A second U.S. farmworker has tested positive for bird flu, public health officials in the patient’s home state of Michigan said. announced on May 22.
During a press conference, health officials said the case was “not unexpected” given the continued spread of avian flu among birds and mammals in the US, and that the risk to the general public remains low. But the case raises the question: Is human-to-human transmission of bird flu a serious concern?
Not at this time, according to Dr. Nirav Shah, principal deputy director of the U.S. Centers for Disease Control and Prevention (CDC). “We have seen no evidence of other cases in this area or anywhere else in any of our monitoring systems, let alone any evidence of human-to-human transmission,” Shah said during the May 22 press conference. “That’s comforting.”
“The risk is incredibly low right now,” agrees Andrew Pekosz, professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health. “There is no real evidence of human-to-human spread.”
Bird flu has spread widely among birds around the world in recent years, affecting nearly 91 million in the US since January 2022. The virus has also affected mammals, infecting cows, goats, cats and more in the US alone. So far, two human infections in the country – one in Texas in April and the new one in Michigan – have been detected in people who work on dairy farms where there are infected cows. Both individuals experienced only mild ocular symptoms similar to conjunctivitis and later recovered.
The person in Michigan tested negative on a nasal swab but positive on an eye swab, According to the CDC. That’s a promising sign, Shah said during the news conference, because it suggests the virus is not spreading like a traditional respiratory virus. The seasonal flu virus, for example, takes root in the upper respiratory tract, which is why a sick person can expel potentially infectious respiratory particles when they cough or sneeze.
The bird flu virus, on the other hand, binds to a type of receptor common in animals and birds and also found in the human eye, but which is not prevalent in the human respiratory tract, explains Michael Osterholm, director of the Center for Research and Infectious Disease Policy at the University of Minnesota. “I would be concerned if we saw genetic changes that allow this virus to spread. [easily] they attach to cells in a human’s respiratory tract,” says Osterholm.
It’s possible, he says, that the virus could eventually change in a way that allows it to do that, but “we’re not seeing anything like that yet.”
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To answer questions about potential risks to humans, it’s important to better understand how the virus is spreading among cows, says Pekosz. If the virus spreads primarily through exposure to contaminated milking equipment, for example, “that’s probably not relevant to how the virus would spread in humans,” he says. This research remains ongoing, as is the genetic analysis of the viral sample taken from the patient in Michigan.
Public health officials are still taking precautions to reduce the chances of continued spread. Health care workers in Michigan are conducting contract tracing and distributing influenza antivirals to people close to the infected person, Shah said during the news conference. A spokesperson for the Michigan Department of Health and Human Services declined to provide additional details.
In April, the Texas patient was told to isolate others and was treated with antivirals. They also received antivirals to distribute to people in their household, according to a spokesperson for the Texas Department of State Health Services. “There has been no evidence of spread between people, so the risk to the general public is low,” the spokesperson added.
The CDC also recently asked states and cities Maintain your flu surveillance efforts at peak season levels to detect any signs of increased transmission. And the federal government is readying nearly 5 million vaccine doses in case they need to be distributed quickly, officials said on the call.
Measures like extra vigilance are preventive and not cause for alarm, says Pekosz. “It’s preventive,” he says. “It’s trying to understand what’s happening so far — it’s not because we’re seeing evidence” of human transmission.
Public health officials also stated during the press conference that while the risk to the general public remains low, farm workers have been instructed to take additional safety precautions, such as using personal protective equipment around sick animals or potentially infected. But the average person doesn’t need to do much right now, says Pekosz. The most important preventative measure most people can take is to avoid raw milk, which is not treated to remove viruses.
This story originally appeared on Time.com read the full story
