Hepatitis A and E

Infections with hepatitis A virus (HAV) or hepatitis E virus (HEV) cause acute, self-limited hepatitis with no progression to chronic liver disease. Hepatitis A and E are enterically transmitted diseases which share several common features such as faecal–oral route of transmission, no chronic carrier state for these two infections, the infection is asymptomatic in a proportion of cases, resulting in virus-specific immunity. However, there are important differences between HAV and HEV with respect to their biology, epidemiology, their impact on morbidity and mortality of humans in different parts of the world. Hepatitis E is usually associated with more severe liver damage than hepatitis A, frequently complicated by coagulopathy and cholestasis. HEV is the primary cause of enterically transmitted non A, non B hepatitis in Asia, Africa, the Middle East and Central America with 20% mortality in HEV-infected pregnant women. Non-travel associated hepatitis E has been diagnosed in indigenous patients in England and Wales, in the majority of cases it was due to HEV genotype 3. Active immunization with attenuated HAV is highly effective, resulting in rapid and long lasting immunity. The prophylaxis of hepatitis E depends primarily on clean water supply and stringent sanitary measures. A vaccine against HEV is undergoing evaluation in clinical trials.