1=Brasil | last10=Cotrim da Cunha | last11=Calvet | last12=Neves | last13=Moreira | last14=Rodrigues Baião | last15=Nassar de Carvalho | last16=Janzen | last17=Valderramos | last18=Cherry | last19=Bispo de Filippis | title=Zika Virus Infection in Pregnant Women in Rio de Janeiro – Preliminary Report | date=4 March 2016 | last2=Pereira | first2=Jose P. Jr. | last20=Nielsen-Saines | last3=Raja Gabaglia | first3=Claudia | last4=Damasceno | last5=Wakimoto | first5=Mayumi | last6=Ribeiro Nogueira | first6=Rita M. | last7=Carvalho de Sequeira | first7=Patrícia | last8=Machado Siqueira | first8=André | last9=Abreu de Carvalho | first9=Liege M. | journal=New England Journal of Medicine | volume=375 | issue=24 | pages=2321–2334 | issn=0028-4793 | doi=10.1056/NEJMoa1602412 | pmid=26943629 | pmc=5323261 | display-authors=3 }} This study did not suffer from some of the difficulties of studying Zika: the study followed women who presented to a Rio de Janeiro clinic with fever and rash within the last five days. The women were then tested for Zika using PCR, then the progress of the pregnancies was followed using ultrasound.{{cite news | url=https://www.nytimes.com/2016/03/05/health/zika-virus-microcephaly-fetus-birth-defects.html | title=Two Studies Strengthen Links Between the Zika Virus and Serious Birth Defects | work=New York Times | date=4 March 2016 | access-date=23 March 2016 | author=McNeil, Donald G. Jr. | last2=Saint Louis | first2=Catherine | url-status=live | archive-url=https://web.archive.org/web/20160322175107/http://www.nytimes.com/2016/03/05/health/zika-virus-microcephaly-fetus-birth-defects.html | archive-date=22 March 2016 | df=dmy-all }}

A high rate of the autoimmune disease Guillain–Barré syndrome (GBS), noted in the French Polynesia outbreak, has also been found in the outbreak that began in Brazil. Laboratory analysis found Zika infections in some patients with GBS in Brazil, El Salvador, Suriname, and Venezuela,{{cite web|url=http://apps.who.int/iris/bitstream/10665/204633/1/zikasitrep_17Mar2016_eng.pdf?ua=1|title=Zika situation report|date=17 March 2016|access-date=23 March 2016|publisher=World Health Organization|format=PDF|url-status=live|archive-url=https://web.archive.org/web/20160320210243/http://apps.who.int/iris/bitstream/10665/204633/1/zikasitrep_17Mar2016_eng.pdf?ua=1|archive-date=20 March 2016|df=dmy-all}} and the WHO declared on 22 March 2016 that Zika appeared to be "implicated" in GBS infection and that if the pattern was confirmed it would represent a global public health crisis.{{cite news | url=https://www.theguardian.com/world/2016/mar/22/who-zika-virus-implicated-in-large-numbers-of-brain-damaged-babies | title=WHO: Zika virus 'implicated' in large numbers of brain-damaged babies | work=The Guardian | date=22 March 2016 | access-date=23 March 2016 | author=Bosley, Sarah | url-status=live | archive-url=https://web.archive.org/web/20160322191426/http://www.theguardian.com/world/2016/mar/22/who-zika-virus-implicated-in-large-numbers-of-brain-damaged-babies | archive-date=22 March 2016 | df=dmy-all }}

Early in the 2015–16 Zika virus epidemic, research was begun to understand how the Zika virus causes microcephaly and other neurological disorders.{{cite journal|last1=Faizan|first1=MI|last2=Abdullah|first2=M|last3=Ali|first3=S|last4=Naqvi|first4=IH|last5=Ahmed|first5=A|last6=Parveen|first6=S|date=2016|title=Zika Virus-Induced Microcephaly and Its Possible Molecular Mechanism.|journal=Intervirology|volume=59|issue=3|pages=152–158|doi=10.1159/000452950|pmid=28081529|df=dmy-all|doi-access=free}} However, with the 2019 election of Jair Bolsonaro in Brazil, who cut funding for research, and the emergence of the COVID-19 pandemic in early 2020, most Zika-related research projects were abandoned or reduced.{{Cite news |last1=Nolen |first1=Stephanie |last2=Galdieri |first2=Dado |date=2022-08-16 |title=The Forgotten Virus: Zika Families and Researchers Struggle for Support |language=en-US |work=The New York Times |url=https://www.nytimes.com/2022/08/16/health/zika-children-research.html |access-date=2022-12-01 |issn=0362-4331}}

It may involve infection of the primary neural stem cells of the fetal brain, known as neural progenitor cells.{{Cite journal|last1=Nayak|first1=Shriddha|last2=Lei|first2=Jun|last3=Pekosz|first3=Andrew|last4=Klein|first4=Sabra|author-link4=Sabra Klein |last5=Burd|first5=Irina|author-link5=Irina Burd|date=2016-09-09|title=Pathogenesis and Molecular Mechanisms of Zika Virus|journal=Seminars in Reproductive Medicine|language=en|doi=10.1055/s-0036-1592071|pmid=27612156|issn=1526-8004|volume=34|issue=5|pages=266–272|doi-access=free}}{{Cite journal|last1=Li|first1=Hongda|last2=Saucedo-Cuevas|first2=Laura|last3=Shresta|first3=Sujan|last4=Gleeson|first4=Joseph G.|title=The Neurobiology of Zika Virus |journal=Neuron|volume=92|issue=5|pages=949–958|doi=10.1016/j.neuron.2016.11.031|pmid=27930910|year=2016|doi-access=free}} The main roles of brain stem cells are to proliferate until the correct number is achieved, and then to produce neurons through the process of neurogenesis.{{cite journal|date=October 2009|title=Evolution of the neocortex: a perspective from developmental biology.|journal=Nature Reviews. Neuroscience|volume=10|issue=10|pages=724–35|pmid=19763105|last1=Rakic|first1=P|doi=10.1038/nrn2719|pmc=2913577}} Zika proteins NS4A and NS4B have also been shown to directly suppress neurogenesis. Infection of brain stem cells can cause cell death, which reduces the production of future neurons and leads to a smaller brain. Zika also appears to have an equal tropism for cells of the developing eye, leading to high rates of eye abnormalities as well.

In addition to inducing cell death, infection of neural progenitor cells may alter the process of cell proliferation, causing a depletion in the pool of progenitor cells.{{Cite journal|last1=Merfeld|first1=Emily|last2=Ben-Avi|first2=Lily|last3=Kennon|first3=Mason|last4=Cerveny|first4=Kara L.|date=2017-07-01|title=Potential mechanisms of Zika-linked microcephaly |journal=Wiley Interdisciplinary Reviews: Developmental Biology|language=en|volume=6|issue=4|pages=e273|doi=10.1002/wdev.273|pmid=28383800|pmc=5516183|issn=1759-7692}} A large number of cases of microcephaly have been associated with inherited gene mutations, and specifically with mutations that lead to dysfunction of the mitotic spindle. There is some evidence that Zika virus may directly or indirectly interfere with mitotic function, this may play a role in altering cell proliferation.{{cite journal|last1=Bullerdiek|first1=J|last2=Dotzauer|first2=A|last3=Bauer|first3=I|title=The mitotic spindle: linking teratogenic effects of Zika virus with human genetics?|journal=Molecular Cytogenetics|date=2016|volume=9|pages=32|pmid=27099632|pmc=4837584|doi=10.1186/s13039-016-0240-1|doi-access=free}}

Another line of research considers that Zika, unlike other flaviviruses, may target developing brain cells after it crosses the placenta, and considers the resulting damage likely to be the result of inflammation as a byproduct of the immune response to the infection of those cells.{{cite journal|last1=Wang|first1=A|last2=Thurmond|first2=S|last3=Islas|first3=L|last4=Hui|first4=K|last5=Hai|first5=R|title=Zika virus genome biology and molecular pathogenesis.|journal=Emerging Microbes & Infections|date=22 March 2017|volume=6|issue=3|pages=e13|doi=10.1038/emi.2016.141|pmid=28325921|pmc=5378920|df=dmy-all}}

Some experimental prevention methods include breeding and releasing mosquitoes that have been genetically modified to prevent them from transmitting pathogens, or have been infected with the Wolbachia bacterium, believed to inhibit the spread of viruses.{{cite news | url=https://www.bloomberg.com/news/articles/2016-02-04/as-zika-virus-goes-global-scientists-breed-infected-mosquitoes | title=The Best Weapon for Fighting Zika? More Mosquitoes | work=Bloomberg | date=4 February 2016 | author=Gale, Jason | url-status=live | archive-url=https://web.archive.org/web/20170406044831/https://www.bloomberg.com/news/articles/2016-02-04/as-zika-virus-goes-global-scientists-breed-infected-mosquitoes | archive-date=6 April 2017 | df=dmy-all }} A strain of Wolbachia helped to reduce the vector competence of the Zika virus in infected Aedes aegypti released in Medellin, Colombia.{{cite journal |title=The w Mel strain of Wolbachia Reduces Transmission of Zika virus by Aedes aegypti |journal=Scientific Reports |volume=6 |pages=28792 |df=dmy-all |doi=10.1038/srep28792 |pmid=27364935 |pmc=4929456 |year=2016 |last1=Aliota |first1=Matthew T. |last2=Peinado |first2=Stephen A. |last3=Velez |first3=Ivan Dario |last4=Osorio |first4=Jorge E. |bibcode=2016NatSR...628792A }} The wMel strain of Wolbachia Reduces Transmission of Zika virus by Aedes aegypti

Gene drive is a technique for changing wild populations, for instance to combat insects so they cannot transmit diseases (in particular mosquitoes in the cases of malaria and Zika).{{cite news | url=https://www.bloomberg.com/view/articles/2016-02-04/fighting-zika-virus-with-genetic-engineering | title=Fighting Zika Virus With Genetic Engineering | work=Bloomberg | date=4 February 2016 | last=Flam | first=Faye | url-status=live | archive-url=https://web.archive.org/web/20160606220755/http://www.bloomberg.com/view/articles/2016-02-04/fighting-zika-virus-with-genetic-engineering | archive-date=6 June 2016 | df=dmy-all }} Another method which been researched aims to render male mosquitoes infertile by nuclear radiation in the hope to reduce populations; this is done with a cobalt-60 gamma cell irradiator.{{cite news | url=https://www.iaea.org/newscenter/news/iaea-helps-brazil-step-up-the-fight-against-zika-mosquitoes | title=IAEA Helps Brazil Step up the Fight Against 'Zika' Mosquitoes | work=International Atomic Energy Agency | date=23 February 2016 | last=Viegas | first=Luciana | url-status=live | archive-url=https://web.archive.org/web/20160629121932/https://www.iaea.org/newscenter/news/iaea-helps-brazil-step-up-the-fight-against-zika-mosquitoes | archive-date=29 June 2016 | df=dmy-all }} In 2016 the World Health Organization encouraged field trials of transgenic male Aedes aegypti mosquitoes developed by Oxitec to try to halt the spread of the Zika virus.{{cite news|last1=Kelland|first1=Kate|title=WHO backs trials of genetically modified mosquitoes to fight Zika|url=https://www.theglobeandmail.com/news/world/who-backs-trials-of-genetically-modified-mosquitoes-to-fight-zika/article29297605/|access-date=19 March 2016|newspaper=The Globe and Mail|date=18 March 2016|url-status=live|archive-url=https://web.archive.org/web/20160318223119/http://www.theglobeandmail.com/news/world/who-backs-trials-of-genetically-modified-mosquitoes-to-fight-zika/article29297605/|archive-date=18 March 2016|df=dmy-all}}

Recent studies have explored the use of the Zika virus (ZIKV) Zhou, C., Chen, Q., Chen, Y., & Qin, C.-F. (2023). Oncolytic Zika virus: New option for glioblastoma treatment. DNA and Cell Biology, 42(6), 267-273. https://doi.org/10.1089/dna.2022.0375.

as a potential treatment for glioblastoma multiforme (GBM), a highly aggressive brain cancer. GBM has a median survival rate of about 15 months due to limited treatment options and high tumor recurrence rates. Oncolytic virotherapy, which uses specific viruses to target and destroy cancer cells, has shown promise as an alternative treatment for GBM.

One study investigated the oncolytic potential of live-attenuated vaccine strains of Zika virus (ZIKV-LAV) against human GBM cells in vitro. The study found that ZIKV-LAV selectively infected and killed GBM cells without affecting terminally differentiated neurons or primary endothelial cells. ZIKV-LAV induced cell death through apoptosis and pyroptosis, two forms of programmed cell death.Victorio, C. B. L., Novera, W., Ganasarajah, A., Ong, J., Thomas, M., Wu, J., Toh, H. S. Y., Sun, A. X., Ooi, E. E., & Chacko, A.-M. (2024). Repurposing of Zika virus live-attenuated vaccine (ZIKV-LAV) strains as oncolytic viruses targeting human glioblastoma multiforme cells. Journal of Translational Medicine, 22(1), 93. https://doi.org/10.1186/s12967-024-04930-4.

This research highlights the potential of ZIKV-LAV as a treatment for GBM through oncolytic virotherapy. However, further clinical trials and research are necessary to assess its efficacy in human patients.

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{{Medical resources

| ICD11 = {{ICD9|1D48}}

| ICD10 = [http://apps.who.int/classifications/icd10/browse/2016/en#/U06 U06]

| ICD9 = {{ICD9|066.3}}

| DiseasesDB = 36480

| MedlinePlus = 007666

| eMedicineSubj =

| eMedicineTopic =

| MeSH = D000071243

| Scholia = Q8071861

}}

• [https://www.cdc.gov/mmwr/volumes/66/wr/mm6641a1.htm?s_cid=mm6641a1_w Managing Zika in babies] (CDC)
• [https://www.invasivespeciesinfo.gov/profile/zika-virus-disease Species Profile – Zika Virus Disease], National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for White-Nose Syndrome.

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