Could Bird Flu in Mink Signal Threat of a Human Pandemic?

studied and evaluated. 

How a Harmless Virus Became Dangerous
Waterfowl have long played host to influenza viruses, but these early strains were low in pathogenicity, said Wolfgang Fiedler, an ornithologist at the Max Planck Institute of Animal Behavior. The viruses weren’t too contagious or damaging.

But when these viruses that were harmless to wild birds spread to factory poultry farms — where thousands of animals were crammed tight — the disease spread rapidly and the virus could mutate, Fiedler explained.

The result was the highly contagious virus strains H5N1 and H5N8, which likely originated on poultry farms in East Asia, according to the Scientific Task Force on Avian Influenza and Wild Birds established by the UN

Farmed ducks likely become infected from wild birds. Ducks are “kept together with pigs, for example,” which aided the mutation process, noted Fiedler. Such animal husbandry methods “make a virus like this insanely happy.”

In fact, outbreaks of these highly pathogenic strains are typically associated with “intensive domestic poultry production and associated trade and marketing systems … via contaminated poultry, poultry products and inanimate objects,” according to the UN’s bird flu task force. 

The highly contagious H5N1 and H5N8 virus strains were in turn transmitted to wild birds via infected farmed birds, explained virologist Timm Harder. The viruses could then be transmitted over great distances during bird migrations.

How Much Damage Has the Bird Flu Outbreak Caused?
The ongoing avian flu outbreak is considered the largest observed in Europe to date, according to the European Food Safety Authority, an EU agency.

Between October 2021 and September 2022, 50 million farm birds had to be culled in 37 countries.

More than 3,800 highly pathogenic bird flu cases were counted in wild birds. Experts believe the number of unreported cases is probably much higher.

Until recently, bird flu mainly occurred in fall and winter.

Now the virus is also circulating in wild birds during the summer months,” confirmed Harder, noting that the animals breed closely in large colonies in the warmer months, providing ideal conditions for the spread of the virus.

The avian influenza wave also reached South America for the first time in the fall. Peru, Venezuela, Ecuador and Colombia were among the countries affected. In Honduras, more than 240 dead pelicans were found in one week alone.

Harder said he is concerned that the virus could spread from South America to Antarctica and endanger penguin populations. Apart from Antarctica, only Australia has escaped the virus. 

Despite the acute outbreak among birds, Harder sees one ray of hope in that the broad spread of the virus could promote immunity in wild birds. Antibodies have already been found in live animals.

Jeannette Cwienk is a DW journalist.This article was adapted from German by Stuart Braun, and it is published courtesy of Deutsche Welle (DW).