Enteric hepatitis viruses: Hepatitis a virus and hepatitis E virus

Abstract

Hepatitis A is an infectious disease of the liver caused by hepatitis A virus. Hepatitis A has a global distribution with endemicity inversely proportional to higher socioeconomic conditions and standards of sanitation and hygiene. Hepatitis A virus infection is predominantly spread directly from one person to another through orofecal transmission and through contaminated food and water. The clinical outcome is strongly correlated with age, being mostly subclinical in young children and symptomatic in older children and adults. Hepatitis A vaccine is safe, highly immunogenic and protective against clinical hepatitis A. Hepatitis E is an infectious disease of the liver caused by the hepatitis E virus. Hepatitis E is the most common cause of large-scale waterborne epidemics of jaundice in developing countries. In addition, around a third to a half of endemic acute viral hepatitis in these countries is caused by hepatitis E. The disease has high incidence and severity in pregnant women. Recently, hepatitis E is being recognized as an important clinical problem in the industrialized world that is related to unique zoonotic foodborne transmission. Hepatitis E in these countries has particular relevance to the solid organ transplant population due to risk of progression of infection to chronic hepatitis E and cirrhosis with liver failure and death in such patients. Hepatitis E causes a number of extrahepatic manifestations including a wide spectrum of neurological syndromes. Hepatitis E virus can be transmitted through blood and blood component transfusions, and donor screening is being done in many countries. There has been a significant advance in drug treatment of chronic hepatitis E and the availability of hepatitis E vaccine promises control of the hepatitis E burden in future.