H5N1 bird flu found in a pig in the U.S. for the first time

A pig in Oregon has tested positive for the H5N1 bird flu virus, the Department of Agriculture said Wednesday. It's the first time the virus has been detected in swine in the U.S.

Test results are pending for two other pigs found on the farm in Crook County, Oregon, the USDA said, while two others tested negative.

The pig that tested positive didn't show signs of illness.

The five pigs were tested for H5N1 out of an abundance of caution, officials said, and "because of the presence of H5N1 in other animals on the premises."

The case is concerning as pigs can become infected with both bird and human viruses at the same time, which can give rise to mutated strains that can more easily infect humans.

Officials said there are no concerns about the safety of the nation's pork supply.

The farm is non-commercial, the USDA said, and the animals weren’t intended for the commercial food supply. Additionally, the farm has been quarantined to prevent the spread of the virus. Sheep, goats and other animals on the farm are under surveillance, officials said.

The update comes H5N1 virus continues to spread rapidly among dairy cows across the United States. 

The bird flu outbreak in dairy cows has infected 387 herds across 14 states so far, according to the Centers for Disease Control and Prevention.

Since March, there have been a total of 36 human cases, the majority of whom had direct contact with farm animals, such as dairy cows and poultry. Most cases have been reported in California and Colorado.

All of the patients who've tested positive have recovered. Most had redness and discharge from the eyes, and some had mild respiratory symptoms.

There is no indication yet that this strain of flu virus is mutating in ways that would allow it to spread easily among people. Last week, the CDC released results of a monthslong investigation that found no evidence of bird flu spreading from human to human.

It's unclear how the pig in Oregon became infected with bird flu, although earlier this month state officials detected the virus in poultry on the farm.

Officials said livestock and poultry on the farm shared water sources, housing and equipment. In other states, officials said, the combination has enabled transmission between species.