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Q Fever Fact Sheet

Synopsis of Q Fever

Q fever, also known as “Query Fever” or “Farmers Flu,” is a zoonotic disease caused by the bacteria Coxiella burnetti . It is an obligate intracellular, rickettsia-like organism of low virulence but high infectivity. A single organism may initiate infection, and despite the fact that the organism is unable to grow or replicate outside host cells, there is an unusual spore-like structure that is highly resistant to environmental conditions. Cattle, sheep, and goats function as the primary reservoir for C. burnetti, where it lives in relatively peaceful coexistence with its host. C. burnetti can also infect dogs, cats, wild rodents, birds, ticks, and humans. Human, however, are the only hosts identified that normally experience an illness as a result of infection. Veterinarians, laboratory personnel, meat processing plant workers, sheep and dairy workers, livestock farmers, and other who come in direct contact with infected animals are at higher risk of acquiring Q fever. The acute clinical disease associated with Q fever infection is usually benign and most patients are able to recover without treatment, the disease, however, can be temporarily incapacitating. C. burnetti can be found worldwide, except in New Zealand. And, although cases of Q fever do occur in the United States, there is less than 1 case per 100,000 populations. The cases that do occur are predominantly in California, Florida, Texas, and Virginia.

  • Primary modes of transmission for C. burnetti
    • Aerosols—body fluids, especially amniotic fluid and unpasteurized milk
    • Direct contact
    • Tick bites
    • Ingestion of an infected tissues or unpasteurized milk.
  • Transmission has also occurred via ticks, blood transfusions, and by sexual contact in humans.
  • C. burnetti is found in the mammary glands, supramammary lymph nodes, uterus, placenta, milk, semen, feces and urine.
  • During gestation, the proliferation of C. burnetti in the placenta facilitates aerosolization of large numbers of the pathogen during parturition.
  • Survival of the organism on inanimate surfaces, such as straw, hay, or clothing, allows for transmission to individuals who are not in direct contact with infected animals.
  • Human-to-human transmission has been reported, but is rare.
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Clinical Signs and Symptoms
Animals
  • Species affected:
    • Sheep, goats, and cattle are the most common domestic animal reservoirs.
    • Dogs, cats, rabbits, horses, pigs, camels, buffalo, rodents, pigeons, geese, and other fowl may carry C. burnetti.
    • Antibodies to C. burnetti have been found in badgers, coyotes, raccoons, opossums, badgers, jackrabbits, feral pigs, black bears, and musk ox.
    • Ticks and wild birds can also harbor C. burnetti.
  • Infection frequently lasts for the life of the animals, in a more-or-less dormant state, with periodic increases in organism numbers during periods of relative immunosuppression, particularly parturition.
  • Clinical signs and symptoms:
    • Other than spontaneous abortion due to profuse growth in the placenta, overt illness in domestic animals is unusual
      • C. burnetti has a propensity for proliferation in the female reproductive system, especially the uterus and mammary glands.
    • Edema and thrombohemorrhagic lesions may be identified in the placentas of infected animals
  • Differences between the manifestations in domestic animals:
    • In sheep, the infection tends to be transient, followed by spontaneous remission. Infected sheep will usually cease shedding the pathogen after a few months and no longer be infectious to other animals in the flock, except during parturition. Infection is associated with epidemic abortions but shedding in the milk is rare.
    • In cattle, chronic shedding—over months or years—occurs and can also be shed in the milk of lactating cows, which can facilitate maintenance of Coxiella in a herd. Infection is associated with an increased incidence of spontaneous abortions and may be associated with infertility.
      • Click here for an assessment of the prevalence and risks of Q fever in dairy cattle published in Emerging Infectious Diseases (Kim et. al., 2005).7
    • In goats, there is an increased disposition for abortion during epizootics of Q Fever, and infection is maintained by chronic shedding.
Humans:
  • Man is the only host susceptible to infection by C. burnetti that commonly develops an illness as a result of infection.
  • Incubation: 10 to 40 days (the duration of the incubation period is inversely correlated with the magnitude of the inoculum and the severity of the associated illness is positively correlated with the magnitude of the inoculum)
  • Illness may be manifested by asymptomatic seroconversion (up to 60% of infected patients), acute illness, or chronic disease.
  • Clinical signs (acute illness):
    • Fever
    • Chills, rigors
    • Headache
    • Diaphoresis
    • Malaise
    • Weakness, fatigue
    • Anorexia
    • Myalgias
    • Arthralgias
    • Chest pain
    • Cough
    • Sore throat
    • Nausea, vomiting
    • Diarrhea
    • Neck stiffness
    • Neurological signs (encephalopathic symptoms, hallucinations, expressive dysphasia, hemi-facial pain, diplopia, and dysarthria)
    • Transient thrombocytopenia
  • Clinical signs (chronic illness):
    • Occurs in less than 1% of infected patients
    • Infective endocarditis
  • Click here for more in-depth information about the pathophysiology of Q fever in humans published in Lancet Infectious Disease (Raoult et. al., 2005).10
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Diagnosis and Treatment
Diagnostic Samples:
  • Q fever is highly infectious to humans; therefore, samples should be collected and handled with all appropriate precautions.
  • Diagnostic samples for animals:
    • Blood
    • Fetal tissues
    • Placenta
    • Vaginal discharges
    • Semen
    • Stomach contents
    • Milk
    • Colostrum
    • Tissues, such as spleen, lung, lymph nodes, uterus, udder, and testis
  • Diagnostic samples for humans:
    • Blood
    • Bone marrow
Differential Diagnosis:

  • In animals, the differential diagnoses include any abortion-causing disease.
  • In humans, the differential diagnoses include viral illness or other types of atypical pneumonia.
Clinical Diagnosis:

  • Q fever should be considered when abortions or infertility are seen in otherwise asymptomatic animals.
  • In humans, Q fever is not a clinically distinct illness and may resemble a viral illness or other types of atypical pneumonia; therefore, serologically-confirmed diagnosis is necessary.

Laboratory Tests:

  • Platelet count—transient thrombocytopenia
  • Serologic testing (potential hazardous nature of C. burnetti cultures to laboratory personnel makes this the safest means of diagnosis).
    • Complement fixation
    • Indirect fluorescent antibody (considered to be the most dependable, most widely used method)
    • Macroagglutination
    • Microagglutination
    • ELISA (most sensitive and the easiest to perform)
      • Sensitivity: 80-84% in early convalescence and 100% in intermediate and late convalescence
  • Indirect immunofluorescence assay
  • Immnuohistochemistry
Treatment:

  • In animals:
    • Antibiotics:
      • Little is known about the efficacy of antibiotic treatment in ruminants or other domestic animals.
      • Antibiotic treatment is sometimes recommended to reduce the risk of abortion.
      • Antibiotics may, in some cases, suppress rather than eliminate infections.
    • Prophylaxis:
      • Vaccines are not available for domestic ruminants in the U.S., but are used in other countries.
      • Vaccines may prevent infections in calves, decrease shedding of organisms, and improve fertility in infected animals, but do not eliminate shedding of the organism.
  • In humans:
    • Supportive care
    • Antibiotics (acute illness):
      • Tetracycline (mainstay of therapy since 1950s)—when initiated within the first few days of illness, this treatment has been shown to shorten the course of the disease
      • Macrolide antibiotics, such as erythromycin and azithromycin
    • Antibiotics (chronic illness):
      • Treatment is very difficult; the mortality rate is ~ 24% even when patients receive appropriate treatment
      • At least two years of therapy is required
      • Tetracycline combined with rifampin or a quinolone or
      • Tetracycline combined with hydroxychloroquine
    • Prophylaxis:
      • Immunization can prevent Q Fever
      • Formalin-killed C. burnetti (30 mg of vaccine antigen) confers protection against Q Fever within two weeks after immunization and persists for at least five years
      • The following groups of individuals should be considered for vaccine prophylaxis:
        1. Veterinarians, veterinary technicians, and animal care workers
        2. Laboratory investigators, technicians, and other laboratory personnel
        3. Abattoir workers
    • Click here for more information on the treatment of Q fever in an article published in Antimicrobial Agents and Chemotherapy (Raoult, 1993).11
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Economic Consequences and Disease Eradication
Economic Consequences:

  • Loss of livestock due to increased rates of abortion.
  • Infertility
  • Decreased milk production
  • Costs associated with eradication efforts.
  • International trade embargoes
  • Increased costs to consumers
Disease Eradication:

  • Immediate notification of state and federal health officials
  • Protective measures:
    • Protective clothing, such as gloves, overalls, and face masks, should be worn when handling infected animals.
    • Personal disinfection after handling animals or carcasses (soapy water)
    • Pasteurization of all dairy products
    • Vaccinate all individuals who come in contact with pregnant ewes or live C. burnetti
    • Site and/or equipment disinfection
      • 1:100 dilution of household bleach with tap water
      • 5:100 dilution of peroxide
      • 1:100 dilution of Lysol
  • Control measures in livestock in endemic areas:
    • Education on the sources of infection
    • Separation of pregnant animals
    • Burning or burying of reproductive discharges including the placentas
    • Safe disposal of carcasses (incineration in a manner that ensures heat sterilization of the underlying soil)
    • Vaccination of all at-risk herds
    • Routine testing
    • Minimize dust and rodents in animal housing areas and slaughter areas.
    • Restrict access to barns and laboratories used to house animals
    • Yard facilities for sheep and cattle should be sited well away from domestic living areas.
  • The carcass should NOT be opened because of potential aerosol exposure of the bacterium in body
  • Viability:
    • The spore-like form is extremely resistant to heat, pressure, desiccation, and many standard antiseptic compounds
    • The organisms can remain viable for several months in water, aborted fetuses, manure, wool, hay, equipment, and clothing during conditions of high humidity, low temperatures, and no sunlight.
      • Up to 4-6°C for 42 months in milk
      • At least 19 months in tick feces
      • 12 to 16 months in wool
      • 120 days in dust
      • 49 days in dried urine
      • 30 days in dried sputum.
    • C. burnetti is highly resistant to physical and chemical agents.
  • Inactivation:
    • Disinfectants:
      • 0.05%hypochlorite (household bleach)
      • 5% peroxide
      • 1:100 solution of Lysol are effective as disinfectants
      • 1% sodium hypochlorite
      • 70% ethanol
      • Iodine/alcohol solutions
      • Gluteraldehyde
      • Formaldehyde
    • Moist heat (121°C for 15 minutes)
    • Dry heat (160-170°C for 1 hour)
    • High temperature pasteurization destroys the organism.
Q Fever and Bioterrorism:
  • Characteristics that make Q fever a good biological weapon:
    • Highly infectious (a single organism is capable of causing illness in a susceptible host)
    • An infectious airborne particle can travel a half-mile or more.
    • Highly resistant to heat and drying
    • Viable in its spore-like form for years
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Outbreaks
Human Cases

2001-2002: According to the CDC, there were 61 reported cases, 12 of which were from California.

2000-2001: A total of 48 patients who met the case definition of Q fever were reported to the CDC (CA, GA, PA, & TN).

1986: The CDC reported on cases in lamb slaughter-house workers in California and in neighbors of a goat farm

1985: Five cases (CA) were reported among workers at a local meatpacking plant that processes sheep.

1984: 18 symptomatic cases linked to visiting or working at a sheep research station (ID) and/or being exposed to animals from this research station.

1980: 81 faculty and staff members of a medical school (CO) associated with perinatel research using pregnant sheep tested positive for C. burnetti.


Note: There is limited national surveillance data for Q fever between the years 1948 to 1986 due to the fact that this was not a nationally reportable disease at that time and less than 30 states required reporting. Between 1948 and 1977, about 58 cases were reported to the CDC per year.


Note: Although reported outbreaks of Q fever in the U.S. population have been relatively uncommon, underreporting most likely occurs.


Click here for more information on Q fever outbreaks among humans and animal in the U.S. published in the Vector Borne and Zoonotic Diseases journal (McQuiston and Childs, 2002).

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Sources and Related Articles
Sources:

  1. CDC Viral and Rickettsial Zoonoses Branch, February 13, 2003. Q Fever. Published on the CDC Website. Available at http://www.cdc.gov/ncidod/dvrd/qfever/index.htm.
  2. CFSPH, 2004. Q Fever. Published on the Iowa State University Website. Available at http://www.cfsph.iastate.edu/Factsheets/pdfs/q_fever.pdf.
  3. OIE Institute for International Cooperation in Animal Biologics and the ISU Center for Food Security and Public Health, January 2004. Q Fever. Published on the OIE Website. Available at http://www.cfsph.iastate.edu/Factsheets/pdfs/q_fever.pdf.
  4. Center for the Study of Bioterrorism at the Institute for Biosecurity, August 2002. Bioterrorism Agent Fact Sheet: Q Fever/Coxiella burnetti. Saint Louis University School of Public Health Website. Available at http://bioterrorism.slu.edu/bt/quick/qfever01.PDF.
  5. Byrne, W. R., 1997. Chapter 26: Q Fever. Zajtchuk, R., R. F. Bellamy, F. R. Sidell, E. T. Takafuji, and D. R. Franz (Eds). Medical Aspects of Chemical and Biological Warfare. pp. 523-537. TMM Publications, Washington, D. C. Available at http://www.nbc-med.org/SiteContent/HomePage/WhatsNew/MedAspects/Ch-26electrv699.pdf.

Related Articles:

  1. Anonymous, April 11, 1986. Q Fever among Slaughterhouse Workers—California. MMWR 35(14):223-226. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml/00000714.htm.
  2. Kim, S. G., E. H. Kim, C. J. Lafferty, and E. Dubovi, April 2005. Coxiella burnetti in bulk tank milk samples, United States, Emerg Inf Dis., 11(4):619-621. Available at http://www.cdc.gov/ncidod/EID/vol11no04/pdfs/04-1036.pdf.←
  3. McQuiston, J. H. and J. E. Childs, November 3, 2002. Q Fever in Humans and Animals in the United States. Vector Borne and Zoonotic Dis. 2(3):179-191. Available at http://www.liebertonline.com/doi/pdf/10.1089/15303660260613747.
  4. Meiklejohn, G. L. G. Reimer, P. S. Graves, and C. Helmick, August 1981. Cryptic Epidemic of Q Fever in a Medical School. J Inf Dis. 144(2):107-113.
  5. Raoult, D., T. J. Marrie, and J. L. Mege, April 2005. Natural History and Pathophysiology of Q Fever. Lancet Infect Dis. 5(4):219-226.
    6. ←
  6. Raoult, D., September 1993. Minireview: Treatment of Q Fever. Antimicrobial Agents and Chemotherapy. 37(9):1733-1736. Available at http://www.pubmedcentral.gov/picrender.fcgi?artid=188061&blobtype=pdf.←
  7. Rauch, A. M., M. Tanner, R. E. Pacer, M. J. Barrett, C. D. Brokopp, and L. B. Schonberger, February 1987. Sheep-Associated Outbreak of Q Fever, Idaho. Arch Intern Med. 147(2):341-344.
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