Continuous outbreaks of Bird flu has decimated poultry and wild birds in the United States and around the world. The virus, known as H5N1, is also increasingly adapting to mammals and has been found in cats, goats and raccoons. In the United States, it has spread to at least 170 dairy herds in 13 states. And in April, health officials confirmed that a dairy farm worker had contracted the virus from an infected cow. This was the first time the virus had jumped from a mammal to a human.
Now, the number of people infected with bird flu is increasing. On July 25, the U.S. Centers for Disease Control and Prevention Three additional human cases confirmedbringing the total number of cases in the United States since April to 13. The infections occurred in people who worked directly with infected poultry at a Colorado egg farm that had reported an outbreak of H5N1 among its birds. All three people have mild symptoms and have been offered Tamiflu, an antiviral drug. The CDC says the risk of H5N1 infection in the general public remains low.
“These cases are not entirely surprising, given that these people were working with infected poultry,” says Stephen Morse, an epidemiologist at Columbia University in New York. “The good news is that, so far, there is no evidence that this has spread from person to person. At that point, we would really have to raise the concern to the red alert level.”
The CDC is investigating whether the Colorado workers were wearing personal protective equipment (PPE), such as gloves, coveralls, footwear, masks and goggles. Historically, most cases of human bird flu infection have occurred in people who were not wearing the recommended PPE, according to the agency.
The new cases come shortly after another cluster of human infections was identified this month. On July 19, the CDC Six human cases were confirmed of bird flu among poultry workers at a different facility in Colorado. Those cases were in workers involved in slaughtering birds infected with H5N1. Once the virus is found on a farm, poultry producers must cull entire flocks. With the latest three infections, Colorado now has nine confirmed cases of bird flu.
The other four cases (one in Texas, two in Michigan and one in Colorado) have been linked to exposure to infected dairy cows. The virus likely spread to workers through raw milk. Study published in May The virus has been found to remain stable on milking equipment for at least an hour, increasing its potential to infect people and other animals. However, pasteurization of milk kills the H5N1 virus.
So far, all cases in the United States this year have resulted in mild symptoms, but in the past, H5N1 has had a fatality rate of around 50 percentBetween 2003 and 2023, a total of 878 people tested positive for the virus and 458 deaths were recorded.
The last time H5N1 caused a major outbreak among US poultry was in 2015. When it killed 50.5 million birdsIt wasn’t until April 2022 that the United States recorded its first human case of bird flu, in a poultry worker in Colorado. No further cases were reported until this year. “Something has changed,” says Anice Lowen, a flu researcher at Emory University in Atlanta, Georgia. “It’s hard to know whether it’s due to changes in the virus or in the circumstances of exposure without more information.”