The spread of H5N1 bird flu in dairy cows is unprecedented; The outbreak of the US is the first of its kind in cows. Virologists and experts in the field of infectious diseases fear that the continuous spread of the virus in household mammals such as cows, which have close interactions with people, will offer the virus countless opportunities to spill over and adapt to people.
Until now, since the beginning of 2024, the US has added 67 human cases of H5N1. Three were cases that had no clear exposure.
Whether the D1.1 -Genotype will be an even greater risk for dairy staff will remain unclear for the time being. In general, H5N1 infections in humans have been rare but dangerous. According to data collected by the World Health Organization, 954 H5N1 Human cases have been documented worldwide since 2003. Of these, 464 were fatal, for a fatal number of documented cases of 49 percent. But so far, almost all human infections in the US have been relatively mild and experts do not know why. There are various possible factors, including transmission route, immunity from the past of employees, the use of antiviral agents or something about the B3.13 genotype specifically.
For now, the USDA says that the detection of the D1.1 -genotype in cows does not change their extermination strategy. It further praised the finding as a “proof of the strength of our national strategy for testing milk.”
