FOR RELEASE: July 8, 1997
Contact: Blaine P. Friedlander, Jr.
Office: (607) 255-3290
Internet: [email protected]
Compuserve: Larry Bernard 72650,565
http://www.news.cornell.edu
ITHACA, N.Y. -- Significant progress in controlling poultry-borne infection
was reported recently at the 69th Northeastern Conference on Avian Diseases
at Cornell University.
Still, two diseases (avian influenza, or AI, and infectious
laryngotracheitis, or ILT) threaten the economic health of the American
poultry industry and at least one (Salmonella enteritidis) worries
Americans who eat eggs, conference participants from as near as New York
and Pennsylvania and as far as Australia were told.
"When it comes to infectious diseases, there's a lot a stake for an
industry that exports up to 20 percent of the 6 billion broilers produced
here each year to other countries," said Benjamin Lucio, the poultry
extension veterinarian who organized the June 11 to 13 meeting at Cornell's
College of Veterinary Medicine. "The general public doesn't know or care
when millions of dollars are lost because hundreds of thousands of infected
birds must be slaughtered. But the public wants assurances," he said,
"that the eggs they consume are not infected with salmonella."
That confidence can come from voluntary egg quality assurance programs,
John Mason of Food Safety Consultant Services told the avian disease
conference. A successful quality-assurance program in Pennsylvania has
producers certifying that whole eggs sold to market come only from
salmonella-free flocks (and that eggs from flocks with evidence of SE are
diverted to processing plants where the eggs are pasteurized to destroy
infectious organisms).
A similar quality-assurance program is expected to start in New York later
this year, according to Syed A. Naqi, professor of avian medicine at
Cornell. The New York program is the result of combined efforts of the New
York State Department of Agriculture and Markets and the Cornell College of
Veterinary Medicine's Diagnostic Laboratory.
"We've made tremendous progress in this century in understanding and
controlling avian diseases," said Lucio, who along with Cornell poultry
scientist Robert C. Baker was the first to prove that SE is transmitted by
eggs. He pointed to successful test and control strategies developed for
potentially devastating conditions in poultry, such as Marek's disease,
mycoplasmosis, infectious bursal disease and infectious bronchitis. "Yet,
there continue to be emerging diseases, and in an era of expanding
international trade, proving that your animals are disease-free is more
important than ever," he said.
One strategy for controlling avian influenza could be a genetically
engineered vaccine that is in use in Mexico, Lucio said. The alternative
to prevention is "depopulation," in which entire flocks of birds are
slaughtered and buried. Earlier this year, infection by the H7N2 strain of
avian influenza cost a Pennsylvania egg producer a flock of 123,000 birds,
Susan C. Trock of the U.S. Department of Agriculture reported. In the
early 1980s, a different avian influenza strain crippled the Pennsylvania
poultry industry, forcing the slaughter of some 17 million birds; the
result was an estimated loss to producers of $400 million and expense to
American taxpayers of $50 million when the federal government partially
compensated poultry producers.
Like avian influenza, infectious laryngotracheitis (ILT) does not affect
humans -- except in the pocketbook -- Lucio said. One out of every six
broiler chickens raised in the United States is exported, primarily to
China and Russia, the Cornell poultry expert said, "and if we can't
eradicate that disease to the satisfaction of our overseas customers, we'll
have a big problem. While conventional vaccines protect against clinical
ILT, they contribute to perpetuating the infection in vaccinated flocks,"
Lucio said. He noted that genetically engineered vaccines, now under
development, show greater promise.
"By hosting the avian disease conference, Cornell University renewed its
long-standing ties to poultry medicine and husbandry," Lucio said. "The
exchange of ideas between university researchers, industry representatives
and veterinarians from the USDA will influence policies for the control and
eradication of these important diseases."
Besides the disease-control strategies with bio-engineered vaccines and
international embargoes, the conference-goers learned of one type of
immunization with which every chicken can identify -- the lowly earthworm.
Canadian researchers reported on studies with salmonella and vermicompost,
the soil-like material that passes through worms when they eat.
The researchers raised earthworms on feces from disease-free
chickens and then fed the vermicompost to newly hatched chicks. In theory,
"good" bacteria in the vermicompost was supposed to thrive and displace any
"bad" bacteria, including salmonella, in the young birds. Yes, the
chicken-worm-chicken connection helps, to some extent, researchers said.
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