In a significant development, avian influenza H5N1, usually carried by wild birds, has been spreading to cows in North America, causing at least 68 cases and one death. Emerging data suggest that this virus can now infect humans, especially when transmitted directly from birds or animals like cows. Researchers are monitoring two main variants: B3.13, which primarily affects cattle, and D1.1, found mostly in birds. The variant transmitted to humans varies based on the source—D1.1 has been linked to severe cases among infected people, while B3.13 has caused mild respiratory issues.
The U.S., where H5N1 is spreading in dairy cows, recently pulled out of the World Health Organization (WHO), sparking concerns about potential bird flu pandemics. Dr. Seema Lakdawala explains that factors like underlying health conditions and exposure routes significantly influence disease severity. However, definitive conclusions remain elusive due to limited data on variant-specific risks.
A study involving Heinz Feldmann found that if the H5N1 virus enters the lungs directly, it could cause severe infection in animals like cynomolgus macaques. Meanwhile, dairy workers face heightened risk due to their exposure during milk handling. As experts continue to monitor these developments, the situation remains uncertain but alarming for global health preparedness.
Source: https://www.nature.com/articles/d41586-025-00245-6