The frequency of hepatitis A and B viruses as the offending viral type in suspected hepatitis.

Three hundred and thirty blood samples from patients suspected of having hepatitis on clinical grounds but in whom the aetiology of the hepatitis was unknown (93 Whites and 237 Blacks) were tested for the presence of hepatitis B surface antigen (HBsAg), anti-HBs, total anti-hepatitis A virus (HAV) activity and anti-HAV of the IgM class. These tests identified the offending hepatitis virus whenever this was type A or type B, and also revealed the patient's immune status in respect of these viruses. Among the White patients HAV was the cause of 32,2% of the cases of hepatitis and was found commonly in patients up to the age of 35 years, with 1 further example being identified among the patients over the age of 50 years. In contrast, among the Black patients this infection was found only in children, with none of the patients over the age of 5 years remaining susceptible to the disease. Hepatitis B virus (HBV) was found frequently in Blacks of all ages and caused 39,7% of the cases of hepatitis, but was far less common among the Whites, in whom it was responsible for only 10,7% of cases. Serological evidence of exposure to HBV in the combined forms of HBsAg and anti-HBs reached 85,7% in Blacks aged between 36 and 50 years, while the highest level to be found in Whites was 45,5%, in the same age group. Active hepatitis A or B infections were diagnosed in 43% of the White patients and 50% of the Black patients in the study.