Age specific prevalence of anti HA in Japan--from multi-institutional analysis.

In order to estimate age specific prevalence of Anti HA in Japan, 1757 serum samples from healthy subjects or patients with nonhepatic disease taken in 6 different districts of Japan were tested for Anti HA using HAVAB Kit. Very low prevalence, less than 10%, was observed in young adults or children. These facts indicate the young Japanese are quite susceptible to HAV infection and the effective preventive measures are urgently needed. Over all prevalence of Anti HA was 56.2%. Comparing the age specific prevalence of Anti HA in Japan with those in other countries, the situation in Japan was in intermediate between highly endemic South-East region and developed European countries.