The first confirmed case has been recorded in Washington State: a person has been infected with a rare variant of avian influenza H5N5, which until now has only been detected in birds. According to virologist Pavel Volchkov, head of the laboratory of genome engineering at MIPT, who shared his opinion with the “Gazeta.Ru” portal, infection with this type of virus is likely only when a person is exposed to a high concentration of viral particles, for example, if they care for a private poultry farm. “It is quite difficult for avian influenza viruses, be it H5N5 or H5N1, to cross the species barrier, due to differences in glycosylation patterns. This only becomes possible when the viral dose reaches a critical level, meaning there is a very large amount of it. In such a case, damage to the lower respiratory tract is possible, where the glycosylation structure of the epithelium is similar to that of birds. Only under these conditions can the infection develop. Consequently, infection requires prolonged and extremely close contact with birds. Furthermore, there must be at least some degree of immune compromise, which can occur due to chronic illnesses or age-related changes: the older an individual, the more pronounced the impairments in their immune system function become, especially in adapting to new viral threats,” explained the virology specialist. Nevertheless, even such an isolated case of infection carries a potential pandemic threat, as the virus is capable of mutating and beginning to effectively replicate in the human body. “The epidemiological threat only arises in the event of subsequent transmission of the virus from person to person. Often, such incidents are not new and are associated with areas where birds are kept, especially domestic poultry houses where basic separation measures are not followed. The first line of defense is separating contacts between wild and domestic birds, and the second is between humans and the waste products of domestic birds. If someone is engaged in removing poultry droppings, they risk receiving a high dose of the virus. As a result of such a single infecting situation, a person can potentially begin to produce viral particles that are already adapted for circulation among people and transmission from one person to another,” the scientist concluded.
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