Bird flu has infected a third US farm worker

A third farm worker in the United States has been infected with avian influenza, raising concerns about an outbreak among dairy cattle first identified in March.

The worker is the first in this outbreak to have respiratory symptoms, including cough, sore throat and watery eyes, which generally increase the likelihood of transmission to other people, federal officials said Thursday.

The other two people only had severe eye infections, probably due to exposure to contaminated milk.

All three individuals had direct exposure to dairy cows, and so far none have spread the virus to other people, Dr. Nirav Shah, principal deputy director of the Centers for Disease Control and Prevention, said at a news conference.

This suggests that the virus, called H5N1, has not acquired the ability to spread between people and that the threat to the general public remains low, Dr. Shah said.

“This most recent case does not change the CDC's level of risk assessment of H5N1 influenza for the general public,” he added. “We must remain vigilant, not alarmed.”

But the case highlights the ongoing risk to farm workers, Dr. Shah said: “Our top priority now in this response is to protect the health of farm workers.”

This case is the second in Michigan, but the individual worked on a different farm than the one who was diagnosed last week. All three people infected so far have been treated with the antiviral drug oseltamivir, sometimes marketed as Tamiflu, officials said.

There were few other details available, disappointing some experts.

“There is no excuse for the lack of testing, transparency and trust,” said Rick Bright, chief executive of Bright Global Health, a consultancy that focuses on improving responses to public health emergencies.

He noted that federal officials are “months behind on sharing virus sequence data.”

“This is how pandemics start,” he said.

The identification of a third case is not surprising because farm workers interact closely with dairy cows, experts said. New flu viruses often cause respiratory symptoms without further spread to other people, Dr. Shah said.

The latter patient may have had different symptoms due to the dose of exposure, a different route of exposure, predisposing genetic or medical factors, or a combination of these attributes, said Angela Rasmussen, a researcher at the Vaccine and Infectious Disease Organization from the University of Saskatchewan. in Canada.

However, it is critical to get more information about how the person became infected and whether the virus has evolved to infect people more easily, he said.

Genetic analysis of the virus that infected the worker can be difficult because the amount obtained from the patient was very low.

“But whenever the virus is able to replicate in a person, there is the potential for the virus to adapt to humans and acquire molecular characteristics for replication in the respiratory tract and spread from person to person,” he said Seema Lakdawala, virologist. at Emory University in Atlanta.

Officials are tracking about 350 people who may have been exposed, including about 220 in Michigan alone. So far, relatively few farm workers, about 40, have agreed to the tests.

The Department of Agriculture announced Thursday that it will provide $824 million in new funding to quickly detect cases in poultry and livestock. The department is also starting a voluntary program to allow producers to test bulk milk, allowing them to transport virus-free herds across state lines without having to test individual cows.

Federal researchers completed analysis of 109 beef samples and found the virus in only one, reported last week, officials said at the briefing.

Federal officials could do more to protect farm workers and the public, experts say.

“Vaccines from the national stockpile should be released to vets and dairy farm workers willing to take them,” Dr Lakdawala said. “We have the opportunity to reduce human infections and we must do it now.”

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