Bird Flu’s Unprecedented Global Spread Sparks Alarm

Rapid spread of the H5N1 avian influenza virus has reached an “unprecedented” scale this season, wiping out hundreds of millions of birds worldwide and increasingly infecting mammals, the Food and Agriculture Organization (FAO) of the United Nations warned on March 16. The spread of the virus poses significant risks from food and public health perspectives.

Food Security

In a statement, FAO deputy director general Godfrey Magwenzi stressed that the crisis threatens to have “serious impacts on food security and food supply in countries.”

In the United States, for instance, egg prices hit record highs in February as workers were forced to cull more than 166 million birds, primarily laying hens, according to the FAO. The organization also reported that “at least 300 new species of wild birds have been affected since 2021, posing a serious threat to biodiversity.”

Beth Bechdol, another FAO deputy director general, emphasized the critical role of private sector involvement, particularly in the development of vaccines, diagnostics, and high-quality veterinary health services.

Public Health

Beyond the food crisis, the intense circulation of the virus has led to spillover from birds to mammals, raising alarms among researchers.

Speaking to Medscape’s French edition, Pierre Bessière, a virology researcher at the National Veterinary School of Toulouse in Toulouse, France, explained that in the United States, as the virus circulates among mammals such as cattle, it acquires adaptive mutations that make it dangerous to humans, even though it was not initially the case.

Currently, the circulating viruses are poorly adapted to humans and cause mild symptoms such as conjunctivitis, fever, and cough. However, earlier this year, a senior citizen in Louisiana became the first person in the United States to die from bird flu. In Canada, a young girl infected with the D1.1 variant was hospitalized in critical condition for 2 months.

“It is important to remember that between 1918 and today, there have been four pandemics caused by avian-origin influenza viruses. Historically, these viruses have often caused pandemics worldwide. Currently, H5N1 viruses have all the tools needed to acquire pandemic potential. The virus isolated from the young Canadian patient showed mutations that indicated pandemic potential. Fortunately, the virus was not transmitted to anyone else because the patient was treated immediately. She could not infect other people. However, one can imagine such a scenario, which could be problematic. This is how an epidemic, and subsequently a pandemic, begins. What must be avoided at all costs are human-to-human transmission chains,” Bessière said.

Is France Safer?

In France, the situation is less concerning than that in the United States, largely due to the vaccination of farmed ducks, a program implemented over the past 2 years. Over the past 12 months alone, 60 million ducks have been vaccinated. This strategy has significantly reduced farm outbreaks, with only 10 reported during 2023-2024 compared with more than 400 in the earlier season.

A study published by the Chair for Avian Health and Biosecurity at the National Veterinary College of Toulouse, Toulouse, France, estimated that, without vaccination, France could have experienced between 273 and 701 poultry farm outbreaks in 2023-2024, significantly exceeding the 10 outbreaks recorded across poultry farms during this period.

“Our team’s modelling work suggests that the vaccination campaign has been a success. In the past, we knew that when we had cases in France, they were always preceded by cases in Scandinavia about a month earlier because the spread followed the migration corridors. Applying this methodology to 2024, when ducks were vaccinated, we observed very few cases in France instead of the hundreds expected based on combined data from Norway, Sweden, and Finland obtained a month earlier,” explained Bessière, who did not participate in the study.

This story was translated from Medscape’s French edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.