Recent changes in serological markers of hepatitis B virus infection in Japanese university students.

University students were screened for serological markers of hepatitis B virus infection every year. Hepatitis B surface antigen (HBsAg) determined by reversed passive hemagglutination and antibody to HBsAg (anti-HBs) by passive hemagglutination were positive in 1.7% and 7.3% of the first-year students in 1978-80, respectively, and 1.1% and 3.8% in 1981-84. The difference in the prevalences of anti-HBs between 1978-80 and 1981-84 was statistically significant (p less than 0.001). Hepatitis B e antigen, which was positive by less sensitive immunodiffusion in 52% of HBsAg carrier students in 1976-79, was detected by more sensitive radioimmunoassay only in 19% in 1980-84. The difference was statistically significant (p less than 0.01). Recently changes in hepatitis B virus infection seem to be occurring in Japanese university students.