Epidemic outbreak of non-A, non-B hepatitis in a plasmapheresis center. II: Clinical observations and a four-year follow-up of patients.

An epidemic outbreak of non-A, non-B hepatitis occurred in 1977/78 involving 30 donors at a plasmapheresis center. Of 27 hospitalized patients with peak ALT values between 334 and 1736 (mean 831) IU/l, only 16 had subjective symptoms like fatigue and lack of appetite, 11 had nausea, 11 were jaundiced and one developed transient arthritis. Patients with jaundice became chronically ill significantly less frequently than those without jaundice. Nineteen of 26 patients followed up had elevated ALT values after 12 months (73%) and 11 after 46 months (42%). Needle liver biopsies performed in 18 of the 19 patients with elevated ALT after 12 months revealed chronic persistent hepatitis in 14 and chronic active hepatitis in three. Follow-up biopsies always showed improvement (nine patients) or complete recovery (eight patients).