Tejal Somvanshi
The World Health Organization (WHO) expressed its huge concern on Thursday regarding the increasing spread of the H5N1 strain of avian influenza to new species, including humans. “This is a huge concern,” said Jeremy Farrar, the chief scientist of the United Nations health agency, during a press briefing in Geneva. The fear is that the H5N1 virus, which has shown an extraordinarily high mortality rate in people infected through their contact with infected animals, might adapt to become capable of human-to-human transmission. Currently, there is no evidence of human-to-human transmission of H5N1.
Between 2003 and April 1, 2024, the WHO has recorded a total of 889 human cases of avian influenza in 23 countries, with 463 deaths, resulting in a lethality rate of 52%. Beyond monitoring Fhumans infected by animals—a recent case observed in the United States involved cows—it is even more important to understand how many human infections occur without being detected, as that is where the adaptation of the virus will take place.
“H5N1 is (an) influenza infection, predominantly started in poultry and ducks and has spread effectively over the course of the last one or two years to become a global zoonotic – animal – pandemic,” explained Farrar. He believes that surveillance and infection detection systems are never sufficient, but notes that this occurs in the richest country in the world, where serological studies have been launched to see if transmission between cow breeders and others occurs.
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For now, cases of transmission to a human are very rare. A nine-year-old child carrying the H5N1 strain died from avian flu in Cambodia in February, following three deaths in the same country in 2023. In the United States, the patient had shown redness of the eyes (corresponding to conjunctivitis) as the only symptom, authorities specified, adding that he was isolated and treated with an antiviral drug used for the flu.
In early April, U.S. authorities indicated that a person had tested positive for avian flu after being infected by a dairy cow in Texas. The latest species affected: cattle. For about a month, the infection has been spreading in dairy cattle farms in the United States. These are unprecedented contaminations, because, until now, these ruminants were considered the mammals least susceptible to avian flu viruses, noted Gilles Salvat, director of research at the French National Agency for Food, Environmental and Occupational Health Safety.
The increasing spread of the avian influenza virus is indeed a significant concern, especially with its potential to affect new species and possibly mutate to enable human-to-human transmission. The evolving situation necessitates vigilant surveillance and research efforts to mitigate the risks posed by this global zoonotic pandemic.
