EPIDEMIOLOGY OF TICK-BORNE ENCEPHALITIS IN JAPAN

A tick-borne encephalitis (TBE) patient has not been reported for many years in Japan although a serological survey of domestic animal sera suggested the presence of TBE foci in Hokkaido, the northern island of Japan. In October 1993 in Hokkaido, a severe encephalitis case in a f arm wife was diagnosed as tick-borne encephalitis. Serological examina tion of paired sera showed a rise of neutralization (NT) antibody tite r to Russian spring summer encephalitis virus. A sero-epizootiological survey of dogs showed that the TBE-related virus was prevalent in the area. Three virus isolates were obtained from the blood of sentinel d ogs and the antigenic analysis grouped the isolates into TBE-related v iruses. Sequence analysis of envelope protein gene identified one of t he isolates as the same subtype as Russian spring summer encephalitis (Far-Eastern TBE) virus. The results provide the evidence that TBE is endemic in a certain area of Japan. (C) 1998 Published by Elsevier Sci ence Ltd. All rights reserved.