A CASE OF TICK-BORNE ENCEPHALITIS IN JAPAN AND ISOLATION OF THE VIRUS

A case of tick-borne encephalitis (TEE) has not been reported for many years in Japan, although a serological survey of sera from domestic a nimals suggested the presence of TEE foci in Hokkaido, the northern is land of Japan. Studies were conducted to prove the presence of an ende mic focus of TEE virus in Japan by means of serology and virus isolati on. In October 1993 in Hokkaido, a severe case of encephalitis in a da iry farmer's nife was diagnosed as TEE. Serological examination of pai red serum specimens showed a rise in the neutralization antibody titer to Russian spring summer encephalitis virus. A seroepizootiological s urvey of dogs showed that the TEE-related virus was prevalent in the a rea. Three virus isolates were obtained from the blood of sentinel dog s, and antigenic analysis grouped the isolates into TEE-related viruse s. Sequence analysis of the envelope protein gene identified one of th e isolates as being of the same subtype as the Russian spring summer e ncephalitis (Far Eastern TEE) virus. The results provide evidence that TEE is endemic in a certain area of Japan.