Q fever is an infectious disease that is spread by the inhalation or ingestion of bacteria of the family Rickettsia and, more specifically, the species known as Coxiella burnetii. Most other rickettsial diseases are spread by the transmission of the bacterium via a tick bite. This disease is spread by breathing contaminated air or eating or drinking a contaminated substance. Farm workers, especially those who work with animals, people who work in slaughterhouses, and veterinarians are especially vulnerable to this disease. Because infection can occur as a result of airborne transmission, this is one of the diseases that has been studied as a possible bacteriological weapon.
Most cases are mild but some (about 2-3% of cases) may be acute and show signs of liver damage (hepatitis), and inflammation of heart muscle (myocarditis) or the heart lining (pericarditis).
Illness typically develops within two to three weeks after exposure. Only about half of those infected ultimately develop symptoms. The symptoms of Q fever may include high fever (up to 104 or 105 degrees), headache, sore throat, cough, nausea, vomiting, diarrhea, abdominal pain, and chest pain. Weight loss can occur.
Q fever patients may experience extreme tiredness and muscle pain (myalgia). Prolonged Q fever may result in inflammation and enlargement of the liver (hepatitis, hepatomegaly) with upper right abdominal pain and yellowing of the skin (jaundice). Inflammation of the lining of the heart (endocarditis) may also occur.
The Q fever bacterium infects primarily farm animals such as cattle, sheep, and goats. Domesticated pets, including cats and rats, may also be infected. People who inhale the bacteria from an infected animal (for instance, by inhaling contaminated air in a barnyard) may become infected and show signs of Q fever after an incubation period of 9 to 39 days.
Organisms may be excreted in milk, urine, or feces of infected animals. Also, when an animal gives birth, the bacteria may be present in high numbers in the amniotic fluid and placenta.
Q fever can also be transmitted by inhaling contaminated aerosols (material from spray cans), working in a slaughterhouse, drinking unpasteurized milk, hunting, slaughtering or dressing infected animals.
According to one review article on the disease, only one documented case of human-to-human transmission has been reported.
Because there are more males than females working in farm and farm-related jobs, there are more males than females known to be affected by Q fever. Of 61 cases reported in 2002, 50 involved men and only 11 involved women. In 2001 and 2002, only 26 and 61 cases of Q fever were reported.
Symptoms of the following disorders can be similar to those of Q fever. Comparisons may be useful for a differential diagnosis:
Legionnaires' disease is a form of pneumonia that got its name from the fact that the first known outbreak occurred at a hotel that was hosting a meeting of the American Legion organization in Pennsylvania. In that outbreak, it was found that water in the hotel's air conditioning system was contaminated with the bacteria. Legionnaires' disease is most often contracted by inhaling contaminated water from sources such as showers and whirlpoor baths. There is no evidence of human-to-human transmission. (For more information on this disorder, choose "Legionnaires' disease" as your search term in the Rare Disease Database.)
Epidemic typhus is an infectious Rickettsial disease caused by the parasitic bacteria, Rickettsia prowazekii. It is transmitted to people by infected body lice. Symptoms of epidemic typhus are similar to those of Rocky Mountain spotted fever except that the rash usually spares the palms of the hands and soles of the feet, but patients may experience a deeper stupor and more tiredness. Epidemic typhus is found worldwide but is more common in warm climates with poor sanitation.
Murine typhus is an infectious Rickettsial disease caused by the parasitic bacteria, Rickettsia typhi (mooseri). Murine typhus is transmitted to people by a bite from an infected rat flea. Symptoms of murine typhus are usually milder than those of epidemic typhus. Murine typhus occurs worldwide, especially in warm climates with poor sanitation.
Rocky Mountain spotted fever (RMSF) is an infectious disease that is caused by contact with a parasitic Rickettsial bacteria (Rickettsia rickettsii). People can develop RMSF after being bitten by an infected tick. After an incubation period of 2 to 12 days, fever with a rash starting on the hands and feet and spreading to the rest of the body may occur. Headache, dulled senses (stupor), chills, cough, nausea, vomiting, diarrhea, and abdominal pain may occur. The patient may experience muscle tenderness and pain, extreme sensitivity to light (photophobia), and infection of the lining of the eyelid and exposed surfaces of the eyeball (conjunctiva). Rocky Mountain spotted fever is found in North, Central, and South America. (For more information on this disorder, choose "Rocky Mountain" as your search term in the Rare Disease Database.)
Diagnosis Diagnosis of Q fever can be confirmed by blood tests for antibodies (specific substances produced by the body to fight off foreign substances) to the Q fever bacteria.
Treatment Doxycycline and other antibiotics may be used to treat Q fever. Some Q fever patients may improve without treatment, while others will get more intensely ill in the absence of treatment.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
TEXTBOOKS Kovacova E, Kazar J. Q Fever. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:293.
Beers MH, Berkow R., eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:1232-33; 1226-28.
Berkow R., ed. The Merck Manual-Home Edition.2nd ed. Whitehouse Station, NJ: Merck Research Laboratories; 2003:1133.
Stein JH, Hutton JJ, Kohler PO, et al., eds. Internal Medicine. 4th ed. Mosby-Yearbook, Inc., St. Louis, MO. 1994:2063-67.
REVIEW ARTICLES Marrie TJ. Empiric treatment of ambulatory community-acquired pneumonia: always include treatment for atypical agents. Infect Dis Clin North Am. 2004;18:829-41.
Foucault C, Lepidi H, Poujet-Abadie JF, et al. Q Fever and lymphadenopathy: report of four new cases and review. Eur J Clin Microbiol Infect Dis. 2004;23:759-64.
Woldehiwet Z. Q fever (coxiellosis): epidemiology and pathogenesis. Res Vet Sci. 2004;77:93-100.
Wortmann G. Pulmonary manifestations of other agents: brucella, Q fever, tularemia and smallpox. Respir Care Clin N Am. 2004;10:99-109.
Marrie TJ. Q fever pneumonia. Curr Opin Infect Dis. 2004;17:137-42.
Madariaga MG, Rezai K, Tenholme GM, et al. Q fever: a biological weapon in your backyard. Lancet Infect Dis. 2003;3:709-21.
Samuel JE, Kiss K, Varghees S. Molecular pathogenesis of Coxiella burnetii in a genomics era. Ann N Y Acad Sci. 2003;990:653-63.
Kovacova E, Kazar J. Q fever—still a query and underestimated infectious disease. Acta Virol. 2002;46:193-210.
FROM THE INTERNET Levy D. Medical Encyclopedia: Q fever. MedlinePlus. Update date: 7/16/2004. 3pp. www.nlm.nih.gov/medlineplus/ency/article/001337.htm
Q fever. CDC. Viral and Rickettsial Zoonoses Branch (VRZB). Last reviewed February 13, 2003. 5pp. www.cdc.gov/ncidod/dvrd/qfever/
Q Fever (Query Fever). University of Florida Environmental Health and Safety. nd. 2pp. www.ehs.ufl.edu/Bio/qfever/qinfo.htm
Centers for Disease Control and Prevention 1600 Clifton Road NE Atlanta, GA 30333 Tel: (404)639-3534 Tel: (800)311-3435 Email: http://www.cdc.gov/netinfo.htm Internet: http://www.cdc.gov/
NIH/National Institute of Allergy and Infectious Diseases 6610 Rockledge Drive MSC 6612 Bethesda, MD 20892-6612 Tel: (301)496-5717 Fax: (301)402-3573 TDD: (800)877-8339 Internet: http://www.niaid.nih.gov/
World Health Organization (WHO) Regional Office for the Americas (AMRO) Pan American Health Organization (PAHO) 525 23rd Street NW Washington, DC 20037 Tel: (202)974-3000 Fax: (202)974-3663 Email: postmaster@paho.org Internet: http://www.who.ch/
Genetic and Rare Diseases (GARD) Information Center PO Box 8126 Gaithersburg, MD 20898-8126 Tel: (301)519-3194 Fax: (240)632-9164 Tel: (888)205-2311 TDD: (888)205-3223 Email: gardinfo@nih.gov Internet: http://www.genome.gov/10000409
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