First US Pig H5N1 Case Detected; Virus with Lethal Mutation in Mammals

Oct 30, 2024, 01:39 PM

The United States is facing a concerning rise in H5N1 avian influenza cases among humans and livestock, with new developments heightening public health vigilance. The USDA has confirmed the first detection of H5N1 in a pig on an Oregon farm, marking the virus's first incursion into swine in the country. This is significant because pigs can serve as "mixing vessels" for flu viruses, potentially facilitating adaptation to humans. The CDC reports a total of 36 human H5N1 cases since April, including recent infections in California and Washington state, many linked to exposure to infected poultry and dairy cows. Research published in *Nature* reveals that an H5N1 virus isolated from a Texas dairy worker carries the PB2-E627K mutation, enhancing its replication in human cells, and has shown high transmissibility and lethality in ferrets and mice, with fatalities occurring within 2-3 days. Despite these developments, no person-to-person transmission has been detected. The USDA is enhancing surveillance measures, including nationwide bird flu testing in raw milk, and is conducting field trials for two H5N1 vaccine candidates for dairy cows. The total number of infected mammal herds in the U.S. has reached 395, with California accounting for 193 affected herds.