Bird flu mutates from cows into different type, bringing new human pandemic closer – Job

The dangerous H5N1 bird flu virus, which has been spreading among dairy cattle in the United States since late March, has mutated in a way that enables it to infect the upper respiratory tract of humans. This means that the risk of a pandemic virus spreading among humans has become one step closer. This writes National Council for Nuclear ResearchSo far, four cases of farmworkers infected with the virus have been reported in the United States.

The H5N1 avian influenza virus infects cells in the digestive tract of birds through what are called sialic acid receptors. The virus replicates in these cells and then makes birds sick. But the researchers discovered that the bovine H5N1 virus also binds to another type of sialic acid receptor in the human upper respiratory tract. This is a completely new property: none of the older H5N1 viruses can bind to the receptors in birds and humans.

Virologist Thijs Kuyken, from the Erasmus MC in Rotterdam, describes the mutation as “worrying”. At the moment, the virus does not appear to be able to be transmitted from person to person, but scientists fear that such a mutation is not far off. “Now that the bird flu virus is replicating in the udders of cows, variants that can infect humans could emerge. Especially since these viruses are also easily transmitted between cows via milking facilities.

The four known infections in the United States have only caused mild symptoms. However, according to Kuiken, this is not good news: “If the symptoms of the disease are not very bad by and large, it means that the virus can easily spread without being noticed. And that actually increases the risk of a pandemic. The cause of the eye infection is probably milk splashing into the eye. People there have receptors for the bird flu virus. But also, for example, in the olfactory organ in the nose, so that the virus could lead to encephalitis via the olfactory nerve.