A 20-year Review of Avian Influenza in Felines Suggests
Surveillance of Domestic Cats is Urgently Needed
COLLEGE
PARK, Md., June 17, 2024 /PRNewswire-PRWeb/ -- The
world is barely out of the COVID-19 pandemic, and the threat of
another virus jumping from animals to humans looms large in our
daily newsfeeds. As public health officials follow the spread of
the rapidly evolving bird flu H5N1, a review of the scientific
literature suggests domestic cats can get bird flu and transmit it
to humans, and should be monitored.
"As companion animals, domestic cats
provide a potential pathway for avian influenza viruses to
spillover into humans," said Kristen
Coleman, an affiliate professor in the University of Maryland Department of Veterinary
Medicine, and an assistant professor in the UMD School of Public
Health.
"As companion animals, domestic cats provide a potential pathway
for avian influenza viruses to spillover into humans," said
Kristen Coleman, an affiliate
professor in the University of Maryland
Department of Veterinary Medicine, and an assistant professor in
the UMD School of Public Health. "We looked at the global
distribution and spread of bird flu infections in feline species
between 2004 and 2024 and found a drastic rise in reports of feline
infections starting in 2023, with a spike in infections reported
among domestic cats, as opposed to wild or zoo-kept animals. This
increase coincides with the rapid spread of the current strain of
H5N1 among mammals."
Bird flu is not currently reported to be contagious between
humans, and it is not guaranteed to evolve in that direction, but
the disease is clearly changing. The current strain of the H5N1 has
been spreading to animals that have never been affected before, and
pets that can pass it to people could play a role in how it
evolves.
Coleman's study, currently in preliminary form without peer
review on MedRxiv, found that cat owners, veterinarians,
zookeepers, and cat shelter volunteers may be at greater risk of
contracting the H5N1 infection if the virus continues to circulate
unabated. The CDC, which provides guidance for veterinarians
working with potentially infected animals, says the risk of
contracting the disease from pets is low, but Coleman suggests pet
owners should still take precautions to protect their cats and
themselves.
"Don't feed your cat raw meat or raw dairy milk and limit their
unsupervised time outdoors," she said. "Cats prey on wild birds
that could be infected, and they could get into raw dairy milk on a
farm if it is not securely stored."
In addition, the virus has been reported in house mice, which
cats also prey on, so it appears the opportunities for
cross-species transmission are increasing, and pet cats may be at
increased risk.
Pet owners should be watching for respiratory and neurological
symptoms. If your cat seems to have trouble breathing or is acting
unusual, you should consider taking them to the vet. The current
H5N1 strain has also reportedly caused blindness in cats.
Since the emergence of H5N1 in U.S. dairy cattle, 21 domestic
cats have been reported to be infected to date. Full genetic
sequences of the viral strains infecting 2 of these cats have been
reported in the scientific literature. Coleman said sequencing and
demographic data for the other cat cases are urgently needed.
Why Cats?
Avian influenza, or bird flu, was once a finicky disease,
infecting mostly migratory waterfowl and farmed poultry. But since
2020, the highly infectious strain known as H5N1 began spreading
among a wider variety of birds. It has recently been appearing in a
growing number of mammals, even decimating whole colonies of sea
lions throughout South America. In
April 2024, it appeared for the first
time in dairy cattle in Texas, and
a farm worker contracted the disease after interacting with sick
animals. Two farm cats that were fed unpasteurized milk also became
infected.
Although the disease is new among many animals, cats have been
occasional victims of avian influenza for decades, most likely
because they eat birds and are exposed through sick or dead prey
carrying the virus.
Coleman reports that the fatality rate for the current strain of
H5N1 in cats has been around 67%, which in itself is a good reason
for pet owners to keep their cats inside and away from wild birds.
She found a number of other worrying aspects of the disease in
cats.
There have been multiple reports of cats contracting bird flu
from other cats, both in zoos and animal shelters, suggesting the
disease could cause repeated outbreaks among these animals.
Both zookeepers and animal shelter workers have contracted bird
flu from cats in their care. Although not the current H5N1 strain,
these cases reveal cats as potential vectors for the disease in
humans.
In April, 2024, two farm cats got H5N1 from drinking raw milk
from an infected dairy cow in Texas, showing that cats can contract this new
variety from other mammals.
These factors, along with the rise in frequency of feline
infections, the severity of disease and the close proximity of cats
to their human companions, suggest that public health officials
should consider a One Health approach to mitigating the disease
beyond dairy cattle and humans. A One Health approach suggests cats
and other animals should be monitored for the disease not only for
their sake, but for the protection of human health as well.
"The virus is going to sneak up in more places, just like it did
in dairy farms. We know cats are being infected, so let's get ahead
of it," Coleman states.
Media Contact
Kimbra Cutlip, University of Maryland, 301-405-2434,
kcutlip@umd.edu, agnr.umd.edu
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SOURCE University of Maryland