Abstract
Japanese encephalitis (JE) cases have been increasingly reported recently especially in Seoul and its vicinity. Pigs are known as amplifying host of JE virus (JEV), but do not play an important role in these recent events because pig-breeding is not common in Seoul. The distribution and the density of migratory birds are correlated with JE cases in cities and they might be highly potential hosts contributing to transmit JEV in metropolitan areas. JE genotype and sero-prevalence in birds should be determined for the verification of the transmission route of JEV in the recent sporadic occurrence of JE cases in Seoul.