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

## TL;DR

This paper reviews the history and current state of Japanese encephalitis in Sulawesi, Indonesia, highlighting transmission risks and the need for improved surveillance and control.

## Contribution

The paper provides a comprehensive ecological and epidemiological review of JE in Sulawesi, emphasizing the role of hosts and vectors.

## Key findings

- JE transmission in Sulawesi is supported by extensive rice fields and a high density of amplifying hosts like pigs.
- Bats such as Dobsonia viridis and Rousettus celebensis act as reservoirs, increasing zoonotic potential.
- Inconsistent surveillance and limited diagnostic programs hinder effective JE control in the region.

## 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.