Four new cases of bird flu have been detected in Washington state farm workers this week, the latest in a series of human infections that are appearing across the United States as the virus continues to spread among farm animals.
Washington is the sixth state to report human cases of bird flu, which has spread rampantly among wild birds, poultry and livestock. Assuming the Centers for Disease Control and Prevention (CDC) confirms this state’s positive results, the number of cases in the United States will rise to at least 31.
Flu experts said the risk of a broader outbreak among humans will remain if the virus remains uncontrolled in animals.
“The longer this virus spends in the environment, the more animals it gets, the more it changes in ways we don’t understand or predict, the more worried we will be about it becoming the next global pandemic,” said Dr. Amber Itle, Ph.D. Washington State Veterinarian.
For now, however, health authorities maintain that the virus has not made key genetic changes that would allow it to spread between people.
“There’s no evidence of any sustained human transmission. And that’s a key thing for all of us. It’s a key trigger for all of us. That’s when we really start to say, ‘Oh, there’s something that’s markedly different about this virus,'” he said. Washington Secretary of Health Dr. Umair Shah at a news conference on Sunday.
A CDC spokesman said Tuesday morning that a federal team was being deployed to Washington and that the risk to the public remained low.
However, the virus is a growing concern for farmworkers. The latest four cases occurred among employees who had slaughtered birds at a commercial egg farm where an outbreak of avian flu in chickens was reported.
Shah explained that the workers were part of a team hired to depopulate – or euthanize – all the chickens at the Franklin County farm in southeastern Washington, which had more than 800,000 birds. Itle said the workers were wearing full protective equipment: suits made of Tyvek, goggles and respirators.
“It’s hot, it’s very dusty. There are a lot of birds in close proximity, and we’re having a lot of viral exposure,” he explained.
The four people who tested positive after that job showed mild respiratory symptoms and conjunctivitis, symptoms that are now considered common when people are infected. None of the workers were hospitalized.
Dr. Richard Webby, director of the World Health Organization Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds, said the Washington cases represented “more of the same” in a pattern seen across the United States. United as workers in charge of sacrificing sick animals have become ill.
However, one human case – in Missouri – has baffled researchers and health officials, because that person had no contact with animals. It’s unclear how the person was exposed, and results from other tests that could offer clues are still pending, according to the CDC. Six health care workers who were in contact with the patient stated that they had respiratory symptoms.
Webby explained that the spread of the virus in cows over the last 10 months has raised the level of concern among experts because they are mammals and they interact with humans frequently. That increases the likelihood that the virus can mutate and pass from one person to another.
“Just because it hasn’t happened in 10 months … doesn’t mean it can’t happen,” said Webby, an infectious disease researcher at St. Jude Children’s Research Hospital in Memphis, Tennessee.
Research suggests that incredible amounts of virus are shed from the mammary glands of infected cows, so it could be spread through raw milk. (The milk sold in supermarkets is pasteurized, which inactivates the virus.)
At the same time, the United States is preparing for flu season, when the circulation of common flu viruses increases in the fall and winter. If two flu viruses share the same host, they can share genetic information and mutate more quickly.
“We don’t want people affected by the seasonal flu virus to get a virus from animals and have those viruses potentially combine,” said Dr. Peter Rabinowitz, a professor of environmental and occupational health sciences at the University of Washington. and director of its Health Research Center.
Rabinowitz added that it is important improve protection protocols for agricultural workers and encourage them to get vaccinated against the flu.
“This is a wake-up call. We have to improve worker protection,” he said.
Itle stated that the cases in poultry were not unexpected in Washington state, because migratory birds passed through there during the summer and early fall. Recently, owls and other birds of prey were found dead, suggesting that some wild animals had been affected by the virus.
Wild birds can transmit the virus to farms through direct contact with poultry or livestock or through droppings, saliva or feed.
More than 103 million birds have become illhave died or been euthanized in the current bird flu outbreak, according to CDC statistics. The virus has been detected in poultry in 48 states.
According to the CDC, 330 dairy herds have been affected.
According to Itle, no outbreak has been detected among dairy farmers in Washington, but milk production facilities are conducting weekly testing.
