Prophylactic treatment regimens for the prevention of hepatitis A. Current concepts.

Hepatitis A virus (HAV) occurs worldwide. In developing countries the virus is endemic, with the majority of the population being exposed to it in childhood, when the infection usually causes, at the most, a mild anicteric illness. In developed countries the majority of HAV infections occur at a later age, often in adults, especially those with a history of recent travel to developing countries. In adults, HAV infection usually causes a symptomatic icteric illness. In addition to community sanitation and hygiene measures, prophylactic prevention of hepatitis A infection can be achieved by 2 methods. The first is the established and widely used method of passive immunisation using human immune globulin from pooled serum. Indications for the use of human immune globulin are: (a) travellers who will be exposed to unhygienic conditions in high risk countries; and (b) contacts of patients with acute hepatitis A infection, in certain circumstances. The second method currently undergoing research, and trials, is active immunisation using either live-attenuated or killed vaccines, which have given encouraging results in a number of trials. Further vaccines, using molecular biology techniques, are currently being developed.