These cases are not related to contamination of water or other foods. Most of these cases are caused by genotype 3 virus and are triggered by infection with virus originating in animals, usually through ingestion of undercooked animal meat (including animal liver, particularly pork). In areas with better sanitation and water supply, hepatitis E infection is infrequent, with only occasional sporadic cases. The cases in these areas are caused mostly by infection with genotype 1 virus, and much less frequently by genotype 2 virus. Sporadic cases are also believed to be related to contamination of water, albeit at a smaller scale. Some of these outbreaks have occurred in areas of conflict and humanitarian emergencies such as war zones and camps for refugees or internally displaced populations, where sanitation and safe water supply pose special challenges. The outbreaks usually follow periods of faecal contamination of drinking water supplies and may affect several hundred to several thousand persons. In these areas, the disease occurs both as outbreaks and as sporadic cases. Hepatitis E infection is found worldwide and is common in low- and middle-income countries with limited access to essential water, sanitation, hygiene and health services. Occasionally a serious disease known as fulminant hepatitis (acute liver failure) develops, which can be fatal. The infection is usually self-limiting and resolves within 2–6 weeks. It is transmitted mainly through contaminated drinking water. The virus is shed in the stools of infected persons and enters the human body through the intestine. Genotypes 3 and 4 circulate in several animals including pigs, wild boars and deer without causing any disease, and occasionally infect humans.

Genotypes 1 and 2 have been found only in humans. The virus has at least 4 different types: genotypes 1, 2, 3 and 4. Hepatitis E is inflammation of the liver caused by the hepatitis E virus (HEV).

Mediacenter 2007