Q Fever

Q Fever 

Definition

Q fever is an illness caused by a type of bacteria, Coxiella burnetii, resulting in a fever and rash.

Description

C. burnetii lives in many different kinds of animals, including cattle, sheep, goats, ticks, cats, rabbits, birds, and dogs. In sheep and cattle, for example, the bacteria tends to accumulate in large numbers in the female's uterus (the organ where lambs and calves develop) and udder. Other animals have similar patterns of bacterial accumulation within the females. As a result, C. burnetii can cause infection through contaminated milk, or when humans come into contact with the fluids or tissues produced when a cow or sheep gives birth. Also, the bacteria can survive in dry dust for months; therefore, if the female's fluids contaminate the ground, humans may become infected when they come in contact with the contaminated dust.

Persons most at risk for Q fever include anybody who works with cattle or sheep, or products produced from them. These include farm workers, slaughterhouse workers, workers in meat-packing plants, veterinarians, and wool workers. Since September 2001, however, Q fever has become an additional concern because of its potential as an agent of bioterrorism.

Q fever has been found all over the world, except in some areas of Scandinavia, Antarctica, and New Zealand.

Causes and symptoms

C. burnetii causes infection when a human breathes in tiny droplets, or drinks milk, containing the bacteria. After three to 30 days, symptoms of the illness appear.

The usual symptoms of Q fever include fever, chills, heavy sweating, headache, nausea and vomiting, diarrhea, fatigue, and cough. Also, a number of other problems may present themselves, including inflammation of the liver (hepatitis); inflammation of the sac containing the heart (pericarditis); inflammation of the heart muscle itself (myocarditis); inflammation of the coverings of the brain and spinal cord, or of the brain itself (meningoencephalitis); and pneumonia.

Chronic Q fever occurs most frequently in patients with other medical problems, including diseased heart valves, weakened immune systems, or kidney disease. Such patients usually have about a year's worth of vague symptoms, including a low fever, enlargement of the spleen and/or liver, and fatigue. Testing almost always reveals that these patients have inflammation of the lining of the heart (endocarditis).

Diagnosis

Q fever is diagnosed by demonstrating that the patient's immune system is making increasing numbers of antibodies (special immune cells) against markers (antigens) that are found on C. burnetii.

Treatment

Doxycycline and quinolone antibiotics are effective for treatment of Q fever. Treatment usually lasts for two weeks. Rifampin and doxycycline together are given for chronic Q fever. Chronic Q fever requires treatment for at least three years.

Minocycline has been found to be useful in treating post-Q fever fatigue. The dosage is 100 mg per day for three months.

Prognosis

Death is rare from Q fever. Most people recover completely, although some patients with endocarditis will require surgery to replace their damaged heart valves.

Prevention

Q fever can be prevented by the appropriate handling of potentially infective substances. For example, milk should always be pasteurized, and people who work with animals giving birth should carefully dispose of the tissues and fluids associated with birth. Industries which process animal materials (meat, wool) should take care to prevent the contamination of dust within the plant.

Vaccines are available for workers at risk for Q fever.

Resources

Books

Beers, Mark H., MD, and Robert Berkow, MD, editors. "Biological Warfare and Terrorism." In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

Beers, Mark H., MD, and Robert Berkow, MD, editors. "Q Fever." In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

Periodicals

Arashima, Y., K. Kato, T. Komiya, et al. "Improvement of Chronic Nonspecific Symptoms by Long-Term Minocycline Treatment in Japanese Patients with Coxiella burnetii Infection Considered to Have Post-Q Fever Fatigue Syndrome." Internal Medicine 43 (January 2004): 1-2.

Gami, A. S., V. S. Antonios, R. L. Thompson, et al. "Q Fever Endocarditis in the United States." Mayo Clinic Proceedings 79 (February 2004): 253-257.

Madariaga, M. G., J. Pulvirenti, M. Sekosan, et al. "Q Fever Endocarditis in HIV-Infected Patient." Emerging Infectious Diseases 10 (March 2004): 501-504.

Wortmann, G. "Pulmonary Manifestations of Other Agents: Brucella, Q Fever, Tularemia and Smallpox." Respiratory Care Clinics of North America 10 (March 2004): 99-109.

Organizations

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. http://www.cdc.gov.

Key terms

Antibodies — Specialized cells of the immune system that can recognize organisms that invade the body (such as bacteria, viruses, and fungi). The antibodies are then able to set off a complex chain of events designed to kill these foreign invaders.

Antigens — Markers on the outside of bacteria or viruses which can be recognized by antibodies.

Bioterrorism — The use of disease microorganisms to intimidate or terrorize a civilian population.

Immune system — The system of specialized organs, lymph nodes, and blood cells throughout the body which work together to prevent foreign invaders (bacteria, viruses, fungi, etc.) from taking hold and growing.

Inflammation — The body's response to tissue damage. Includes increased heat, swelling, redness, and pain in the affected part.

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Q fever

n.

An infectious disease caused by the rickettsia Coxiella burnetii, characterized by fever, malaise, and muscular pains.

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Q fever

(query fever) a rickettsial infection of most animal species, including humans, and some birds. It is caused by Coxiella burnetii and spread by inhalation, especially of inspissated reproductive exudates, and by ticks, and by the ingestion of raw infected milk. The disease is inapparent in most infected animals but can cause abortion in sheep and goats, and probably cattle. Called also Queensland fever.