Surveillance of Japanese encephalitis virus in piggery effluent and environmental samples: a complementary tool for outbreak detection.

Japanese encephalitis virus (JEV) is an emerging public health and biosecurity concern in Australia, with recent human cases and detections in mosquitoes and pigs across multiple states highlighting the risk to susceptible human and animal populations. While traditional surveillance methods such as mosquito trapping, sentinel chicken programs, and direct testing of pig specimens remain essential, monitoring effluents offers a valuable complementary approach for detecting infections within livestock herds. This study presents the first evidence of JEV in Australian piggery effluents and environmental waters, demonstrating the feasibility of effluent and environmental water surveillance for JEV monitoring. Effluent and environmental samples from multiple piggery sites were analyzed using real-time reverse transcription polymerase chain reaction, revealing the presence of JEV genetic fragments in solid and liquid fractions of effluents at three farms, with corresponding veterinary cases in some herds. Viral RNA was detected more frequently in the solid fraction of effluent samples, aligning with previous findings on the partitioning behavior of mosquito-borne viruses. The detection of JEV in environmental water from an excavated area highlights the potential for transmission via mosquito vectors. These findings demonstrate the value of effluent monitoring as an additional tool for JEV surveillance in piggery settings, supporting potential early warning systems and mitigation strategies. Integrating effluent-based monitoring with traditional surveillance approaches could improve livestock-industry-related disease detection, risk assessments, and response efforts for human and animal health in both endemic regions and areas where livestock diseases are emerging. Wastewater and effluent surveillance may have important applications for the management of a wide range of emerging animal diseases.IMPORTANCEThis study presents the first evidence of JEV detection in Australian piggery effluents, establishing effluent surveillance as a valuable complementary tool for monitoring viral pathogens in animal herds. Our findings support the integration of effluent monitoring with traditional surveillance systems to improve early warning capabilities, enhance biosecurity, and mitigate risks to both human and animal health.