Health officials in Los Angeles are investigating three household cats presumed to have bird flu, as officials confirmed the disease in two other cats who drank recalled raw milk and died.
The Los Angeles county department of public health confirmed two fatal cases of H5 bird flu in cats on Wednesday. The two felines had consumed raw milk linked to Raw Farm, a dairy in Fresno, California, that was subject to a recall of raw milk and cream products last month.
The two cats initially showed a lack of appetite, fever and neurologic signs. As their symptoms worsened, they tested positive for influenza A, a rare result in cats, that was later confirmed as H5 bird flu.
The three cats who may also now be infected with bird flu all lived in the same household, according to authorities. Humans who came into contact with the animals are now being monitored for symptoms. Cats are considered highly susceptible to bird flu.
At a Texas dairy earlier this year, 12 barn cats died after drinking infected raw milk.
But the three sick cats in Los Angeles are not known to have consumed raw milk and other sources of infection, including raw meat, are being investigated. The alert noted that cats are known to have transmitted another influenza strain to humans, but there have been no known cases to date of H5 bird flu transmitted from cats to humans.
“The risk of H5 bird flu remains low in Los Angeles county, but these confirmed cases of the virus in pet cats are a reminder that consuming raw dairy and meat products can lead to severe illness in cats,” said Dr Barbara Ferrer, director of the Los Angeles county department of public health, in a statement.
“To avoid the spread of disease, including H5 bird flu, we strongly encourage residents and their pets to avoid raw dairy and undercooked meat products, limit contact with sick or dead animals, report sick or dead birds, and keep pets or poultry away from wild animals and birds,” Ferrer added.
The report of cats infected with bird flu comes as the California governor, Gavin Newsom, declared a state of emergency as the bird flu virus moved from the Central valley to southern California dairy herds.
On Wednesday, the US Centers for Disease Control and Prevention (CDC) confirmed the first case of severe bird flu in a 65-year-old patient with underlying medical conditions in Louisiana.
The patient is in critical condition in a hospital after experiencing severe respiratory illness related to bird flu infection. The patient is the first case of human bird flu in the US, linked to exposure to a backyard flock that may have been infected by migrating birds.
Genomic data showed the Louisiana patient was infected with a version of the virus recently found to be spreading in wild birds and poultry in the US, and found in some human cases in Canada and Washington state, according to the CDC.
This version of the H5N1 virus is different from the virus circulating in dairy cattle and some poultry populations in the US. To date, more than 846 cattle herds across 16 states in the US have been hit, interrupting milk supplies.
But the H5N1 infection of cats is alarming to virus experts; a new study found that cat cells allow viruses to mix and mutate, potentially providing a bridge that allows the H5N1 bird flu to mutate and jump to humans.
A study, published in the academic journal Emerging Microbes & Infections, found that cats, like pigs, had cellular receptors which allow them to act as “mixing vessels for reassortment of avian and mammalian influenza viruses”.
Furthermore, cats which had recently died of H5N1 bird flu were found to have “unique mutations” suggestive of “potential virus adaptation”.
“The continued exposure, viral circulation, and adaptation of the H5N1 virus in cats raise significant concerns for transmission and public health,” the authors of the University of Pittsburgh report said.
Cats, they added, frequently interact with humans and other species and could therefore “serve as a bridge for cross-species transmission of H5N1 viruses”.
In April, Maryland’s school of public health warned that a review of 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 spill over into humans,” said Kristen Coleman, an assistant professor at the school.
So far, there have been 61 human cases of bird flu in the US since April, according to the CDC. The patients had mostly been in contact with infected cattle or infected livestock.
Prior to the Louisiana patient, cases had been mild and patients had all recovered after receiving antiviral medication, according to the CDC and state health officials. One previous case in Missouri ended up in hospitalization.
In addition to the Louisiana case, Delaware recently reported a probable H5N1 case that was detected by routine state influenza surveillance.
The infected person did not have known contact with sick animals. The CDC could not confirm the type of influenza A virus after multiple tests and has classified it as a “probable case”.
In Los Angeles, public health officials “strongly encourage residents to avoid consuming raw milk and to not feed it to their pets”.
They also advised people to limit unprotected contact with sick or dead animals or birds or any materials contaminated with bird feces, to keep pets or poultry away from wild animals and birds, and to remove bird feeders and baths “to reduce the risk of the virus spreading from bird to bird”.
