Rapid decline of hepatitis A in Finland

Infectious hepatitis, based on clinical diagnosis, has been reported by practicing doctors in Finland to the National Board of Health since 1943. Two epidemics of infectious hepatitis have been recorded. The first one with more than 16000 cases occurred in 1948 and the second one in 1954-57 with a peak of more than 7000 cases in 1956. After that infectious hepatitis has declined rapidly. In 1966 only 363 cases were reported. Although the figures are incomplete they reflect the changes that have taken place in the frequency of infectious hepatitis in Finland. The statistics are supported by serological studies. 24% of the sera collected in 1970 from 20-24-yr-old Finns, born in 1946-50, contained antibodies of the IgG class to hepatitis A while only 0.3% of the sera collected in 1982-83 from the same age group, born in 1958-63, contained these antibodies. Only 3.2% of the sera sent to our laboratory for hepatitis A diagnosis in 1980-82 contained antibodies of the IgM class to hepatitis A, and at least 68% of these infections were connected with travel in foreign countries. This paper shows that the prevalence of hepatitis A is low in Finland and that a rapid decline in its frequency has taken place during the last 25 years.