Europe Warns of ‘Lack of Immune Defenses’ Among Humans If Bird Flu Changes

Birds congregate in France in a file image. Stephane Mahe/Reuters

Avian influenza could quickly spread among humans if it mutates further, European authorities are warning.

“These viruses continue to evolve globally, and with the migration of wild birds, new strains carrying potential mutations for mammalian adaptation could be selected. If avian A(H5N1) influenza viruses acquire the ability to spread efficiently among humans, large‐scale transmission could occur due to the lack of immune defences against H5 viruses in humans,” the European Food Safety Authority said in an April 3 article.

Monique Eloit, head of the World Organisation for Animal Health, also said this week that the spread of bird flu to an increasing number of species and its widening geographic reach has raised the risk of humans being infected by the virus.

“Over the last few months, we have had a whole series of diverse and varied mammals. It is worrying to see this extension to other species,” Ms. Eloit said. “Ultimately, we find ourselves with more and more species and more animals which are contaminated, therefore necessarily a higher viral load with a risk of contamination of humans.”

Avian influenza, commonly known as bird flu, has led to the culling of hundreds of millions of poultry around the globe in past years, with the virus mostly carried by migrating wild birds. Although the number of outbreaks has been lower this season, the virus has spread to new regions, including South America and Antarctica, and has hit a larger number of animals.

Some outbreaks of bird flu have caused serious or fatal infections among people who have close contact with wild birds or poultry, but to date, there has been no sustained human-to-human transmission observed, according to scientists. Animal and human flu viruses tend to mutate, though, raising concern that one will turn into a virus that can be transmitted between mammals, including humans.

“I don’t think we are seeing evidence of human-to-human transmission at this time, and this particular 2.3.4.4b strain of virus H5N1 may cause less severe disease than other H5N1 viruses,” John Lowe, who holds a doctorate in medical science and is director of the University of Nebraska Medical Center’s Global Center for Health Authority, told The Epoch Times via email.

“We should keep in mind, however, that we have only a small number of cases to guide our assumptions at this point, and overall, H5N1 viruses infections in humans historically have been severe, with a case fatality rate over 50 [percent].”

The case fatality rate is the proportion of people who contract an illness who die.

Between 2003 and March 25, 2024, 888 human cases of highly pathogenic avian influenza A virus, also known as H5N1 bird flu, have been reported to the World Health Organization from 23 countries. Of those patients, 463 died, the organization said.

The only human infection in the United States during that time happened in 2022, and that individual recovered.

The avian influenza viruses have primarily been spreading among birds around the world, but scores of cattle in the United States have recently begun testing positive for the H5N1 bird flu. Cattle have tested positive at eight farms in Texas, three farms in Kansas, two farms in New Mexico, one farm in Idaho, one farm in Michigan, and one farm in Ohio, according to the U.S. Department of Agriculture.

A person in the state of Texas also tested positive, health authorities announced on April 1.

Sequencing of a specimen from that patient showed the virus had one mutation from nearby animals, PB2 E627K. The change “is known to be associated with viral adaptation to mammalian hosts,” the U.S. Centers for Disease Control and Prevention stated.

The agency emphasized that the mutation has been seen in the past but that there remains “no evidence of onward spread among people” and that it maintains the position that the risk from the influenza is low.

Cattle in Texas in a file image. Evan Garcia/Reuters

Mr. Lowe said that people should be concerned but not alarmed.

“Any time a new flu virus affects multiple species or a large number of animals, it creates potential for accelerated virus evolution that could produce a change in the virus to spread between people and we have little immune protection against. While the virus has a single mutation adapting to infecting mammals, we have not yet seen evidence of accelerated evolution for human-to-human transmission,” he said.

Bryan Richards, emerging disease coordinator at the U.S. Geological Survey’s National Wildlife Health Center, told the Epoch Times that “it would take sustained human-to-human transmission in order for it to turn into any sort of a global threat to people.”

He said he was on the fence regarding whether people should be worried.

“It’s hard to say it’s something to worry about,” Mr. Richards said. “It’s hard to say it’s not something to worry about.”

For now, the primary risk is to people who work with animals, or live near them, authorities and other experts say.

Those people should wear protective equipment when six feet or closer to sick or dead animals, animal feces, or materials that may be contaminated with the avian influenza viruses, according to the CDC.

Those people should isolate and call a doctor immediately if they fall ill, Mr. Lowe said. He said the general public does not need to take protective measures against the flu as of now.

Reuters contributed to this report.