A Case Control Survey of Farm Characteristics, Biosecurity Measures, and Risk Events in Flocks With and Without Infectious Coryza

The Pennsylvania poultry industry experienced an outbreak of infectious coryza (IC) starting at the end of 2018. Since the disease had not previously been found routinely in Pennsylvania, many questions emerged about the source of the infection and routes of transmission. To better understand the factors related to farm characteristics, risk events, and biosecurity that could influence the risk for the occurrence of IC, a case control study was undertaken to survey those flocks affected and a matched set of controls. Several factors were identified that increased the odds of being a case, including multiple vehicle entrances and having multiple categories of visitors. Other factors, such as bench entry, were found to be protective. This study indicates that fomites are a likely route of transmission for IC and that improvements in biosecurity can mitigate the risk of IC introduction.