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Bird flu has been spreading among domestic and wild birds, dairy cows, and other animals in the U.S. Viara Mileva/Getty Images
  • A pig tested positive for H5N1 bird flu for the first time in the United States.
  • USDA officials said the farm in Crook County, Oregon, is a non-commercial operation, and there is no concern about the safety of the nation’s pork supply.
  • The CDC reported three dozen human bird flu cases in 2024 so far. The agency says the risk to the general public remains low because there is no sign of person-to-person transmission of the virus.

H5N1 bird flu virus has been detected in a pig for the first time in the United States, according to the U.S. Department of Agriculture.

USDA officials said five pigs were tested from a backyard farm in Crook County, Oregon, including one that tested positive and two others that tested negative. Test results for two additional swine are pending as of October 29. Officials said the pig that tested positive did not display signs of illness.

“The livestock and poultry on this farm shared water sources, housing, and equipment; in other states, this combination has enabled transmission between species,” the agency said in a news release. “This farm is a non-commercial operation, and the animals were not intended for the commercial food supply.”

The agency stated that this finding does not raise concerns about the safety of the nation’s pork supply.

“In addition, the farm has been quarantined to prevent further spread of the virus. Other animals, including sheep and goats on the farm, remain under surveillance,” according to the press release.

The Centers for Disease Control and Prevention reported at least 39 human casesTrusted Source of bird flu so far in 2024. The main sources of exposure are dairy cows and poultry. However, the CDC says the risk to the general public remains low because there is no sign of person-to-person transmission of the virus across the U.S.

While the risk to the general public remains low, the CDC recommends precautionsTrusted Source for people who are exposed to infected or potentially infected animals.

The agency told reporters on a call in May that there is no evidence that the virus is spreading from person to person, Reuters reported.

Genetic testsTrusted Source carried out by the CDC on samples from the patient in Texas and infected cattle show that the virus lacks changes that would make it better able to infect mammals. There is also no sign that the virus has developed resistance to antiviral treatments, the CDC said.

Federal agriculture officials have repeatedly emphasized that the food supply remains safe. Milk from sick cows is diverted or destroyed, and pasteurization kills any viruses or bacteria in milk.

Bird flu cases in Texas, Michigan and Colorado were the first linked to exposure to cattle, federal health officials said.

Outside of the 2024 outbreak, the only other human caseTrusted Source of bird flu in the United States occurred in Colorado in 2022 in a person who had contact with infected poultry.

Bird flu is a disease caused by an influenza virus that mainly infects birds.

These types of viruses, known as avian influenza A virusesTrusted Source, spread naturally among wild aquatic birds such as ducks and geese. From there, they can pass to chickens and other domesticated poultry.

There are two groups of these viruses: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI).

The second group causes severe disease and high death rates in infected birds. It includes the highly pathogenic avian influenza A (H5N1) virus—aka H5N1 bird flu—detected in cattle and the patient in Texas.

Certain bird flu viruses can spread to and infect mammalsTrusted Source, including seals, bears, foxes, skunks, domestic cats and dogs, and humansTrusted Source.

“People who are at risk are those who have direct and prolonged exposure with infected, ill or dead animals, or areas contaminated by infected birds or animals,” said Dean Blumberg, MD, chief of pediatric infectious diseases at UC Davis Children’s Hospital.

It is rare for bird flu viruses to spread from one person to another, but it has happened. In these casesTrusted Source, the virus has spread to only a few people and often within a person’s household, where there is prolonged, close contact.

“Human-to-human transmission is extraordinarily rare,” Blumberg told Healthline, “and in fact there is no risk of sustained human-to-human transmission, so this [virus] poses no threat to the general public.”

The federal government maintains a stockpileTrusted Source of vaccines, including ones that target H5N1 and H7N9 bird flu viruses. If there are signs of the virus spreading from human to human, these vaccines could be mobilized.

However, Blumberg said the chance of that happening right now is low.

“It would be concerning if avian influenza evolved to be more easily transmitted among people, since [we have] little to no immunity to this virus,” he said. “However this has not happened since bird flu was first described almost 150 years ago.”

SymptomsTrusted Source of bird flu in people range from mild to severe and may include:

  • eye redness
  • flu-like upper respiratory symptoms such as cough, sore throat, runny or stuffy nose
  • pneumonia
  • fever
  • muscle or body aches
  • headaches
  • fatigue
  • difficulty breathing or shortness of breath

As of December 2023, 902 peopleTrusted Source have contracted avian influenza H5N1 virus worldwide in 23 countries, reports the CDC. More than 50% of people died as a result of their infection.

However, the severity of the cases varied depending upon the genetic characteristics of the virus involved, ranging from causing no symptoms to leading to severe illness and death.

Health officials are closely watching the outbreak in the U.S., and it is unclear if all cases will be mild.

To protect yourself and your pets from bird flu, the CDC recommendsTrusted Source:

  • Avoid direct contact with wild birds or with wild or domestic birds that appear sick or have died.
  • Avoid unprotected exposure to infected live or dead animals, including cattle, domestic pets, and other mammals.
  • To move or discard a dead bird or other animals, don’t touch it with your bare hands. Use gloves or a plastic bag to place the body inside a garbage bag.
  • Wash your hands with soap and water after exposure to wild birds or other animals, including domesticated farm animals.

If you find a dead bird, contact your state health department, state veterinary diagnostic laboratory, or state wildlife agency to learn how to report it.

In addition, “for those who work in the [animal] industry and do have contact with potentially infectious animals and environments, full personal protective equipment) should be used including goggles, N95 or equivalent, gown, gloves, hair and boot covers,” said Blumberg.

The CDC also recommends that you get a seasonal flu vaccine. This won’t protect you from bird flu, but will reduce your risk of getting seasonal flu and bird flu simultaneously.