Avian flu: recurring epidemics increase risk to humans

Massive poultry culling, soaring egg prices... and several deaths among people who came into contact with infected birds. The number of bird flu outbreaks in mammals more than doubled worldwide last year, increasing the risk of the virus spreading to humans, the World Organization for Animal Health (WHO) warned on Friday, May 23.

While the overall risk of transmission to humans remains low, the recurrence of avian influenza epidemics in mammals such as cattle, dogs and cats increases the possibility of the virus adapting and transmitting between humans, WHO said in a new report.

But the number of outbreaks in mammals climbed to 1,022 in 55 countries last year, compared to 459 in 2023, according to the Paris-based agency, which monitors animal diseases worldwide. "This is worrying because we are seeing a change in the epidemiological pattern of the virus," Emmanuelle Soubeyran, director-general of WHO, told WHO.

Health experts have warned of the pandemic threat posed by avian flu, which has already demonstrated its ability to mutate, particularly by spreading among dairy farms in the United States.

The report comes as the Trump administration cut budgets for U.S. health and science agencies, including the decision to end an epidemiology program known as "Disease Detectives" earlier this year.

Avian influenza "is more than an animal health crisis: it is a global emergency that destabilizes agriculture, food security, trade, and ecosystems," the report warns. According to the Agency's first annual report on the state of animal health worldwide, more than 630 million farm birds have died from avian influenza or been culled in the past 20 years. Wild birds have also suffered massive losses, the scale of which is difficult to estimate.

The report highlights the role vaccination can play in curbing outbreaks in birds, thereby reducing the risk to mammals and humans. It cites the example of France, which began vaccinating ducks against avian flu in 2023. According to modeling by the Toulouse Veterinary School (southern France), there could have been as many as 700 outbreaks in France that year, but there were only 10, the report states.

For Emmanuelle Soubeyran, this strategy is a win-win situation: it reduces human exposure while also allowing for more poultry exports. She emphasizes, however, that vaccines are not a "magic wand" and are not suitable for all situations.

Biosecurity, surveillance, increased transparency, and global collaboration are also important tools to combat the threat of avian flu, added Emmanuelle Soubeyran, calling for more investment in these areas.

Last month, Mexico reported its first death from bird flu, a three-year-old girl. The United States recorded its first death in January, while bird flu killed two people in Cambodia in January and February. According to the World Health Organization (WHO), approximately 50% of cases of bird flu infection have been fatal.

The WHO report also warns, more generally, of the growing danger of animal diseases spreading to humans, as climate change pushes species to establish themselves in new areas. Nearly 70% of emerging diseases reported to the agency over the past 20 years have been considered likely to pose a threat to human health.

Another danger is the growing resistance of certain diseases to antibiotics, which constitutes "one of the greatest threats to global health, food security and economic stability," according to the report.