Matched case-control study of the influence of inland waters surrounding poultry farms on avian influenza outbreaks in Japan.

To successfully control highly pathogenic avian influenza (HPAI), understanding the risk factors related to the incursion of the virus into poultry farms is essential. In this study, we focused on the presence of inland waters surrounding poultry farms as a potential risk factor of incursion of the virus. To evaluate the influence of inland waters surrounding poultry farms on HPAI outbreaks in Japan, a simple matched case-control study was conducted. The results of the conditional regression analyses indicated that the number of farms with neighbouring inland waters was significantly high among the affected farms during the 2016-2017 outbreak period. These results provide good grounds for strengthening biosecurity management at farms located near inland waters.