WASHINGTON, July 3, 2024
/PRNewswire/ -- In March 2024, dairy
cows in Texas were found to be
infected with highly pathogenic avian flu, or H5N1 bird flu, in the
first known case of the virus spreading to cattle. Since then, H5N1
has been found in about 200 animals—and 3 people—across 12 states,
according to the Centers for Disease Control and Prevention. The
virus was soon detected in raw milk, leading researchers to
investigate whether dairy products pose a risk to consumers. Their
results are reported this week in the Journal of Virology, a
journal of the American Society for Microbiology.
"How far is the virus getting through?" asked Erica Spackman, Ph.D., a virologist at the U.S.
Department of Agriculture (USDA) in Athens, Georgia. To find out, she and her
collaborators tested nearly 300 milk products from 132
processors.
The researchers found no infectious virus in the samples.
"Milk is safe," Spackman said. "Just like bacterial
pathogens that occur in milk, or other viruses that could occur in
milk, the sanitation processes that are in place are getting rid of
the pathogens."
The milk processing pipeline includes multiple layers of
protection, Spackman said. Microbiological surveillance of milk
products can identify pathogens, and milk from cows with mastitis
or other disease conditions does not enter the food supply.
Finally, heating during the pasteurization process can destroy H5N1
and other, more common bacterial pathogens.
Bird flu primarily infects and spreads among migratory birds and
can be transmitted to domestic poultry, but the virus has been
detected in other animals as well. Recently, those have included
cats, dogs and juvenile goats, as well as a polar bear in
Alaska and elephant and fur seals
in the Antarctic. However, the discovery of H5N1 on dairy farms in
March was a surprise—the virus had never been found in dairy cattle
before.
Soon after the discovery, diagnostic testing revealed that an
infectious form of the virus was present in raw milk, suggesting
the virus passes from cow to milk. That finding led the U.S. Food
and Drug Administration and the USDA to investigate whether
pasteurization effectively eliminated risks posed to consumers.
Between April 18 and April 22, 2024,
researchers used real-time PCR to analyze 297 samples of
pasteurized retail milk products, including 23 types of products,
collected from 17 states.
"We did a viability assay to detect live virus and went as
sensitive as we could to get even the least little bit of virus,
but couldn't detect anything," Spackman said. Using PCR, the
researchers did identify viral genetic material in 20% of samples.
"It looks like the virus is just totally inactivated," she
said.
Spackman said the new findings "give us reassurance that what we
have been doing— pasteurization—is keeping us safe from what we
don't know about."
The American Society for Microbiology is one of the largest
professional societies dedicated to the life sciences and is
composed of 32,000 scientists and health practitioners. ASM's
mission is to promote and advance the microbial sciences.
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SOURCE American Society for Microbiology