It’s Here: Porcine H5N1

USDA confirms first H5N1 case detected in pigs.

On Oct. 29, 2024, the USDA National Veterinary Services Laboratories confirmed one pig in a backyard farm in Oregon was infected with H5N1, marking the first detection of this highly pathogenic avian influenza (HPAI) strain in swine within the United States.

This discovery followed an investigation of positive cases in a backyard flock operation in the state, which housed a mix of poultry and livestock, including swine.

Shared environments with infected poultry

According to the Washington State Department of Agriculture, the infection was detected during a precautionary testing of the pigs, which had been in direct contact with infected birds. The pigs were given access to the birds’ carcasses, a key factor in the transmission of the virus. Importantly, throughout the observation period, the pigs did not exhibit any clinical signs of illness, suggesting that the infection did not manifest in a way that posed immediate health risks to the animals.

Michael Osterholm, Ph.D., MPH, director of the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP), stated that it is not yet known if the pig was truly infected or if the nasal passages had been contaminated by environmental exposure. He noted that earlier scientific work suggested that the virus doesn’t easily infect pigs.

Continued food safety

The USDA emphasized there is no concern about public health risks associated with this strain of influenza in pigs. The risk to the public from H5N1 remains low, as human infections with this strain have been exceedingly rare and typically associated with direct exposure to infected birds.

The importance of surveillance

This incident underscores the importance of ongoing surveillance and rapid response efforts in agriculture. The detection of H5N1 in swine highlights the necessity for precautionary measures in animal husbandry, especially for operations that mix different species, such as poultry and livestock. Enhanced monitoring can help prevent potential outbreaks and ensure that both livestock and public health are protected, according to the Washington State Department of Agriculture.

Risks to the U.S. swine industry

The Swine Health Information Center believes this strain has the potential for severe consequences to the U.S. pork industry as well as human health. The center emphasized enhanced surveillance, improved biosecurity measures and vaccination strategies are crucial for considering how to best prevent and rapidly control a potential H5N1 infection in pigs.

Key Points:

According to the U.S. Centers for Disease Control and Prevention (CDC), humans cannot get the flu from eating or handling properly cooked pork. Properly cooked pork and pork products are safe.

While pigs are susceptible to influenza A viruses, swine health experts do not know if H5N1 virus poses a higher risk of disease, illness or mortality in pigs than other influenza strains in circulation.

Influenza A viruses are constantly changing in both the animal and human population. Variant influenza A viruses that contain components of human, avian and swine adapted viruses are not unusual. Movement of these viruses between humans and animals is closely monitored by the CDC and other public health entities.

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