A recent study has found that the H5N1 bird flu virus is not adapting to infect humans at an alarming rate, despite its ability to infect both birds and cows.
When traces of H5N1 bird flu appeared in cow’s milk last year, it raised concerns that the virus could become more infectious to humans. However, a recent study has shown that the virus is not adapting to infect humans at an alarming rate.
How Bird Flu Infections Cows and Humans
Influenza viruses latch onto sialic acid attached to sugar molecules on cell surfaces. The way this acid is attached to cells in cow mammary glands resembles the attachments used by flu viruses to infect human cells. This similarity allows H5N1 virus to infect both birds and cows.
Cattle have receptors that are similar to those found in bird flu viruses, which can lead to a higher risk of transmission between people. However, researchers have found that the levels of H5N1 virus in cow mammary glands are extremely high, with some reaching levels that are comparable to laboratory-grown viruses.
Why Bird Flu is Not Adapting to Humans
The growth of H5N1 virus within the mammary gland of cows may actually work to humans’ advantage. Since there is no real pressure on the virus to change its attachment mechanism in order to infect human cells, it has not adapted to become more infectious to people.
The Dangers of Bird Flu Infections
While the risk of bird flu infection from cow milk or dairy herds appears low, there are still concerns about transmission between people. If more people catch H5N1 bird flu after contact with infected cattle or milk, the virus may adapt to become easier to spread between humans.
To date, 70 people in the United States have been infected with H5N1 bird flu, with 41 cases linked to exposure to dairy herds. However, this is likely due to the widespread presence of the virus in birds and animals rather than a new property of the virus itself.
The Wide Range of Mammals Infected by Bird Flu
The fact that many mammals, including dolphins and porpoises, have been infected with related variants of H5N1 may seem alarming. However, this is likely due to the high levels of virus replication in birds and animals rather than a new property of the virus.
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- sciencenews.org | Bird flu in cows shows no signs of adapting to humans — yet
