‘Great concern’: WHO urges vigilance over risk of H5N1 avian influenza transmission to humans

Should we be concerned about a disease outbreak? The World Health Organization (WHO) expressed “tremendous concern” on Thursday about the growing spread of the H5N1 strain of bird flu to new species, including humans. Earlier this month, a case of human infection from a dairy cow in the United States raised concerns.

“I think this remains a huge concern,” Jeremy Farrar, chief scientist at the U.N. health agency, said at a briefing in Geneva. The H5N1 virus, which regularly kills migratory or farmed birds, has demonstrated an “extremely high mortality rate” among people infected through contact with infected animals.

According to the WHO, from the beginning of 2003 to April 1, 2024, a total of 889 cases of avian influenza were reported in humans in 23 countries, including 463 deaths, resulting in a case fatality rate of 52%. For example, a nine-year-old child carrying the H5N1 strain died of bird flu in Cambodia in February, following three deaths in the same country in 2023.

At the moment, cases of transmission of the virus from animals to humans are very rare, but nevertheless concern scientists. There are also concerns that this virus will adapt and become capable of transmitting from person to person. There is currently no evidence of direct transmission of the virus between two people, but the WHO is calling for further research into this.

“Start cycle”

In addition to observing people infected by animals, he said, “it’s even more important to understand how many cases of human infection are happening without you knowing, because that’s where the adaptation” of the virus will happen, he explained. “As sad as it is to say, if I get infected with H5N1 and die, everything will be over,” he said. In other words, the transmission chain is broken. But “if I go around the community and pass it on to someone else, then you start a cycle,” he explained, believing surveillance and infection detection systems are “never sufficient” in the face of such risk.

Concerns were renewed in early April when US authorities reported that a person exposed to cattle tested positive for avian influenza after being infected by a dairy cow in Texas, while the virus had previously been transmitted to humans, particularly through birds. Since then, the virus has devastated entire herds in different states, Bloomberg reports. The patient had “red eyes (consistent with conjunctivitis) as the only symptom,” authorities said, adding that he was isolated and treated with an antiviral drug used for influenza.

In February, the WHO chief estimated that the spread of H5N1 influenza among people remained low and the number of infections was still limited. “But we cannot assume that this will continue, and we must be prepared for any change in the status quo,” warned Dr. Tedros Adhanom Ghebreyesus, as quoted by Reuters.

He has already called for vigilance, recommending increased surveillance in areas where people and animals are likely to interact. “WHO also continues to work with manufacturers to ensure that supplies of vaccines and antivirals are available for global use if necessary,” he also said. The head of the organization simultaneously reminded that it is not recommended to touch dead or sick wild animals, and also to promptly report your presence to the authorities.