It seems like the bird flu H5N1 is affecting more people than we realize. A new study from the Centers for Disease Control and Prevention found that 7% of dairy farmers in Michigan and Colorado tested positive for antibodies to the virus. Since 2022, this highly pathogenic avian flu has been jumping from birds to mammals more often. This year alone, it's spread widely among dairy cows and other livestock in the U. S. There have been 46 confirmed human cases, mostly linked to cattle or poultry.

The CDC teamed up with health officials in Michigan and Colorado, where there were dairy cow outbreaks. They interviewed and tested local dairy farm workers. Out of 115 workers, eight had H5N1 antibodies, indicating past infection. Only four of these workers remembered being sick recently. The good news is that this doesn't mean the virus has adapted to humans yet. The infected workers had been milking cows or cleaning the milking area. Of the four who got sick, all worked on farms where H5N1 was found in cows nearby.

H5N1 outbreaks in dairy cows have happened in 48 states this year. Thousands of workers have probably been exposed. So, the number of confirmed human cases is likely much lower than the actual number. The more this virus spreads from birds to mammals, the higher the chance it could evolve into a strain that easily spreads between mammals. This could lead to a human pandemic. If we don't find these early cases, it'll be harder to stop H5N1 from becoming a big problem.

The researchers said we need to do more to track and prevent the spread of H5N1 on dairy farms. They suggested monitoring exposed workers, testing for and treating infections, even in those with mild symptoms. They also recommended educating farmworkers about risks and prevention measures.

The Hidden Spread of H5N1 Bird Flu

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