Objective: To determine and compare the etiology of sporadic acute and fulminant viral hepatitis in two groups of patients 16 years apart. Methods: Serologic diagnostic tests for hepatitis A, B, C, D and E, and cytomegalovirus infection were carried out in 276 patients during 1994-1997 (Group A) and 206 patients during 1978-1981 (Group B). Results: Among children, hepatitis A virus was the major etiologic agent (81.6% in Group A and 51.4% in Group B), followed by hepatitis E virus (12.2%, 46.4%) and hepatitis B virus (5.4%, none). Among adults, hepatitis E virus was the main causative agent (42.4% in Group A and 71.2% in Group B) followed by HBV (28%, 25.5%) and hepatitis A virus (10.6%, 3.5%). Delta hepatitis was found only in Group A. No viral cause was found in 25% of patients in Group A and 13.5% patients in Group B. Conclusions: Hepatitis E virus is a major cause of sporadic acute and fulminant hepatitis. There has been an increase in hepatitis A in adults who developed fulminant hepatic failure. Our data points to the emergence of hepatitis A in adults and emergence of delta virus infection. Hepatitis C virus was unimportant in causing sporadic hepatitis
