Protecting Children Against Japanese Encephalitis in Bali, Indonesia

Japanese encephalitis is a zoonosis and a mosquito­borne flaviviral disease. Culex species mosquitoes thrive in rice fields and transmit the virus from their natural hosts, primarily pigs, to humans; children younger than 15 years who reside in endemic areas are particularly at risk of infection. Mounting evidence of the presence of Japanese encephalitis prompted the need for a vaccination programme tailor­made for Bali. A policy maker meeting hosted by the Ministry of Health (MOH) and Balinese authorities was convened in 2007. International stakeholders included the IVI, UNICEF, WHO, and PATH. The outcome specified the need for a Japanese encephalitis mass vaccination programme followed by routine immunisation in Bali. As a result of unavoidable challenges, the programme halted in 2008. In 2011, the MOH reinitiated surveillance to measure the persistence of Japanese encephalitis risk and established a national, serum­ based surveillance programme in eight sites. In Bali, 408 probable Japanese encephalitis cases were identified from 2014 to 2016. Although diagnostic tests of cerebrospinal fluid were not conducted for these cases, they served as evidence that Japanese encephalitis was still endemic in Bali. Monitoring the cumulative effects of this vaccination programme in Bali will inform the global community and serve as a blueprint for future Japanese encephalitis vaccine introductions.