Did Your Flu Come From Your Cat?
A flu epidemic sickening cats at a NYC shelter reminds that some viruses can jump from species to species, posing a low risk to people.
It's the flu season, so there is a good chance that if you come down with a virus and have a pet, you could sneeze or cough all over them. Your ailing dog or parrot could do the same to you. If you and your pet both then become ill with similar symptoms, is that just a coincidence?
Perhaps not, according to new research showing how certain flu viruses can sometimes jump from species to species.
For example, there is a flu epidemic currently at a Manhattan shelter that has sickened some 45 cats and killed one. Given the number of victims, the University of Wisconsin-Madison (UW) School of Veterinary Medicine investigated the outbreak and determined that the culprit was "low pathogenic avian influenza H7N2." This marks the first known time that this relatively mild bird flu has sickened cats.
"Many of the cats who became ill are recovering, and the one who developed pneumonia and died was an older feline," Sandra Newbury, director of the UW Shelter Medicine Program and a clinical assistant professor at the university's School of Veterinary Medicine, told Seeker. "Their symptoms included fever, runny nose, lip smacking and a persistent cough."
She added that there have been two documented cases of people catching H7N2 in the United States: a 2002 incident involving a farmer who worked closely with chickens, and another case in New York a year later, with the source of his infection unknown. Both people recovered.
Because people can contract H7N2, however infrequently, the New York City Department of Health & Mental Hygiene (NYC Health) is advising staff at the site of the current outbreak-Manhattan Animal Care Center-to take precautions.
"The infected cats are housed separately from the other animals," Julien Martinez, an NYC Health spokesperson, told Seeker. "We are contacting all people who adopted cats from ACC's Manhattan care center since November 12, the earliest date when the virus was introduced into the shelter. They can also call the Health Department at 866-692-3641 for care instructions."
The instructions, he explained, include keeping the affected cat away from other animals, and regular washing of hands and clothing that come into contact with the cats.
Cats and birds aren't the only animals that can carry flu viruses with the potential of spreading to different species. In fact, Newbury and her team initially thought the Manhattan shelter cats had caught H3N2 canine influenza. H3N2 first appeared in sick dogs in the Midwest in 2015 and later infected a group of cats in northwest Indiana in 2016.
H3N2 can mutate into "variant" viruses, according to the Centers for Disease Control and Prevention (CDC). These can then spread to humans, such as from infected pigs to people who have had prolonged exposure to them.
Humans, in turn, can carry viruses that may affect other animals. Newbury told Seeker that cats have been known to develop antibodies to viruses harbored by their owners. Even though the cats did not necessarily become ill, the presence of the antibodies proves that the felines were exposed to a particular virus and reacted to it.
Diseases that transmit from animals to people, are called zoonotic. Cases of human flu from zoonotic viruses appear to be rare, likely because each virus has evolved to target a particular species.
Nevertheless, "influenza viruses are constantly changing and it is possible for a virus to change so that it could infect humans and spread easily between humans," reports a CDC fact sheet. "Human infections with new influenza viruses (against which the human population has little immunity) are concerning when they occur. Such viruses could present pandemic influenza threats."
One of the worst such pandemics was the flu of 1918–1919, which killed as many as 50 million people worldwide. The virus H1N1, which exists in a different form today, was responsible. Its original source animal remains unknown, but H1N1 today is known to infect pigs, turkeys, ferrets, dogs, cats, and even cheetahs in addition to humans, reports the California Department of Health.
Because this and other influenza viruses can mutate, the CDC and various other health departments closely monitor flu outbreaks in animals. A red flag in the Manhattan case is that influenza in cats is extremely rare, Newbury said. She explained that "the most common causes of upper respiratory infection in cats are actually due to feline-specific herpes viruses," such as feline herpesvirus type-1.
So if your pet comes down with cold or flu-like symptoms, you will probably not catch the illness, even if your dog or bird sneezes right in your face. Basic illness prevention measures are wise to follow, however.
As VCA Animal Hospitals advise, "If you follow good hygiene practices including proper hand washing ... you will minimize the chance that you can get an illness from this or any other infectious disease."
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