By Josh Nathan-Kazis

Federal health authorities on Thursday broadened their response to the H5N1 avian flu outbreak based on new data suggesting that the current approach to testing and treating farmworkers may have missed cases.

A new Centers for Disease Control and Prevention study that tested dairy workers on farms with infected herds found that half of the workers who showed signs of having had H5N1 didn't recall having symptoms.

Health agencies had largely been looking for human cases of H5N1 among on farms by monitoring for symptoms, and only testing and treating workers who reported feeling sick.

The new study suggests that strategy doesn't go far enough. In missing asymptomatic or very mild cases, health authorities may have been giving the virus an opportunity to evolve into a greater threat.

Now, the CDC says it is recommending that antivirals be given to any farmworker who had a high-risk exposure to sick animals without wearing sufficient safety gear, regardless of whether or not they have symptoms. The agency had previously only advised offering the antiviral Tamiflu to people with symptoms who were suspected of having H5N1.

The CDC also said it now recommends testing workers exposed to the virus, even if they have no symptoms. It previously only recommended testing sick workers.

On a call with reporters on Thursday, CDC officials said that the new guidance could help keep the virus from gaining the ability to spread easily between people.

"Although we have not seen changes to the virus that would suggest the capacity for it to spread from person to person, we want to keep that risk as low as where it is right now," said Dr. Nirav Shah, the CDC's principal deputy director. "One of the best ways to do that is to identify individuals who have been exposed through greater testing, and provide them with Tamiflu to drive down the levels of virus in their body."

This is breaking news. Check back soon for more detail.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com

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November 07, 2024 13:02 ET (18:02 GMT)

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