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Bird flu is ‘low risk’ to the public, experts say. Here’s how to avoid it.
Despite a number of farm workers in the US contracting bird flu, experts say there is little risk to the general public, with some exceptions.
Health officials are investigating whether a person in Missouri who was hospitalized with bird flu in early September may have infected a handful of others.
Testing is being conducted among five healthcare workers and one household member who were exposed to the infected person and all developed mild respiratory symptoms. A cluster of infections would mark a significant expansion of the bird flu virus, indicating it can be transmitted from person to person.
On Friday, Missouri and federal health officials emphasized that there is currently no evidence of human-to-human transmission. The immediate risk to the general public is still low, the Centers for Disease Control and Prevention said.
Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said he sees no cause for concern unless or until one of these tests comes back positive.
“Right now, we don’t have any evidence that this one case in Missouri has transmitted the virus to anyone,” said Osterholm, an epidemiologist. “I’m not saying it couldn’t have happened, but based on what we know so far, we haven’t had ongoing transmission. There is no crisis.”
This time of year, Osterholm said, about 2% of Americans have respiratory symptoms, which could be H5N1 or COVID-19, or just a cold. The blood and DNA test results will tell the story, not the symptoms.
“The fact that someone has symptoms of respiratory illness doesn’t tell me anything about ‘is it likely or not likely that it’s the flu,’” he said. “At this point we want to be careful not to become alarmist.”
So far this year, 14 people in the US have been infected with the H5N1 bird flu. With the exception of the Missouri individual, all became infected after coming into close contact with poultry or dairy cows known to be infected.
Officials don’t know how that person became infected with H5N1. Their infection was first reported on September 6.
Earlier this month, federal health officials had initially said the hospitalized person was likely an isolated case that did not appear to pose any additional risk.
Soon after, officials in Missouri determined that a person in the same household developed “similar symptoms” as the confirmed case on the same day, said Lisa Cox, communications director for the Department of Health and Senior Services. But neither person had typical “flu-like symptoms or conjunctivitis,” Cox said in an email, referring to symptoms seen in previous cases of bird flu in the U.S. this year.
The timing of onset suggested general exposure, such as from a wild bird, rather than person-to-person transmission, she added. Another person reported limited contact with the infected patient, but that person reported no complaints either before or after the visit.
On Friday, CDC said state officials identified 18 health care workers who were at higher risk. Three of these reported workers reported mild respiratory symptoms.
One person tested negative for influenza A, which includes bird flu. The other two were not clinically tested because they had passed the 10-day follow-up period during which those test results could be linked to a previous exposure, Cox said. Their symptoms were also not severe enough to require medical tests.
Instead, these two health care workers provided blood samples to CDC to test for H5N1 antibodies, which appear at least three weeks after symptoms disappear.
Blood samples were collected from five health care workers, Cox said. The original person and their household contact have already sent their samples to the CDC. The samples from the five workers will be sent to the CDC laboratory in Atlanta for testing. However, the remnants of Hurricane Helene moving through the American South are delaying shipments of the specimens, Cox said.
“This type of testing is an additional diagnostic test that indicates that an H5 infection has occurred in the person,” she said. “However, under other limitations it will not be able to determine the source or time of any infection.”
Seeing the results of the tests will be critical, said Dr. Jesse Goodman, an infectious disease specialist at Georgetown University.
“We don’t know yet if any of these other people have or have gotten the H5 flu – that’s very important to investigate,” he said.
Goodman added that public health workers should be more aggressive in testing people with mild or no symptoms, because it is not clear exactly how H5N1 manifests in humans. “We need to take aggressive action,” he said.
He also said there needs to be more widespread testing for H5N1 because he expects more people likely have it than have been detected. The Missouri case was discovered purely by chance, because the person’s flu was tested, which doesn’t always happen. When it came back as an unusual type, it was sent for further testing, which is also atypical, Goodman said.
“We can’t look at this in panic, but we need to see this as a warning shot and we need to lean forward with our surveillance and preparedness,” he said. “Most public health threats are exaggerated by people. This one, in my opinion, is a little underexposed.”
Karen Weintraub contributed to this report.
(This story has been updated to add new information.)
