Chong-Gee Teo

Infectious Agent

Infection is caused by hepatitis E virus (HEV), which contains a single-stranded RNA molecule. It is classified in its own family, Hepeviridae.

Mode of Transmission

HEV is transmitted primarily by the fecal–oral route. Epidemics of hepatitis E are principally due to drinking fecally contaminated water. Sporadic disease in Japan is zoonotic and food-borne and is associated with eating meat and viscera of deer, boars, and pigs. Sporadic disease also is observed in other temperate countries, including the United States, but its cause is unknown in most cases. Disease from blood transfusion has been reported, although rare. Perinatal HEV transmission from women infected during pregnancy is common.

Occurrence

• Waterborne outbreaks (often large, involving hundreds to thousands of people) have occurred in South and Central Asia, tropical East Asia, Africa, and Central America (Map 5-4). Clinical attack rates are highest in young adults 15–49 years of age.
• In outbreak-prone areas, interepidemic disease is sporadically encountered.
• In these areas, pregnant women—whether infected sporadically or during an epidemic—are at significant risk of progressing to liver failure and death.
• Sporadic disease also occurs in the Middle East, temperate East Asia (including China), North and South America, and Europe (except Scandinavian countries). Symptomatic disease is observed most frequently in adults >60 years old, especially men.
• Chronic infection has been reported in organ transplant recipients undergoing immunosuppressive therapy.

Risk for Travelers

• Persons of all ages are at risk of HEV infection when they travel to areas where epidemics have occurred, but symptomatic disease is most frequent in young adults.
• In hyperendemic areas, infection and disease are due to eating and drinking in settings where sanitary conditions are poor.
• When traveling in Japan, eating raw or inadequately cooked venison, boar meat, or pig liver is a significant risk factor for hepatitis E.
• It is unknown if the risk of acquiring hepatitis E in the United States is higher than when traveling to regions outside the United States where sanitation is adequate and sporadic hepatitis E also occurs.

Clinical Presentation

• Incubation period is 2–9 weeks (mean 6 weeks).
• Signs and symptoms of disease during primary infection include jaundice, fever, loss of appetite, abdominal pain, and lethargy.
• Acute hepatitis E is frequently self-limited.
• Pregnant women (particularly those infected during the second or third trimester) may present with or progress to liver failure, and their infants are at risk of spontaneous abortion and premature delivery.
• People with pre-existing chronic liver disease may undergo further hepatic decompensation during HEV infection.

Diagnosis

• The diagnosis of acute hepatitis E is established by the positive detection of both immunoglobulin IgM and IgG anti-HEV antibodies in serum.
• Detection of HEV RNA in serum or stools further confirms the serological diagnosis but is seldom required.
• Longer-term, serial detection of HEV RNA in serum or stools, regardless of the HEV antibody serostatus, suggests chronic HEV infection.
• No FDA-approved diagnostic test is available.

Treatment

Treatment is supportive.

Preventive Measures for Travelers

• No vaccine is available.
• No drugs for preventing infection are available.
• Travelers should avoid drinking unboiled or unchlorinated water and beverages that contain unboiled water or ice.
• Travelers should eat only food that is thoroughly cooked, including seafood, meat, and meat products.

References

1. Appleton H, Banks M, Dentinger CM, Teo CG. Foodborne Viral Hepatitis. In: Foodborne Diseases. Shimjee S, editor. Totowa (NJ): Humana; 2007. p. 175–214.
2. Panda SK, Thakral D, Rehman S. Hepatitis E virus. Rev Med Virol. 2007;17(3):151–80.
3. Teo CG. Hepatitis E indigenous to economically developed countries: to what extent a zoonosis? Curr Opin Infect Dis. 2006;19(5):460–6.
4. Boccia D, Guthmann JP, Klovstad H, et al. High mortality associated with an outbreak of hepatitis E among displaced persons in Darfur, Sudan. Clin Infect Dis. 2006;42(12):1679–84.
5. Patra S, Kumar A, Trivedi SS, et al. Maternal and fetal outcomes in pregnant women with acute hepatitis E virus infection. Ann Intern Med. 2007;147(1):28–33.
6. Lewis HC, Boisson S, Ijaz S, et al. Hepatitis E in England and Wales. Emerg Infect Dis. 2008;14(1):165–7.
7. Renou C, Moreau X, Pariente A, et al.; ANGH, France. A national survey of acute hepatitis E in France. Aliment Pharmacol Ther. 2008;27(11):1086–93.
8. Kamar N, Selves J, Mansuy JM, et al. Hepatitis E virus and chronic hepatitis in organ-transplant recipients. N Engl J Med. 2008;358(8):811–7.
9. Feagins AR, Opriessnig T, Guenette DK, Halbur PG, Meng XJ. Detection and characterization of infectious hepatitis E virus from commercial pig livers sold in local grocery stores in the USA. J Gen Virol. 2007; 88:912–7.
10. Albinana-Gimenez N, Clemente-Casares P, Bofill-Mas S, et al. Distribution of human polyomaviruses, adenoviruses, and hepatitis E virus in the environment and in a drinking-water treatment plant. Environ Sci Technol. 2006;40(23):7416–22.
11. Jeyamani R, Kurian G. Hepatitis E virus and acute-on-chronic liver failure. Indian J Gastroenterol. 2004;23(2):45–6.
12. Emerson SU, Arankalle VA, Purcell RH. Thermal stability of hepatitis E virus. J Infect Dis. 2005;192(5):930–3.
13. Feagins AR, Opriessnig T, Guenette DK, et al. Inactivation of infectious hepatitis E virus present in commercial pig livers sold in local grocery stores in the United States. Int J Food Microbiol. 2008;123(1–2):32–7.