Bird flu's U.S. flyby?

Bird flu's U.S. flyby?

Dec 01, 2005

Recent outbreaks among poultry in the United States with no transmission to humans.
NATIONAL REPORT — For the first time in history, scientists could be on the forefront of predicting an influenza pandemic.

"We have never had the technology or the funding to be in the driver's seat that we are today," says Dr. Carol Cardona, Dipl. ACPV, avian influenza expert with the National Center for Foreign Animal and Zoonotic Disease Defense. "We know that a pandemic will undoubtedly occur at some point in our near future. But we don't know what virus that will be. The H5N1 looks like a good candidate, however, it might never, ever become a pandemic virus."

Despite the plague of media attention, H5N1 largely remains an avian flu with little immediate threat to the food supply or companion birds in the United States.

Recent North American outbreaks of avian influenza with transmission to humans
Still, the country's producers are under the microscope for the next killer bug, and border control has become a public health issue. About 38,000 animals cross U.S. borders each day, and the illegal exotic animal trade is a $4-billion to $6-billion industry, according to Dr. Lonnie King, director of the Office of Strategy and Innovation for the Centers for Disease Control and Prevention (CDC).

Smugglers could introduce an array of disruptive viruses to the country. Cockfighting organizers are thought to have introduced exotic Newcastle disease into the United States in 2002, resulting in millions of depopulated birds and a multi-national boycott of U.S. poultry products. Newcastle disease remains a virulent threat, says Dr. Thomas Tully, MS, Dipl. ABVP, president of the Association of Avian Practitioners and professor of clinical sciences at Louisiana State University.

Influenza pandemics during the 20th Century
"We are keeping our eyes on H5N1 for sure, but it's more likely that Newcastle would rear up than H5N1 at this point," Tully says. "We don't know if all the birds are going to respond to the virus, but we are trying to determine that. With West Nile, for example, some birds are more susceptible than others. With H5N1, there are certain birds that incubate a highly pathogenic strain that affects them, so there is a lot still up in the air."

Historically, the incidence of influenza in exotic birds is very low, says Dr. Susan Clubb, Dipl. ABVP, owner of Rainforest Clinic for Birds. Influenza has been detected only once in the 30 years the United States has observed a one-month quarantine for exotics, she says.

"If you look back at import records (according to the National Veterinary Services Laboratory) there has only been one occasion since 1974 where a pathogenic bird flu has come into the United States in exotic birds. That was in Peking Robins that came in from China," she says. "Now people are afraid to feed the birds in their back yard, and there is a state of fear that we are living in. Exotic birds are not the risk. The risk is in poultry and waterfowl."

Still, practitioners who see new patients have a duty to inquire about the origin of an animal to deflect a range of diseases. Many breeders in this country use aluminum identification bands that identify the producer to ensure companion birds are made in America.

"Practicing veterinarians need to be aware and encourage people to purchase only those birds that have been legally imported. That's an important safeguard that we need to protect at this time," says Cardona, who is also associate professor and cooperative extension poultry veterinarian in the University of California-Davis School of Veterinary Medicine.

Assessing risks

Stringent surveillance and reporting protocols already in place to monitor for food-safety risks routinely test flocks for avian influenza, among other diseases. More than a thousand broiler, layer, turkey, game bird and ostrich operations are monitored by the Animal and Plant Health Inspection Service (APHIS) National Poultry Improvement Plan (NPIP). The program was developed with industry, state and federal cooperation to identify and eradicate infectious diseases; 48 state agencies and 130 authorized laboratories monitor close to 10,000 flocks comprised of about 85 million birds for avian influenza. Most are broilers.