UM scientists study role of wild birds in spread of avian flu

Project seeks vaccines tests, survey of flyways

June 28, 2005|By Michael Stroh | Michael Stroh,SUN STAFF

COLLEGE PARK - In a low-slung building far from virus-plagued Southeast Asia, scientists are leading a sweeping inquiry into the role that migratory waterfowl and other wild birds might play in spreading avian flu.

The research is one groundbreaking aspect of a $5 million project intended to address some of the many unanswered questions about the virus. Avian flu resides harmlessly in the gut of ducks and other waterfowl but is capable of hopscotching into species such as chickens, pigs and-most worrysome-humans.

The project, which is based here at the University of Maryland and involves more than a dozen labs around the United States, is funded by the U.S. Department of Agriculture. An agency official said the grant is the largest the USDA has awarded for a single disease.

The commitment reflects a growing unease among animal and human health experts that avian flu viruses now circulating in Asia could wind up in North America. The lethal H5N1 strain of the virus has led to the culling of millions of chickens and other birds and killed 54 people. Human cases have been documented in four Asian countries, the latest this month in Indonesia.

"It's a disease that is not going to go away," says Daniel Perez, a University of Maryland avian flu researcher and director of the new, three-year project.

As part of the effort, Perez said, researchers will attempt to develop faster and more sensitive tests to detect the presence of the virus in animals. They also are seeking new animal vaccines that could check the spread of the disease.

Another key goal: the first comprehensive survey of the continent's major flyways to determine which strains of avian flu are found in migrating birds.

"We're trying to find out where the viruses are and where they're most likely to move between species," says Richard Slemons, an avian flu researcher at Ohio State University who is coordinating the survey.

Slemons said this knowledge could help commerical poultry producers avoid building farms in areas where the threat of encounters with infected wild birds is high.

Despite the drumbeat of headlines about the disease, avian flu is not a new disease. For much of the 20th century, it attracted only a handful of curious veterinarians and virologists.

"We didn't get much respect," says Ohio State's Slemons, who has been studying the virus for more than 30 years. The first appearance of the disease in the scientific literature, he says, was in 1878, when chickens in Italy came down with what was then dubbed "fowl plague."

It would take nearly 80 years before scientists determined that fowl plague was caused by a virus-influenza A-genetically similar to the one that causes flu in humans. Fowl plague soon acquired a new name: avian influenza.

The disease was mostly considered a problem for poultry producers, who occasionally watched in horror as the virus raced through their flocks. A 1983 outbreak in Pennsylvania, for example, forced officials to destroy nearly 17 million chickens and turkeys to check its spread. The price tag was $65 million; poultry prices soared.

The threat to people became apparent in 1997, when six people in Hong Kong died from severe respiratory infections. Investigators learned the victims had all been to farms or live markets where birds harbored an avian flu strain called H5N1. It was the first documented instance of avian flu passing directly from poultry to people.

Since then other avian flu viruses have caused infections in humans. Global health authorities fear H5N1 or another variant could touch off a devastating pandemic. Another cause for suspicion: genetic sleuthing has shown that the influenza viruses responsible for the three last pandemics-1918, 1957, 1968-bore similiarities to strains in birds.

Inside his laboratory at the University of Maryland's Avrum Gudelsky Veterinary Center, Daniel Perez is grappling with the question of what makes a flu virus so versatile, enabling it to jump from one species to another and how to spot the most potent variations.

"If we isolate a virus from a duck and say, Is this going to go into a chicken or a pig? Right now we have no idea," says Perez, who hopes the USDA project he's heading will fill in some of these blanks.

Born in Argentina, Perez , 41, arrived in College Park in 2003 after spending three years working at St. Jude's Children's Research Hospital in Memphis under Robert Webster, one of the world's most renowned flu investigators. At St. Jude's, Webster encouraged Perez to look at a bird that Perez suspected might be a unknown culprit in the spread of avian flu: quail.

Regarded as a game birds in the United States, quail are staples of many Asian markets. Perez soon found they were carriers of numerous of avian flu strains. The work, Webster says, helped persuade Hong Kong officials in the wake of the 1997 H5N1 human outbreak to ban quail from the city's bird markets. Webster said Perez's work may have helped thwart the spread of the disease.

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