Biosecurity Tight with Avian Flu Looming

The Arkansas poultry industry uses the most sophisticated biosecurity available, but with 1.2 billion broilers being processed in the state each year and a highly pathogenic strain of the avian flu on the other side of the globe, companies must be particularly vigilant.

Avian influenza was first identified in Italy in 1878 and spread to New York by 1924.

For 50 years, experts didn’t think the avian flu would pass from bird to man. But that theory changed in 1997 when researchers discovered that had happened in Hong Kong.

Then, by analyzing tissue from World War I soldiers, they discovered the flu of 1918, which killed 15 million people worldwide, had originated in birds.

Scientists believe the H5N1 strain of avian flu that has recently killed 63 people in Asia can spread from bird to human but not from human to human.

“The fear is a person with human flu will pick up avian flu at the same time, and we’ll get a new strain,” said Dustan Clark, poultry veterinarian for the University of Arkansas Cooperative Extension Service. “They’ll be a mixing vessel, and it’ll spread from person to person. That’s the big concern.”

Biosecurity

The biosecurity employed by U.S. poultry firms primarily concerns keeping different species of birds apart. Such measures aren’t taken in Asia.

“Biosecurity is a major priority for our company,” Tyson Foods Inc. of Springdale said in a statement on avian flu. “For example, chickens raised for our North American processing operations are housed in modern, enclosed facilities, which prevent contact with wild birds and other potential carriers of disease. By contrast, most chickens and ducks raised in Asia are allowed to run free with little separation from the environment.”

Minor strains of avian flu are occasionally detected in U.S. poultry.

“Any outbreak of avian flu, whether it’s low-pathogenic or high-pathogenic, they quarantine the birds and destroy them,” Clark said.

Clark said 17 million birds were killed last year in British Columbia because of a strain of avian influenza. In 2004, 7,200 birds were destroyed in Texas because of avian flu virus. Low-pathogenic avian flu was also detected last year — and the birds destroyed — in Maryland, Pennsylvania, Delaware and New Jersey.

“That helps reduce the risk because we’re taking out birds that could spread the disease,” he said.

Although no live birds are imported to the U.S. from overseas, avian influenza is found in many American waterfowl.

“They’re just a natural reservoir, and it doesn’t bother them,” Clark said. “It’s not like every duck has it or every goose has it.”

One problem, Clark said, is live bird markets have multiple species of birds, allowing viruses to spread from one species to another. Someone could accidentally buy an infected bird, take it back to his farm and infect every bird on the farm.

Clark noted that avian flu is spread only by live birds, not by birds that are cooked and eaten by humans.

Vaccines

The medical community is working on a vaccine that would help prevent the spread of avian influenza.

Until then, four different antiviral drugs (amantadine, rimantadine, oseltamivir and zanamivir) are approved by the U.S. Food and Drug Administration for the treatment or prevention of human influenza.

But influenza strains can become resistant to these drugs, and therefore the drugs may not always be effective. The H5N1 virus in Asia is a case in point. It is resistant to amantadine and rimantadine.