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DVMs who handle birds at increased risk of avian flu, study finds

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Jul 01, 2007

IOWA CITY, IOWA — Veterinarians who regularly work with birds have substantially higher levels of antibodies in their blood against avian virus strains than do control subjects, according to a two-year study conducted by researchers at the University of Iowa College of Public Health.


Kendall P. Myers
That's a clear signal that those DVMs would be at high risk for infection in the event of a serious avian flu outbreak and argues that they should be given the same priority access to pandemic influenza vaccines and antivirals that public-health doctors and nurses would have, the recently published study says.

The researchers, led by Kendall Myers, a doctoral student in occupational and environmental health, and Gregory Gray, MD, UI professor of epidemiology and director of IU's Center for Emerging Infectious Diseases, performed a controlled, cross-sectional seroprevalence study among 42 Iowa veterinarians and 66 healthy control subjects using serum samples collected from 2004 through 2006.

The study showed that, compared with the control subjects, DVMs who regularly worked with birds had greatly elevated titers against the H5, H6 and H7 avian influenza virus strains, indicating previous infections with those strains, likely due to mild forms of virus that occasionally circulated among wild and domestic birds.

"Veterinarians and others with frequent and close contact to infected birds may be among the first to be infected with a pandemic strain of influenza," Myers says. "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."

Of the 42 veterinarians in the study, 32 worked with live chickens, 21 with ducks, 18 with turkeys, 12 with geese and seven with quail.

Few DVMs in the study reported that they regularly use protective gloves and masks.

However, that simple measure could help reduce virus transmission, Myers tells DVM Newsmagazine.

Receiving an annual human-influenza vaccination also might be a mitigating factor, she adds.

Gray explains that, "While these earlier avian-flu infections (antibodies for which showed up in the blood of veterinarians) were likely mild or subclinical, the story might be very different should aggressive strains enter the United States like the H5N1 strains infecting domestic birds in Asia.

"It is increasingly important to identify the best ways to protect veterinarians and other agricultural workers most at risk for zoonotic diseases," Gray believes.

How well prepared is the United States for a pandemic outbreak of H5N1?

"We're more prepared than we were six months ago, and not as well prepared as we will be six months from now," Gray says. "But there's no question we aren't yet ready to handle anything with a fast rate of transmission."


Gregory C. Gray, MD
The American agriculture industry "has been particularly neglected in pandemic planning," Grau adds. Should the virus infect swine and poultry, as occurred with the pandemic strain of flu that killed millions in 1918, "it would greatly increase the speed of transmission to humans," he says.

DVM Newsmagazine asked Myers to elaborate on several key points from the study. Here are our questions and her responses:

DVM: Is there a surprise element to your finding that DVMs who work with birds would be at increased risk in the event of a major outbreak? Wouldn't that be a logical assumption?

MYERS: We suspected that veterinarians would be at greater risk for avian influenza infections. In this pilot study, we sought to estimate the seroprevalence of antibodies against avian influenza viruses in veterinarians with exposure to birds and to determine risk factors for infection.

We examined a number of possible risk factors, including age, chronic medical conditions, race and ethnicity, medication use, military service, children in the home, and smoking.