View source for Fever Q

{{Imported|Wikipedia|https://en.wikipedia.org/wiki/Q_fever}}
{{Infobox medical condition (new)
 | name            = Q&nbsp;fever
 | synonyms        = Query fever, coxiellosis<ref name="cdc_epi_stats">{{Cite web|title=Epidemiology and Statistics &verbar; Q&nbsp;Fever|url=https://www.cdc.gov/q-fever/data-research/?CDC_AAref_Val=https://www.cdc.gov/qfever/stats/index.html|date=2024-05-15|website=[[wikipedia:Centers for Disease Control and Prevention|CDC]]|archive-url=https://web.archive.org/web/20240927041041if_/https://www.cdc.gov/q-fever/data-research/?CDC_AAref_Val=https://www.cdc.gov/qfever/stats/index.html|archive-date=2024-09-27|url-status=live|language=en-US|access-date=2024-09-26|df=mdy-all}}</ref><ref name="nord">{{Cite book|author=National Organization for Rare Disorders|title=NORD Guide to Rare Disorders|year=2003|publisher=Lippincott, Williams & Wilkins|chapter=Q Fever|chapter-url=https://books.google.com/books?id=99YPDvFWBB0C&pg=PA293|page=293|isbn=978-0-7817-3063-1|language=en|df=mdy-all}}</ref>
 | image           = Immunohistochemical detection of Coxiella burnetii in resected cardiac valve of a 60-year-old man with Q fever endocarditis.jpg
 | image_size      = 280px
 | caption         = Immunohistochemical detection of ''C.&nbsp;burnetii'' in a resected cardiac valve from a 60-year-old infected man from Cayenne, French Guiana, using [[wikipedia:Monoclonal antibody|monoclonal antibodies]] against ''C.&nbsp;burnetii'' and hematoxylin for staining. ''(Shown at 50x magnification)''
 | symptoms        = {{Hlist|[[wikipedia:Fever|fever]]|[[wikipedia:Chills|chills]]|profuse [[wikipedia:Perspiration|perspiration]]|[[wikipedia:Malaise|malaise]]|severe [[wikipedia:Headache|headache]]|[[wikipedia:Myalgia|muscle pain]]|[[wikipedia:Arthralgia|joint pain]]|[[wikipedia:Anorexia (symptom)|loss of appetite]]|[[wikipedia:Respiratory tract#Upper respiratory tract|upper respiratory tract]] issues|dry [[wikipedia:Cough|cough]]|[[wikipedia:Pleurisy|pleuritic pain]]|[[wikipedia:Confusion|confusion]]|[[wikipedia:Nausea|nausea]]|[[wikipedia:Gastroenteritis|gastroenteritis]]}}
 | onset           = 2–3 weeks
 | duration        = Approx. 3 days when treated early, 2 weeks if left untreated
 | types           = {{Hlist|acute<ref name="cdc_epi_stats" />|chronic<ref name="cdc_epi_stats" />}}
 | causes           = Contact with infected livestock or other domestic mammals, their [[wikipedia:Milk|milk]], [[wikipedia:Urine|urine]], [[wikipedia:Feces|feces]], [[wikipedia:Vaginal epithelium#Mucus|vaginal mucus]] or [[wikipedia:Semen|semen]]<ref name="nord" />
 | diagnosis       = [[wikipedia:Immunofluorescence#Secondary (indirect)|Indirect fluorescent antibody]] test (ref. standard) or [[wikipedia:Polymerase chain reaction|PCR]] assay for more rapid results
 | differential    = {{Hlist|[[wikipedia:Pneumonia|pneumonia]]|[[wikipedia:Influenza|influenza]]|[[brucellosis]]|[[leptospirosis]]|[[wikipedia:Meningitis|meningitis]]|[[wikipedia:Viral hepatitis|viral hepatitis]]|[[wikipedia:Dengue fever|dengue fever]]|[[wikipedia:Malaria|malaria]]|other [[wikipedia:Rickettsia|rickettsial infections]]}}<ref name="nord" />
 | treatment       = two-week course of oral antibiotics
 | medication      = {{Hlist|[[wikipedia:Doxycycline|doxycycline]]|[[wikipedia:Tetracycline|tetracycline]]|[[wikipedia:Chloramphenicol|chloramphenicol]]|[[wikipedia:Ciprofloxacin|ciprofloxacin]]|[[wikipedia:Ofloxacin|ofloxacin]]|[[wikipedia:Hydroxychloroquine|hydroxychloroquine]]}}
 | prognosis       = {{Unbulleted indent list|indent=4em|Acute:&emsp;&thinsp;full recovery|Chronic: 10% mortality when treated, otherwise fatal}}
}}
'''Q&nbsp;fever''' or '''query fever''' is a [[wikipedia:Disease|disease]] caused by [[wikipedia:Infection|infection]] with the [[wikipedia:Intracellular parasite#Obligate|obligate intracellular pathogenic parasite]] ''[[wikipedia:Coxiella burnetii|Coxiella burnetii]]'',<ref name="cdc_epi_stats" /><ref name="beare">{{Cite journal|last1=Beare|first1=Paul A.|last2=Samuel|first2=James E.|last3=Howe|first3=Dale|last4=Virtaneva|first4=Kimmo|last5=Porcella|first5=Stephen F.|last6=Heinzen|first6=Robert A.|title=Genetic diversity of the Q&nbsp;Fever Agent, ''Coxiella burnetii'', Assessed by Microarray-Based Whole-Genome Comparisons|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1428397/|journal=Journal of Bacteriology|volume=188|issue=7|pages=2309–2324|date=April 2006|pmid=16547017|pmc=1428397|doi=10.1128/JB.188.7.2309-2324.2006|access-date=2024-09-26|df=mdy-all}}</ref><ref name="gard">{{Cite web|url=https://rarediseases.info.nih.gov/diseases/7515/q-fever|title=Q fever &verbar; About the disease|website=Genetic and Rare Diseases Information Center|date=September 2024|archive-url=https://web.archive.org/web/20240714084745if_/https://rarediseases.info.nih.gov/diseases/7515/q-fever|archive-date=2024-07-14|url-status=live|language=en|access-date=2024-09-26|df=mdy-all}}</ref> a [[wikipedia:Gram-negative bacteria|Gram-negative]] [[wikipedia:Bacteria|bacterium]] that affects humans and other animals. This organism is uncommon, but may be found in [[wikipedia:Cattle|cattle]], [[wikipedia:Sheep|sheep]], [[wikipedia:Goat|goats]] and other [[wikipedia:List of domesticated animals|domestic mammals]]—including [[wikipedia:Cat|cats]] and [[dog]]s. The infection results from [[wikipedia:Inhalation|inhalation]] of a spore-like small-cell variant of the [[wikipedia:Pathogen|pathogen]] or from direct contact with the [[wikipedia:Milk|milk]], [[wikipedia:Urine|urine]], [[wikipedia:Feces|feces]], [[wikipedia:Vaginal epithelium#Mucus|vaginal mucus]] or [[wikipedia:Semen|semen]] of infected animals, with an [[wikipedia:Incubation period|incubation period]] of 9–40&nbsp;days. Rarely, the disease is [[wikipedia:Tick|tick]]-borne.<ref name="cdc_about">{{Cite web|url=https://www.cdc.gov/q-fever/about/index.html|title=About Q&nbsp;fever|date=2024-05-15|website=[[wikipedia:Centers for Disease Control and Prevention|CDC]]|archive-url=https://web.archive.org/web/20240913060310if_/https://www.cdc.gov/q-fever/about/index.html|archive-date=2024-09-13|url-status=live|language=en-US|access-date=2024-09-26|df=mdy-all}}</ref>

== Signs and symptoms ==
The typical incubation period is between two to three weeks.<ref name="brunette">{{Cite book|author=Centers for Disease Control and Prevention|editor-last=Brunette|editor-first=Gary W., MD, MS|display-editors=etal|title=CDC Health Information for International Travel 2012|url=https://archive.org/details/cdchealthinforma0000unse/page/270/mode/2up|url-access=registration|publisher=[[wikipedia:Oxford University Press|Oxford University Press]]|year=2012|pages=270–271|chapter=Q Fever|chapter-url=https://books.google.com/books?id=5vCQpr1WTS8C&pg=PA270|isbn=978-0-19-976901-8|issn=0095-3539|access-date=2024-09-26|df=mdy-all}}</ref> Common presentations include [[wikipedia:Influenza-like illness|flu-like symptoms]] with an abrupt onset of [[wikipedia:Fever|fever]], [[wikipedia:Chills|chills]], profuse [[wikipedia:Perspiration|perspiration]], [[wikipedia:Malaise|malaise]], severe [[wikipedia:Headache|headache]], [[wikipedia:Myalgia|muscle]] and [[wikipedia:Arthralgia|joint pain]], [[wikipedia:Anorexia (symptom)|loss of appetite]], [[wikipedia:Respiratory tract#Upper respiratory tract|upper respiratory tract]] problems, a dry [[wikipedia:Cough|cough]], [[wikipedia:Pleurisy|pleuritic pain]], [[wikipedia:Confusion|confusion]], [[wikipedia:Nausea|nausea]] and [[wikipedia:Gastroenteritis|gastroenteritis]]. However, roughly half of infected individuals are [[wikipedia:Asymptomatic|asymptomatic]].<ref name="brunette" />

During its course, the disease can progress to an [[wikipedia:Atypical pneumonia|atypical, or "walking," pneumonia]] which can result in life-threatening [[wikipedia:Acute respiratory distress syndrome|acute respiratory distress syndrome]] (ARDS), with such symptoms usually occurring during the first four to five days of infection.{{Citation needed}}

Less often, Q&nbsp;fever causes granulomatous (chronic) [[wikipedia:Hepatitis#Bacterial hepatitis|hepatitis]], which may be asymptomatic or becomes symptomatic with malaise, fever, [[wikipedia:Hepatomegaly|liver enlargement]] and [[wikipedia:Quadrants and regions of abdomen|abdominal right upper quadrant]] pain. [[wikipedia:Elevated transaminases|Elevated transaminase]] (liver enzymes) values are common, however [[wikipedia:Jaundice|jaundice]] is not. [[wikipedia:Retinal vasculitis|Retinal vasculitis]] is also a known symptom, though rare.<ref name="kuhne">{{Cite journal|last1=Kuhne|first1=F.|last2=Morlat|first2=P.|last3=Riss|first3=I.|last4=Dominguez|first4=M.|last5=Hostyn|first5=P.|last6=Carniel|first6=N.|last7=Paix|first7=M.A.|last8=Aubertin|first8=J.|last9=Raoult|first9=D.|last10=Le Rebeller|first10=M.J.|title=La vascularite A29, B12, est-elle déclenchée par l'agent de la fièvre Q? (Coxiella burnetii)|trans-title=Is A29, B12 vasculitis caused by the Q fever agent? (Coxiella burnetii)|journal=Journal Francais d'Ophtalmologie|year=1992|volume=15|issue=5|pages=315–321|issn=0181-5512|pmid=1430809|oclc=116712679|language=fr}}</ref>

The chronic form of Q&nbsp;fever is virtually identical to [[wikipedia:Endocarditis|endocarditis]] ([[wikipedia:Inflammation|inflammation]] of the [[wikipedia:Endocardium|inner lining of the heart]], often involving the [[wikipedia:Heart valve|heart valves]], as well)<ref name="chronic">{{Cite journal|last1=Karakousis|first1=Petros C.|last2=Trucksis|first2=Michele|last3=Dumler|first3=J. Stephen|title=Chronic Q&nbsp;Fever in the United States|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1489455/|journal=Journal of Clinical Microbiology|date=June 2006|volume=44|issue=6|pages=2283–2287|pmc=1489455|pmid=16757641|doi=10.1128/JCM.02365-05|access-date=2024-09-26|df=mdy-all}}</ref> and can occur months or decades following the initial infection. It is usually fatal if left untreated, but with appropriate treatment the mortality rate falls to roughly 10%.{{Citation needed}}

== Diagnosis ==
[[File:Q fever management algorithm.gif|thumb|Q&nbsp;fever management algorithm from the [[wikipedia:Centers for Disease Control and Prevention|CDC]].]]
Several aspects of the disease make [[wikipedia:Medical diagnosis|diagnosis]] of Q&nbsp;fever a difficult and lengthy process, usually relying on [[wikipedia:Serology|serology]],<ref name="maurin">{{Cite journal|last1=Maurin|first1=M.|last2=Raoult|first2=D.|title=Q fever|url=https://journals.asm.org/doi/10.1128/cmr.12.4.518|journal=Clinical Microbiology Reviews|date=1999-10-01|volume=12|issue=4|pages=518–553|doi=10.1128/CMR.12.4.518|pmc=88923|pmid=10515901|access-date=2024-09-26|df=mdy-all}}</ref><ref name="scola">{{Cite journal|last=La Scola|first=Bernard|title=Current laboratory diagnosis of Q&nbsp;fever|journal=Seminars in Pediatric Infectious Diseases|date=October 2002|volume=13|issue=4|pages=257–262|doi=10.1053/spid.2002.127199|pmid=12491231}}</ref> after the onset of symptoms. The reference standard is an [[wikipedia:Immunofluorescence#Secondary (indirect)|indirect fluorescent antibody (IFA)]] test to look for an [[wikipedia:Immunoglobulin G|immunoglobulin G]] (IgG) [[wikipedia:Immune response|response]] to the infection, performed on [[wikipedia:Paired data|paired]] [[wikipedia:Serum (blood)|serum]] samples taken at least two weeks apart. A fourfold or greater rise in [[wikipedia:Titer#Antibody titer|antibody titers]] is needed for a positive result, with accuracy increasing commensurate to the interval between when the samples are taken, three to six weeks being optimal. [[wikipedia:Antibody|Antibodies]] to ''C. burnetii'' tend to remain elevated for many months and sometimes even years after the disease has resolved. [[wikipedia:Sampling (statistics)|Statistical sampling]] suggests that approximately 3% of healthy adults in the U.S. and up to 20% of people in high-risk professions—[[wikipedia:Veterinarian|veterinarians]], [[wikipedia:Ranch|ranchers]], etc.—have elevated titers from past Q&nbsp;fever infections, though the large majority of those prior infections will have been asymptomatic, and thus, untreated.<ref name="cdc_diagnosis">{{Cite web|title=Clinical and Laboratory Diagnosis for Q&nbsp;Fever|date=2024-05-15|url=https://www.cdc.gov/q-fever/hcp/diagnosis-testing/index.html|website=[[wikipedia:Centers for Disease Control and Prevention|CDC]]|archive-url=https://web.archive.org/web/20240927064825if_/https://www.cdc.gov/q-fever/hcp/diagnosis-testing/index.html|archive-date=2024-09-27|url-status=live|language=en-US|access-date=2024-09-26|df=mdy-all}}</ref>

If a more rapid determination of Q&nbsp;fever infection is needed during the [[wikipedia:Acute (medicine)|acute]] phase of the illness (such as when a [[wikipedia:Differential diagnosis|differential diagnosis]] cannot exclude other, more serious potential causes), a [[wikipedia:Polymerase chain reaction|polymerase chain reaction]] (PCR) [[wikipedia:Assay|assay]] can be performed on a sample of [[wikipedia:Whole blood|whole blood]]—or serum, at some laboratories—to detect the presence of ''C. burnetii'' [[wikipedia:Nucleic acid sequence|DNA sequences]] at the molecular level. This method is most sensitive in the first week of illness, before the appearance of detectable levels of organism-specific antibodies, and is quickly rendered mostly ineffective following the start of standard treatment regimens. While a positive PCR result can be a key element in diagnosis, particularly for patients suffering an extreme course of symptoms, a negative result does not rule out the infection and a serological result should be determined afterwards for greater certainty.<ref name="cdc_diagnosis" />

Diagnosis of the [[wikipedia:Chronic condition|chronic form]] of the infection relies on the two distinct [[wikipedia:Antigen|antigenic]] [[wikipedia:Phase variation|phases]] (I and II, corresponding to the more and less [[wikipedia:Virulence|virulent]] forms of the pathogen, respectively) of human antibody responses. In acute infections, the phase II antigen will be predominant, due to a combination of natural immune response as well as the necessary delay between patient samples for the test comparison. However, the reverse is true for chronic infections, which are associated with a rising phase I IgG titer (≥1:2<sup>10</sup>)—potentially higher than even phase II—showing the failure of the immune system to arrest the progression of the disease as expected.<ref name="cdc_diagnosis" />

Looking for the bacteria themselves in blood via [[wikipedia:Microbiological culture|culture isolation]] is both technically difficult and time consuming, and only available at specialized microbiology laboratories, making it ill-suited for routine diagnoses; common hospital [[wikipedia:Blood culture|blood cultures]] are unable to detect the organism.<ref name="cdc_diagnosis" />

When Q&nbsp;fever causes endocarditis, [[wikipedia:Echocardiography#Transesophageal echocardiogram|transesophageal echocardiography]] may be required to properly diagnose it. Q&nbsp;fever hepatitis manifests as an elevation of [[wikipedia:Alanine transaminase|alanine transaminase]] and [[wikipedia:Aspartate transaminase|aspartate transaminase]], but a definitive diagnosis is only possible on [[wikipedia:Liver biopsy|liver biopsy]], which shows the characteristic [[wikipedia:Fibrin ring granuloma|fibrin ring granulomas]].<ref name="veerdonk">{{Cite journal|last1=van de Veerdonk|first1=Frank Leo|last2=Schneeberger|first2=Peter Martin|title=Patient with Fever and Diarrhea|url=https://academic.oup.com/cid/article/42/7/1051/322183|journal=Clinical Infectious Diseases|date=2006-04-01|volume=42|issue=7|pages=1051–1052|archive-url=https://web.archive.org/web/20240928005750if_/https://academic.oup.com/cid/article/42/7/1051/322183|archive-date=2024-09-28|url-status=live|doi=10.1086/501027|doi-access=free|access-date=2024-09-27|df=mdy-all}}</ref>

== Prevention ==
Prophylactic protection is possible with the use of Q-Vax: a whole-cell, inactivated [[wikipedia:Vaccine|vaccine]] developed by Australian vaccine manufacturer [[wikipedia:CSL Limited|CSL Limited]].<ref name="csl">{{Cite web|url=http://www.csl.com.au/docs/39/836/Q-Vax_PI_V4_TGA-Approved-17%20January%202014.pdf|title=Q&nbsp;fever Vaccine|publisher=CSL|date=17 January 2014|access-date=11 July 2015|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}}</ref> The intradermal vaccination is composed of killed ''C.&nbsp;burnetii'' organisms. Skin and blood tests should be done before vaccination to identify pre-existing immunity, because vaccinating people who already have an 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.<ref>{{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 }}</ref>

In 2001, Australia introduced a national Q&nbsp;fever vaccination program for people working in “at risk” occupations. Vaccinated or previously exposed people may have their status recorded on the Australian Q&nbsp;Fever Register,<ref>{{cite web|url=https://www.qfever.org|title=Australian Q Fever Register|publisher=AusVet|access-date=12 February 2016}}</ref> which may be a condition of employment in the meat processing industry or in [[University of Melbourne Faculty of Veterinary and Agricultural Sciences|veterinary research]].<ref>{{Cite web|last=Mckenzie|first=Bex|date=2019-11-20|title=Q-Fever Vaccinations|url=https://fvas.unimelb.edu.au/students/admin/q-fever|access-date=2020-07-11|website=Faculty of Veterinary and Agricultural Sciences|language=en}}</ref> 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.&nbsp;burnetii'' is the major cause of these problems.<ref>{{Cite journal|last1=Camuset|first1=Ph.|last2=Remmy|first2=D.|title= Q&nbsp;Fever (Coxiella Burnetii) Eradication in a Dairy Herd by using Vaccination with a Phase&nbsp;1 Vaccine (Coxevac®, Ceva S.A.)|url=https://www.ivis.org/library/wab/wbc-congress-hungary-2008/q-fever-coxiella-burnetii-eradication-a-dairy-herd-by-using|journal=Proceedings of the XXV Jubilee World Buiatrics Congress|year=2008|pages=80–81|publisher=Magyar Állatorvosol Lapja|location=[[wikipedia:Budapest|Budapest]]|url-access=registration|oclc=324998468}}</ref><ref>{{cite journal|pmid=21392427|year=2011|last1=Hogerwerf|first1=L|last2=Van Den Brom|first2=R|last3=Roest|first3=HI|last4=Bouma|first4=A|last5=Vellema|first5=P|last6=Pieterse|first6=M|last7=Dercksen|first7=D|last8=Nielen|first8=M|title=Reduction of Coxiella burnetii prevalence by vaccination of goats and sheep, the Netherlands| volume=17| issue=3| pages=379–386|doi=10.3201/eid1703.101157|pmc=3166012|journal=Emerging Infectious Diseases}}</ref><!--what is "Wannyn (2007) meant to be?-->

== Treatment ==
Treatment of acute Q&nbsp;fever with [[antibiotic]]s is very effective{{Citation needed|date=November 2009}} and should be given in consultation with an [[infectious disease]]s specialist.{{Citation needed|date=November 2009}} Commonly used antibiotics include [[doxycycline]], [[tetracycline]], [[chloramphenicol]], [[ciprofloxacin]], [[ofloxacin]], and [[hydroxychloroquine]]. {{citation needed|date=May 2020}}Chronic Q&nbsp;fever is more difficult to treat and can require up to four years of treatment with doxycycline and [[Quinolone antibiotic|quinolones]] or doxycycline with hydroxychloroquine.{{citation needed|date=May 2020}}Q&nbsp;fever in pregnancy is especially difficult to treat because doxycycline and ciprofloxacin are contraindicated in pregnancy. The preferred treatment is five weeks of [[co-trimoxazole]].<ref>{{cite journal|journal=Clin Infect Dis|year=2007|volume=45|pages=548–555|title=Managing Q fever during pregnancy: The benefits of long-term Cotrimoxazole therapy|vauthors=Carcopino X, Raoult D, Bretelle F, Boubli L, Stein A | doi = 10.1086/520661|pmid=17682987|issue=5|doi-access=free}}</ref>

==Epidemiology==
[[Image:Coxiella burnetii 01.JPG|thumb|right|''C. burnetii'', the Q fever-causing agent]]

The pathogenic agent is found worldwide, with the exception of New Zealand.<ref name="pmid17147957">{{cite journal |vauthors=Cutler SJ, Bouzid M, Cutler RR |title=Q fever |journal=J. Infect. |volume=54 |issue=4 |pages=313–8 |date=April 2007 |pmid=17147957 |doi=10.1016/j.jinf.2006.10.048 }}</ref> The bacterium is extremely sustainable and virulent: a single organism is able to cause an infection. The common source of infection is inhalation of contaminated dust, contact with contaminated milk, meat, or wool, and particularly birthing products. [[Ticks]] can transfer the pathogenic agent to other animals. Transfer between humans seems extremely rare and has so far been described in very few cases.{{citation needed|date=November 2020}}

Some studies have shown more men to be affected than women,<ref name="pmid10589906">{{cite journal |vauthors=Domingo P, Muñoz C, Franquet T, Gurguí M, Sancho F, Vazquez G |title=Acute Q fever in adult patients: report on 63 sporadic cases in an urban area |journal=Clin. Infect. Dis. |volume=29 |issue=4 |pages=874–9 |date=October 1999 |pmid=10589906 |doi=10.1086/520452}}</ref><ref name="pmid3301708">{{cite journal |vauthors=Dupuis G, Petite J, Péter O, Vouilloz M |title=An important outbreak of human Q fever in a Swiss Alpine valley |journal=Int J Epidemiol |volume=16 |issue=2 |pages=282–7 |date=June 1987 |pmid=3301708 |doi= 10.1093/ije/16.2.282}}</ref> which may be attributed to different employment rates in typical professions.{{cn|date=June 2021}}

“At risk” occupations include:<ref>{{Cite web|url=https://medlineplus.gov/ency/article/000611.htm|title=Q fever: MedlinePlus Medical Encyclopedia|website=medlineplus.gov|language=en|access-date=2018-04-17}}</ref>
* [[Veterinary]] personnel
* [[Feedlot|Stockyard]] workers
* [[Farmer]]s
* [[Sheep shearer]]s
* Animal transporters
* Laboratory workers handling potentially infected veterinary samples or visiting [[abattoir]]s
* People who cull and process [[kangaroos]]
* Hide ([[Tanning (leather)|tannery]]) workers

== History ==
[[Image:Pneumonia x-ray.jpg|right|thumb|''Image&nbsp;A'': A normal [[chest X-ray]] ''Image&nbsp;B'': Q&nbsp;fever pneumonia]]
Q&nbsp;fever was first described in 1935 by [[Edward Holbrook Derrick]]<ref>{{cite journal |last1=Derrick |first1=E. H. |title='Q'&nbsp;Fever a new fever entity: clinical features. diagnosis, and laboratory investigation |journal=Medical Journal of Australia |date=August 1937 |volume=2 |issue=8 |pages=281–299 |doi=10.5694/j.1326-5377.1937.tb43743.x }}</ref> 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.<ref>{{cite book | author = Joseph E. McDade | chapter = Historical aspects of Q&nbsp;Fever | title = Q&nbsp;Fever, Volume I: The Disease | editor = Thomas J. Marrie | publisher = CRC Press | year = 1990 | isbn = 978-0-8493-5984-2 | page = 8}}</ref>

The [[pathogen]] of Q&nbsp;fever was discovered in 1937, when [[Frank Macfarlane Burnet]] and Mavis Freeman isolated the bacterium from one of Derrick's patients.<ref>{{cite journal |last1=Burnet |first1=F. M. |last2=Freeman |first2=M. |title=Experimental Studies on the Virus of 'Q' Fever |journal=Clinical Infectious Diseases |date=1 July 1983 |volume=5 |issue=4 |pages=800–808 |doi=10.1093/clinids/5.4.800 |pmid=6194551 }}</ref> It was originally identified as a species of ''[[Rickettsia]]''. [[H.R. Cox]] and [[Gordon Davis (scientist)|Gordon Davis]] elucidated the transmission when they isolated it from [[tick]]s found in the US state of [[Montana]] in 1938.<ref>{{cite journal |last1=Davis |first1=Gordon E. |last2=Cox |first2=Herald R. |last3=Parker |first3=R. R. |last4=Dyer |first4=R. E. |title=A Filter-Passing Infectious Agent Isolated from Ticks |journal=Public Health Reports |date=1938 |volume=53 |issue=52 |pages=2259 |doi=10.2307/4582746 |jstor=4582746 }}</ref>  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 [[proteobacteria|proteobacterium]].{{citation needed|date=July 2020}}

== Society and culture ==
An early mention of Q&nbsp;fever was important in one of the early [[Dr. Kildare]] films (1939, ''[[Calling Dr. Kildare]]''). Kildare's mentor Dr.&nbsp;Gillespie ([[Lionel Barrymore]]) tires of his protégé working fruitlessly on "exotic diagnoses" ("I think it's Q&nbsp;fever!") and sends him to work in a neighborhood clinic, instead.<ref>{{cite web|url=http://www.san.beck.org/MM/1939/CallingDrKildare.html|title=''Calling Dr.&nbsp;Kildare''|publisher=Movie Mirrors Index|access-date=30 April 2013}}</ref><ref>{{cite journal |last1=Kalisch |first1=Philip A |last2=Kalisch |first2=Beatrice J |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 |date=September 1985 |volume=1 |issue=5 |pages=348–363 |pmid=11616027 |url=http://www.truthaboutnursing.org/images/kalisch/when_americans_called_dr_kildare.pdf }}</ref>

Q&nbsp;fever was also highlighted in an episode of the U.S. television medical drama ''[[House (TV series)|House]]'' ("[[The Dig (House)|The&nbsp;Dig]]", season seven, episode&nbsp;18).{{cn|date=June 2021}}

=== Biological warfare ===
''C&nbsp; burnetii'' has been developed as a [[biological agent|biological weapon]].<ref name="pmid14592601">{{cite journal |vauthors=Madariaga MG, Rezai K, Trenholme GM, Weinstein RA |title=Q&nbsp;Fever: A biological weapon in your backyard |journal=Lancet Infect Dis |volume=3 |issue=11 |pages=709–21 |date=November 2003 |pmid=14592601 |doi= 10.1016/S1473-3099(03)00804-1}}</ref>

The United States investigated it as a potential biological warfare agent in the 1950s, with eventual standardization as agent&nbsp;OU. At Fort Detrick and Dugway Proving Ground, human trials were conducted on [[Operation Whitecoat|Whitecoat volunteers]] to determine the median infective dose (18&nbsp;MICLD<sub>50</sub>/person i.h.) and course of infection. The [[Deseret Test Center]] dispensed biological Agent&nbsp;OU with ships and aircraft, during [[Project 112]] and [[Project SHAD]].<ref name="Shady">[http://mcm.fhpr.osd.mil/Librries/CBexposuresDocs/shady_grove_revised.sflb.ashx Deseret Test Center, Project&nbsp;SHAD, Shady Grove revised fact sheet]{{Dead link|date=May 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>  As a standardized biological, it was manufactured in large quantities at [[Pine Bluff Arsenal]], with 5,098&nbsp;gallons in the arsenal in bulk at the time of demilitarization in 1970.

''C.&nbsp;burnetii'' is currently ranked as a "[[Bioterrorism#Types of agents|category&nbsp;B]]" [[bioterrorism]] agent by the [[Centers for Disease Control and Prevention|CDC]].<ref name="pmid12704232">{{cite journal  |vauthors=Seshadri R, Paulsen IT, Eisen JA, etal |title=Complete genome sequence of the Q-fever pathogen Coxiella burnetii |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=100 |issue=9 |pages=5455–60 |date=April 2003 |pmid=12704232 |pmc=154366 |doi=10.1073/pnas.0931379100 |bibcode=2003PNAS..100.5455S }}</ref> It can be contagious, and is very stable in aerosols in a wide range of temperatures. Q&nbsp;fever microorganisms may survive on surfaces up to 60&nbsp;days. It is considered a good agent in part because its ID<sub>50</sub> (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.}}

==Other animals==
Cattle, goats, and sheep are most commonly infected, and can serve as a reservoir for the bacteria. Q&nbsp;fever is a well-recognized cause of abortions in [[ruminant]]s and pets. ''C.&nbsp;burnetii'' infection in dairy cattle has been well documented and its association with reproductive problems in these animals has been reported in Canada, the US, Cyprus, France, Hungary, Japan, Switzerland, and Germany.<ref>{{cite journal |last1=To |first1=Ho |last2=Sakai |first2=Ritsuko |last3=Shirota |first3=Kazutoshi |last4=Kano |first4=Chiaki |last5=Abe |first5=Satomi |last6=Sugimoto |first6=Tomoaki |last7=Takehara |first7=Kazuaki |last8=Morita |first8=Chiharu |last9=Takashima |first9=Ikuo |last10=Maruyama |first10=Tsutomu |last11=Yamaguchi |first11=Tsuyoshi |last12=Fukushi |first12=Hideto |last13=Hirai |first13=Katsuya |title=Coxiellosis in domestic and wild birds from Japan |journal=Journal of Wildlife Diseases |date=April 1998 |volume=34 |issue=2 |pages=310–316 |doi=10.7589/0090-3558-34.2.310 |pmid=9577778 |s2cid=36217068 }}</ref> For instance, in a study published in 2008,<ref>{{cite journal |last1=Czaplicki |first1=Guy |last2=Houtain |first2=Jean-Yves |last3=Mullender |first3=Cédric |last4=Porter |first4=Sarah Rebecca |last5=Humblet |first5=Marie-France |last6=Manteca |first6=Christophe |last7=Saegerman |first7=Claude |title=Apparent prevalence of antibodies to ''Coxiella burnetii'' (Q&nbsp;fever) in bulk tank milk from dairy herds in southern Belgium |journal=The Veterinary Journal |date=June 2012 |volume=192 |issue=3 |pages=529–531 |doi=10.1016/j.tvjl.2011.08.033 |pmid=21962829 |hdl=2268/103290 |hdl-access=free }}</ref> a significant association has been shown between the seropositivity of herds and the appearance of typical clinical signs of Q&nbsp;fever, such as abortion, stillbirth, weak calves, and repeat breeding. Moreover, experimental inoculation of ''C.&nbsp;burnetii'' in cattle induced not only respiratory disorders and cardiac failures ([[myocarditis]]), but also frequent abortions and irregular repeat breedings.<ref>{{cite journal |first1=M |last1=Plommet |first2=M |last2=Capponi |first3=J |last3=Gestin |first4=G |last4=Renoux |title=Fièvre Q expérimentale des bovins |trans-title=Experimental Q fever in cattle |language=fr |journal=Annales de Recherches Vétérinaires |year=1973 |volume=4 |issue=2 |pages=325–346 |url=https://hal.archives-ouvertes.fr/hal-00900769 }}</ref>

==References==
{{Reflist}}

[[Category:Health]]