Knowledge of the clinical, epidemiological, and laboratory aspects of viral hepatitis is essential for the differential diagnosis of infections caused by A (IH) and B (SH) viruses. Studies of the natural history of the disease and observations of patients during the course of epidemics have provided valuable clues for the differentiation of infectious hepatitis from serum hepatitis.
Clinical Aspects
The incubation period of viral hepatitis, type A ranges between 15 to 50 days with an average of about 30 days regardless of the route of infection; it is essentially the same following an oral or parenteral exposure.1 In contrast, the incubation period of viral hepatitis, type B is much longer, ranging between 60 and 160 days, the average is 90 days. Although hepatitis B virus is usually transmitted by the parenteral route, it is well recognized that it can also be spread by contact and by the oral route.