Hunters and wildlife workers test positive for bird flu virus

WASHINGTON - A US duck hunter and two state wildlife employees had evidence of an uncommon type of bird flu virus in their blood, researchers reported on Monday in one of the first studies to show that hunters might be at risk.

The virus was H11N9, not known to be dangerous to humans and not related to the feared H5N1 virus circulating in wild and domestic birds and among some people, the researchers said.

But their study, published in the journal Emerging Infectious Diseases, shows that people who work with wildlife should take care.

"To our knowledge, this study is the first to show direct transmission of influenza A viruses from wild birds to humans," Dr. James Gill of the University of Iowa and colleagues wrote in their report.

The H5N1 avian influenza virus has not yet caused a human pandemic, but it has killed 132 people out of the 230 infected. It has infected birds in about 50 countries and is spreading faster than any other avian influenza ever has.

Many experts believe it may pose the worst threat of an influenza pandemic in 30 years.

The natural host is ducks, and migrating waterfowl have been shown to spread the disease. Most ducks do not become sick from avian influenza, but some strains can can kill chickens in a day.

The researchers studied 39 duck hunters who were hunting in southeastern Iowa at Lake Odessa Wildlife Management Area, and 68 Iowa Department of Natural Resources employees who either hunted or help band wild ducks.

Three of the men had antibodies against H11N9, suggesting they had either been infected in the past or had fought off an infection.

All three "had substantial lifetime exposures to wild waterfowl", the researchers wrote.

None of the other hunters or wildlife workers had evidence of H11N9 virus in their blood, the researchers said.

In addition, the two wildlife employees had antibodies against a mallard duck strain of H2N2 influenza, which caused human epidemics in the 1950s and 1960s.

"Even though the H11-positive study participants had several years of exposure to wild birds infected with avian influenza virus through hunting and duck banding, they did not wear personal protective equipment, such as gloves, masks, or eye protection," the researchers wrote.

They did not ask the three men if they had flu-like symptoms.

"Although the sample size of our study was relatively small, our results suggest that handling wild waterfowl, especially ducks, is a risk factor for direct transmission of avian influenza virus to humans," they wrote.

The US Fish and Wildlife Service and the US Geological Survey are testing wild birds for H5N1 flu, which has not been seen in the Americas yet.

"Many species that breed in Alaska migrate and winter throughout parts of Russia and Asia," the USGS said.

"Birds could be exposed to H5N1 in Asia or Russia during winter or on migration and carry the virus to Alaska in spring along migratory corridors."

- REUTERS