Longitudinal Screening of Retail Milk from Canadian Provinces Reveals No Detections of Influenza A Virus RNA (April - July 2024): Leveraging a Newly-Established Pan-Canadian Network for Responding to Emerging Viruses.

Highly pathogenic avian influenza (HPAI) H5N1 has been associated with significant morbidity and mortality. Given recent detections of HPAI H5N1 in dairy cattle and RNA detections in pasteurized retail milk in the United States, we established the Pan-Canadian Milk Network in April 2024. Through this, retail milk was procured longitudinally and sent to a central laboratory to test for the presence of influenza A virus RNA. We tested 109 retail milk samples from all ten Canadian provinces and all samples tested negative. Our independent testing results have aligned with reporting from federal retail milk testing initiatives. Despite no known HPAI infections of dairy cattle in Canada to date, H5N1 poses a significant threat to the health of both humans and other animals. By performing routine surveillance of retail milk on a national scale, we have shown that academic networks and initiatives can rapidly establish nationwide emerging infectious disease surveillance that is cost-effective, standardized, scalable, and easily accessible. Our network can serve as an early detection system to help inform containment and mitigation activities if positive samples are identified and can be readily reactivated should H5N1 or other emerging zoonotic viruses be identified in agricultural or livestock settings.