The U.S. Department of Agriculture’s Animal & Plant Health Inspection Service (APHIS) reported Jan. 17 that eight of the nine H7N8 avian influenza detections announced on Jan. 16 have been confirmed as low-pathogenic avian influenza (LPAI). The ninth flock is undergoing additional testing.

These Jan. 16 detections in turkey flocks were identified as part of surveillance testing in the control area surrounding the initial highly pathogenic avian influenza (HPAI) H7N8 case in southwestern Indiana, identified on Jan. 15.

The pathogenicity of a virus refers to its ability to produce disease. Birds with LPAI often show no signs of infection or only have minor symptoms. HPAI viruses spread quickly and cause high mortality in domestic poultry. H7 strains of LPAI viruses have been known to mutate into HPAI viruses in the past.

"It appears that there was a low-pathogenic virus circulating in the poultry population in this area, and that virus likely mutated into a highly pathogenic virus in one flock,” USDA chief veterinarian Dr. John Clifford said. "Through cooperative industry, state and federal efforts, we were able to quickly identify and isolate the highly pathogenic case and depopulate that flock. Together, we are also working to stop further spread of the LPAI virus and will continue aggressive testing on additional premises within the expanded control area to ensure any additional cases of either HPAI or LPAI are identified and controlled quickly."

APHIS continues to work closely with the Indiana State Board of Animal Health and the affected poultry industry on a joint incident response. State officials quarantined the additional affected premises, and depopulation of birds has already begun. Depopulation prevents the spread of the disease. Birds from the flock will not enter the food system.