[Hepatitis non-A, non-B. Retro- and prospective studies on the epidemiology of the acute disease].

The epidemiology was studied in 159 consecutively admitted patients (1981-1983) with acute and chronic parenteral and non-parenteral type non A, non B hepatitis (HNANB). To establish the frequencies of types A (HAV), B (HBV) and HNANB data were collected from the official health statistic of the Federal Republic of Germany (1980-1982). Accordingly, 5 out of 100 000 persons acquired HNANB each year. There was no regional prevalence (i. e. industrial areas, cities) in HNANB as it was present in HAV. The relation of HNANB to HAV and HBV was 1:3:2,4 (health statistic), but was 1:1,1:3 in clinical studies (1979-1983, n = 2027). Of the patients with non-parenteral HNANB (n = 50) most were elder than 20 years of age. Susceptibility for parenteral acquired HNANB was observed in all groups of age. The evaluation of the possible modes of infection revealed 59% of the patients with non-parenteral ("sporadic") type HNANB, other 28,9% had posttransfusion HNANB. When monthly incidence was examined the HNANB infectivity of bloodtransfusions was high during May, June and October. Most cases of sporadic HNANB became clinically ill during summer and October. Difficulties in determination of incubation periods became evident because of the fluctuating increases and decreases of aminotransferases: In posttransfusion HNANB (n = 28) the first increases of aminotransferases were recorded at day 18 +/- 13 whereas peak values happened at day 77 +/- 21. It is concluded, that HNANB is an infection which affects a high proportion of the population, and needs consideration as a common infectious disease.