The H5N1 bird flu virus can be transmitted between mammals through milk and sometimes through the air.

A study has confirmed the ability of the H5N1 bird flu virus to spread between mammals. A new analysis by the Influenza Research Institute at the University of Wisconsin-Madison found that the variant can attach to the mammary glands of mice and ferrets, making it easier for nursing mothers to pass the pathogen to their offspring.

The study used the H5N1 type A virus isolated from contaminated cow’s milk. The sample was injected into mice and ferrets to assess its ability to be transmitted between mammals. The scientists found that the pathogen could replicate in mustelids and rodents, causing systemic infection. The study highlights the presence of the strain in the mammary glands of both species and confirms that lactating female mice can transmit the disease to their offspring through breastfeeding. “The HPAI virus (Highly pathogenic avian influenza) bullish H5N1 has characteristics that may facilitate infection and transmission to mammals.” he points out.

Experiments with ferrets have shown that the disease can be transmitted through the air, albeit inefficiently. The researchers placed a group of infected animals next to other healthy animals, at a distance that prevented physical contact. Of the four healthy ferrets, none became ill. However, one of them developed antibodies against the virus, suggesting that at some point during the test it had become infected.

“It’s good news that the virus is not widely spread between ferrets through the air, but it is still The concern is that it can be transmitted (in this way)” said Yoshihiro Kawaoka, a virologist at the University of Wisconsin-Madison and lead author of the study.

The analysis allowed the authors to characterize the virus isolated from contaminated cow’s milk. They found that the infectious agent variant has a significant affinity for receptors in avian (alpha 2.3) and mammalian (alpha 2.6) cells. These are the enzymes that are typically used by the H5N1 type A virus to cause infections at the cellular level.

Elisa Perez Ramirez, a veterinary virologist at the Animal Health Research Center, noted that these proteins “are present in the human upper respiratory tract, so this specific genotype of H5N1 may have a greater ability to infect and transmit between humans,” she added in a note published on the scientific dissemination portal Science Media Center that the pandemic potential of this subtype of the virus is high.

Bird flu virus fears grow

The H5N1 avian influenza virus was first detected in cow’s milk in March 2024. Previous studies have shown that this unpasteurized product can transmit the pathogen through ingestion and contact. The most recent analysis has identified new forms of infection and confirmed that the pathogen can be transmitted directly through breastfeeding in mice.

“The importance of careful monitoring of the H5N1 virus is even more obvious. In this case, the situation is particularly alarming because it is a subtype that affects a livestock species that interacts intensively with humans. When faced with this risk scenario, it is important to bet on strategy. one health “It is essential to strengthen health surveillance for both cattle and workers who come into contact with these animals,” warns Pérez Ramírez.

Health authorities around the world say bird flu poses a low risk to the general population. However, despite the new data, they have taken measures to prevent the virus from spreading further. The European Centre for Disease Prevention and Control (ECDC) said it was “implementing a broad strategy to support the early detection and containment of potential human cases in the European Union.” A “rare and unusual event,” but warns of the ability of this variant to jump between species.