Who Is At Highest Risk For Contracting Hepatitis E?

Introduction 

Hepatitis E Virus (HEV) affects the liver and it is the most common cause of acute liver inflammation. HEV is a disease common in environments with poor sanitation. It is transferred from person to person, and can be contracted by ingesting food and water contaminated with feces. Although it may resolve naturally within weeks for acute hepatitis, it can result in chronic hepatitis in immunocompromised persons and poses a high risk of death.

Pregnancy is an important risk factor of contracting the virus and it is a major cause of death in women and children, especially for those  with poor access to resources such as good water and healthcare.

There is no specific treatment for Hepatitis E virus, so it is important to take proactive prevention and management especially in immunocompromised people. If not promptly managed, HEV can lead to chronic hepatitis which causes liver failure and may even require a liver transplant.^1,2  

General Population at Risk

People living in  Endemic Regions

Any location can become endemic to Hepatitis E virus if water, sanitation, hygiene and general living conditions are poor. 

This is particularly with people living in low-income countries with limited access to clean potable water. Most of the people who belong to these communities depend on a general source of water for their daily activities including bathing, washing, defecating and even as their source of drinking and cooking. And so, the virus passed through defecation by one person is drunk by the other or ingested through food cooked with the contaminated water and the cycle continues putting the people in the danger of an outbreak of HEV. 

In some other communities, a major problem faced is waste disposal and this includes fecal wastes; Improper disposal  contaminates the environment, exposing  people to contact with feces and increasing  risk of accidental ingestion of the virus and transfer from person to person in the community.^3,4

Travelers 

Travelers are at  risk of HEV when they travel to endemic regions, such as those described earlier; travelers, especially those from regions not endemic to the virus may have not developed immunity to the virus and hence are susceptible to acute HEV infection.^5,6  

Specific high risk groups

1. Pregnant women

Changes in hormone levels and changes in the immune system during pregnancy play important roles in making a pregnant woman susceptible to HEV infection. Normally, during pregnancy, the T-cells of the woman’s immune system which normally fight invaders, are usually suppressed in order to allow and maintain the fetus in the mother’s body without harming it, this suppression makes the mother vulnerable to infections, including HEV. 

Furthermore, an increase in the level of hormones such as progesterone and estrogen as the pregnancy advances result in insufficient micronutrients and folate deficiencies which alter immune regulation and this causes an increased replication of the virus in the mother.^7,3

Resultant damage to the liver, if viral load is not properly managed, may cause serious adverse pregnancy outcomes especially during the third trimester, including preterm birth, jaundice in the newborn, low birth weight in the infant, stillbirth and even death of the mother.^3,8

2. Infants and Older adults

Infants are particularly vulnerable to infections due to their undeveloped or developing immune systems. While still in the womb, the mother’s immune system protects the fetus, although HEV can pass from mother to child during childbirth and also through breastfeeding. 

Infants who live in endemic areas are at risk of contracting the virus through poor bottle and general hygiene; the child is also exposed to the virus through the water the baby drinks. The child’s immune system is not adapted enough to fight off the infection when ingested and so the child comes down with symptoms such as fever, joint pain, or jaundice. The symptoms may be acute which can be resolved within 2-6 weeks but HEV in children can also lead to clinical or chronic liver diseases.^4,8  

In like manner, older adults are also at the increased risk of severe disease resulting from HEV infection, this is due to age-related decline in functioning of the immune system. The presence  of comorbidities also predisposes to infections; some older patients already manage existing conditions such as liver decompensation. These put them at higher risk of severe HEV infection and can result in liver failure and even death in patients who have a history of alcoholic liver disease.^8,9  

3. Individuals with pre-existing liver conditions

Having been already diagnosed with any of these conditions: Hepatitis B virus, Hepatitis C, liver cirrhosis, fatty liver disease(metabolic dysfunction-associated fatty liver disease” (MAFLD)), affects how HEV manifests clinically and the outcome of the infection. These persons are at higher risks of liver failure, other complications, and even death.³

Hepatitis B causes abnormal immune response and when superinfected by HEV, would lead to other complications such as ascites. Hepatitis C on the other hand, can bypass the immune system and may cause no symptoms for a very long time, still following infection with HEV, it influences the expression of the symptoms which is usually chronic. 

Pre-existing chronic liver conditions influence how chronic infection with HEV results and in the same way, HEV can result in more serious liver conditions.^8,10

4. Immunocompromised individuals

Immunocompromised persons are persons whose immune defenses are low and cannot fight infections, the most common examples of these are: individuals living with HIV and persons who have received organ transplant.

Arguably, the persons living with HIV are at risk of chronic HEV infections; this is because they are highly sensitive and susceptible to infectious diseases. HIV is associated with depletion of the T-cells of the immune system, meanwhile, depletion of the T-cells is vital in the infection process of acute and chronic hepatitis; this can lead to a complicated episode of infection. 

The patients who receive solid organ transplants on the other hand, use medications to suppress the immune system from fighting the organ received and this can predispose to susceptibility to HEV infection and replication of the virus.^8,12

5. Occupational risks

Animals such as pigs, games, are reservoirs of HEV and the infection can be transferred through direct contact. Individuals that work in contact with these animals such as swine workers, veterinarians,hunters, people working in abattoirs are at risk of being infected.⁸

Transmission routes

• Waterborne transmission

Hepatitis E Virus is transmitted majorly through drinking water that is contaminated with the feces of an infected person. This is why Hepatitis E is common in areas where sanitation is poor and there is no access to clean sterilized water or at the minimum boiling. 

• Foodborne Transmission

In developed countries where clean water and sanitation is not a problem, the virus can be contracted from eating undercooked meat, particularly liver, especially from pork meat and other meat from venison (deer), wild boar meat and shellfish.⁴  

• Blood transfusion

HEV replicates in the liver and exists in a form that circulates in the liver and can be transferred to individuals with different health conditions requiring blood transfusion. For example, immunocompromised patients such as pregnant women, leukemia patients etc. HEV infection that occurs through this route can be more severe or lead to more chronic Hepatitis.^8,11 

Conclusion

Identifying if one is at risk of HEV is important as it helps prevent the risk of more chronic or severe infections. Defying popular belief that HEV is a disease of the poor and endemic only to undeveloped regions, caution should be taken about the food in the developed countries as animals eaten as meat can be reservoirs of the virus. Special cautions should be taken however, if one lives in developing countries where sanitation and clean water is not readily available.

Water, sanitation and hygiene (WASH) intervention should be implemented and maintained in the endemic areas even before there is an outbreak of the virus. The continuous education should be of utmost priority in these areas as well; adequately educating pregnant women and other high-risk groups about prevention and management.