Veterinarians who work with birds are at increased risk of infection with avian influenza virus and should be among those with priority access to pandemic influenza vaccines and antivirals, according to a study conducted by researchers in the University of Iowa (UI) College of Public Health.
The investigators, led by Kendall Myers, a doctoral student in occupational and environmental health, and Gregory Gray, MD, UI professor of epidemiology, examined blood samples from a group of US veterinarians for evidence of previous avian influenza virus infection. The veterinarians all had occupational exposure to live chickens, ducks, turkeys, geese or quail.
The study showed that, compared with the control group, the veterinarians who worked with birds had significantly higher levels of antibodies in their blood against the H5, H6 and H7 avian virus strains, indicating previous infections with these viruses. The infections were likely due to the mild forms of avian influenza virus that have occasionally circulated among wild and domestic birds in the United States, according to the researchers. The greatest risk factor for infection reported by veterinarians was examining birds known to be sick with influenza.
"Veterinarians and others with frequent and close contact to infected birds may be among the 1st to be infected with a pandemic strain of influenza,” Myers said. “They have the potential to spread the illness to their families and communities. Because of this, we suggest that veterinarians should be considered for inclusion on priority access lists for pandemic influenza vaccines and antivirals."
Birds are the source of all influenza viruses in all other species, the authors noted in their study, and a better understanding of inter-species transmission of avian influenza is a crucial component in efforts to minimize the effects of the next pandemic. Health authorities worldwide are closely monitoring the H5N1 virus strain that emerged in Asia as a possible source of a pandemic.
"While these avian influenza virus infections in veterinarians were likely mild or subclinical, the story might be very different should aggressive avian influenza strains enter the United States like the H5N1 strains infecting domestic birds in Asia," Gray said. "As federal officials continue to plan for a pandemic event, it is increasingly important to identify the best ways to protect veterinarians and other agricultural workers most at risk for zoonotic diseases." (The study is being published in the July 2007 issue of the journal Clinical Infectious Diseases.)