Achi news desk-
US health and agriculture officials are increasing bird flu testing and tracking in dairy cows in an urgent effort to understand – and stop – the growing outbreak.
So far, the risk to humans remains low, officials say, but scientists are wary that the virus could change to spread more easily among people.
The virus, known as Type A H5N1, has been detected in nearly three dozen dairy herds in eight states. Inactive viral residues have been found in grocery store milk. Tests also show that the virus spreads between cows, including those that don’t show symptoms, and between cows and birds, according to the US Department of Agriculture.
Starting Monday, hundreds of thousands of lactating dairy cows in the United States will have to be tested – with negative results – before they can be moved between states, under a new federal order.
Here’s what you need to know about the ongoing bird flu investigation:
This strain of what is known as highly pathogenic bird flu has been circulating in wild birds for decades. In recent years, it has been found in scores of mammals around the world. Most have been wild animals, such as foxes and bears, which ate sick or dying birds. But it has also appeared in farm minks. It is also found in aquatic mammals, such as harbor seals and porpoises. The virus was even found in a polar bear in northern Alaska.
The virus was discovered in ruminants – goats and then dairy cattle – in the US this spring, surprising many scientists who have studied it for years.
“When we think of influenza A, cows are not typically in that conversation,” said Richard Webby, an influenza specialist at St. John’s Children’s Research Hospital. Jude.
Influenza viruses are notorious for adapting to spread among new species, so the finding in dairy cows raises concerns that it could spread to humans, Webby said.
Scientists confirmed the virus in cows in March after weeks of reports from dairy farms that the animals were getting sick. Symptoms included lethargy, a sudden drop in milk supply and changes to the milk, which became thick and yellow.
Finding the remains of the virus in milk on the market “suggests that this has been going on longer, and more widely, than we have previously recognized,” said Matthew Aliota, a medicine researcher veterinary at the University of Minnesota.
Under pressure from scientists, USDA officials released new genetic data about the outbreak this week.
The data omitted some information about when and where samples were collected, but showed that the virus was likely spread by birds to cattle late last year, said Michael Worobey, an evolutionary biologist with the University of Arizona.
Since then, it has spread among cattle and among farms, likely through contact with physical objects such as workers’ shoes, trucks or milking machines, Worobey said.
And then the cows spread the virus back to birds, he said.
“The genetic evidence is as clear as it could be,” Worobey said. “Birds sampled on these farms have viruses with clear mammalian adaptations.”
Several experts said the USDA’s plans to require tests on cows are a good start.
“We need to be able to do more surveillance so we know what’s going on,” said Thomas Friedrich, professor of virology at the University of Wisconsin’s veterinary school.
Worobey said the ideal would be to screen every herd. In addition to looking for active infections, agriculture officials should also be looking to see if cattle have antibodies to the virus, indicating past infections, he said.
“That’s a very accessible and quick way to find out how widespread this is,” he said.
More testing of workers exposed to infected animals is also essential, experts say. Some farm owners and some individual workers have been reluctant to work with public health officials during the outbreak, experts say.
“Increased surveillance is basically an early warning system,” Aliota said. “It helps to characterize the scope of the problem, but also to eliminate possible adverse consequences.”
Scientists are working to analyze more samples of retail milk to confirm that pasteurization, or heat treatment, kills the H5N1 virus, said Dr. Don Prater, acting director of the FDA’s food safety center. Those results are expected soon.
Although the public need not worry about drinking pasteurized milk, experts said they should avoid raw or unpasteurized milk.
Also, dairy farm workers should consider additional precautions, such as masking, washing hands and changing work clothes, Aliota said.
So far, 23 people have been tested for the virus during the outbreak in dairy cows, with one person testing positive for a mild eye infection, CDC officials said. At least 44 people who came into contact with infected animals in the current outbreak are being monitored for symptoms.
David O’Connor, a virology expert at the University of Wisconsin-Madison, compared recent bird flu developments to a tornado watch versus a warning.
“There are some of the ingredients that would be necessary for there to be a threat, but we are not there,” he said. As with hurricane watching, “you wouldn’t change anything about how you live your life every day, but you might have a little heightened awareness that something is happening.”
Worobey said this is the type of case that “we hoped, post-COVID, would go unnoticed. But it has.”
He said ambitious screening was needed “to detect things like this very quickly, and possibly nip them in the bud.”
© Copyright 2024 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.
Ad blocking test (Why?)
Source link
Related
