[Japanese encephalitis: a fast-changing viral disease].

The following aspects are dealt with in this article: 1) current geographical distribution of Japanese encephalitis; 2) clinical patterns of Japanese encephalitis; 3) vertebrate hosts of Japanese encephalitis virus; 4) vectors of JE virus; 5) epidemiological locations (endemic area, endemoepidemic area, epidemic area); 6) unknown epidemiological aspects; 7) JE virus serotypes; 8) evolution of the disease and recent epidemiological changes; 9) phylogenetic origin of the JE virus; 10) ecological changes in the past, factors in the emergence of the disease; and 11) the future: Can we predict how the situation will evolve?