The detection of Japanese encephalitis virus in Megachiropteran bats in West Kalimantan, Indonesia: A potential enzootic transmission pattern in the absence of pig holdings

The West Kalimantan province in Borneo island, Indonesia belongs to endemic area of Japanese encephalitis (JE)
that accounts for approximately 30% of total cases yearly. As the presence of pig holdings is uncommon in West
Kalimantan, another reservoir host might have played a role in the local transmission of JE virus in this area.
Current study aimed to identify the potential role of bats in the local transmission of JE by performing molecular
detection of JE virus in bats and mosquitoes using RT-PCR. Sample collection was performed in 3 districts in
West Kalimantan, covering 3 different ecosystems: forest, coastal, and residential areas. Bat collection was
performed using mist net and harp net, while mosquito collection was carried out using animal-baited trap and
human landing collection. A total of 373 blood samples from bats were tested for JE virus, among which 21
samples (5.6%) showed positive results, mainly from Cynopterus brachyotis (lesser short-nosed fruit bat) found in
residential areas. Out of 53 mosquito pools, 3 JE-positive pools of Culex tritaeniorhynchus and Cx. vishnui were
collected at the same location as JE-positive bats. Current study showed the first evidence of JE virus detection in
several species of Megachiropteran bats in Indonesia, demonstrated the potential role of frugivorous bats in local
transmission of JE in West Kalimantan. More aggressive measures are required in JE risk mitigation, particularly
in initiating JE vaccination campaign and in avoiding disruption of bats’ natural habitats through changes in
land-use.