Historical and current perspectives on Japanese encephalitis in Sulawesi, Indonesia.

Abstract

Japanese encephalitis (JE), a mosquito-borne viral disease, poses significant public health risks in endemic regions, such as Indonesia. Sulawesi, one of the archipelago's largest islands, presents a high potential for JE transmission due to its conducive environmental, economic, and cultural factors. Between 1972 and 2017, JE-positive samples were detected sporadically in various hosts, including humans, pigs, bats, cattle, goats, chickens, and mosquitoes (Culex tritaeniorhynchus). This review consolidates historical data and provides a contemporary perspective on JE ecology in Sulawesi. The island's extensive rice fields (95% of districts) and its high density of amplifying hosts - especially pigs, which inhabit 65.5% of districts - highlight critical transmission dynamics. In addition, Sulawesi supports a diverse array of reservoir hosts, such as endemic bats and bird species, which enhance JE's zoonotic potential. Bats, including Dobsonia viridis and Rousettus celebensis, are particularly notable for their reservoir roles. Furthermore, at least nine mosquito vector species, led by C. tritaeniorhynchus, thrive in Sulawesi's wetland ecosystems, amplifying transmission risk. Despite the island's high-risk profile, JE surveillance remains inconsistent, with limited government-led diagnostic programs. Historical and recent data underscore the need for systematic investigations into JE's epidemiology, emphasizing molecular and serological detection, vector surveillance, and the role of amplifying hosts in transmission cycles. Key challenges include limited awareness, diagnostic infrastructure, and climate change, which exacerbate vector bionomics and disease dynamics. This review advocates for the integration of JE diagnostic tools, public health interventions, and vaccination programs tailored to Sulawesi's ecological and sociocultural context. These measures are essential to mitigate JE transmission and protect both human and animal health.