Re-emergence of echovirus type 13 infections in 2002 in Yamagata, Japan.

Objectives: To analyze the prevalence of echovirus type 13 (Echo13) in Yamagata, Japan.

Methods: Virus isolation was performed from 6514 clinical specimens using six cell lines between January 1999 and December 2002. We also carried out a seroepidemiological study against Echo13, using 234 serum samples collected in 2001.

Results: In 2002, we isolated a total of 50 Echo13 strains, which had not been detected from 1981 until 2001 in Japan. The antibody positive rate was higher (57.2-62.0%) in subjects 50 years or over than in those under 50 years (0-14.4%).

Conclusions: Serological study suggested that Echo13 had been present in Yamagata until around 1960, at which time the antibody positive persons were exposed to Echo13 in their childhood. Furthermore, results of virus isolation demonstrated that Echo13 re-emerged in around 2002 after a hiatus of several decades.