Hepatitis E is believed to be transmitted by the fecal–oral route, principally through contaminated water in areas with poor sani-tation. The incubation period is variable, estimated to range be-tween 15 and 65 days. In general, hepatitis E resembles hepatitis A. It has a self-limiting course with an abrupt onset. Jaundice is nearly always present. Chronic forms do not develop.
Avoiding contact with the virus through good hygiene, in-cluding hand washing, is the major method of prevention of hep-atitis E. The effectiveness of immune globulin in protecting against hepatitis E virus is uncertain.
It has long been believed that there is another non-A, non-B, non-C agent causing hepatitis in humans. The incubation period for post-transfusion hepatitis is 14 to 145 days, too long for hepatitis B or C. In the United States, about 5% of chronic liver disease re-mains cryptogenic (does not appear to be autoimmune or viral in origin), and half the patients have previously received transfu-sions. Thus, a new form of hepatitis (hepatitis G or GBV-C) has been described. They are two different isolates of the same virus. Autoantibodies are absent.
The clinical significance of this virus remains uncertain. Risk factors are similar to those for hepatitis C. There is no clear rela-tionship between GBV-C/HGV infection and progressive liver disease. Persistent infection does occur but does not affect the clinical course.