CDC reports or official announcements on new H5N1 cases

First U.S. H5N1 Bird Flu Case Detected in Oregon Pig; USDA Enhances Surveillance Amid Rising Human Cases

Oct 30, 2024, 05:54 PM

In October 2024, the United States Department of Agriculture (USDA) confirmed the first detection of H5N1 avian influenza in a pig in Oregon, marking the first such case in the U.S. The pig, which was asymptomatic, was part of a backyard farming operation that also had outbreaks of H5N1 in poultry. This discovery has raised concerns among health officials and experts about the potential risk to humans, as pigs can serve as "mixing vessels" for influenza viruses, facilitating the adaptation of avian flu viruses to humans. The USDA announced plans to enhance national surveillance of H5N1 on dairy farms, including beginning nationwide bird flu testing in raw milk, and stated that two H5N1 vaccine candidates for dairy cows are undergoing field trials. There have been multiple human cases of H5N1 reported in the United States, with the Centers for Disease Control and Prevention (CDC) reporting 36 confirmed cases since April 2024, including six cases in poultry farm workers in Washington state and 16 cases in California linked to dairy farms. Of these cases, 15 were associated with exposure to infected poultry and 20 were linked to sick dairy cows. The total number of infected mammal herds in the U.S. has reached 395 in 14 states, with California reporting 193 infected herds. The CDC emphasizes that while the risk to the public remains low and there has been no confirmed person-to-person transmission, they are closely monitoring the situation. Studies have shown that a human isolate of bovine H5N1 from Texas is transmissible and lethal in animal models, raising further concerns about the potential for the virus to adapt to humans.