A number of studies over the past 25 years have demonstrated the efficacy of γglobulin in modifying the clinical expression of infectious hepatitis, without reducing the attack rate.1 The disease, like poliomyelitis, occurs most often in children and has a latent, mild, and anicteric course; whereas in adults, while it is less prevalent, it is more virulent. Most studies have, perforce, been conducted in closed, institutionalized populations or during localized epidemics in small communities. The presence of icterus has identified obvious cases, while inapparent infections have been detected on the basis of elevated serum transaminase activity. Recent studies utilizing liver biopsy as well have revealed the prevalence of hepatitis in Asian nationals to be 1% to 2%.
The true incidence of the disease acquired under natural circumstances (occasional short exposures) is unknown. However, Keusch and co-workers2 have recently presented an estimate of the incidence of biopsy-confirmed hepatitis in