Dairy workers to domestic cats hypothesis of avian flu transmission

A recent report by the US Centers for Disease Control and Prevention (USCDC) examined the potential transmission of avian influenza virus from two dairy farm employees in Michigan to their companion cats. The two employees, working in a county with confirmed H5N1 presence, reported symptoms indicative of H5N1 avian influenza before the onset of illness in their cats. In May 2024, post-mortem analysis revealed both cats to have tested positive for the H5N1 virus. They resided exclusively indoors and exhibited symptoms including, but not limited to, decreased appetite, increased ocular discharge, respiratory distress, disorientation, and lethargy. This was followed by progressive neurological decline, and both cats were found dead. It was ascertained that neither the family members nor the cats had consumed unpasteurised milk. Post-mortem analysis and collected and sequenced samples of both cats confirmed the presence of the H5N1 virus, clade 2.3.4.4b genotype B3.13, and this was found to be indistinguishable from the strain circulating among dairy cattle in Michigan. While a definitive correlation between these events has not yet been established, CDC experts emphasise the importance of utilising personal protective equipment by individuals at elevated risk of contracting avian influenza in medium- and high-exposure settings.