Avian flu is advancing in cow farms in the US. Alert for the jump of species towards humans

Every day he takes a small step forward. The H5N1 avian influenza virus has begun circulating on a large scale among wild birds since 2020, including Italy. Then, with a leap in species, it infected mammals: around thirty species have been touched so far, from foxes to bears.

At the end of March the virus also entered dairy goat and cow farms: those affected by the epidemic in 6 states of the United States rose to 16. A Texas cattle also infected one of its farmers a week ago. It has only mild symptoms, but the detection of H5N1 in the milk of infected cows is shaking the dairy industry after having upended the poultry industry, forced to cull over 100 thousand animals in two years worldwide.

In the meantime, the avian virus has even reached Antarctica. Hundreds of Adélie penguins have been found lifeless buried in the snow. Scientists from various Australian universities are analyzing samples taken from their bodies to confirm the infection.

The Centers for Disease Control in the United States and the ECDC, the European equivalent body responsible for monitoring infectious diseases, have raised their alert level. The Texan farmer infected by his sick cow harbored a virus with a particular genetic mutation: precisely one of those that scientists believe is necessary for the adaptation of H5N1 to humans.

It is not the first time that a person has been infected by avian flu. The first versions of the virus were detected among wild birds in 1996. Since then several hundred humans have been infected (with a very high fatality rate, around 50%), but only after close and prolonged contact with infected poultry . Direct human-to-human infections have never been observed, not even since 2020, when the virus kicked into high gear in animals. Since then, circulation has become massive throughout almost the entire world, leading to slaughter on poultry farms and deaths of mammals, such as seals. Even some domestic cats have been found with the virus, probably from hunting infected birds.

The fact that H5N1 has a long history behind it has however allowed researchers to develop vaccine candidates over time that could be put into production in a short time. However, no steps in this direction have been taken at the moment. The circulation of avian flu keeps public health experts on alert, but it does not yet represent an emergency for our species. The presence of viruses in milk or eggs can be counteracted by pasteurization or cooking. The Texan farmer also only survived with conjunctivitis.

However, the virus continues to make progress, and the ECDC urges us not to lower our guard: “If H5N1 were to acquire the ability to spread among humans – it wrote in a report last Wednesday – we could witness large-scale transmission , given our species’ lack of immunity against H5 viruses.”