Three UN agencies warn that recent H5N1 outbreaks among birds, animals, and some people may pose an ongoing risk to human health.
In a July 12 statement, the Food and Agriculture Organization of the United Nations (FAO), the World Health Organization (WHO), and the World Organization for Animal Health (WOAH) raised concerns over the uptick in bird flu cases worldwide, calling for international cooperation to help protect animals and people from the disease.
The agencies say H5N1 avian influenza viruses emerged in 1996, causing numerous outbreaks over the last 27 years. However, since 2020, a viral variant called H5 clade 22.214.171.124b has killed a record number of wild birds and poultry in Africa, Asia, and Europe. Moreover, the virus spread to North America in 2021 and Central and South America in 2022.
Sixty-seven countries in five continents reported H5N1 outbreaks in wild birds and poultry in 2022, resulting in more than 131 million poultry deaths due to culling or the disease. This year, influenza A(H5N1) clade 126.96.36.199b viruses caused several mass death events in wild birds as the disease spread to the Americas.
However, concern arises when a bird flu virus infects animals, as animals are closer to humans than birds. When this happens, it means the virus might adapt to infect people more easily.
The WHO says that ten countries across three continents have reported influenza A(H5) virus outbreaks in animals. These include farmed mink in Spain, seals in the United States, and sea lions in Peru and Chile. In addition, several countries have detected H5N1 in domestic animals such as cats and dogs. Most recently, Poland authorities reported H5N1 in cats.
In the statement, Gregorio Torres, Head of the Science Department at WOAH, warns, "There is a recent paradigm change in the ecology and epidemiology of avian influenza which has heightened global concern as the disease spread to new geographical regions and caused unusual wild bird die-offs, and alarming rise in mammalian cases."
According to the UN agencies, eight human cases of influenza A(H5N1) clade 188.8.131.52b have been reported since December 2021.
This year, the Ministry of Health of Chile reported its first case of the H5N1 bird flu in a 53-year-old person. In addition, Chinese officials reported that a 56-year-old woman died from H3N8, a different bird flu strain, while yet another strain, H5 clade 184.108.40.206c, sickened a father and caused the death of a child in Cambodia.
However, in these cases, transmission occurred through contact with infected birds or environments. So, currently, it appears these viruses cannot transmit from human to human.
"WHO is working closely with FAO and WOAH, and laboratory networks to monitor the evolution of these viruses, looking for signals of any change that could be more dangerous to humans," says Sylvie Briand, the Director of Epidemic and Pandemic Preparedness and Prevention at WHO. "We encourage all countries to increase their ability to monitor these viruses and to detect any human cases. This is especially important as the virus is now affecting countries with limited prior experience in avian flu surveillance."
The UN agencies will continue to monitor increasing bird flu cases and update recommendations as needed. Still, they stress that the spread of the virus to five continents underscores the need for global cooperation and vigilance to protect animals, people, and economies.