Epidemiology

Veterinarians frequently exposed to Q fever

Last Updated: 2009-03-11 8:00:29 -0400 (Reuters Health)

NEW YORK (Reuters Health) - The seroprevalence of Coxiella burnetii - the causative organism of the zoonotic disease Q-fever - is high among US veterinarians, particularly those who frequently work with livestock or wildlife, investigators report in the March 1 issue of Clinical Infectious Diseases.

In July 2006, Ellen A. S. Whitney, at Emory University in Atlanta, and co-investigators conducted serologic testing among 508 healthy veterinarians attending a national conference. Seroprevalence was 22.2%.

Subjects who routinely wore masks and lab coats while working were less likely to be seropositive, whereas those who accidentally cut themselves more than twice during the previous year were more at risk.

In multivariate analysis, age > 45 years, routine contact with ponds, and treatment of cattle, swine, or wildlife were significantly associated with positive test results (odds ratios 1.67-2.69).

As to why pond water exposure would be a risk factor, Whitney's group explains that female livestock often seek low-lying areas in which to give birth, thus contaminating an area that subsequently fills with water during rainstorms.

"Because acute Q fever may present with symptoms of influenza-life illness or with evidence of unexplained pneumonia or hepatitis," they advise, "physicians treating ill veterinarians and others with occupational exposures should consider C. burnetii to be a differential diagnosis."

Q fever can cause chronic infections years after the initial infection. The research team concludes that among individuals with underlying heart disease, those who are immunosuppressed, or who are pregnant, "it is essential to diagnose endocarditis due to C. burnetii in the early stages, to prevent complications."

Because of the perceived threat after the terrorist attack on the US in 2001, when C. burnetii was categorized as a class B potential bioweapon, and the number of cases among military personnel in Iraq, Q fever seems to be rapidly reemerging, Dr. Didier Raoult, at Universite de la Mediterranee in Marseille, France, comments in a related editorial.

He notes that in a previous study, 16% of 130 tested military personnel returning from Iraq had antibodies to C. burnetii. "If this rate of exposure is consistent, it can be expected that as many as 100,000 soldiers have been infected during the current war," who will be "an important reservoir of potential chronic Q fever cases in the US in the future."

Clin Infect Dis 2009;48:550-559.