Person Tests Positive for Bird Flu in Texas After Exposure to Cattle
It is the second known human case of H5N1 infection in the U.S.
By Brianna Abbott The Wall Street Journal Updated April 1, 2024
A person in Texas tested positive for avian influenza after exposure to dairy cattle presumed to be infected with the H5N1 bird flu, the Centers for Disease Control and Prevention said Monday.
The case marks the second known instance that a person in the U.S. has been infected with H5N1 bird flu. The person reported eye redness, or conjunctivitis, as their only symptom and is being treated with an antiviral drug. The human health risk of the bird flu remains low for the U.S. general public, the CDC said, but people with close, prolonged exposures to infected animals or their environments are at higher risk.
“At this point, there’s nothing that suggests that there is any serious risk of a larger human outbreak,” said Dr. Tom Inglesby, director of the Johns Hopkins Center for Health Security. “I’m trying to understand why the cows are getting infected. That’s a really important scientific question right now.”
The
previous human case was reported in Colorado in 2022, in a person with
direct contact with poultry. Human infections are rare, but the agency
said it has been monitoring for infections among people exposed to
infected birds after reported outbreaks in U.S. poultry and wild birds
began in late 2021.
Human illnesses with the virus typically have occurred through exposure to infected poultry or wild birds. Sick birds can shed the virus in their saliva, mucus and feces, and humans can become infected when enough virus gets into their eyes, nose or mouth. Infections have also been reported in other animals including foxes, bears, seals, minks, cats and dogs.
The disease in humans ranges from mild infections, which include upper-respiratory and eye-related symptoms, to severe pneumonia. Since 1997, some 890 human cases have been reported across the globe, with a case-fatality rate of roughly 50%, the CDC said.
“It’s still a very uncommon illness in humans,” Inglesby said. “It is a very serious infection, but it’s possible there are cases that are occurring that we’re not detecting that are much milder.”
The U.S. Agriculture Department reported the avian influenza in dairy cows in Texas and Kansas in late March this year. Unpasteurized milk from sick cattle at two dairy farms in Kansas and one in Texas, as well as a throat swab from a cow in Texas, tested positive for the same strain of the virus that is currently widespread among birds.
A few days later, the virus was also confirmed among a Michigan dairy herd that had recently added cows from Texas. This is the first time the H5N1 influenza virus has been detected in cattle in the U.S., according to the Texas Department of State Health Services. There was little or no mortality among affected dairy herds, Agriculture Department officials said.
Bird flu has historically been a problem for the poultry industry in the U.S. The current outbreak is the deadliest on record for the U.S. agricultural industry, and has led to the death of tens of millions of chickens, turkeys and other birds since early 2022. Industry officials have attributed the disease’s rapid spread to wild birds carrying it to farms during the birds’ migration.
The disease is usually fatal in chickens that contract it, the CDC has said, and is contagious enough that wild-bird droppings blown on the wind near barn vents can trigger an outbreak. To curb further spread, poultry farms often destroy entire flocks after a single case is detected.
People should avoid unprotected exposures to sick or dead animals as well as raw milk, feces or other contaminated materials, the CDC said. People also shouldn’t prepare or eat uncooked or undercooked food, including raw milk, from animals with a confirmed or suspected infection, the agency said.
“For the vast majority of people, this isn’t going to affect them,” said Dr. Dean Blumberg, chief of pediatric infectious diseases at UC Davis Health. “Who it will affect are people who have close contact with animals or economic interest in animals.”
There are no concerns with the safety of the commercial milk supply right now because products on store shelves are pasteurized, according to the USDA and the Food and Drug Administration. Dairies must send milk from only healthy animals to processing, and milk must be pasteurized for it to enter interstate commerce for human consumption. Milk from infected animals is being diverted or destroyed, the CDC said.
—Jacob Bunge contributed to this article.
Write to Brianna Abbott at brianna.abbott@wsj.com