Prevention of hepatitis

Human viral hepatitis is caused by several biologically and immunologically distinct agents. Most commonly observed are hepatitis A (HAV), hepatitis B (HB V) and the group of at least three viruses classified as non-A, non-B (NANB). Less frequently other viruses associated with disease in which hepatitis is not necessarily the primary manifestation of infection may be identified. Included in this group are cytomegalovirus, Epstein-Barr virus, varicella-zoster, herpes simplex, coxsackie, echo, yellow fever and hemor-rhagic fever viruses. Knowledge of the immunology and epidemiology of HAV, HBV and NANB has al-lowed formulation of effective prophylactic regimens for these infections. The routes of transmission and incubation periods for each of the three types of primary hepatitis are presented for comparison in Table 2.