There are 4 genotypes of hepatitis E virus (HEV). All can cause acute viral hepatitis.
Genotypes 1 and 2 usually cause waterborne outbreaks that are linked to fecal contamination of the water supply and fecal-oral person-to-person transmission. Outbreaks have occurred in China, India, Mexico, Pakistan, Peru, Russia, and central and northern Africa. These outbreaks have epidemiologic characteristics similar to hepatitis A virus epidemics. Sporadic cases also occur. No outbreaks have occurred in the US or in Western Europe. Most cases in the developed world occur in travelers returning from a developing country, but sporadic cases not associated with travel have been reported.
Genotypes 3 and 4 typically cause sporadic cases rather than outbreaks. Transmission is food-borne and can involve eating uncooked or undercooked meat; cases have been associated with consumption of pork, deer, and shellfish.
HEV was not originally thought to cause chronic hepatitis, cirrhosis, or chronic carrier state; however, reports document chronic genotype 3 hepatitis E exclusively in immunocompromised patients (including organ-transplant recipients, patients receiving cancer chemotherapy, and HIV-infected patients).
In the initial diagnosis of acute hepatitis, viral hepatitis should be differentiated from other disorders causing jaundice (see figure Simplified approach to possible acute viral hepatitis ). If acute viral hepatitis is suspected, the following tests are done to screen for hepatitis viruses A, B, and C:
If tests for hepatitis A, B, and C are negative but the patient has typical manifestations of viral hepatitis and has recently traveled to an endemic area, IgM antibody to HEV (IgM anti-HEV) should be measured if the test is available.
No treatments attenuate acute viral hepatitis, including hepatitis E.
Preliminary studies suggest ribavirin, given for 12 weeks, has antiviral efficacy in the treatment of chronic hepatitis E.
Alcohol should be avoided because it can increase liver damage. Restrictions on diet or activity, including commonly prescribed bed rest, have no scientific basis.
Viral hepatitis should be reported to the local or state health department.
Good personal hygiene and standard universal precautions help prevent fecal-oral transmission of hepatitis E. Boiling water appears to reduce risk of infection. Because person-to-person transmission is rare, isolation of infected patients is not indicated.
A vaccine for hepatitis E is now available in China; it is not available in the US. The vaccine appears to have about 95% efficacy in preventing symptomatic infection in males and is safe. Efficacy in other groups, duration of protection, and efficacy in preventing asymptomatic infection are unknown.
Transmission of hepatitis E is usually by the fecal-oral route.
Most patients recover spontaneously, but pregnant women have an increased risk of fulminant hepatitis and death.
Genotype 3 may cause chronic hepatitis in immunocompromised patients.
Suspect hepatitis E in travelers to endemic regions; do IgM anti-HEV testing if available.
Treat patients supportively; consider using ribavirin for chronic hepatitis E.
A vaccine is available in China.