[What are the indications in France for vaccination against Japanese encephalitis?]

Japanese encephalitis is a mosquito-borne viral disease occurring in rural and rice-growing areas of Asia, where mosquitoes proliferate, transmitting the Flavivirus from viremic animals, mostly pigs, to humans. Japanese encephalitis has recently spread to previously non-affected regions, leading to serious outbreaks among non-immune populations. Although it has a high proportion of unsymptomatic infection, clinical encephalitis is usually severe, resulting in a very high mortality rate, and neurologic sequellae are common among survivors. Vaccines are used in several Asian countries. One of these vaccines is now available to French travellers, but only in international vaccination centres with an authorization from the French drug agency (Agence française de sécurité sanitaire des produits de santé). The aim of this paper is to clarify the recommendations for immunisation in each country of the affected regions. The area can be divided into three epidemiological zones, with tropical, subtropical and temperate characteristics. For the first two, vaccination is recommended before a long stay in a rural area, especially during the rainy season; in temperate climates, outbreaks occur in summer and autumn. However, local variations such as intensive rice-growing or development of pig breeding may interfere with these patterns. Long-term visitors should consult a local physician and prevention of mosquito bites is always recommended.