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Ohio State University Extension


Hepatitis E: A Foodborne Zoonotic Threat in the U.S. and Abroad

Agriculture and Natural Resources
Scott P. Kenney, PhD, Assistant Professor, Ohio Agricultural Research and Development Center, Ohio State University Extension, Wooster

Hepatitis is inflammation of the liver, a condition caused by several viruses including hepatitis A, B, C, and E. Hepatitis E virus (HEV) is a pathogen found in several agriculturally important animal species and in humans. Humans can acquire some strains of HEV from animals. HEV is endemic in many U.S. swine herds without producing detectable disease and has been detected in pork products sold in grocery stores (Feagins et al. 2007). People can become infected by consumption of undercooked pork or other meat products, by drinking tainted water, or through produce irrigated or fertilized with feces from infected swine herds. Currently there are no FDA-approved vaccines for HEV. Avian HEV does not infect humans but does cause liver and spleen disease and hepatitis-splenomegaly syndrome in poultry, negatively affecting commercial broiler, breeder, and laying flocks. 

Pig standing in mud with mountains and a herd of swine in the background.

Figure 1. In the United States, 6.5% of pigs at slaughter have the hepatitis E virus. Photo by Jai79, Pixabay

Symptoms of Illness

Symptoms of hepatitis E are like those of other types of acute viral hepatitis and liver injury. They include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, jaundice, dark urine, clay-colored stool, and joint pain. Many cases of hepatitis E are asymptomatic and most resolve on their own (Centers for Disease Control and Prevention n.d.).

Public Health Consequences

The exact number of hepatitis E cases that occur each year is difficult to determine.  Many cases do not have symptoms, symptoms often occur weeks after exposure, and some cases spontaneously self-resolve making accurate diagnoses difficult. Symptomatic hepatitis E commonly occurs among teens and young adults (people aged 15–44 years). Pregnant women are more likely to experience severe illness, including fulminant hepatitis and death (Kumar et al. 2004). Immunocompromised individuals with hepatitis E can progress to chronic infection that affects many parts of the body including the kidneys, nerves, and brain (Kamar, Izopet, and Dalton 2013).

Risk Factors

Anyone can get hepatitis E, but persons who have lowered immune function due to underlying factors like organ transplantation, cancer, or AIDS are more likely to develop chronic and severe infections. People with underlying liver issues are also at higher risk of severe disease. Finally, pregnant women in their third trimester are more susceptible to severe disease for unknown reasons. A higher exposure rate has been noted in swine workers and veterinarians (Cossaboom et al. 2016).

Foods Implicated

In developing countries, drinking unsanitary water is the primary cause of HEV infection.  In developed countries, eating improperly cooked animal meats, including pork (liver and sausage), boar, deer, camel, and rabbit can lead to infections. In the United States, 6.5% of pigs at slaughter have been shown to have the virus (Sooryanarain and Meng 2020; Sooryanarain et al. 2020). Live virus survives meat processing procedures and can be found in pork products for sale in the supermarket (Feagins et al. 2007; Cossaboom et al. 2016). HEV has been detected in shellfish such as oysters and on strawberries that were fertilized with infected pig manure (Meng 2011). 

Underwater view of strawberries being dumped into clean water.

Figure 2. To prevent HEV, strawberries should be washed before eating. Photo: by Triggermouse, Pixabay

How to Prevent Infection

  1. Use a thermometer to make sure that raw foods are cooked to safe temperatures; at least 71 C (159.8 F) for 5 minutes to destroy HEV (Feagins et al. 2008).
    Note: The only way to be sure food is heated to 159.8 F is to check with a food thermometer.
  2. Wash fruits and vegetable before eating them.
  3. Wash hands with warm soapy water before and after handling raw foods and if you’ve come into contact with live animals such as pigs or rabbits.
  4. If traveling in countries with poor sanitation, only consume bottled water without ice.


Centers for Disease Control and Prevention. n.d. "Hepatitis E Questions and Answers for Health Professionals." Viral Hepatitis. Accessed August 11, 2021.

Cossaboom, Caitlin, Connie L. Heffron, Dianjun Cao, Danielle M. Yugo, Alice E. Houk-Miles, Davis S. Lindsay, Anne M. Zajac, Andrea S. Bertke, François Elvinger, and Xiang-Jim Meng.  2016. "Risk factors and sources of foodborne hepatitis E virus infection in the United States." J Med Virol, 88 (9): 1641–45.

Feagins, Alicia, Tanja Opriessnig, Denis Guenette, Patrick Gerard Halbur, and Xiang-Jin Meng. 2007. "Detection and characterization of infectious Hepatitis E virus from commercial pig livers sold in local grocery stores in the USA." J Gen Virol, 88 (Pt 3): 912–917.

Feagins, Alicia, Tanja Opriessnig, Denis Guenette, Patrick Gerard Halbur, and Xiang-Jin Meng. 2008. "Inactivation of infectious hepatitis E virus present in commercial pig livers sold in local grocery stores in the United States." Int J Food Microbiol, 123 (1-2): 32–37.

Kamar, Nassim, Jacques Izopet, and Harry R. Dalton. 2013. "Chronic hepatitis E virus infection and treatment." J Clin Exp Hepatol, 3 (2): 134–40.

Kumar, Ashish, M. Beniwal, Premashis Kar, J.B. Sharma, and N.S. Murthy. 2004. "Hepatitis E in pregnancy." Int J Gynaecol Obstet, 85 (3): 240–44.

Meng, Xiang-Jin. 2011. "From barnyard to food table: the omnipresence of hepatitis E virus and risk for zoonotic infection and food safety." Virus Res, 161 (1): 23–30.

Sooryanarain, Harini, Connie L. Heffron, Dolores E. Hill, Jorrell Fredericks, Benjamin M. Rosenthal, Stephen R. Were, Tanja Opriessnig, and Xiang-Jin Meng. 2020. "Hepatitis E Virus in Pigs from Slaughterhouses, United States, 2017-2019." Emerg Infect Dis, 26 (2): 354–57. doi:10.3201/eid2602.191348.

Sooryanarain, Harini, and Xiang-Jin Meng. 2020. "Swine hepatitis E virus: Cross-species infection, pork safety and chronic infection." Virus Res, 284.

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Originally posted Aug 24, 2021.