chickenpox

File:Chickenpox blister.jpg

The early (prodromal) symptoms in adolescents and adults are nausea, loss of appetite, aching muscles, and headache.{{cite web | title = Chickenpox | publisher = Mayo Clinic | url = https://www.mayoclinic.org/diseases-conditions/chickenpox/symptoms-causes/syc-20351282 | access-date = 10 September 2020 | archive-date = 4 September 2020 | archive-url = https://web.archive.org/web/20200904095005/https://www.mayoclinic.org/diseases-conditions/chickenpox/symptoms-causes/syc-20351282 | url-status = live }} This is followed by the characteristic rash or oral sores, malaise, and a low-grade fever that signals the presence of the disease. Oral manifestations of the disease (enanthem) not uncommonly may precede the external rash (exanthem). In children, the illness is not usually preceded by prodromal symptoms, and the first sign is the rash or the spots in the oral cavity. The rash begins as small red dots on the face, scalp, torso, upper arms, and legs; progressing over 10–12 hours to small bumps, blisters, and pustules; followed by umbilication and the formation of scabs.{{cite web | url = http://emedicine.medscape.com/article/1131785 | title = Chickenpox Clinical Presentation | author = Anthony J Papadopoulos | editor = Dirk M Elston | access-date = 4 August 2012 | work = Medscape Reference | archive-date = 7 April 2020 | archive-url = https://web.archive.org/web/20200407210652/https://emedicine.medscape.com/article/1131785-overview | url-status = live }}{{cite web|title=Symptoms of Chickenpox|url=http://www.nhs.uk/Conditions/Chickenpox/Pages/Symptoms.aspx|work=Chickenpox|publisher=NHS Choices|access-date=14 March 2013|url-status=live|archive-url=https://web.archive.org/web/20130318081447/http://www.nhs.uk/Conditions/Chickenpox/Pages/Symptoms.aspx|archive-date=18 March 2013}}

At the blister stage, intense itching is usually present. Blisters may also occur on the palms, soles, and genital area. Commonly, visible evidence of the disease develops in the oral cavity and tonsil areas in the form of small ulcers which can be painful, itchy, or both; this enanthem (internal rash) can precede the exanthem (external rash) by 1 to 3 days or can be concurrent. These symptoms of chickenpox appear 10 to 21 days after exposure to a contagious person. Adults may have a more widespread rash and longer fever, and they are more likely to experience complications, such as varicella pneumonia.

Because watery nasal discharge containing live virus usually precedes both exanthem (external rash) and enanthem (oral ulcers) by one to two days, the infected person becomes contagious one to two days before recognition of the disease. Contagiousness persists until all vesicular lesions have become dry crusts (scabs), which usually entails four or five days, by which time nasal shedding of live virus ceases.{{Cite web | url = https://www.cdc.gov/chickenpox/hcp/clinical-overview.html | publisher = Centers for Disease Control and Prevention | title = Chickenpox (Varicella): Clinical Overview | url-status = live | archive-url = https://web.archive.org/web/20170225050958/https://www.cdc.gov/chickenpox/hcp/clinical-overview.html | archive-date = 25 February 2017| date = 22 April 2019 }} The condition usually resolves by itself within a week or two.{{cite web |url=http://www.netdoctor.co.uk/diseases/facts/chickenpox.htm |title=Chickenpox (varicella) |access-date=6 November 2010 |url-status=live |archive-url=https://web.archive.org/web/20101205125530/http://www.netdoctor.co.uk/diseases/facts/chickenpox.htm |archive-date=5 December 2010}} The rash may, however, last for up to one month.{{medical citation needed|date=April 2017}}{{Cite web |title=Chickenpox - Symptoms and causes |url=https://www.mayoclinic.org/diseases-conditions/chickenpox/symptoms-causes/syc-20351282 |access-date=27 April 2022 |website=Mayo Clinic |language=en |archive-date=9 May 2022 |archive-url=https://web.archive.org/web/20220509164732/https://www.mayoclinic.org/diseases-conditions/chickenpox/symptoms-causes/syc-20351282 |url-status=live }}

Chickenpox is rarely fatal, although it is generally more severe in adult men than in women or children. Non-immune pregnant women and those with a suppressed immune system are at highest risk of serious complications. Arterial ischemic stroke (AIS) associated with chickenpox in the previous year accounts for nearly one-third of childhood AIS.{{cite journal | vauthors = Askalan R, Laughlin S, Mayank S, Chan A, MacGregor D, Andrew M, Curtis R, Meaney B, deVeber G | title = Chickenpox and stroke in childhood: a study of frequency and causation | journal = Stroke | volume = 32 | issue = 6 | pages = 1257–1262 | date = June 2001 | pmid = 11387484 | doi = 10.1161/01.STR.32.6.1257| doi-access = free }} The most common late complication of chickenpox is shingles (herpes zoster), caused by reactivation of the varicella zoster virus decades after the initial, often childhood, chickenpox infection.

File:Chickenpox Adult back.jpg|The back of a 30-year-old male after five days of the rash

File:Ploketes d' aiwe dj3 costé.jpg|A 3-year-old girl with a chickenpox rash on her torso

File:Bem chickenpox vannkopper 20140318.jpg|Lower leg of a child with chickenpox

File:Vicki Pandit - Howrah 2014-04-06 9845.JPG|A child with chickenpox

File:A child with chickenpox (01).jpg|A child with chickenpox on her face.

File:Windpocken.jpg|A child with chickenpox

File:Chickenpox blister-(closeup).jpg|Chickenpox blister closeup, day 7 after start of fever

{{Main article|Congenital varicella syndrome}}

{{anchor|pregnancy}}During pregnancy the dangers to the fetus associated with a primary VZV infection are greater in the first six months. In the third trimester, the mother is more likely to have severe symptoms.{{cite journal | vauthors = Heuchan AM, Isaacs D | title = The management of varicella-zoster virus exposure and infection in pregnancy and the newborn period. Australasian Subgroup in Paediatric Infectious Diseases of the Australasian Society for Infectious Diseases. | journal = The Medical Journal of Australia | volume = 174 | issue = 6 | pages = 288–292 | date = 19 March 2001 | pmid = 11297117 | url = https://www.mja.com.au/journal/2001/174/6/management-varicella-zoster-virus-exposure-and-infection-pregnancy-and-newborn | url-status = live | archive-url = https://web.archive.org/web/20130212103609/https://www.mja.com.au/journal/2001/174/6/management-varicella-zoster-virus-exposure-and-infection-pregnancy-and-newborn | archive-date = 12 February 2013| doi = 10.5694/j.1326-5377.2001.tb143273.x | s2cid = 37646516 }} For pregnant women, antibodies produced as a result of immunization or previous infection are transferred via the placenta to the fetus.{{cite web |first = Heather |last = Brannon |title = Chickenpox in Pregnancy |url = http://dermatology.about.com/cs/pregnancy/a/chickenpreg.htm |work = Dermatology |publisher = About.com |date = 22 July 2007 |access-date = 20 June 2009 |url-status = live |archive-url = https://web.archive.org/web/20090727114411/http://dermatology.about.com/cs/pregnancy/a/chickenpreg.htm |archive-date = 27 July 2009}} Varicella infection in pregnant women could lead to spread via the placenta and infection of the fetus. If infection occurs during the first 28 weeks of gestation, this can lead to fetal varicella syndrome (also known as congenital varicella syndrome).{{cite journal |vauthors=Boussault P, Boralevi F, Labbe L, Sarlangue J, Taïeb A, Leaute-Labreze C | title = Chronic varicella-zoster skin infection complicating the congenital varicella syndrome | journal = Pediatr Dermatol | volume = 24 | issue = 4 | pages = 429–432 | year = 2007 | pmid = 17845179 | doi = 10.1111/j.1525-1470.2007.00471.x | s2cid = 22389596 }} Effects on the fetus can range in severity from underdeveloped toes and fingers to severe anal and bladder malformation. Possible problems include:

• Damage to the brain: encephalitis,{{cite journal |vauthors=Matsuo T, Koyama M, Matsuo N | title = Acute retinal necrosis as a novel complication of chickenpox in adults | journal = Br J Ophthalmol | volume = 74 | issue = 7 | pages = 443–444 | date = July 1990 | pmid = 2378860 | pmc = 1042160 | doi = 10.1136/bjo.74.7.443 }} microcephaly, hydrocephaly,{{cite journal |vauthors=Mazzella M, Arioni C, Bellini C, Allegri AE, Savioli C, Serra G | title = Severe hydrocephalus associated with congenital varicella syndrome | journal = Canadian Medical Association Journal | volume = 168 | issue = 5 | pages = 561–563 | year = 2003 | pmid = 12615748 | pmc = 149248 }} aplasia of brain
• Damage to the eye: optic stalk, optic cup, and lens vesicles, microphthalmia, cataracts, chorioretinitis, optic atrophy
• Other neurological disorder: damage to cervical and lumbosacral spinal cord, motor/sensory deficits, absent deep tendon reflexes, anisocoria/Horner's syndrome
• Damage to body: hypoplasia of upper/lower extremities, anal and bladder sphincter dysfunction
• Skin disorders: (cicatricial) skin lesions, hypopigmentation

Infection late in gestation or immediately following birth is referred to as "neonatal varicella".{{cite journal | vauthors = Sauerbrei A, Wutzler P | title = Neonatal varicella | journal = J Perinatol | volume = 21 | issue = 8 | pages = 545–549 | date = December 2001 | pmid = 11774017 | doi = 10.1038/sj.jp.7210599| doi-access = free }} Maternal infection is associated with premature delivery. The risk of the baby developing the disease is greatest following exposure to infection in the period 7 days before delivery and up to 8 days following the birth. The baby may also be exposed to the virus via infectious siblings or other contacts, but this is of less concern if the mother is immune. Newborns who develop symptoms are at a high risk of pneumonia and other serious complications of the disease.{{cite web | author=Royal College of Obstetricians and Gynaecologists | title=Chickenpox in Pregnancy | url=http://www.rcog.org.uk/files/rcog-corp/uploaded-files/GT13ChickenpoxinPregnancy2007.pdf | date=September 2007 | access-date=22 July 2009 | url-status=dead | archive-url=https://web.archive.org/web/20101111043941/http://www.rcog.org.uk/files/rcog-corp/uploaded-files/GT13ChickenpoxinPregnancy2007.pdf | archive-date=11 November 2010}}

{{main|Varicella zoster virus}}

Exposure to VZV in a healthy child initiates the production of host immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) antibodies; IgG antibodies persist for life and confer immunity. Cell-mediated immune responses are also important in limiting the scope and the duration of primary varicella infection. After primary infection, VZV is hypothesized to spread from mucosal and epidermal lesions to local sensory nerves. VZV then remains latent in the dorsal ganglion cells of the sensory nerves. Reactivation of VZV results in the clinically distinct syndrome of herpes zoster (i.e., shingles), postherpetic neuralgia,{{cite journal |vauthors=Kanbayashi Y, Onishi K, Fukazawa K, Okamoto K, Ueno H, Takagi T, Hosokawa T | s2cid = 11980597 | title = Predictive Factors for Postherpetic Neuralgia Using Ordered Logistic Regression Analysis | journal = The Clinical Journal of Pain | volume = 28 | issue = 8 | pages = 712–714 | year = 2012 | pmid = 22209800 | doi = 10.1097/AJP.0b013e318243ee01 }} and sometimes Ramsay Hunt syndrome type II.{{cite journal |vauthors=Pino Rivero V, González Palomino A, Pantoja Hernández CG, Mora Santos ME, Trinidad Ramos G, Blasco Huelva A | title = Ramsay-Hunt syndrome associated to unilateral recurrential paralysis | journal = Anales Otorrinolaringologicos Ibero-americanos | volume = 33 | issue = 5 | pages = 489–494 | year = 2006 | pmid = 17091862 }} Varicella zoster can affect the arteries in the neck and head, producing stroke, either during childhood, or after a latency period of many years.{{cite journal |title = The varicella zoster virus vasculopathies: clinical, CSF, imaging, and virologic features. |journal = Neurology |date=March 2008 |pmid=18332343 |doi=10.1212/01.wnl.0000304747.38502.e8 |volume=70 |issue = 11 |pmc=2938740 |pages=853–860 |vauthors=Nagel MA, Cohrs RJ, Mahalingam R, Wellish MC, Forghani B, Schiller A, Safdieh JE, Kamenkovich E, Ostrow LW, Levy M, Greenberg B, Russman AN, Katzan I, Gardner CJ, Häusler M, Nau R, Saraya T, Wada H, Goto H, de Martino M, Ueno M, Brown WD, Terborg C, Gilden DH }}

{{Main|Herpes zoster}}

After a chickenpox infection, the virus remains dormant in the body's nerve tissues for about 50 years. This, however, does not mean that VZV cannot be contracted later in life. The immune system usually keeps the virus at bay, but it can still manifest itself at any given age causing a different form of the viral infection called shingles (also known as herpes zoster).{{cite web |title=Chickenpox |date=19 April 2012 |work=NHS Choices |publisher=UK Department of Health |url=http://www.nhs.uk/conditions/chickenpox/Pages/Introduction.aspx |url-status=live |archive-url=https://web.archive.org/web/20091124215212/http://www.nhs.uk/Conditions/Chickenpox/Pages/Introduction.aspx |archive-date=24 November 2009}} Since the efficacy of the human immune system decreases with age, the United States Advisory Committee on Immunization Practices (ACIP) suggests that every adult over the age of 50 years get the herpes zoster vaccine.{{cite web|title=Shingles Vaccine|url=http://www.webmd.com/skin-problems-and-treatments/shingles/shingles-vaccine|website=WebMD|url-status=live|archive-url=https://web.archive.org/web/20130129004139/http://www.webmd.com/skin-problems-and-treatments/shingles/shingles-vaccine|archive-date=29 January 2013}}

Shingles affects one in five adults infected with chickenpox as children, especially those who are immune-suppressed, particularly from cancer, HIV, or other conditions. Stress can bring on shingles as well, although scientists are still researching the connection.{{cite web|title=An Overview of Shingles|url=http://www.webmd.com/skin-problems-and-treatments/shingles/shingles-skin|website=WebMD|url-status=live|archive-url=https://web.archive.org/web/20130208234940/http://www.webmd.com/skin-problems-and-treatments/shingles/shingles-skin|archive-date=8 February 2013}} Adults over the age of 60 who had chickenpox but not shingles are the most prone age demographic.{{cite web|title=Shingles|url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001861/|publisher=PubMed Health|access-date=30 August 2017|archive-date=23 August 2014|archive-url=https://web.archive.org/web/20140823055650/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001861/|url-status=live}}

File:Chickenpox.png

The diagnosis of chickenpox is primarily based on the signs and symptoms, with typical early symptoms followed by a characteristic rash. Confirmation of the diagnosis is by examination of the fluid within the vesicles of the rash, or by testing blood for evidence of an acute immunologic response.{{Citation|last1=Ayoade|first1=Folusakin|title=Varicella Zoster (Chickenpox)|date=2020|url=http://www.ncbi.nlm.nih.gov/books/NBK448191/|work=StatPearls|place=Treasure Island (FL)|publisher=StatPearls Publishing|pmid=28846365|access-date=21 October 2020|last2=Kumar|first2=Sandeep|archive-date=7 January 2021|archive-url=https://web.archive.org/web/20210107151028/https://www.ncbi.nlm.nih.gov/books/NBK448191/|url-status=live}}

Vesicular fluid can be examined with a Tzanck smear, or by testing for direct fluorescent antibody. The fluid can also be "cultured", whereby attempts are made to grow the virus from a fluid sample. Blood tests can be used to identify a response to acute infection (IgM) or previous infection and subsequent immunity (IgG).{{cite book |author1=Pincus, Matthew R. |author2=McPherson, Richard A. |author3=Henry, John Bernard |title=Henry's clinical diagnosis and management by laboratory methods |publisher=Saunders Elsevier |year=2007 |isbn=978-1-4160-0287-1 |edition=21st |chapter=Ch. 54}}

Prenatal diagnosis of fetal varicella infection can be performed using ultrasound, though a delay of 5 weeks following primary maternal infection is advised. A PCR (DNA) test of the mother's amniotic fluid can also be performed, though the risk of spontaneous abortion due to the amniocentesis procedure is higher than the risk of the baby's developing fetal varicella syndrome.

The spread of chickenpox can be prevented by isolating affected individuals. Contagion is by exposure to respiratory droplets, or direct contact with lesions, within a period lasting from three days before the onset of the rash, to four days after the onset of the rash.{{cite book |author1=Murray, Patrick R. |author2=Rosenthal, Ken S. |author3=Pfaller, Michael A. |title=Medical Microbiology |publisher=Elsevier Mosby |year=2005 |isbn=978-0-323-03303-9 |page=551 |edition=5th}}, edition'' (Elsevier), p. The chickenpox virus is susceptible to disinfectants, notably chlorine bleach (i.e., sodium hypochlorite). Like all enveloped viruses, it is sensitive to drying, heat and detergents.

{{Main|Varicella vaccine}}

Chickenpox can be prevented by vaccination. The side effects are usually mild, such as some pain or swelling at the injection site.

A live attenuated varicella vaccine, the Oka strain, was developed by Michiaki Takahashi and his colleagues in Japan in the early 1970s.{{Citation|last=Gershon|first=Anne A.|title=Varicella-zoster vaccine|date=2007|url=http://www.ncbi.nlm.nih.gov/books/NBK47446/|work=Human Herpesviruses: Biology, Therapy, and Immunoprophylaxis|editor-last=Arvin|editor-first=Ann|place=Cambridge|publisher=Cambridge University Press|isbn=978-0-521-82714-0|pmid=21348127|access-date=6 February 2021|editor2-last=Campadelli-Fiume|editor2-first=Gabriella|editor3-last=Mocarski|editor3-first=Edward|editor4-last=Moore|editor4-first=Patrick S.|archive-date=23 November 2020|archive-url=https://web.archive.org/web/20201123205428/https://www.ncbi.nlm.nih.gov/books/NBK47446/|url-status=live}} In 1995, Merck & Co. licensed the "Oka" strain of the varicella virus in the United States, and Maurice Hilleman's team at Merck invented a varicella vaccine in the same year.{{Cite journal|last=Tulchinsky|first=Theodore H.|date=2018|title=Maurice Hilleman: Creator of Vaccines That Changed the World|journal=Case Studies in Public Health|pages=443–470|doi=10.1016/B978-0-12-804571-8.00003-2|pmc=7150172|isbn=978-0-12-804571-8}}{{Cite web|title=Chickenpox (Varicella) {{!}} History of Vaccines|url=https://www.historyofvaccines.org/content/articles/chickenpox-varicella|access-date=6 February 2021|website=www.historyofvaccines.org|language=en|archive-date=22 January 2021|archive-url=https://web.archive.org/web/20210122165132/https://www.historyofvaccines.org/content/articles/chickenpox-varicella|url-status=live}}{{Cite web|title=Maurice Ralph Hilleman (1919–2005) {{!}} The Embryo Project Encyclopedia|url=https://embryo.asu.edu/pages/maurice-ralph-hilleman-1919-2005|access-date=6 February 2021|website=embryo.asu.edu|archive-date=27 August 2017|archive-url=https://web.archive.org/web/20170827180232/https://embryo.asu.edu/pages/maurice-ralph-hilleman-1919-2005|url-status=live}}

The varicella vaccine is recommended in many countries. Some countries require the varicella vaccination or an exemption before entering elementary school. A second dose is recommended five years after the initial immunization.{{cite journal |vauthors=Chaves SS, Gargiullo P, Zhang JX, Civen R, Guris D, Mascola L, Seward JF | title = Loss of vaccine-induced immunity to varicella over time | journal = N Engl J Med | volume = 356 | issue = 11 | pages = 1121–1129 | year = 2007 | pmid = 17360990 | doi = 10.1056/NEJMoa064040 | doi-access = free }} A vaccinated person is likely to have a milder case of chickenpox if they become infected.{{cite web |title=Chickenpox (varicella) vaccination |date=19 April 2012 |work=NHS Choices |publisher=UK Department of Health |url=http://www.nhs.uk/conditions/varicella-vaccine/pages/introduction.aspx |url-status=live |archive-url=https://web.archive.org/web/20100713010530/http://www.nhs.uk/Conditions/varicella-vaccine/Pages/Introduction.aspx |archive-date=13 July 2010}} Immunization within three days following household contact reduces infection rates and severity in children. Being exposed to chickenpox as an adult (for example, through contact with infected children) may boost immunity to shingles. Therefore, it was thought that when the majority of children were vaccinated against chickenpox, adults might lose this natural boost, so immunity would drop and more shingles cases would occur.{{cite web |title=Chickenpox vaccine FAQs |date=23 January 2019 |url=https://www.nhs.uk/conditions/vaccinations/chickenpox-vaccine-questions-answers/ |access-date=25 October 2020 |archive-date=12 April 2020 |archive-url=https://web.archive.org/web/20200412144833/https://www.nhs.uk/conditions/vaccinations/chickenpox-vaccine-questions-answers/ |url-status=live }} On the other hand, current observations suggest that exposure to children with varicella is not a critical factor in the maintenance of immunity. Multiple subclinical reactivations of varicella-zoster virus may occur spontaneously and, despite not causing clinical disease, may still provide an endogenous boost to immunity against zoster.{{cite web |title=Live Attenuated Varicella Vaccine: Prevention of Varicella and of Zoster |date=30 September 2021 |url=https://academic.oup.com/jid/article/224/Supplement_4/S387/6378094/ |access-date=1 December 2021 |archive-date=1 December 2021 |archive-url=https://web.archive.org/web/20211201073649/https://academic.oup.com/jid/article/224/Supplement_4/S387/6378094 |url-status=live }}

The vaccine is part of the routine immunization schedule in the US.{{cite web |title=Child, Adolescent & "Catch-up" Immunization Schedules |work=Immunization Schedules |publisher=Centers for Disease Control and Prevention |url=https://www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html |url-status=live |archive-url=https://web.archive.org/web/20160305212647/http://www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html |archive-date=5 March 2016|date=11 March 2019 }} Some European countries include it as part of universal vaccinations in children,{{cite journal|last1=Carrillo-Santisteve|first1=P|last2=Lopalco|first2=PL|title=Varicella vaccination: a laboured take-off.|journal=Clinical Microbiology and Infection|date=May 2014|volume=20|issue=Suppl 5|pages=86–91|pmid=24494784|doi=10.1111/1469-0691.12580|doi-access=free}} but not all countries provide the vaccine. In the UK as of 2014, the vaccine is only recommended in people who are particularly vulnerable to chickenpox. This is to keep the virus in circulation, thereby exposing the population to the virus at an early age when it is less harmful, and to reduce the occurrence of shingles through repeated exposure to the virus later in life.{{cite web|title=Why aren't children in the UK vaccinated against chickenpox?|url=https://www.nhs.uk/common-health-questions/childrens-health/why-are-children-in-the-uk-not-vaccinated-against-chickenpox/|website=NHS|publisher=UK National Health Service|access-date=11 November 2018|url-status=live|archive-url=https://web.archive.org/web/20180731024325/https://www.nhs.uk/conditions/vaccinations/chickenpox-vaccine/|archive-date=31 July 2018|date=26 June 2018}} In November 2023, the UK Joint Committee on Vaccination and Immunisation recommended all children be given the vaccine at ages 12 months and 18 months; however, this has not yet been implemented. In populations that have not been immunized or if immunity is questionable, a clinician may order an enzyme immunoassay. An immunoassay measures the levels of antibodies against the virus that give immunity to a person. If the levels of antibodies are low (low titer) or questionable, reimmunization may be done.{{cite book | last = Leeuwen | first = Anne | title = Davis's comprehensive handbook of laboratory & diagnostic tests with nursing implications | publisher = F.A. Davis Company | location = Philadelphia | year = 2015 | isbn = 978-0-8036-4405-2 |page=1579}}

Treatment mainly consists of easing the symptoms. As a protective measure, people are usually required to stay at home while they are infectious to avoid spreading the disease to others. Cutting the fingernails short or wearing gloves may prevent scratching and minimize the risk of secondary infections.{{Cite web |last=CDC |date=28 April 2021 |title=Chickenpox Prevention and Treatment |url=https://www.cdc.gov/chickenpox/about/prevention-treatment.html |access-date=27 April 2022 |website=Centers for Disease Control and Prevention |language=en-us |archive-date=4 February 2015 |archive-url=https://web.archive.org/web/20150204120816/http://www.cdc.gov/chickenpox/about/prevention-treatment.html |url-status=live }}

Although there have been no formal clinical studies evaluating the effectiveness of topical application of calamine lotion (a topical barrier preparation containing zinc oxide, and one of the most commonly used interventions), it has an excellent safety profile.{{cite journal | vauthors = Tebruegge M, Kuruvilla M, Margarson I | title = Does the use of calamine or antihistamine provide symptomatic relief from pruritus in children with varicella zoster infection? | journal = Arch. Dis. Child. | volume = 91 | issue = 12 | pages = 1035–1036 | year = 2006 | pmid = 17119083 | pmc = 2082986 | doi = 10.1136/adc.2006.105114 }} Maintaining good hygiene and daily cleaning of skin with warm water can help to avoid secondary bacterial infection;{{cite book |author=Domino, Frank J. |title=The 5-Minute Clinical Consult |publisher=Lippincott Williams & Wilkins |year=2007 |isbn=978-0-7817-6334-9 |page=248 }} scratching may increase the risk of secondary infection.Brannon, Heather (21 May 2008). [http://dermatology.about.com/cs/chickenpox/a/chickentreat.htm Chicken Pox Treatments] {{webarchive|url=https://web.archive.org/web/20090826150024/http://dermatology.about.com/cs/chickenpox/a/chickentreat.htm |date=26 August 2009 }}. About.com.

Paracetamol (acetaminophen) but not aspirin may be used to reduce fever. Aspirin use by someone with chickenpox may cause serious, sometimes fatal disease of the liver and brain, Reye syndrome. People at risk of developing severe complications who have had significant exposure to the virus may be given intra-muscular varicella zoster immune globulin (VZIG), a preparation containing high titres of antibodies to varicella zoster virus, to ward off the disease.{{cite journal | vauthors = Parmet S, Lynm C, Glass RM | title = JAMA patient page. Chickenpox | journal = JAMA | volume = 291 | issue = 7 | pages = 906 | date = February 2004 | pmid = 14970070 | doi = 10.1001/jama.291.7.906| doi-access = free }}{{cite journal |author=Naus M |journal=Canada Communicable Disease Report |volume=32 |issue=ACS-8 |date=15 October 2006 |title=Varizig™ as the Varicella Zoster Immune Globulin for the Prevention of Varicella in At-Risk Patients |url=http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/06vol32/acs-08/index-eng.php |display-authors=etal |url-status=live |archive-url=https://web.archive.org/web/20130117233029/http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/06vol32/acs-08/index-eng.php |archive-date=17 January 2013}}

Antivirals are sometimes used.{{cite journal | author = Huff JC | title = Antiviral treatment in chickenpox and herpes zoster. | journal = Journal of the American Academy of Dermatology | volume = 18 | issue = 1 Pt 2 | pages = 204–206 | date = January 1988 | pmid = 3339143 | doi = 10.1016/S0190-9622(88)70029-8 }}{{cite book|last=Gnann|first=John W. Jr.|title=Human herpesviruses: biology, therapy, and immunoprophylaxis|year=2007|publisher=Cambridge University Press|location=Cambridge|isbn=978-0-521-82714-0|chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK47401/|editor=Arvin, Ann|display-editors=etal|access-date=20 January 2014|chapter=Chapter 65Antiviral therapy of varicella-zoster virus infections|archive-date=29 September 2019|archive-url=https://web.archive.org/web/20190929163225/https://www.ncbi.nlm.nih.gov/books/NBK47401/|url-status=live}}

If aciclovir by mouth is started within 24 hours of rash onset, it decreases symptoms by one day but does not affect complication rates.{{cite journal | title = Allergy and allergic diseases. First of two parts | journal = The New England Journal of Medicine | volume = 344 | issue = 1 | pages = 30–37 | year = 2001 | pmid = 11136958 | doi = 10.1056/NEJM200101043440106 | last = Kay | first = A. B. }}{{cite journal | title = Allergy and allergic diseases. Second of two parts | journal = The New England Journal of Medicine | volume = 344 | issue = 2 | pages = 109–113 | year = 2001 | pmid = 11150362 | doi = 10.1056/NEJM200101113440206 | last = Kay | first = A. B.}} Use of aciclovir, therefore, is not currently recommended for individuals with normal immune function. Children younger than 12 years old and older than one month are not meant to receive antiviral drugs unless they have another medical condition that puts them at risk of developing complications.{{cite web |url=http://children.webmd.com/vaccines/antiviral-medications-for-chickenpox |title=Antiviral medications for chickenpox |access-date=27 March 2011 |url-status=dead |archive-url=https://web.archive.org/web/20101228111741/http://children.webmd.com/vaccines/antiviral-medications-for-chickenpox |archive-date=28 December 2010}}

Treatment of chickenpox in children is aimed at symptoms while the immune system deals with the virus. With children younger than 12 years, cutting fingernails and keeping them clean is an important part of treatment as they are more likely to scratch their blisters more deeply than adults.{{cite web|url=http://www.patient.info/health/Chickenpox-in-Children-Under-12.htm|title=Chickenpox in Children Under 12|access-date=6 November 2010|archive-date=29 August 2021|archive-url=https://web.archive.org/web/20210829185650/https://patient.info/skin-conditions/viral-rashes/chickenpox-in-children|url-status=live}}

Aspirin is highly contraindicated in children younger than 16 years, as it has been related to Reye syndrome.{{cite web |url=http://children.webmd.com/tc/reyes-syndrome-topic-overview |title=Reye's Syndrome-Topic Overview |access-date=27 March 2011 |url-status=live |archive-url=https://web.archive.org/web/20110405233431/http://children.webmd.com/tc/reyes-syndrome-topic-overview |archive-date=5 April 2011}}

Infection in otherwise healthy adults tends to be more severe.{{cite journal |vauthors=Tunbridge AJ, Breuer J, Jeffery KJ | title = Chickenpox in adults – clinical management | journal = The Journal of Infection | volume = 57 | issue = 2 | pages = 95–102 | date = August 2008 | pmid = 18555533 | doi = 10.1016/j.jinf.2008.03.004 }} Treatment with antiviral drugs (e.g. aciclovir or valaciclovir) is generally advised, as long as it is started within 24–48 hours from rash onset. Remedies to ease the symptoms of chickenpox in adults are generally the same as those used for children. Adults are more often prescribed antiviral medication, as it is effective in reducing the severity of the condition and the likelihood of developing complications. Adults are advised to increase water intake to reduce dehydration and relieve headaches. Painkillers such as paracetamol (acetaminophen) are recommended, as they are effective in relieving itching and other symptoms such as fever or pain. Antihistamines relieve itching and may be used in cases where the itching prevents sleep because they also act as a sedative. As with children, antiviral medication is considered more useful for those adults who are more prone to develop complications. These include pregnant women or people who have a weakened immune system.{{cite web|url=http://www.patient.info/health/Chickenpox-in-Adults-and-Teenagers.htm|title=What is chickenpox?|access-date=6 November 2010|archive-date=29 August 2021|archive-url=https://web.archive.org/web/20210829113905/https://patient.info/skin-conditions/viral-rashes/chickenpox-in-adults-and-teenagers|url-status=live}}

The duration of the visible blistering caused by varicella zoster virus varies in children usually from four to seven days, and the appearance of new blisters begins to subside after the fifth day. Chickenpox infection is milder in young children, and symptomatic treatment, with sodium bicarbonate baths or antihistamine medication may ease itching.

In adults, the disease is more severe,{{cite journal |vauthors=Baren JM, Henneman PL, Lewis RJ | title = Primary Varicella in Adults: Pneumonia, Pregnancy, and Hospital Admissions | journal = Annals of Emergency Medicine | volume = 28 | issue = 2 | pages = 165–169 | date = August 1996 | pmid = 8759580 | doi = 10.1016/S0196-0644(96)70057-4 | doi-access = free }} though the incidence is much less common. Infection in adults is associated with greater morbidity and mortality due to pneumonia (either direct viral pneumonia or secondary bacterial pneumonia),{{cite journal | vauthors = Mohsen AH, McKendrick M | title = Varicella pneumonia in adults | journal = Eur. Respir. J. | volume = 21 | issue = 5 | pages = 886–891 | date = May 2003 | pmid = 12765439 | doi = 10.1183/09031936.03.00103202| doi-access = free }} bronchitis (either viral bronchitis or secondary bacterial bronchitis), hepatitis,{{cite journal | last1 = Anderson | first1 = D.R. | last2 = Schwartz | first2 = J. | last3 = Hunter | first3 = N.J. | last4 = Cottrill | first4 = C. | last5 = Bissaccia | first5 = E. | last6 = Klainer | first6 = A.S. | title = Varicella Hepatitis: A Fatal Case in a Previously Healthy, Immunocompetent Adult | journal = Archives of Internal Medicine | volume = 154 | issue = 18 | pages = 2101–2106 | year = 1994 | doi = 10.1001/archinte.1994.00420180111013 | pmid = 8092915}} and encephalitis.{{cite journal | vauthors = Abro AH, Ustadi AM, Das K, Abdou AM, Hussaini HS, Chandra FS | title = Chickenpox: presentation and complications in adults | journal = Journal of Pakistan Medical Association | volume = 59 | issue = 12 | pages = 828–831 | date = December 2009 | pmid = 20201174 | url = http://www.jpma.org.pk/full_article_text.php?article_id=1873 | access-date = 17 April 2013 | url-status = live | archive-url = https://web.archive.org/web/20140520001048/http://www.jpma.org.pk/full_article_text.php?article_id=1873 | archive-date = 20 May 2014}} In particular, up to 10% of pregnant women with chickenpox develop pneumonia, the severity of which increases with onset later in gestation. In England and Wales, 75% of deaths due to chickenpox are in adults. Inflammation of the brain, encephalitis, can occur in immunocompromised individuals, although the risk is higher with herpes zoster.{{cite web | title=Definition of Chickenpox | url=http://www.medterms.com/script/main/art.asp?articlekey=2702 | publisher=MedicineNet.com | access-date=18 August 2006 | url-status=live | archive-url=https://web.archive.org/web/20060728121623/http://www.medterms.com/script/main/art.asp?articlekey=2702 | archive-date=28 July 2006}} Necrotizing fasciitis is also a rare complication.{{cite web| title=Is Necrotizing Fasciitis a complication of Chickenpox of Cutaneous Vasculitis?| url=http://www.atmedstu.com/exam%20plus/Is%20Necrotizing%20Fasciitis%20a%20complication%20of%20Chickenpox%20or%20of%20Cutaneous%20Vasculitis.php| publisher=atmedstu.com| access-date=18 January 2008| url-status=usurped| archive-url=https://web.archive.org/web/20080415040053/http://atmedstu.com/exam%20plus/Is%20Necrotizing%20Fasciitis%20a%20complication%20of%20Chickenpox%20or%20of%20Cutaneous%20Vasculitis.php| archive-date=15 April 2008}}

Varicella can be lethal to individuals with impaired immunity. The number of people in this high-risk group has increased, due to the HIV epidemic and the increased use of immunosuppressive therapies.{{cite journal |vauthors=Strangfeld A, Listing J, Herzer P, Liebhaber A, Rockwitz K, Richter C, Zink A | title = Risk of herpes zoster in patients with rheumatoid arthritis treated with anti-TNF-alpha agents | journal = JAMA | volume = 301 | issue = 7 | pages = 737–744 | date = February 2009 | pmid = 19224750 | doi = 10.1001/jama.2009.146 | doi-access = free }} Varicella is a particular problem in hospitals when there are patients with immune systems weakened by drugs (e.g., high-dose steroids) or HIV.{{cite book |author=Weller TH |chapter=Varicella-herpes zoster virus |title=Viral Infections of Humans: Epidemiology and Control |veditors=Evans AS, Kaslow RA |publisher=Plenum Press |year=1997 |pages=865–892 |isbn=978-0-306-44855-3}}

Secondary bacterial infection of skin lesions, manifesting as impetigo, cellulitis, and erysipelas, is the most common complication in healthy children. Disseminated primary varicella infection usually seen in the immunocompromised may have high morbidity. Ninety percent of cases of varicella pneumonia occur in the adult population. Rarer complications of disseminated chickenpox include myocarditis, hepatitis, and glomerulonephritis.[http://dermatology.about.com/cs/chickenpox/a/chickencomp.htm Chicken Pox Complications] {{webarchive|url=https://web.archive.org/web/20080428150919/http://dermatology.about.com/cs/chickenpox/a/chickencomp.htm |date=28 April 2008 }}

Hemorrhagic complications are more common in the immunocompromised or immunosuppressed populations, although healthy children and adults have been affected. Five major clinical syndromes have been described: febrile purpura, malignant chickenpox with purpura, postinfectious purpura, purpura fulminans, and anaphylactoid purpura. These syndromes have variable courses, with febrile purpura being the most benign of the syndromes and having an uncomplicated outcome. In contrast, malignant chickenpox with purpura is a grave clinical condition that has a mortality rate of greater than 70%. The cause of these hemorrhagic chickenpox syndromes is not known.

Primary varicella occurs in all countries worldwide. In 2015 chickenpox resulted in 6,400 deaths globally – down from 8,900 in 1990. There were 7,000 deaths in 2013. Varicella is highly transmissible, with an infection rate of 90% in close contacts.{{Cite web |last=CDC |date=11 August 2021 |title=Chickenpox for HCPs |url=https://www.cdc.gov/chickenpox/hcp/index.html |access-date=29 March 2022 |website=Centers for Disease Control and Prevention |language=en-us |archive-date=6 December 2011 |archive-url=https://web.archive.org/web/20111206225423/http://www.cdc.gov/chickenpox/hcp/index.html |url-status=live }}

In temperate countries, chickenpox is primarily a disease of children, with most cases occurring during the winter and spring, most likely due to school contact. In such countries it is one of the classic diseases of childhood, with most cases occurring in children up to age 15;{{Cite journal |last1=Di Pietrantonj |first1=Carlo |last2=Rivetti |first2=Alessandro |last3=Marchione |first3=Pasquale |last4=Debalini |first4=Maria Grazia |last5=Demicheli |first5=Vittorio |date=22 November 2021 |title=Vaccines for measles, mumps, rubella, and varicella in children |url= |journal=The Cochrane Database of Systematic Reviews |volume=2021 |issue=11 |pages=CD004407 |doi=10.1002/14651858.CD004407.pub5 |issn=1469-493X |pmc=8607336 |pmid=34806766}} most people become infected before adulthood, and 10% of young adults remain susceptible.

In the United States, a temperate country, the Centers for Disease Control and Prevention (CDC) do not require state health departments to report infections of chickenpox, and only 31 states volunteered this information {{As of|2013|lc=y}}.{{cite web|url=http://onlineathens.com/health/2013-06-13/georgia-ranks-10th-social-media-admissions-chickenpox|title=Georgia ranks 10th for social media admissions of chickenpox|access-date=13 June 2013|url-status=live|archive-url=https://web.archive.org/web/20130621234041/http://onlineathens.com/health/2013-06-13/georgia-ranks-10th-social-media-admissions-chickenpox|archive-date=21 June 2013}} A 2013 study conducted by the social media disease surveillance tool called Sickweather used anecdotal reports of chickenpox infections on social media systems Facebook and Twitter to measure and rank states with the most infections per capita, with Maryland, Tennessee and Illinois in the top three.{{cite web|url=http://www.sickweather.com/blog/post_061213.php|title=Chickenpox in the USA|access-date=12 June 2013|url-status=live|archive-url=https://web.archive.org/web/20130726160346/http://www.sickweather.com/blog/post_061213.php|archive-date=26 July 2013}}

In the tropics, chickenpox often occurs in older people and may cause more serious disease.{{cite journal | author = Wharton M | title = The epidemiology of varicella-zoster virus infections | journal = Infect Dis Clin North Am | volume = 10 | issue = 3 | pages = 571–581 | year = 1996 | pmid = 8856352 | doi = 10.1016/S0891-5520(05)70313-5 | url = https://zenodo.org/record/1260109 | access-date = 19 July 2019 | archive-date = 27 July 2020 | archive-url = https://web.archive.org/web/20200727225009/https://zenodo.org/record/1260109 | url-status = live }} In adults, the pockmarks are darker and the scars more prominent than in children.{{cite web|url=http://virology-online.com/viruses/VZV3.htm|title=Epidemiology of Varicella Zoster Virus Infection, Epidemiology of VZV Infection, Epidemiology of Chicken Pox, Epidemiology of Shingles|access-date=22 April 2008|url-status=live|archive-url=https://web.archive.org/web/20080613001717/http://virology-online.com/viruses/VZV3.htm|archive-date=13 June 2008}}

How the term chickenpox originated is not clear but it may be due to it being a relatively mild disease. It has been said to be derived from chickpeas, based on resemblance of the vesicles to chickpeas,{{cite book |author=Belshe, Robert B. |title=Textbook of human virology |publisher=PSG |location=Littleton, MA |year=1984 |isbn=978-0-88416-458-6 |page=829 |edition=2nd}}{{cite book |author=Teri Shors |chapter=Herpesviruses: Varicella Zoster Virus (VZV) |title=Understanding Viruses |chapter-url=https://books.google.com/books?id=Uk8xP5LRHr4C&pg=PA459 |year=2011 |publisher=Jones & Bartlett |isbn=978-0-7637-8553-6 |page=[https://archive.org/details/understandingvir0000shor/page/459 459] |edition=2nd |url=https://archive.org/details/understandingvir0000shor/page/459 }} or to come from the rash resembling chicken pecks. Other suggestions include the designation chicken for a child (i.e., literally 'child pox'), a corruption of itching-pox,{{cite book |author1=Pattison, John |author2=Zuckerman, Arie J. |author3=Banatvala, J.E. |title=Principles and practice of clinical virology |publisher=Wiley |year=1994 |page=37 |isbn=978-0-471-93106-5 |edition=3rd }} or the idea that the disease may have originated in chickens.Chicken-pox is recorded in Oxford English Dictionary 2nd ed. since 1684; the OED records several suggested etymologies Samuel Johnson explained the designation as "from its being of no very great danger".{{cite book |author=Johnson, Samuel |title=Dictionary of the English language |publisher=Williamson |location=London |year=1839 |page=195 }}

Because chickenpox is usually more severe in adults than it is in children, some parents deliberately expose their children to the virus, for example by taking them to "chickenpox parties". Doctors say that children are safer getting the vaccine, which is a weakened form of the virus, than getting the disease, which can be fatal or lead to shingles later in life.{{cite news | title=Doctors say Kentucky Gov. Matt Bevin is wrong about 'chickenpox on purpose' | website=NBC News | date=22 March 2019 | url=https://www.nbcnews.com/health/kids-health/doctors-say-kentucky-gov-matt-bevin-wrong-about-chickenpox-purpose-n986091 | access-date=22 March 2019 | first=Shamard | last=Charles | quote=Chickenpox parties were once a popular way for parents to expose their children to the virus so they would get sick, recover and build up immunity to the disease. ... Most doctors believe that deliberately infecting a child with the full-blown virus is a bad idea. While chickenpox is mild for most children, it can be a dangerous virus for others – and there's no way to know which child will have a serious case, experts say. | archive-date=17 August 2020 | archive-url=https://web.archive.org/web/20200817184257/https://www.nbcnews.com/health/kids-health/doctors-say-kentucky-gov-matt-bevin-wrong-about-chickenpox-purpose-n986091 | url-status=live }}{{cite web |title=Chicken Pox parties do more harm than good, says doctor |publisher=KSLA News 12 Shreveport, Louisiana News Weather & Sports |url=http://www.ksla.com/story/16317324/chicken-pox-parties-do-more-harm-than-good-says-doctor |url-status=dead |archive-url=https://web.archive.org/web/20120127173602/http://www.ksla.com/story/16317324/chicken-pox-parties-do-more-harm-than-good-says-doctor |archive-date=27 January 2012|access-date=17 December 2011 }}{{cite book |title=Adverse Effects of Vaccines: Evidence and Causality.

|year=2011 |doi=10.17226/13164 |pmid=24624471|isbn=978-0-309-21435-3 |author1=Committee to Review Adverse Effects of Vaccines |last2=Institute of |first2=Medicine |last3=Stratton |first3=K. |last4=Ford |first4=A. |last5=Rusch |first5=E. |last6=Clayton |first6=E. W. |s2cid=67935593 }} Repeated exposure to chickenpox may protect against zoster.{{cite journal |last1=Ogunjimi |first1=B |last2=Van Damme |first2=P |last3=Beutels |first3=P |title=Herpes Zoster Risk Reduction through Exposure to Chickenpox Patients: A Systematic Multidisciplinary Review. |journal=PLOS ONE |date=2013 |volume=8 |issue=6 |pages=e66485 |doi=10.1371/journal.pone.0066485 |pmid=23805224|pmc=3689818 |bibcode=2013PLoSO...866485O |doi-access=free }}

Humans are the only known species that the disease affects naturally. However, chickenpox has been caused in animals, including chimpanzees{{cite journal | vauthors = Cohen JI, Moskal T, Shapiro M, Purcell RH | title = Varicella in Chimpanzees | journal = Journal of Medical Virology | volume = 50 | issue = 4 | pages = 289–292 | date = December 1996 | pmid = 8950684 | doi = 10.1002/(SICI)1096-9071(199612)50:4<289::AID-JMV2>3.0.CO;2-4 | s2cid = 28842789 | url = https://zenodo.org/record/1235476 | access-date = 19 July 2019 | archive-date = 27 July 2020 | archive-url = https://web.archive.org/web/20200727214030/https://zenodo.org/record/1235476 | url-status = live }} and gorillas.{{cite journal|vauthors=Myers MG, Kramer LW, Stanberry LR | title = Varicella in a gorilla | journal = Journal of Medical Virology | volume = 23 | issue = 4 | pages = 317–322 | date = December 1987 | pmid = 2826674 | doi = 10.1002/jmv.1890230403 | s2cid = 84875752 }}

Sorivudine, a nucleoside analog, has been reported to be effective in the treatment of primary varicella in healthy adults (case reports only), but large-scale clinical trials are still needed to demonstrate its efficacy.{{Cite journal|title=Chickenpox Treatment & Management: Approach Considerations, Treatment in Healthy Children, Treatment in Immunocompetent Adults|website=Medscape emedicine|date=3 June 2022|url=https://emedicine.medscape.com/article/1131785-treatment#d10|url-access=registration|access-date=12 July 2022|archive-date=12 July 2022|archive-url=https://web.archive.org/web/20220712214850/https://emedicine.medscape.com/article/1131785-treatment#d10|url-status=live}} There was speculation in 2005 that continuous dosing of aciclovir by mouth for a period of time could eradicate VZV from the host, although further trials were required to discern whether eradication was actually viable.{{Cite journal|last1=Klassen |first1=TP |last2=Hartling |first2=L. |s2cid=11018303 |title=Acyclovir for treating varicella in otherwise healthy children and adolescents |journal=Cochrane Database of Systematic Reviews |year=2005 |volume=2011 |issue=4 |pages=CD002980 |doi=10.1002/14651858.CD002980.pub3 |pmid=16235308 |pmc=8407192 }}

• Measles

{{Reflist}}

{{Commons}}

{{offline|med}}

• [https://www.cdc.gov/mmwr/preview/mmwrhtml/00042990.htm Prevention of Varicella: Recommendations of the Advisory Committee on Immunization Practices (ACIP)], 1996
• [https://www.ncbi.nlm.nih.gov/books/NBK47401/ Antiviral therapy of varicella-zoster virus infections], 2007
• [https://www.cdc.gov/vaccines/pubs/pinkbook/downloads/varicella.pdf Epidemiology and Prevention of Vaccine-Preventable Diseases: Varicella], US CDC's "Pink Book"
• [https://medlineplus.gov/chickenpox.html Chickenpox] at MedlinePlus

{{Medical condition classification and resources

|ICD11 = {{ICD11|1E90 }}

|ICD10 = {{ICD10|B|01| |b|00}}

|ICD9 = {{ICD9|052}}

|DiseasesDB = 29118

|ICDO =

|OMIM =

|MedlinePlus = 001592

|eMedicineSubj = ped

|eMedicineTopic = 2385

|eMedicine_mult = {{eMedicine2|derm|74}}, {{eMedicine2|emerg|367}}

|MeshName = Chickenpox

|MeshNumber = C02.256.466.175

}}

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{{Diseases of the skin and appendages by morphology}}

{{Viral cutaneous conditions}}

{{Varicella zoster}}

{{Authority control}}

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