Watt Poultry Analysis suggests that highly pathogenic avian influenza may have entered the U.S. dairy herd late last year, as one in five milk samples in the country test positive for HPAI virus fragments. While it may be a truism to say that a virus must be present to be detected, simply reporting virus’ detection tells you little more than that. The March 25 statement from the U.S. Department of Agriculture (USDA) that H5N1 highly pathogenic avian influenza had been detected in dairy cattle for the first time was no more than that, an announcement that it had been detected. It would seem that the virus could have been present in the U.S. dairy herd since late last year.
A recently published paper in scientific journal Nature details an analysis, albeit preliminary and rapidly conducted, of scientific evidence entered into a public depository by the U.S. Food and Drug Administration (FDA) that suggests that the outbreak is likely to have begun in late December 2023 or early January 2024.
Nature suggests that cattle across the U.S., and even in neighboring regions, could have been infected with HPAI, and the World Health Organization has warned that it could spread to cattle in other countries.