Person gets bird flu after contact with cattle
At least one person in Texas has been diagnosed with bird flu after having contact with dairy cows presumed to be infected, state officials said Monday.
The announcement adds a worrying dimension to an outbreak that has affected millions of birds and sea mammals worldwide and, most recently, cows in the United States.
So far, there are no signs that the virus has evolved in ways that would help it spread more easily among people, federal officials have said.
The patient worked directly with sick dairy cows, said Lara Anton, a spokesperson for the Texas Department of State Health Services. “We have tested around a dozen symptomatic people who work at dairies, and only the one person has tested positive” for the virus, she said in an email.
The patient’s primary symptom was conjunctivitis; the individual is being treated with an antiviral drug and is recovering, according to the Centers for Disease Control and Prevention.
The Department of Agriculture announced the first cases in dairy herds in Texas and Kansas last week and a few days later, in an additional herd in Michigan. Preliminary testing suggests cows in New Mexico and Idaho may also be infected.
The virus has been identified as the same version of H5N1, an influenza subtype, that is circulating in North American birds.
The CDC is working with state health departments to monitor other people who may have been in contact with infected birds and animals, the agency said Monday. It also urged people to avoid exposure to sick or dead birds and animals, as well as to raw milk, feces or other potentially contaminated materials.
This is only the second case of H5N1 bird flu in people in the United States; the first was in 2022. The risk to the general public remains low, experts said. But testing and analysis is ongoing, and there are many unanswered questions.
“This is a rapidly evolving situation,” the USDA said in its announcement last week.
Here’s what to know:
What is bird flu?
Bird flu, or avian influenza, is a group of flu viruses that are primarily adapted to birds. The particular virus in these new cases, called H5N1, was first identified in 1996 in geese in China, and in people in Hong Kong in 1997.
In 2020, a new, highly pathogenic form of H5N1 emerged in Europe and spread quickly around the world. In the United States, it has affected more than 82 million farmed birds, the worst bird flu outbreak in U.S. history.
Since the virus was first identified, sporadic cases have been found in people in other countries. But a vast majority resulted from prolonged, direct contact with birds.
H5N1 does not yet seem to have adapted to spread efficiently among people, experts say.
How did cows get bird flu?
Cows were not thought to be a species at high risk.
“The fact that they are susceptible — the virus can replicate, can make them sick — that is something I wouldn’t have predicted,” said Richard Webby, an influenza researcher at St. Jude Children’s Research Hospital.
But this year, reports of sick cows began to emerge in Texas and New Mexico. Dead birds were also found on some of these farms, and laboratory testing confirmed that some cows were infected with bird flu.
There are a variety of ways that the virus might have found its way into cattle. The likely route, several experts said, is that infected wild birds, which shed the virus in their feces, saliva and other secretions, contaminated the cows’ food or water.
But other free-ranging animals known to be susceptible to the virus, such as cats and raccoons, could also have brought the virus onto dairy farms.
How have cows been affected?
Although the virus is often fatal in birds, it appears to be causing relatively mild illness in cows.
“It’s not killing animals, and they seem to be recovering,” said Dr. Joe Armstrong, a veterinarian and cattle production expert at the University of Minnesota Extension. Last week, the USDA said that there were no plans to “depopulate,” or kill, affected herds, which is the standard procedure when poultry flocks become infected with the virus.