[The relationship between changing of anti-HAV in population and prevalence of hepatitis A].

Hepatitis A was prevalent in 43 villages of the suburbs of Jinan, Shandong Province in 1986. The annual morbidity rate was 1,104.46/100,000. The authors studied the development of anti-HAV among children of under 14 years of age during the early epidemic and post-epidemic periods, compared the prevalence of anti-HAV between epidemic and non-epidemic villages, and analysed the types of HAV infection. The positive rate of anti-HAV was 35.42% during the early epidemic period and was 82.1% during the post-epidemic period, while it was 79.75% in non-epidemic villages. The result indicates that, in rural area, hepatitis A is chiefly influenced by the prevalence of anti-HAV in the population. If it remains at about 80%, the occurrence of an epidemic can be prevented. The ratio of clinical, subclinical and apparent infection during the epidemic was 1:0.75:0.81.