Is an outbreak of cases to be feared? The World Health Organization (WHO) expressed "tremendous concern" on Thursday over the increasing spread of the H5N1 strain of avian flu to new species, including humans. A case of a person being infected by a dairy cow in the United States sparked fears earlier this month.
“It remains, I think, a huge concern,” Jeremy Farrar, chief scientist at the U.N. health agency, told a news briefing in Geneva. The H5N1 virus, which regularly decimates migratory or farmed birds, has demonstrated “an extraordinarily high mortality rate” among people contaminated by their contact with infected animals.
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%. A nine-year-old child carrying the H5N1 strain, for example, died of avian flu in Cambodia in February, after three deaths in the same country in 2023.
For the moment, cases of transmission from animals to humans are very rare, but nevertheless worry scientists. The fear is also that this virus will adapt to become capable of transmitting from human to human. Currently, there is no evidence of direct transmission between two people, but the WHO calls for further research on this subject.
“Start cycle”
Beyond monitoring humans infected by animals, "it's even more important to understand how many human infections occur without your knowledge, because that's where the adaptation" of the virus will occur, he said. explained Jeremy Farrar. “It's tragic to say, but if I'm infected with H5N1 and I die, it's over,” he pointed out. In other words, the chain of transmission is broken. But “if I go around the community and transmit it to someone else, then you start the cycle,” he explained, believing that infection surveillance and detection systems “do not are never sufficient” in the face of such risk.
Fears were rekindled in early April, when American authorities indicated that a person exposed to cattle had tested positive for avian flu after being infected by a dairy cow in Texas, while the virus had previously been transmitted to humans especially by birds. Since then, the virus has ravaged entire herds in different states, according to the agency according to Bloomberg. The patient had shown “redness of the eyes (corresponding to conjunctivitis), as the only symptom,” the authorities said, adding that he was isolated and treated with an antiviral drug used for the flu.
In February, the head of the WHO estimated that the spread of H5N1 influenza to humans remained low, with the number of cases of infection being limited until then. “But we cannot assume that this will remain the case and we must prepare for any change in the status quo,” warned Dr. Tedros Adhanom Ghebreyesus, quoted by the Reuters agency.
He had already launched a call for vigilance, recommending strengthening surveillance in spaces where humans and animals could interact. “WHO also continues to collaborate with manufacturers to ensure that, if necessary, stocks of vaccines and antivirals are available for global use,” he also said. The head of the organization reminded in passing that it was not recommended to touch dead or sick wild animals, and to quickly report their presence to the authorities.