The World Health Organization (WHO) expressed its “tremendous concern” this Thursday, April 18, about the increasing spread of the H5N1 strain of avian flu to new species, including humans.
“It remains, I think, a huge concern,” Jeremy Farrar, chief scientist at the U.N. health agency, told a news briefing in Geneva. The fear is that the H5N1 virus, which in people infected through contact with infected animals has demonstrated “an extraordinarily high mortality rate,” will adapt to become capable of human-to-human transmission. There is currently no evidence of human-to-human transmission of H5N1.
A fatality rate of 52%
Between the start of 2003 and April 1, 2024, the WHO said it recorded a total of 889 human cases of avian flu in 23 countries, including 463 deaths, bringing the case fatality rate to 52%.
Beyond monitoring humans infected by animals – cows in a recent case observed in the United States – “it is even more important to understand how many human infections occur without your knowledge, because it is “that’s where the adaptation” of the virus will occur, explained Jeremy Farrar. “It’s tragic to say, but if I get infected with H5N1 and die, it’s over (the chain of transmission is broken, editor’s note). If I go around the community and transmit it to someone else, then you start the cycle,” he explained.
He believes that infection surveillance and detection systems “are never sufficient” but notes “that this is happening in the richest country in the world” where serological studies have been launched “to see if transmission between breeders of cows and the like happens.”
Very rare cases
At the beginning of April, American authorities indicated that a person had tested positive for avian flu after being infected by a dairy cow in Texas. Currently, cases of transmission to humans are very rare. A nine-year-old child carrying the H5N1 strain died of bird flu in Cambodia in February, after three deaths in the same country in 2023.
In the United States, the patient showed “redness of the eyes (corresponding to conjunctivitis) as the only symptom,” authorities said, adding that he was isolated and treated with an antiviral drug used for the flu.