Q Fever
Background and Symptoms
Q fever is a bacterial
disease caused by Coxiella burnetii, a rickettsial
organism. Q fever in humans is usually either asymptomatic or
mistaken for an acute viral illness due to the symptoms of
fever, chills, headache, weakness, malaise (a general sick
feeling), and severe sweats. In most cases, the illness is of
short duration, lasting less than two weeks, even without
treatment. Rare complications include pneumonitis (inflammation
of the lungs), neurologic problems and, among people with
abnormal or prosthetic heart valves, endocarditis (inflammation
of the heart). Complications are more likely to occur among
people who have weakened immune systems.
While Q fever
is rarely reported, anyone may contract the disease if they are
infected with C. burnetii bacteria. People at highest
risk for Q fever are those who work with infected animals,
including veterinarians, researchers, meat workers, sheep
workers and farmers. The incubation period is variable, although
2-3 weeks is considered common. Blood tests can be used to
diagnose Q fever.
Transmission
C. burnetii may be
found in sheep, cattle, goats, cats, dogs, some wild animals
(including many wild rodents), birds and ticks. Animals shed the
organism in their urine, feces, milk and especially in their
birth products. Most infected animals do not show signs of
illness. Q fever is spread to people primarily through airborne
dissemination of contaminated dust. Dust becomes contaminated
from the tissues or bodily fluids of animals infected with C.
burnetii bacteria.
Direct
contact with infected animals or materials that they have
contaminated (such as straw or other bedding materials) may also
cause an infection. Raw or unpasteurized milk from infected cows
or goats may be capable of spreading C. burnetii. Direct
person-to-person spread is not likely.
Prevention is based on the control of this disease in domestic
animals. People who work with animals that may be infected need
to know the signs and symptoms of Q fever and seek treatment if
they feel they could be infected. There is a Q fever vaccine
that is currently not available for general use, but may be
available through the Department of Defense for persons who are
known to be at high risk of exposure. Q fever is listed as a
potential bioterrorism agent because it can be spread to people
through an airborne route.
Q Fever in Florida
A documented
cluster of Q fever in Florida occurred during 1999 in Alachua
County among researchers exposed to an infected sheep. In
response to this outbreak, Q fever was listed as a reportable
disease. As of September 2005, thirteen confirmed and probable
cases of Q fever have been reported within the state of
Florida. Nine of these cases (69%) occurred in males, and the
average age of affected patients was 49 years. Q fever can be
successfully treated with antibiotics, especially when treatment
is initiated early in the course of the disease.
References
1. Benenson AS (ed.). Q fever.
In Control of Communicable Diseases Manual, Sixteenth Edition.
United Book Press, Baltimore. 1995: 379 - 382.
2. Dupont HT, Thirion X, Raoult
D. Q Fever Serology: cutoff determination for
microimmunofluorescence. Clin Diagn Lab Immunol. 1994
Mar;1(2):189-96.
3. Fournier PE, Raoult D.
Predominant immunoglobulin A response to phase II antigen of
Coxiella burnetii
in acute Q fever. Clin
Diagn Lab Immunol. 1999 Mar;6(2):173-177.
4. Florida Department of Health
Preventable Diseases Annual Report. 1964 p.191.
5. Harrison RJ, Vugia DJ, Ascher
MS. Occupational health guidelines for control of Q fever in sheep research.
Ann NY Acad Sci.
1990;590:283-90.
6. Marrie TJ, Stein A, Janigan D.
Route of infection determines the clinical manifestation of
acute Q fever. J Infect Dis.
1996;173:484-7.
7. Pinsky RL, Fishbein DB, Greene
CR, Gensheimer KF. An outbreak of cat-associated Q fever in the United States.
J Infect Dis
1991 Jul;164(1):202-4.
8. Wisseman, CL, Strickland, GT
(Ed) 26. Q Fever Hunters Trop Med 7th Edition. W B
Saunders Co 1991, pp 282-285.
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