The Japanese encephalitis serological group of flaviviruses: a brief introduction to the group.

Abstract

Japanese encephalitis (JE) and West Nile (WN) viruses are two of the four major encephalitic flaviviruses of public health importance in the Japanese encephalitis serological group, the other two being St. Louis encephalitis (SLE) virus in North America and Murray Valley encephalitis (MVE) virus in Australasia. JE and WN share a number of similarities, including natural transmission cycles involving avian reservoir hosts and culicine mosquitoes and their ability to cause fatal infections in horses. The two viruses also differ in aspects of their transmission cycles and in their host range. Thus, unlike WN virus, JE virus also has a major mammalian amplifying host in the pig, and indeed most epidemic activity is driven by mosquito—pig transmission cycles. Some strains of WN virus, on the other hand, can cause a fatal disease in both domestic geese and various species of wild birds. However, most importantly, they also share a propensity to emerge and become established in new geographic areas. The recent spread of JE virus into western Asia and Australasia has probably been through natural mosquito—vertebrate host cycles, possibly assisted by changes in land use. However, the most recent example of the emergence of WN virus in New York and its subsequent spread in the eastern seaboard of the United States, was almost certainly due to inadvertent human involvement through transportation of either a viraemic human or bird, or an infected mosquito, from Israel or the Middle East. Although JE virus appears to have become established in New Guinea, it has not yet done so in Pakistan or in mainland Australia (Mackenzie et al., this volume).KeywordsWest Nile VirusJapanese Encephalitis VirusJapanese EncephalitisJapanese EncephalitisJapanese Encephalitis VirusThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.