UNIVERSITY PARK, Pa. -- Despite the recent outbreak of a milder form of avian influenza in Delaware, the type of bird flu that is devastating poultry flocks and causing human illness in Asia is unlikely to occur in Pennsylvania, according to a veterinary scientist in Penn State's College of Agricultural Sciences.

"The strains of avian flu that are crossing over to humans are the highly pathogenic strains, and we currently don't have those in the United States," says Patty Dunn, an avian veterinarian in Penn State's Animal Diagnostic Laboratory.

Delaware officials on Feb. 7 destroyed a 12,000-bird poultry flock infected with the low-pathogenic H7 strain of avian flu. About 72,000 chickens on another Delaware farm were destroyed Feb. 10 after bird flu was found. Officials in Pennsylvania, where poultry is a $700-million-a-year industry, are watching the situation carefully.

"Pennsylvania has one of the most aggressive avian influenza monitoring programs in the country," Dunn says. "By closely monitoring for the low-pathogenic strains, we can contain and eradicate outbreaks quickly. And when we keep those strains from circulating, we keep them from mutating into a highly pathogenic form that could kill millions of birds and possibly cross over to humans, as it has in Asia."

Pennsylvania learned this lesson the hard way. In April 1983, a seemingly mild outbreak of low-pathogenic bird flu simmered and spread, and by October the virus had mutated into a highly pathogenic strain (H5N2) that cost the state's poultry industry 22 million birds and hundreds of millions of dollars. Since then, improved production practices, enhanced monitoring and new technologies have helped to limit avian influenza in Pennsylvania. Aided by a rapid diagnostic test developed by Penn State veterinary scientists, a 2001 outbreak of low-pathogenic H7N2 avian flu was limited to 140,000 birds and cost the state's poultry industry only about $350,000.

"Using that test, we were able to diagnose the 2001 problem in just one day, which enabled the state and poultry producers to contain and eliminate the outbreak," says Dunn. "An outbreak of the same virus a few months later in another Mid-Atlantic state took about seven days to confirm, giving the virus more time to spread. As a result, that state lost almost 5 million birds at a cost of $114 million."

Dunn says that avian influenza is not a food safety concern. "Infected broilers typically would not reach the food chain," she explains. "Even if they did, thorough cooking would kill the virus, which is spread primarily through respiratory secretions and fecal droppings." She adds that the virus is not carried in eggs.

The human health implications of bird flu stem from the virus' ability to "reassort" and mutate over time. The recent human deaths caused by the highly pathogenic H5N1 strain in Asia are believed to have been the result of people coming into close contact with infected birds. While officials say that strain does not appear to spread from person to person, health organizations worry that a highly pathogenic strain could combine with a strain of human influenza that's easily passed between people, which could cause a flu pandemic.

Meantime, Dunn says Pennsylvanians shouldn't spend a lot of time worrying. "We need to be vigilant," she says. "But with close monitoring and surveillance, and implementation of proper biosecurity measures by poultry producers and backyard flock owners, it's not likely that highly pathogenic H5 avian flu will develop independently here in the United States."

###

EDITORS: Patty Dunn can be reached at 814-863-1983.

Chuck Gill Office 814-863-2713 FAX 814-863-9877