Seroprevalence of Japanese Encephalitis in Pigs in Central Province, Papua New Guinea

BACKGROUND: Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic flavivirus of significant public health and veterinary concern in Asia and the Western Pacific. In Papua New Guinea (PNG), the epidemiology of JEV remains poorly understood, with limited data on its circulation in pig populations. This study aimed to determine the seroprevalence of JEV in commercial and semicommercial pig farms in Central Province, PNG, a region experiencing rapid urban and agricultural expansion. METHODS: Serum samples (n = 136) were collected from grower (5-7 months old) and breeder pigs (8-36 months old) on three farms and tested using competitive ELISA for JEV antibodies, with follow-up testing to resolve cross-reactivity with antigenically related orthoflaviviruses. RESULTS: Overall, 45% of pigs tested positive for JEV-specific antibodies. By age, a significantly greater proportion of grower pigs were seronegative to JEV, and although seropositivity was similar in grower and breeder pigs, breeder pigs showed higher proportions of cross-reactive results, suggesting multiple exposure to JEV or other orthoflaviviruses. No significant association was found between JEV serostatus and reproductive outcomes in breeding sows. CONCLUSION: These findings provide evidence of JEV circulation in a densely populated region of PNG and support the need for integrated One Health surveillance to inform risk-based control strategies.