First-ever bird flu case in pigs raises concern in the US

By Elizabeth Schroeder | 10 November 2024 | 8:12 pm

Scientists in the US have expressed concern about the detection of the first case of H5N1 avian influenza (bird flu) flu in a pig in that country.

According to the agriculturedive.com, this was considered to be a warning that the transfer of the virus to swine “could be a bellwether for a potential pandemic”.

Although the US Department of Agriculture (USDA) reassured the public that the pigs were never intended to enter the country’s food supply chain, all pigs on the farm in Oregon were euthanised.

The website reported that the case was identified on a backyard farm with both poultry and livestock, including pigs.

The USDA and the Centers for Disease Control and Prevention (CDC) reportedly said the risk to humans was still low, but Katelyn Jetelina, an epidemiologist and CDC consultant, told Agriculture Dive that “these moves the virus is making is making public health [authorities] very uncomfortable”.

“Pigs are known as mixing vessels for flu viruses because they can harbour both human and zoonotic influenza viruses at the same time, increasing the threat of a new virus that can more easily infect people,” the report said.

“If a pig is infected with human and bird flu strains, then the virus can switch genes,” Jetelina explained. “And when this happens, the virus could become more adaptable to human spread and then become a pandemic.”

According to her, pigs had been the source of the H1N1 pandemic in 2009.

The USDA reported that all the livestock and poultry on this farm had shared water, shelter and equipment, mimicking conditions that had also resulted in the transmission of bird flu between species in other states.

The pigs had no flu-like symptoms, unlike other animals on the farm, the report said.

However, when local and federal officials tested five pigs for the virus earlier this month, one tested positive for the virus, two tested negative, and results for two more were still pending.

The CDC earlier reported that about 39 people across the US had tested positive for bird flu as a result of the current outbreak among poultry and dairy cattle.

Of these, most were farmworkers who had direct access to animals that were ill, but one person in Missouri contracted the virus from “an unknown source”, according to the CDC.

USDA officials were currently conducting an investigation into the case on the Oregon farm, and Jetelina stressed that the risk for further transmission would be lower if it was determined that this was an isolated case.