Diagnosis of hepatitis E.

Hepatitis E, caused by infection with hepatitis E virus (HEV), is a common cause of enterically-transmitted acute hepatitis in developing countries. Occasional cases of sporadic hepatitis E have been increasingly recognized in developed countries over the past decade. These cases differ from those in developing countries in being possibly caused by zoonotic transmission, often affecting people with a suppressed immune system and occasionally leading to persistent HEV infection. The commonly used tests for HEV infection include detection of IgM and IgG anti-HEV antibodies and detection of HEV RNA. IgM anti-HEV antibodies can be detected during the first few months after HEV infection, whereas IgG anti-HEV antibodies represent either recent or remote exposure. The presence of HEV RNA indicates current infection, whether acute or chronic. Although several diagnostic assays for anti-HEV antibodies are available, they have undergone fairly limited testing and often provide discordant results, particularly for IgG antibodies. Thus, although the available antibody assays might be useful for case diagnosis in areas with high disease endemicity, their use for case diagnosis in areas with low endemicity and for seroprevalence studies remains problematic. Improved validation of existing anti-HEV antibody assays or development of new assays with superior performance characteristics is urgently needed.