Antibodies for avian flu discovered in dairy farm workers in Michigan and Colorado

There may be more human cases of avian influenza in the United States than previously thought. Health officials in the two states conducted blood tests on workers at dairy farms known to have received infected cattle and found that about 7% of them had antibodies to the disease. This included people who had never experienced any flu symptoms.

Since March, an avian influenza virus known as H5N1 has been circulating among dairy cows across the United States. so far, 446 cows People have tested positive for the virus in 15 states in the United States. From April, 44 people In the United States, people have tested positive for H5, the influenza subtype that includes H5N1. All but one of these cases occurred in poultry or dairy farm workers infected with H5N1.

To better understand how many farmworkers may have been infected with the virus. U.S. Centers for Disease Control and Prevention (CDC) collaborates with state health departments Blood samples were taken from 115 people working on dairy farms raising H5N1-infected cows in Colorado and Michigan. All samples were taken between 15 and 19 days after a cow on the farm tested positive for the virus.

Nirav Shah The CDC and his colleagues then removed seasonal influenza antibodies from the samples before testing them for the presence of H5N1 antibodies. H5N1 antibodies were detected in eight of the samples, or about 7%, suggesting that eight of the workers may have been unknowingly infected with the virus. Furthermore, four of the employees did not remember having symptoms.

“This is very important because by this point, [H5N1] “Testing is primarily focused on symptomatic workers.” Megan Davis at Johns Hopkins University in Maryland. “If workers are unaware that they are infected, they may inadvertently expose others in the community to infection.”

H5N1 is poorly adapted to infecting humans and is not known to be transmitted between humans. Still, more than that, 900 people worldwide People have been reported to have been infected with the virus since 2003, and about half of them have died from the virus. Each of these infections gives the virus a chance to mutate, potentially making it more dangerous to people.

“Those of us in public health need to cast a wider net in who we provide testing to,” Shah said at a press conference today. “Going forward, CDC plans to expand testing recommendations to include infected workers.” [to H5N1] And there are no symptoms. ”

The agency also recommends providing antiviral drugs to asymptomatic workers who are at high risk of infection, such as dairy farm workers who may get raw milk on their faces. That way, even if you do get infected with the virus, the amount of virus circulating in your body will be reduced and the risk of spreading the virus to others will be lower. “The less room we give this virus to spread, the less chance it has of changing,” Shah said.

The data also highlights that many H5N1 infections remain undetected, a concern public health officials have long suspected to be true. But until more data is available, “we can't estimate how many unconfirmed cases there are,” Shah said.

The CDC is currently analyzing an additional 150 blood samples taken from veterinarians who work with cattle. Once these results are available, Shah said it should give a clearer picture of how many cases are slipping through the cracks.