[Frequency of hepatitis A antibodies in populations of various European countries].

Using a solid phase radioimmunoassay, prevalence of anti-HA was determined in sera of 661 German patients treated following accidents, 70 persons born in Mediterranean countries and 175 persons from Lillehammer, Norway. In Germany (55% positive) an increase in prevalence of anti-HA from 13% in the group below 20 years of age to 92% in persons over 49 was noted. This and further data suggest that after infection anti-HA is detectable for life. Persons from Norway (17% positive) aged below 40 years had a low prevalence of anti-HA (4-10%), whereas even young persons from Mediterranean countries (81% positive) hat antibody in about 80% of cases. Prevalence rates in different age groups suggest a remarkable decrease in incidence of hepatitis A infection over the last three decades in Germany. This results in a rise in the mean age at which hepatitis A infection is acquired and high morbidity during travel abroad. Only one of 10 hepatitis A infections appears to produce clinical disease. Young anti-HA positive individuals exhibit higher titers on average than older ones.