A third farm worker in the United States has been infected with bird flu, heightening concerns about an outbreak among dairy cattle first identified in March.
The worker is the first in this outbreak to exhibit respiratory symptoms, including cough, sore throat and watery eyes, which typically increase the risk of transmission to others, federal officials said Thursday.
The other two people only had serious eye infections, likely from exposure to contaminated milk.
All three individuals were directly exposed to dairy cows and, so far, none have transmitted the virus to other people, Dr. Nirav Shah, principal deputy director of the Centers for Disease Control and Prevention, said during from a press briefing.
This suggests that the virus, called H5N1, has not acquired the ability to spread among humans and that the threat to the general public remains low, Dr. Shah said.
“This new case does not change the CDC’s H5N1 risk assessment level for the general public,” he added. “We must remain vigilant and not alarmed. »
But this case highlights the continuing risk to farmworkers, Dr Shah said: “Our top priority in this response now is to protect the health of farmworkers. »
This case is the second in Michigan, but the person worked on a different farm than the worker diagnosed last week. So far, the three infected people have been treated with the antiviral drug oseltamivir, sometimes marketed as Tamiflu, authorities 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 consulting firm that focuses on improving responses to health emergencies public.
He noted that federal officials are “months behind in sharing virus sequence data.”
“This is how pandemics start,” he said.
The identification of a third case is not surprising because farmworkers interact closely with dairy cows, experts say. New flu viruses often cause respiratory symptoms without spreading further to other people, Dr. Shah said.
The latter patient could have experienced 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 research scientist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan. in Canada.
Still, it’s crucial to get more information about how the person became infected and whether the virus has evolved to infect people more easily, she said.
Genetic analysis of the virus infecting the worker can be difficult because the quantity obtained from the patient was very small.
“But whenever the virus is able to replicate in a person, it has the potential to adapt to humans and acquire molecular characteristics that allow it to replicate in the respiratory tract and spread from person to person to anyone,” said Seema Lakdawala, a virologist. at Emory University in Atlanta.
Authorities are monitoring about 350 people who may have been exposed, including about 220 in Michigan alone. So far, relatively few farmworkers, about 40, have consented to testing.
The Agriculture Department announced Thursday it was setting aside $824 million in new funds to quickly detect cases in poultry and livestock. The department is also launching a voluntary program for producers to test milk in bulk, allowing them to transport virus-free herds across state lines without having to individually test cows.
Federal researchers completed their analysis of 109 beef samples and found the virus in only one, officials said at the news conference last week.
Federal authorities could do more to protect farm workers and the public, experts say.
“Vaccines from the national stockpile should be made available to veterinarians 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. »
News Source : www.nytimes.com
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