What you need to know about bird flu after person became infected in Texas

There are only two cases on record reported in the U.S., according to the CDC.

April 3, 2024, 9:47 PM

Bird flu, also known as highly pathogenic avian influenza H5N1 virus, was first detected in 1996 among birds in China, according to the Centers for Disease Control and Prevention. One year later, an outbreak occurred in Hong Kong that resulted in 18 human cases, including 6 deaths, after the people were infected directly by birds.

In late 2021, a version of the virus arrived on U.S. shores and was detected in wild birds. Since February of 2022, the virus has been causing outbreaks in commercial poultry supply – leaving over 80 million birds affected in nearly all states, according to the CDC. Nearly 10,000 wild birds have also been impacted.

While the virus is most common in birds it has more recently spread to some other animal populations such as harbor seals, mountain lions, raccoons, polar bears, red foxes, as well as striped skunks, according to the U.S. Department of Agriculture.

Rarely, the virus can infect humans after interacting with an animal. Most recently, a dairy worker in Texas was presumed to be infected by sick cattle, according to the CDC. This is the second human case ever to be reported in the U.S.

There has not been any spread of the virus between people in the U.S., according to CDC Director Dr. Mandy Cohen. The risk to the public remains low, she added.

A total of nearly 900 human cases have been identified since 2003, with about half dying from the infection, according to the World Health Organization. Almost all the human cases were linked to close contact with infected birds or contaminated environments.

Colorized transmission electron micrograph of Avian influenza, H5N1 viruses (seen in gold) grown in MDCK cells (seen in green).
Smith Collection/GADO/Getty Images

"I want folks to know that for 20 years, the United States government has been preparing and trying to learn about avian flu," Cohen told ABC News.

The sick patient out of Texas reported eye redness as their only symptom and is recovering after isolating and being treated with an antiviral drug, according to the public health agency.

"We have treatment that is available, things like Tamiflu. Not only do we have that in pharmacies, but we have it in stockpile, here in the country. And we have vaccine candidates that are matched to the current virus," Cohen said.

She maintained that the U.S. government is closely monitoring the situation. "The fact that it spread to one human case is certainly making us want to take this very seriously. But folks should know that right now, the risk to them is very low," Cohen said.

"These are the things that reassure me: 20 years of preparation, no genetic changes to this virus, no human-to-human spread and nothing in the virus in terms of adaptations that would make us think it is more adaptive to human spread," she added.

Recent analyses from the CDC indicate that the virus has not adapted to better infect humans.

"As we look more closely at the virus's genetics, it is very similar to the virus that we've seen spread in bird populations. And so, we're not seeing an important change in the virus that would increase our alarm," said Dr. John Brownstein, chief innovation officer at Boston Children's Hospital and an ABC News medical contributor.

Those who work with wild animals or livestock may be at higher risk of being exposed and infected with bird flu, according to the CDC.

People should avoid direct contact with wild birds and observe them from a distance, according to the CDC. It is also important to avoid contact with sick or dead animals, in general. Human infections can occur when the virus gets into a person's eyes nose or mouth, or is inhaled, typically after prolonged contact.

"The risk really is concentrated in those that are working in close proximity to animals and birds," Brownstein said.

"And those are the people that we, of course, need to improve our surveillance and make sure that we identify any case as early as possible," he added.

Because milk products are pasteurized, there is no concern about the safety of the commercial milk supply, according to the USDA. Other federal agencies like the FDA and CDC warn against drinking raw milk or products made from it, due to the risk of viruses and bacteria, which may lead to infection or foodborne illnesses.

"So far, there is no concern for food in our supply chain. There is no risk to those that are consuming dairy and meat products," Brownstein said.

The USDA also remains confident that the meat supply is safe and reminds us that cooking to a safe internal temperature kills bacteria and viruses, including bird flu.

"We feel in a good place to be able to understand this, learn more, and be prepared. But we are taking it very seriously. And so, you are seeing a mobilization of all of the government levers that we have to make sure that we are prepared," Cohen said.