Epidemiologic concerns and advances in knowledge on hepatitis E.

RA Hepatitis E, a disease caused by infection with the hepatitis E virus (HEV), is highly endemic in several developing countries in Asia and Africa where contamination of water supplies and lack of adequate sanitation are frequent. In these areas, a large proportion of cases of acute viral hepatitis are due to genotype 1 or 2 HEV infection. In contrast, the disease is quite infrequent in developed countries. Most of the cases of hepatitis E in these areas are related to travel to disease-endemic areas; however, some cases with locally acquired HEV (usually belonging to genotype 3 and occasionally genotype 4) infection do occur. With the global trend of increasing travel and migration, an increased frequency of travel-associated hepatitis E may be expected. However, the number of cases of travel-associated HEV in developed countries has remained small. This is possibly because most short-term business travellers take precautions to avoid consumption of potentially contaminated food or water. Also, in several endemic areas (eg, China), the frequency of hepatitis E has fallen in recent years with economic development and consequent improvement in water quality and sanitation. In fact, travel-associated hepatitis E is seen more often among immigrants residing in developed countries who visit their home countries where the disease is endemic. This is possibly because visits of such travellers to diseaseendemic areas are longer in duration and their likelihood of exposure to contaminated food or drink may be higher. G&H What have been the common sources of hepatitis E in nonendemic areas?