April 01, 2009


 Study: 22 percent of veterinarians screened had antibodies against Q fever

Posted March 15, 2009

More than one-fifth of veterinarians screened in a study on Q fever had antibodies against the causative Coxiella burnetii, according to a recent article.

The study, which appeared in the March 1 edition of Clinical Infectious Diseases, found that 113 of the 508 veterinarians tested at the 2006 AVMA Annual Convention in Honolulu carried antibodies against the bacteria. The report has also been published online.

Information from the Centers for Disease Control and Prevention indicates most human Q fever outbreaks in the U.S. relate to occupational exposure involving "veterinarians, meat processing plant workers, sheep and dairy workers, livestock farmers, and researchers at facilities housing sheep."

The Clinical Infectious Diseases article, "Seroepidemiologic and occupational risk survey for Coxiella burnetii antibodies among US veterinarians," suggests some veterinarians should consider undergoing routine serologic evaluation. It states early diagnosis of endocarditis attributable to C burnetii can prevent complications in individuals with heart disease, those undergoing immunosuppressive therapy, and those who are pregnant.

The article states that about 65 percent of those tested who had positive results for the antibodies were men, and a similar portion of those screened were more than 46 years old.

Veterinarians in mixed animal practice or food animal practice were more likely to be seropositive than veterinarians in small animal practice, the article states. Veterinarians with mobile practices were also more likely to be seropositive.

Routine exposure to freshwater rivers, streams, lakes, and ponds, as well as ditch or sewage water, was also associated with antibody presence.

Infection in humans is primarily related to inhalation of airborne bacteria, according to the AVMA backgrounder on Q fever. The bacteria can survive in dust contaminated with feces, birth fluids, and fetal membranes, and humans can also become infected by consuming contaminated, unpasteurized dairy products.

"Vector transmission to humans via ticks and human-to-human transmission is rare," the backgrounder states. "Domestic dogs and cats may be infected by exposure (ingestion or aerosol) to contaminated excretions or birth products and may then shed the bacteria in milk and urine, thus serving as potential sources of human infection."

Cattle, sheep, and goats are the bacteria's primary reservoirs, but other livestock species and domesticated pets can become infected, according to the CDC.

About half the people infected develop clinical signs, most within three weeks after exposure, the backgrounder states. The typical symptoms of acute infections are fevers of up to 105 F for one to two weeks, severe headache, muscle pain, sore throat, disorientation, chills, sweating, coughing, nausea, vomiting, diarrhea, abdominal pain, chest pain, and weight loss.

Information from the CDC states that between 30 percent and 50 percent of people with symptoms develop pneumonia, most have abnormal liver function, and some develop hepatitis. Between 1 percent and 2 percent of people with acute fever die of infection.

The backgrounder includes additional information on symptoms in humans, clinical signs in animals, prevention in humans and animals, and treatment and chronic infection in humans. To read the backgrounder or a Zoonosis Update on Q fever, click here.