The US has confirmed a case of bird flu or H5N1 in a pig for the first time, even as the infection in poultry and cows is still spreading. "The U.S. Department of Agriculture [USDA] and Oregon state veterinary officials are investigating positive cases of H5N1 in a backyard farming operation in Oregon that has a mix of poultry and livestock, including swine," the USDA said in a news release while announcing the case.

"The Oregon Department of Agriculture announced that poultry on this farm represented the first H5N1 detection in Crook County, Oregon," the agency added. "On Tuesday, Oct. 29, the USDA National Veterinary Services Laboratories also confirmed one of the farm’s five pigs to be infected with H5N1, marking the first detection of H5N1 in swine in the United States."

According to the health officials, even though the pig did not show symptoms of infection, all five swine on the farm were tested for H5N1 because of the presence of the virus in other animals on the farm. The USDA said all five pigs were euthanized for further testing, which showed results that two of the pigs were negative, while results are pending for two others.

“The livestock and poultry on this farm shared water sources, housing, and equipment; in other states, this combination has enabled transmission between species,” the USDA noted. The farm has been quarantined, but since it wasn't a commercial farm, “there is no concern about the safety of the nation’s pork supply as a result of this finding,” the agency added.

According to scientists, they have been worried that the H5N1 infection may spread to pigs, - considered a “mixing bowl” species for flu viruses because they carry the same kind of receptors on cells in their lungs as humans and birds.

In 2009, when the swine flu pandemic spread, it is believed to have been sparked by a virus that mutated in pigs in Mexico before it jumped to people.

According to reports, a second person in Missouri who was not exposed to either poultry or dairy cows has been infected with bird flu. The person shared a home with a patient who was first hospitalized with bird flu in August, but antibody tests have since shown that symptomatic healthcare workers who cared for the patient were not infected with the H5N1 virus, the US Centers for Disease Control and Prevention said.

The CDC said that to date, the human-to-human spread of H5 bird flu has not been identified in the country and the immediate risk to the general public from H5N1 bird flu remains low. However, people with exposure to infected animals are at higher risk of infection, the CDC has warned.

The state of California has confirmed 16 human cases of bird flu, while Washington State has reported two poultry workers who are infected and five others presumed to be positive. The CDC data says in total, 39 people have been infected with bird flu in the US this year.

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