Pulse - July 2024 - 12

UC DAVIS UPDATE
UC Davis Active in Avian
Influenza Research
Kat Kerlin, Amy Quinton, and Rob Warren, UC Davis
H
ighly pathogenic avian
influenza (HPAI) has been
detected on commercial farms
in California and other parts
of the United States. The most
recent outbreak of the highly
transmissible strain of bird flu
began in early 2022 and has
resulted in the deaths of millions
of chickens and turkeys. It has
also been detected in cows in the
U.S., marine mammals in South
America, and other species globally.
The CDC has confirmed a
handful of human cases in the
U.S. and several cases of avian
flu in cats on dairy farms.
Several UC Davis School of Veterinary
Medicine veterinarians are actively researching
the subject, and the experts are being featured
in media throughout the world as the topic
continues to grow.
Most recently, research from veterinarians
with the school's Wildlife Health Center shows
that HPAI strain H5N1viruses are increasingly
flexible and are adapting to mammals in
new ways that could have global consequences
for humans, wildlife, and livestock, according
to a new study of an especially devastating
2023 outbreak in Argentina. By the end of the
season, a breeding colony of elephant seals lost
96% of its pups to the virus.
The study shows clear mammal-to-mammal
transmission of the virus. It states the outbreak
is the first known, multinational transmission
of the virus in mammals ever observed globally,
with the same virus appearing in several pinniped
species across different countries over a
short period of time.
The study's genomic analysis showed the
virus is now evolving into separate avian and
marine mammal clades in South America,
which is unprecedented. There is growing
12
Dead elephant seals and a bird carcass line the beach in Argentina during a 2023 H5N1 outbreak.
(Ralph Vanstreels, UC Davis)
concern that H5N1 viruses adapted to mammal
transmission could jump to other species,
including people.
" This is increased evidence that we should
be alert, especially for marine mammals, " said
Dr. Marcela Uhart, co-leading author on the
research. " The more it adapts to mammals the
more important it becomes for humans. "
Elsewhere around the school, experts in
infectious diseases in cattle are looking into
what the spread of H5N1 in cows means for
the dairy industry and milk drinkers.
No vaccines or specific therapies are available
for avian influenza infections in dairy
cattle. But following good sanitation and biosecurity
practices for both people and cows will
help to reduce risk of exposure and spread of
the avian influenza virus among dairy cattle.
" For cows that get the virus, providing supportive
care, including fluids and fever reducers
as needed, can help them get through the illness, "
said Dr. Terry Lehenbauer, director of
the school's Veterinary Medicine Teaching
and Research Center in Tulare. " However,
contracting the virus may cause loss of appetite
and affect the cow's milk production. "
The commercial milk supply maintains
strict safety measures and there is currently no
concern for the safeness of milk. Any product
sourced from sick animals is promptly diverted
or disposed of, ensuring it does not enter the
food chain. Additionally, all milk at grocery
stores is heat treated to reduce pathogen load to
safe levels, mainly by pasteurization. Pasteurization
has been shown to effectively inactivate
H5N1 in eggs, and that process occurs at a
lower temperature than is used for milk.
Drinking raw milk, however, does represent
a risk for exposure to multiple diseases, including
H5N1. The FDA and CDC strongly
recommend drinking only pasteurized milk
and dairy products.
UC Davis veterinarians continue to monitor
the crisis worldwide. For more on the school's
efforts, see news coverage at www.ucdavis.edu/
blog-tags/avian-influenza. P
JULY 2024
PULSE

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Pulse - July 2024

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