The prevalence of hepatitis E is low in developed nations such as the UK and is higher in developing regions where the standard of sanitation and water quality are low.
The infection is spread via the fecal-oral route which means it is passed out of the body in feces and can be transmitted by ingesting food or water contaminated with infected feces.
Studies have shown that in regions where hepatitis E is endemic, the antibodies to hepatitis E virus (anti-HEV antibodies) are only present in a low proportion of individuals (between 3% and 26%). In central Europe and North America, blood screening showed that anti-HEV antibodies were present among 1.4% to 2.5% of individuals. In South Africa the percentage was 1.4%; in Thailand it was 2.8%; in Saudi Arabia 9.5% and in Egypt 24.0%. In non-emdemic areas such as the United States, the prevalence of anti-HEV antibodies has been surprisingly high, at 1% to 3%. In some highly endemic areas, the infection is responsible for more than half of the acute sporadic hepatitis cases that occur.
The symptoms of hepatitis E are generally mild and the associated fatality rate is low. The condition usually resolves on its own and patients recover completely within a few months. Chronic or long-term infection with hepatitis E is very rare and usually only occurs in immunocompromised patients, such as those with those taking immunosuppressants after an organ transplant.
However, the infection can be more serious among those with pre-existing liver disease or in cases of pregnancy. In pregnant women, a severe form of the condition can occur with a sudden onset and lead to liver failure. This condition is called fulminant hepatitis and can lead to premature birth and death of the baby in the third trimester. As many as 25% of women who become infected with hepatitis E while pregnant, develop liver failure and lose their baby.
There are four strains of hepatitis E and these are referred to as “genotypes.” Of these, Genotypes 1 and 2 are found in Asia and Africa; genotype 3 exists worldwide, and genotype 4 occurs in China and Japan. Any cases of hepatitis E found in people in the UK are usually caused by genotpye 1 in people who have travelled, while genotype 3 accounts for cases in individuals who have not travelled.