Q fever

The incubation period is usually two to three weeks. The most common manifestation is flu-like symptoms: abrupt onset of fever, malaise, profuse perspiration, severe headache, muscle pain, joint pain, loss of appetite, upper respiratory problems, dry cough, pleuritic pain, chills, confusion, and gastrointestinal symptoms, such as nausea, vomiting, and diarrhea. About half of infected individuals exhibit no symptoms.{{cite book|chapter=Q Fever| veditors = Brunette GW, McQuiston J, etal |title=CDC Health Information for International Travel: The Yellow Book|publisher=Oxford University Press|year=2011|isbn=978-0-19-976901-8|page=[https://archive.org/details/cdchealthinforma0000unse/page/270 270]|chapter-url=https://books.google.com/books?id=5vCQpr1WTS8C&pg=PA270| vauthors = Anderson A |url-access=registration|url=https://archive.org/details/cdchealthinforma0000unse/page/270}}

During its course, the disease can progress to an atypical pneumonia, which can result in a life-threatening acute respiratory distress syndrome, usually occurring during the first four to five days of infection.{{cite web|title=Coxiella/Q Fever|url=https://www.lecturio.com/concepts/coxiella-q-fever/|url-status=live|archive-url=https://web.archive.org/web/20210515174110/https://www.lecturio.com/concepts/coxiella-q-fever/|archive-date=2021-05-15|access-date=7 July 2021|website=The Lecturio Medical Concept Library}}

Less often, Q fever causes (granulomatous) hepatitis, which may be asymptomatic or become symptomatic with malaise, fever, liver enlargement, and pain in the right upper quadrant of the abdomen. This hepatitis often results in the elevation of transaminase values, although jaundice is uncommon. Q fever can also rarely result in retinal vasculitis.{{cite journal | vauthors = Kuhne F, Morlat P, Riss I, Dominguez M, Hostyn P, Carniel N, Paix MA, Aubertin J, Raoult D, Le Rebeller MJ | display-authors = 6 | title = [Is A29, B12 vasculitis caused by the Q fever agent? (Coxiella burnetii)] | language = fr | journal = Journal Français d'Ophtalmologie | volume = 15 | issue = 5 | pages = 315–321 | date = 1992 | pmid = 1430809 | trans-title = Is A29, B12 vasculitis caused by the Q fever agent? (Coxiella burnetii) | oclc = 116712679 }}

The chronic form of Q fever is virtually identical to endocarditis (i.e. inflammation of the inner lining of the heart),{{cite journal | vauthors = Karakousis PC, Trucksis M, Dumler JS | title = Chronic Q fever in the United States | journal = Journal of Clinical Microbiology | volume = 44 | issue = 6 | pages = 2283–2287 | date = June 2006 | pmid = 16757641 | pmc = 1489455 | doi = 10.1128/JCM.02365-05 }} which can occur months or decades following the infection. It is usually fatal if untreated. However, with appropriate treatment, the mortality falls to around 10%.{{citation needed|date=May 2021}}

A minority of Q fever survivors develop Q fever fatigue syndrome after acute infection, one of the more well-studied post-acute infection syndromes. Q fever fatigue syndrome is characterised by post-exertional malaise and debilitating fatigue. People with Q fever fatigue syndrome frequently meet the diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Symptoms often persist years after the initial infection.{{cite journal |vauthors=Choutka J, Jansari V, Hornig M, Iwasaki A |date=May 2022 |title=Unexplained post-acute infection syndromes |url= |journal=Nature Medicine |volume=28 |issue=5 |pages=911–923 |doi=10.1038/s41591-022-01810-6 |pmid=35585196|s2cid=248889597 |doi-access=free }}

File:Q fever management algorithm.gif]]

Diagnosis is usually based on serology{{cite journal | vauthors = Maurin M, Raoult D | title = Q fever | journal = Clinical Microbiology Reviews | volume = 12 | issue = 4 | pages = 518–553 | date = October 1999 | pmid = 10515901 | pmc = 88923 | doi = 10.1128/CMR.12.4.518 }}{{cite journal | vauthors = Scola BL | title = Current laboratory diagnosis of Q fever | journal = Seminars in Pediatric Infectious Diseases | volume = 13 | issue = 4 | pages = 257–262 | date = October 2002 | pmid = 12491231 | doi = 10.1053/spid.2002.127199 }} (looking for an antibody response) rather than looking for the organism itself. Serology allows the detection of chronic infection by the appearance of high levels of the antibody against the virulent form of the bacterium. Molecular detection of bacterial DNA is increasingly used. Contrary to most obligate intracellular parasites, Coxiella burnetii can be grown in an axenic culture, but its culture is technically difficult and not routinely available in most microbiology laboratories.{{cite journal | vauthors = Omsland A, Cockrell DC, Howe D, Fischer ER, Virtaneva K, Sturdevant DE, Porcella SF, Heinzen RA | display-authors = 6 | title = Host cell-free growth of the Q fever bacterium Coxiella burnetii | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 11 | pages = 4430–4434 | date = March 2009 | pmid = 19246385 | pmc = 2657411 | doi = 10.1073/pnas.0812074106 | doi-access = free | bibcode = 2009PNAS..106.4430O }}

Q fever can cause infective endocarditis (infection of the heart valves), which may require transoesophageal echocardiography to diagnose. Q fever hepatitis manifests as an elevation of alanine transaminase and aspartate transaminase, but a definitive diagnosis is only possible on liver biopsy, which shows the characteristic fibrin ring granulomas.{{cite journal|vauthors=van de Veerdonk FL, Schneeberger PM|date= May 2006 |title=Patient with fever and diarrhea|journal=Clinical Infectious Diseases|volume=42|issue=7|pages=1051–2|doi=10.1086/501027|doi-access=free}}

Research done in the 1960s{{ndash}}1970s by French Canadian-American microbiologist and virologist Paul Fiset was instrumental in the development of the first successful Q fever vaccine.{{cite news| vauthors = Saxon W |date=March 8, 2001|title=Dr. Paul Fiset, 78, Microbiologist And Developer of Q Fever Vaccine|page=C-17|newspaper=The New York Times|url=https://www.nytimes.com/2001/03/08/us/dr-paul-fiset-78-microbiologist-and-developer-of-q-fever-vaccine.html|url-status=live|access-date=2022-01-28|archive-url=https://web.archive.org/web/20150527155503/https://www.nytimes.com/2001/03/08/us/dr-paul-fiset-78-microbiologist-and-developer-of-q-fever-vaccine.html|archive-date=2015-05-27}}

Protection is offered by Q-Vax, a whole-cell, inactivated vaccine developed by an Australian vaccine manufacturing company, CSL Limited.{{cite web|date=17 January 2014|title=Q fever Vaccine|url=http://www.csl.com.au/docs/39/836/Q-Vax_PI_V4_TGA-Approved-17%20January%202014.pdf|url-status=dead|archive-url=https://web.archive.org/web/20170309080855/http://www.csl.com.au/docs/39/836/Q-Vax_PI_V4_TGA-Approved-17%20January%202014.pdf|archive-date=9 March 2017|access-date=11 July 2015|website=CSL Limited}} The intradermal vaccination is composed of killed C. burnetii organisms. Skin and blood tests should be done before vaccination to identify pre-existing immunity because vaccinating people who already have immunity can result in a severe local reaction. After a single dose of vaccine, protective immunity lasts for many years. Revaccination is not generally required. Annual screening is typically recommended.{{cite web |url=http://cdp.ucsf.edu/fileUpload/UCSF_CDP_Q_Fever_Surveillance_Policy_Q_Neg_Wethers.pdf |title=USCF communicable disease prevention program animal exposure surveillance program |access-date=2007-05-08 |url-status=dead |archive-url=https://web.archive.org/web/20070701075855/http://cdp.ucsf.edu/fileUpload/UCSF_CDP_Q_Fever_Surveillance_Policy_Q_Neg_Wethers.pdf |archive-date=2007-07-01 }}

In 2001, Australia introduced a national Q fever vaccination program for people working in "at-risk" occupations. Vaccinated or previously exposed people may have their status recorded on the Australian Q Fever Register,{{cite web|title=Australian Q Fever Register|url=https://www.qfever.org|url-status=live|archive-url=https://web.archive.org/web/20160216183213/https://www.qfever.org/|archive-date=2016-02-16|access-date=12 February 2016|publisher=AusVet}} which may be a condition of employment in the meat processing industry or in veterinary research.{{Cite web|date=2019-11-20|title=Q-Fever Vaccinations|url=https://fvas.unimelb.edu.au/students/general/q-fever|url-status=live|archive-url=https://web.archive.org/web/20190625021440/https://fvas.unimelb.edu.au/students/admin/q-fever|archive-date=2019-06-25|access-date=2020-07-11|website=Faculty of Veterinary and Agricultural Sciences {{!}} The University of Melbourne|language=en}} An earlier killed vaccine had been developed in the Soviet Union, but its side effects prevented its licensing abroad.{{citation needed|date=November 2020}}

Preliminary results suggest vaccination of animals may be a method of control. Published trials proved that use of a registered phase vaccine (Coxevac) on infected farms is a tool of major interest to manage or prevent early or late abortion, repeat breeding, anoestrus, silent oestrus, metritis, and decreases in milk yield when C. burnetii is the major cause of these problems.{{cite conference | vauthors = Camuset P, Remmy D |title=Q Fever (Coxiella burnetii) Eradication in a Dairy Herd by Using Vaccination with a Phase 1 Vaccine| conference =XXV World Buiatrics Congress|year=2008|location=Budapest}}{{cite journal | vauthors = Hogerwerf L, van den Brom R, Roest HI, Bouma A, Vellema P, Pieterse M, Dercksen D, Nielen M | display-authors = 6 | title = Reduction of Coxiella burnetii prevalence by vaccination of goats and sheep, The Netherlands | journal = Emerging Infectious Diseases | volume = 17 | issue = 3 | pages = 379–386 | date = March 2011 | pmid = 21392427 | pmc = 3166012 | doi = 10.3201/eid1703.101157 }}

Q fever is primarily transmitted to humans through inhalation of aerosols contaminated with Coxiella burnetii from infected animals, notably cattle, sheep, and goats. Occupational groups such as farmers, veterinarians, and abattoir workers are at heightened risk. Preventive strategies include:{{Cite web |last=CDC |date=2025-03-05 |title=Clinical Guidance for Q fever |url=https://www.cdc.gov/q-fever/hcp/clinical-guidance/index.html?utm_source=chatgpt.com |access-date=2025-03-23 |website=Q Fever |language=en-us}}

• Vaccination: In countries like Australia, where Q fever is endemic, vaccination programs targeting high-risk populations have been implemented. The vaccine has proven effective in reducing the incidence of the disease among these groups. CDC
• Hygiene Measures: Implementing strict biosecurity and hygiene practices in livestock handling facilities can minimize environmental contamination. This includes proper disposal of animal waste and birthing products, which are known to harbor high concentrations of bacteria.
• Public Awareness: Educating at-risk populations about Q fever transmission, symptoms, and preventive measures is crucial. Awareness campaigns can lead to early diagnosis and treatment, thereby reducing complications associated with the disease.

Treatment of acute Q fever with antibiotics is very effective. Commonly used antibiotics include doxycycline, tetracycline, chloramphenicol, ciprofloxacin, and ofloxacin; the antimalarial drug hydroxychloroquine is also used. Chronic Q fever is more difficult to treat and can require up to four years of treatment with doxycycline and quinolones or doxycycline with hydroxychloroquine. If a person has chronic Q fever, doxycycline and hydroxychloroquine will be prescribed for at least 18 months. Q fever in pregnancy is especially difficult to treat because doxycycline and ciprofloxacin are contraindicated in pregnancy. The preferred treatment for pregnancy and children under the age of eight is co-trimoxazole.{{cite journal | vauthors = Carcopino X, Raoult D, Bretelle F, Boubli L, Stein A | title = Managing Q fever during pregnancy: the benefits of long-term cotrimoxazole therapy | journal = Clinical Infectious Diseases | volume = 45 | issue = 5 | pages = 548–555 | date = September 2007 | pmid = 17682987 | doi = 10.1086/520661 | doi-access = free }}{{Cite web|date=20 July 2021|title=Query Fever - MARI REF|url=https://mariref.com/query-fever-professional/|url-status=live|archive-url=https://web.archive.org/web/20210827163844/https://mariref.com/query-fever-professional/|archive-date=2021-08-27|access-date=2021-08-27|website=Misdiagnosis Association and Research Institute|language=en-US}}

Image:Coxiella burnetii 01.JPG

Q fever is a globally distributed zoonotic disease caused by a highly sustainable and virulent bacterium. The pathogenic agent is found worldwide, except New Zealand{{cite journal |vauthors=Cutler SJ, Bouzid M, Cutler RR |date=April 2007 |title=Q fever |journal=The Journal of Infection |volume=54 |issue=4 |pages=313–318 |doi=10.1016/j.jinf.2006.10.048 |pmid=17147957}} and Antarctica.{{Cite journal |last1=Salifu |first1=Samson Pandam |last2=Bukari |first2=Abdul-Rahman Adamu |last3=Frangoulidis |first3=Dimitrios |last4=Wheelhouse |first4=Nick |date=2019-05-01 |title=Current perspectives on the transmission of Q fever: Highlighting the need for a systematic molecular approach for a neglected disease in Africa |url=https://www.sciencedirect.com/science/article/pii/S0001706X19300889 |journal=Acta Tropica |volume=193 |pages=99–105 |doi=10.1016/j.actatropica.2019.02.032 |pmid=30831112 |s2cid=73461378 |issn=0001-706X}} Understanding the transmission and risk factors of Q fever is crucial for public health due to its potential to cause widespread infection.

Recent data indicate that Q fever remains a significant public health concern worldwide. In 2019, the United States reported 178 acute Q fever cases and 34 chronic cases. Notably, in 2024, the state of Victoria, Australia, experienced a marked increase in Q fever cases, with 77 reported instances—a significant rise compared to the previous five years. This surge prompted health authorities to issue alerts emphasizing the importance of preventive measures and awareness.{{Cite web |last=CDC |date=2024-05-20 |title=Epidemiology and Statistics |url=https://www.cdc.gov/q-fever/data-research/index.html?utm_source=chatgpt.com |access-date=2025-03-23 |website=Q Fever |language=en-us}}

Transmission primarily occurs through the inhalation of contaminated dust, contact with contaminated milk, meat, or wool, and particularly birthing products. Ticks can transfer the pathogenic agent to other animals. While human-to-human transmission is rare, often associated with the transmission of birth products, sexual contact, and blood transfusion, certain occupations pose higher risks for Q fever:{{Cite web |title=Q fever: MedlinePlus Medical Encyclopedia |url=https://medlineplus.gov/ency/article/000611.htm |url-status=live |archive-url=https://web.archive.org/web/20160728022742/https://medlineplus.gov/ency/article/000611.htm |archive-date=2016-07-28 |access-date=2018-04-17 |website=MedlinePlus |language=en}}

• Veterinary personnel
• Stockyard workers
• Farmers
• Sheep shearers
• Animal transporters
• Laboratory workers handling potentially infected veterinary samples or visiting abattoirs
• People who cull and process kangaroos
• Hide (tannery) workers

It is important to note that anyone who has contact with animals infected with Q fever bacteria, especially people who work on farms or with animals, is at an increased risk of contracting the disease.{{Cite web |last=CDC |date=2021-08-06 |title=Q fever epidemiology and statistics {{!}} CDC |url=https://www.cdc.gov/qfever/stats/index.html |access-date=2023-11-21 |website=Centers for Disease Control and Prevention |language=en-us}} Understanding these occupational risks is crucial for public health.

Studies indicate a higher prevalence of Q fever in men than in women,{{cite journal |vauthors=Domingo P, Muñoz C, Franquet T, Gurguí M, Sancho F, Vazquez G |date=October 1999 |title=Acute Q fever in adult patients: report on 63 sporadic cases in an urban area |journal=Clinical Infectious Diseases |volume=29 |issue=4 |pages=874–879 |doi=10.1086/520452 |pmid=10589906 |doi-access=free}}{{cite journal |vauthors=Dupuis G, Petite J, Péter O, Vouilloz M |date=June 1987 |title=An important outbreak of human Q fever in a Swiss Alpine valley |journal=International Journal of Epidemiology |volume=16 |issue=2 |pages=282–287 |doi=10.1093/ije/16.2.282 |pmid=3301708}} potentially linked to occupational exposure rates.{{Cite web |date=2019-09-16 |title=Epidemiology and Statistics {{!}} Q Fever {{!}} CDC |url=https://www.cdc.gov/qfever/stats/index.html |url-status=live |archive-url=https://web.archive.org/web/20200529130025/https://www.cdc.gov/qfever/stats/index.html |archive-date=2020-05-29 |access-date=2020-05-27 |website=www.cdc.gov |language=en-us}} Other contributing risk factors include geography, age, and occupational exposure. Diagnosis relies on blood compatibility testing, with treatment varying for acute and chronic cases. Acute disease often responds to doxycycline, while chronic cases may require a combination of doxycycline and hydroxychloroquine.{{Cite journal |last1=Hartzell |first1=Joshua D. |last2=Wood-Morris |first2=Robert N. |last3=Martinez |first3=Luis J. |last4=Trotta |first4=Richard F. |date=May 2008 |title=Q Fever: Epidemiology, Diagnosis, and Treatment |journal=Mayo Clinic Proceedings |volume=83 |issue=5 |pages=574–579 |doi=10.4065/83.5.574 |issn=0025-6196|doi-access=free |pmid=18452690 }} It is worth noting that Q fever was officially reported in the United States as a notifiable disease in 1999 due to its potential biowarfare agent status.{{Citation |last1=Patil |first1=Sachin M. |title=Q Fever |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK556095/ |work=StatPearls |access-date=2023-11-21 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32310555 |last2=Regunath |first2=Hariharan}}

Q fever exhibits global epidemiological patterns, with higher incidence rates reported in certain countries. In Africa, wild animals in rainforests primarily transmit the disease, making it endemic. Unique patterns are observed in Latin America, but reporting is sporadic and inconsistent between and among countries, making it difficult to track and address.{{Cite journal |last1=Fernandes |first1=Jorlan |last2=Sampaio de Lemos |first2=Elba Regina |date=2023-04-01 |title=The multifaceted Q fever epidemiology: a call to implement One Health approach in Latin America |journal=The Lancet Regional Health - Americas |volume=20 |pages=100463 |doi=10.1016/j.lana.2023.100463 |issn=2667-193X |pmc=10006848 |pmid=36915670}}

Recent outbreaks in European countries, including the Netherlands and France, have been linked to urbanized goat farming, raising concerns about the safety of intensive livestock farming practices and the potential risks of zoonotic diseases. Similarly, in the United States, Q fever is more common in livestock farming regions, especially in the West and the Great Plains. California, Texas, and Iowa account for almost 40% of reported cases, with a higher incidence during the spring and early summer when livestock are breeding, regardless of whether the infection is acute or chronic.

These outbreaks have affected a significant number of people, with immunocompromised individuals being more severely impacted. The global nature of Q fever and its association with livestock farming highlight the importance of implementing measures to prevent and control the spread of the disease, particularly in high-risk regions.

Older men in the West and Great Plains regions, involved in close contact with livestock management, are at a higher risk of contracting chronic Q fever. This risk may be further increased for those with a history of cardiac problems. The disease can manifest years after the initial infection, presenting symptoms such as non-specific fatigue, fever, weight loss, and endocarditis. Additionally, certain populations are more vulnerable to Q fever, including children living in farming communities, who may experience similar symptoms as adults.{{Cite journal |last1=Bwatota |first1=Shedrack Festo |last2=Cook |first2=Elizabeth Anne Jessie |last3=de Clare Bronsvoort |first3=Barend Mark |last4=Wheelhouse |first4=Nick |last5=Hernandez-Castor |first5=Luis E |last6=Shirima |first6=Gabriel Mkilema |date=2022-11-17 |title=Epidemiology of Q-fever in domestic ruminants and humans in Africa. A systematic review |journal=CABI One Health |language=en |doi=10.1079/cabionehealth.2022.0008 |s2cid=253662234 |issn=2791-223X|doi-access=free |hdl=20.500.11820/8b572652-80f8-4983-a0f0-c2586c7d1b9e |hdl-access=free }} There have also been reported cases of Q fever among United States military service members,{{cite web |last1=Anderson |first1=Alicia D. |last2=Smoak |first2=Bonnie |last3=Shuping |first3=Eric |last4=Ockenhouse |first4=Christopher |last5=Petruccelli |first5=Bruno |title=Q Fever and the US Military - Volume 11, Number 8—August 2005 - Emerging Infectious Diseases journal - CDC |url=https://wwwnc.cdc.gov/eid/article/11/8/05-0314_article |language=en-us |doi=10.3201/eid1108.050314|pmid=16110586 }} particularly those deployed to Iraq or Afghanistan, which further highlights the importance of understanding and addressing the occupational risks associated with Q fever.{{Cite journal |last=Hartzell |first=Joshua |date=May 2008 |title=Q Fever: Epidemiology, Diagnosis, and Treatment |journal=Concise Review for Physicians |volume=83 |issue=5 |pages=574–579|doi=10.4065/83.5.574 |pmid=18452690 }}

Proper public health education is crucial in reducing the number of Q fever cases. Raising awareness about transmission routes, occupational risks, and preventive measures, such as eliminating unpasteurized milk products from the diet, can help prevent the spread of disease.{{Cite web |author=((CDC))|date=2019-01-15 |title=Prevention of Q fever {{!}} CDC |url=https://www.cdc.gov/qfever/prevention/index.html |access-date=2023-12-12 |website=Centers for Disease Control and Prevention |language=en-us}}

Interdisciplinary collaboration between medical personnel and farmers is critical when developing strategies for control and prevention in a community.{{Cite journal |last1=Ullah |first1=Qudrat |last2=Jamil |first2=Tariq |last3=Saqib |first3=Muhammad |last4=Iqbal |first4=Mudassar |last5=Neubauer |first5=Heinrich |date=2022-07-28 |title=Q Fever—A Neglected Zoonosis |journal=Microorganisms |volume=10 |issue=8 |pages=1530 |doi=10.3390/microorganisms10081530 |issn=2076-2607 |pmc=9416428 |pmid=36013948 |doi-access=free }} Awareness campaigns should particularly target occupations that work with livestock, focusing on risk-reduction procedures such as herd monitoring, implementing sanitation practices and personal protective equipment, and vaccinating animals. Locating livestock farms at least 500 meters away from residential areas can also help reduce animal-to-human transmission.

Image:Pneumonia x-ray.jpg Image B: Q fever pneumonia]]

Q fever was first described in 1935 by Edward Holbrook Derrick{{cite journal| vauthors = Derrick EH |date=August 1937|title='Q' Fever a new fever entity: clinical features. diagnosis, and laboratory investigation|url=https://onlinelibrary.wiley.com/doi/abs/10.5694/j.1326-5377.1937.tb43743.x|journal=Medical Journal of Australia|volume=2|issue=8|pages=281–299|doi=10.5694/j.1326-5377.1937.tb43743.x|url-access=subscription}} in slaughterhouse workers in Brisbane, Queensland. The "Q" stands for "query" and was applied at a time when the causative agent was unknown; it was chosen over suggestions of abattoir fever and Queensland rickettsial fever, to avoid directing negative connotations at either the cattle industry or the state of Queensland.{{cite book| vauthors = McDade JE |title=Q Fever: The Disease | volume = I|publisher=CRC Press|year=1990|isbn=978-0-8493-5984-2|page=8|language=en|chapter=Historical aspects of Q Fever}}

The pathogen of Q fever was discovered in 1937, when Frank Macfarlane Burnet and Mavis Freeman isolated the bacterium from one of Derrick's patients.{{cite journal | vauthors = Burnet FM, Freeman M | title = Experimental studies on the virus of "Q" fever | journal = Reviews of Infectious Diseases | volume = 5 | issue = 4 | pages = 800–808 | date = 1 July 1983 | pmid = 6194551 | doi = 10.1093/clinids/5.4.800 }} It was originally identified as a species of Rickettsia. H.R. Cox and Gordon Davis elucidated the transmission when they isolated it from ticks found in the US state of Montana in 1938.{{cite journal | vauthors = | title = Public Health Weekly Reports for DECEMBER 30, 1938 | journal = Public Health Reports | volume = 53 | issue = 52 | pages = 2259–2309 | date = December 1938 | pmid = 19315693 | doi = 10.2307/4582746 | jstor = 4582746 | pmc = 2110862 }} It is a zoonotic disease whose most common animal reservoirs are cattle, sheep, and goats. Coxiella burnetii – named for Cox and Burnet – is no longer regarded as closely related to the Rickettsiae, but as similar to Legionella and Francisella, and is a Gammaproteobacterium.{{citation needed|date=July 2020}}

An early mention of Q fever was important in one of the early Dr. Kildare films (1939, Calling Dr. Kildare). Kildare's mentor Dr. Gillespie (Lionel Barrymore) tires of his protégé working fruitlessly on "exotic diagnoses" ("I think it's Q fever!") and sends him to work in a neighborhood clinic, instead.{{cite web|title=Calling Dr. Kildare|url=http://www.san.beck.org/MM/1939/CallingDrKildare.html|url-status=live|archive-url=https://web.archive.org/web/20120204042757/http://www.san.beck.org/MM/1939/CallingDrKildare.html|archive-date=2012-02-04|access-date=30 April 2013|publisher=Movie Mirrors Index}}{{cite journal | vauthors = Kalisch PA, Kalisch BJ | title = When Americans called for Dr. Kildare: images of physicians and nurses in the Dr. Kildare and Dr. Gillespie movies, 1937-1947 | journal = Medical Heritage | volume = 1 | issue = 5 | pages = 348–363 | date = September 1985 | pmid = 11616027 | url = http://www.truthaboutnursing.org/images/kalisch/when_americans_called_dr_kildare.pdf | url-status = live | archive-url = https://web.archive.org/web/20101130235053/https://www.truthaboutnursing.org/images/kalisch/when_americans_called_dr_kildare.pdf | archive-date = 2010-11-30 }}

C. burnetii has been used to develop biological weapons.{{cite journal | vauthors = Madariaga MG, Rezai K, Trenholme GM, Weinstein RA | title = Q fever: a biological weapon in your backyard | journal = The Lancet. Infectious Diseases | volume = 3 | issue = 11 | pages = 709–721 | date = November 2003 | pmid = 14592601 | doi = 10.1016/S1473-3099(03)00804-1 }}

The United States investigated it as a potential biological warfare agent in the 1950s, with eventual standardization as agent OU. At Fort Detrick and Dugway Proving Ground, human trials were conducted on Whitecoat volunteers to determine the median infective dose (18 MICLD₅₀/person i.h.) and course of infection. The Deseret Test Center dispensed biological Agent OU with ships and aircraft, during Project 112 and Project SHAD.{{Cite web|url=https://www.health.mil/Reference-Center/Fact-Sheets/2003/12/02/Shady-Grove-Revised|title=Deseret Test Center, Project SHAD, Shady Grove revised fact sheet}} As a standardized biological, it was manufactured in large quantities at Pine Bluff Arsenal, with 5,098 gallons in the arsenal in bulk at the time of demilitarization in 1970.{{citation needed|date=January 2023}}

C. burnetii is currently ranked as a "category B" bioterrorism agent by the CDC.{{cite journal | vauthors = Seshadri R, Paulsen IT, Eisen JA, Read TD, Nelson KE, Nelson WC, Ward NL, Tettelin H, Davidsen TM, Beanan MJ, Deboy RT, Daugherty SC, Brinkac LM, Madupu R, Dodson RJ, Khouri HM, Lee KH, Carty HA, Scanlan D, Heinzen RA, Thompson HA, Samuel JE, Fraser CM, Heidelberg JF | display-authors = 6 | title = Complete genome sequence of the Q-fever pathogen Coxiella burnetii | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 100 | issue = 9 | pages = 5455–5460 | date = April 2003 | pmid = 12704232 | pmc = 154366 | doi = 10.1073/pnas.0931379100 | bibcode = 2003PNAS..100.5455S | doi-access = free }} It can be contagious and is very stable in aerosols in a wide range of temperatures. Q fever microorganisms may survive on surfaces for up to 60 days. It is considered a good agent in part because its ID₅₀ (number of bacilli needed to infect 50% of individuals) is considered to be one, making it the lowest known.{{Dubious|date=July 2020|reason=The CDC (https://www.cdc.gov/qfever/transmission/index.html) states that in some cases, fewer than ten bacteria are enough to cause an infection. There is no source here backing up the claim that one is enough 50% of the time.}}

Q fever can affect many species of domestic and wild animals, including ruminants (cattle, sheep, goats, bison,{{cite journal | vauthors = Didkowska A, Klich D, Hapanowicz A, Orłowska B, Gałązka M, Rzewuska M, Olech W, Anusz K | display-authors = 6 | title = Pathogens with potential impact on reproduction in captive and free-ranging European bison (Bison bonasus) in Poland - a serological survey | journal = BMC Veterinary Research | volume = 17 | issue = 1 | pages = 345 | date = November 2021 | pmid = 34736464 | doi = 10.1186/s12917-021-03057-8 | pmc = 8567710 | doi-access = free }} deer species{{cite journal | vauthors = Rijks JM, Roest HI, van Tulden PW, Kik MJ, IJzer J, Gröne A | title = Coxiella burnetii infection in roe deer during Q fever epidemic, the Netherlands | journal = Emerging Infectious Diseases | volume = 17 | issue = 12 | pages = 2369–2371 | date = December 2011 | pmid = 22172398 | doi = 10.3201/eid1712.110580 | pmc = 3311195 }}{{cite journal | vauthors = Kirchgessner MS, Dubovi EJ, Whipps CM | title = Seroepidemiology of Coxiella burnetii in wild white-tailed deer (Odocoileus virginianus) in New York, United States | journal = Vector Borne and Zoonotic Diseases | volume = 12 | issue = 11 | pages = 942–947 | date = November 2012 | pmid = 22989183 | doi = 10.1089/vbz.2011.0952 }}...), carnivores (dogs, cats,{{cite journal | vauthors = Cyr J, Turcotte MÈ, Desrosiers A, Bélanger D, Harel J, Tremblay D, Leboeuf A, Gagnon CA, Côté JC, Arsenault J | display-authors = 6 | title = Prevalence of Coxiella burnetii seropositivity and shedding in farm, pet and feral cats and associated risk factors in farm cats in Quebec, Canada | journal = Epidemiology and Infection | volume = 149 | pages = e57 | date = February 2021 | pmid = 33583452 | doi = 10.1017/s0950268821000364 | pmc = 8060820 }} seals{{cite journal | vauthors = Conway R, Duncan C, Foster RA, Kersh GJ, Raverty S, Gelatt T, Frank C | title = Histologic lesions in placentas of northern fur seals (callorhinus ursinus) from a population with high placental prevalence of coxiella burnetii | journal = Journal of Wildlife Diseases | volume = 58 | issue = 2 | pages = 333–340 | date = April 2022 | pmid = 35245373 | doi = 10.7589/jwd-d-21-00037 | s2cid = 247236730 | pmc = 11290099 }}...), rodents,{{cite journal | vauthors = Pascucci I, Di Domenico M, Dall'Acqua F, Sozio G, Cammà C | title = Detection of Lyme Disease and Q Fever Agents in Wild Rodents in Central Italy | journal = Vector Borne and Zoonotic Diseases | volume = 15 | issue = 7 | pages = 404–411 | date = July 2015 | pmid = 26134933 | doi = 10.1089/vbz.2015.1807 | pmc = 4507354 }} reptiles and birds. However, ruminants (cattle, goats, and sheep) are the most frequently affected animals and can serve as a reservoir for the bacteria.{{Cite journal |last1=Arricau-Bouvery |first1=Nathalie |last2=Rodolakis |first2=Annie |date=May 2005 |title=Is Q Fever an emerging or re-emerging zoonosis? |journal=Veterinary Research |volume=36 |issue=3 |pages=327–349 |doi=10.1051/vetres:2005010 |pmid=15845229 |issn=0928-4249|doi-access=free }}

In contrast to humans, though a respiratory and cardiac infection could be experimentally reproduced in cattle,{{Cite journal|vauthors=Plommet M, Capponi M, Gestin J, Renoux G, Marly J, Sahuc D, Petit A|language=fr |title=FIÈVRE Q EXPÉRIMENTALE DES BOVINS|journal=Annales de Recherches Vétérinaires|oclc=862686843|year=1973|volume=4|issue=2|pages=325–346}} the clinical signs mainly affect the reproductive system. Q fever in ruminants is, therefore, mainly responsible for abortions, metritis, retained placenta, and infertility.

The clinical signs vary between species. In small ruminants (sheep and goats), it is dominated by abortions, premature births, stillbirths, and the birth of weak lambs or kids. One of the characteristics of abortions in goats is that they are very frequent and clustered in the first year or two after contamination of the farm. This is known as an abortion storm.{{cite journal | vauthors = Arricau-Bouvery N, Rodolakis A | title = Is Q fever an emerging or re-emerging zoonosis? | journal = Veterinary Research | volume = 36 | issue = 3 | pages = 327–349 | date = May 2005 | pmid = 15845229 | doi = 10.1051/vetres:2005010 | doi-access = free }}

In cattle, although abortions also occur, they are less frequent and more sporadic. The clinical picture is rather dominated by nonspecific signs such as placental retentions, metritis, and consequent fertility disorders.{{cite journal | vauthors = De Biase D, Costagliola A, Del Piero F, Di Palo R, Coronati D, Galiero G, Uberti BD, Lucibelli MG, Fabbiano A, Davoust B, Raoult D, Paciello O | display-authors = 6 | title = Coxiella burnetii in Infertile Dairy Cattle With Chronic Endometritis | journal = Veterinary Pathology | volume = 55 | issue = 4 | pages = 539–542 | date = July 2018 | pmid = 29566608 | doi = 10.1177/0300985818760376 | s2cid = 4268347 | doi-access = free }}{{Cite web | vauthors = Valla G |title=Prevalenza di Coxiella burnetii nel latte di massa in allevamenti di bovine da latte italiani e possibile correlazione con problemi riproduttivi |url=https://www.vetjournal.it/images/archive/pdf_riviste/4649.pdf}}{{Cite book | vauthors = Ordronneau S |url= http://worldcat.org/oclc/836117348 |title=Impact de la vaccination et de l'antibiothérapie sur l'incidence des troubles de la reproduction et sur la fertilité dans des troupeaux bovins laitiers infectés par Coxiella Burnetii |oclc=836117348}}

Except for New Zealand, which is currently free of Q fever, the disease is present throughout the world. Numerous epidemiological surveys have been carried out. They have shown that about one in three cattle farms and one in four sheep or goat farms are infected,{{cite journal | vauthors = Guatteo R, Seegers H, Taurel AF, Joly A, Beaudeau F | title = Prevalence of Coxiella burnetii infection in domestic ruminants: a critical review | journal = Veterinary Microbiology | volume = 149 | issue = 1–2 | pages = 1–16 | date = April 2011 | pmid = 21115308 | doi = 10.1016/j.vetmic.2010.10.007 }} but wide variations are seen between studies and countries. In China, Iran, Great Britain, Germany, Hungary, the Netherlands, Spain, the US, Belgium, Denmark, Croatia, Slovakia, the Czech Republic, Serbia, Slovenia, and Jordan, for example, more than 50% of cattle herds were infected with Q fever.{{cite journal | vauthors = Pexara A, Solomakos N, Govaris A | title = Q fever and seroprevalence of Coxiella burnetii in domestic ruminants | journal = Veterinaria Italiana | volume = 54 | issue = 4 | pages = 265–279 | date = December 2018 | pmid = 30681125 | doi = 10.12834/VetIt.1113.6046.3 }}{{Cite journal | vauthors = Pexara A, Solomakos N, Govaris A |date=2018-01-01 |title=Q fever and prevalence of Coxiella burnetii in milk |journal=Trends in Food Science & Technology |language=en |volume=71 |pages=65–72 |doi=10.1016/j.tifs.2017.11.004 |issn=0924-2244}}{{cite journal | vauthors = Dobos A, Gábor G, Wehmann E, Dénes B, Póth-Szebenyi B, Kovács ÁB, Gyuranecz M | title = Serological screening for Coxiella burnetii in the context of early pregnancy loss in dairy cows | journal = Acta Veterinaria Hungarica | volume = 68 | issue = 3 | pages = 305–309 | date = September 2020 | pmid = 33156002 | doi = 10.1556/004.2020.00035 | s2cid = 226269478 | doi-access = free }}{{cite journal | vauthors = Dobos A, Fodor I | title = Prevalence of Coxiella burnetii in bovine placentas in Hungary and Slovakia: Detection of a novel sequence type - Short communication | journal = Acta Veterinaria Hungarica | volume = 69 | issue = 4 | pages = 303–307 | date = October 2021 | pmid = 34735368 | doi = 10.1556/004.2021.00047 | s2cid = 243762186 | doi-access = free }}{{cite journal | vauthors = Obaidat MM, Kersh GJ | title = Prevalence and Risk Factors of Coxiella burnetii Antibodies in Bulk Milk from Cattle, Sheep, and Goats in Jordan | journal = Journal of Food Protection | volume = 80 | issue = 4 | pages = 561–566 | date = April 2017 | pmid = 28272921 | pmc = 6489127 | doi = 10.4315/0362-028X.JFP-16-377 }}{{cite journal | vauthors = Espí A, Del Cerro A, Oleaga Á, Rodríguez-Pérez M, López CM, Hurtado A, Rodríguez-Martínez LD, Barandika JF, García-Pérez AL | display-authors = 6 | title = One Health Approach: An Overview of Q Fever in Livestock, Wildlife and Humans in Asturias (Northwestern Spain) | journal = Animals | volume = 11 | issue = 5 | pages = 1395 | date = May 2021 | pmid = 34068431 | pmc = 8153578 | doi = 10.3390/ani11051395 | doi-access = free }}{{cite journal | vauthors = Agger JF, Paul S | title = Increasing prevalence of Coxiella burnetii seropositive Danish dairy cattle herds | journal = Acta Veterinaria Scandinavica | volume = 56 | issue = 1 | pages = 46 | date = July 2014 | pmid = 25056416 | pmc = 4115160 | doi = 10.1186/s13028-014-0046-2 | doi-access = free }}

Infected animals shed the bacteria by three routes - genital discharge, faeces, and milk.{{cite journal | vauthors = Guatteo R, Beaudeau F, Joly A, Seegers H | title = Coxiella burnetii shedding by dairy cows | journal = Veterinary Research | volume = 38 | issue = 6 | pages = 849–860 | date = November 2007 | pmid = 17903418 | doi = 10.1051/vetres:2007038 | doi-access = free }} Excretion is greatest at the time of parturition or abortion, and placentas and aborted fetuses are the main sources of bacteria, particularly in goats.

As C. burnetii is small and resistant in the environment, it is easily airborne and can be transmitted from one farm to another, even if several kilometres away.{{cite journal | vauthors = Hawker JI, Ayres JG, Blair I, Evans MR, Smith DL, Smith EG, Burge PS, Carpenter MJ, Caul EO, Coupland B, Desselberger U, Farrell ID, Saunders PJ, Wood MJ | display-authors = 6 | title = A large outbreak of Q fever in the West Midlands: windborne spread into a metropolitan area? | journal = Communicable Disease and Public Health | volume = 1 | issue = 3 | pages = 180–187 | date = September 1998 | pmid = 9782633 | url = https://pubmed.ncbi.nlm.nih.gov/9782633 }}

Based on the epidemiological data, biosecurity measures can be derived:{{Cite journal |last1=Plummer |first1=Paul J. |last2=McClure |first2=J.Trenton |last3=Menzies |first3=Paula |last4=Morley |first4=Paul S. |last5=Van den Brom |first5=René |last6=Van Metre |first6=David C. |date=September 2018 |title=Management of Coxiella burnetii infection in livestock populations and the associated zoonotic risk: A consensus statement |journal=Journal of Veterinary Internal Medicine |language=en |volume=32 |issue=5 |pages=1481–1494 |doi=10.1111/jvim.15229 |pmc=6189356 |pmid=30084178}}

• The spread of manure from infected farms should be avoided in windy conditions
• The level of hygiene must be very high during parturition and fetal annexes, and fetuses must be collected and destroyed as soon as possible

A vaccine for cattle, goats, and sheep exists. It reduces clinical expression, such as abortions, and decreases the excretion of the bacteria by the animals, leading to control of Q fever in herds.{{Cite web|url=https://www.ema.europa.eu/en/medicines/veterinary/EPAR/coxevac|title=Coxevac | European Medicines Agency|date=17 September 2018 }}

Vaccination of herds against Q fever has been shown to reduce the risk of human infection.{{cite journal | vauthors = Roest HI, Tilburg JJ, van der Hoek W, Vellema P, van Zijderveld FG, Klaassen CH, Raoult D | title = The Q fever epidemic in The Netherlands: history, onset, response and reflection | journal = Epidemiology and Infection | volume = 139 | issue = 1 | pages = 1–12 | date = January 2011 | pmid = 20920383 | doi = 10.1017/S0950268810002268 | s2cid = 29026616 | doi-access = free }}

{{Reflist}}

{{Sister project links|auto=y}}

• [https://www.cdc.gov/qfever/index.html Q fever] at the CDC
• [https://web.archive.org/web/20110727165631/http://patricbrc.org/portal/portal/patric/Taxon?cType=taxon&cId=777 Coxiella burnetii] genomes and related information at [http://patricbrc.org/ PATRIC], a Bioinformatics Resource Center funded by [https://www.niaid.nih.gov/ NIAID]

{{U.S. biological weapons}}

{{Bacterial diseases}}

{{Bacterial cutaneous infections}}

{{Vaccines}}

{{Medical resources

| ICD10 = {{ICD10|A|78||a|75}}

| ICD9 = {{ICD9|083.0}}

| DiseasesDB = 11093

| MedlinePlus = 001337

| eMedicineSubj = med

| eMedicineTopic = 1982

| eMedicine_mult = {{eMedicine2|ped|1973}}

| MeshID = D011778

| Orphanet = 781

}}

{{Authority control}}

{{DEFAULTSORT:Q Fever}}

Category:Atypical pneumonias

Category:Bacterial diseases

Category:Bacterium-related cutaneous conditions

Category:Biological agents

Category:Bovine diseases

Category:Rare infectious diseases

Category:Rodent-carried diseases

Category:Sheep and goat diseases

Category:Tick-borne diseases

Category:Zoonoses

Category:Zoonotic bacterial diseases