Hepatitis E Virus and the HEV vaccine
Copyright 2012 - Kris Heeter, Ph.D.
The Hepatitis E virus (HEV) is capable of causing an acute or chronic infection that can lead to an inflammatory liver disease.
There are four major Hep E variants or genotypes have been described. HEV genotypes 1 and 2 are typically found to infect humans whereas genotypes 3 and 4 have been found in both humans and several animal species. A majority of the animal infections are found in swine.
Globally, HEV is the most common cause of acute viral hepatitis.
Transmission and Outbreaks of Hepatitis E
Transmission of the Hepatitis E virus to humans generally happens when someone drinks water that is contaminated with feces containing the virus.
Hepatitis E viral infections in humans have been considered rare in most industrialized countries, including the United States. However, in these countries, there have been reports of acute and chronic HEV infections among transplant recipients and other immunocompromised individuals like those with HIV.
Transmission through blood between humans is rare and only a few cases of Hepatitis E have resulted from person-to-person contact. Research suggests that this virus cannot be spread through sexual activity.
Major HEV outbreaks typically occur in regions of the world where sanitation is poor and where there is excessive rain or flooding.
For example, in countries like Nepal, the virus can cause annual outbreaks during the rain and flooding season. During this season, it is a leading cause of hospitalization of all age groups.
Acute vs. Chronic Hepatitis E
An acute Hepatitis E virus infection can occur as either as epidemic outbreak or as sporadic cases. These are typically short-lived infections. Epidemic outbreaks are more common in countries with flooding and poor sanitation whereas sporadic cases occur in industrialized countries.
Chronic HEV infections are less common and are long-term. These have been reported in immunosuppressed patients, those with HIV, and those with hematological malignancies. Recently, a case has been reported in a patient with leukemia.
Once a person is infected with HEV, there are no drug treatments available.
The typical medical course of action is rest, plenty of fluids, and a healthy diet. According the National Institute of Allergy and Infectious Disease (NIAIC), it is recommended that those infected avoid any over-the-counter or prescription medication that could damage the liver. Drinking alcohol during the recovery period could compound the problem and increase the risk for liver damage.
A HEV vaccine has been developed and has proven to be safe and highly effective. According the NIAIC, three doses are 96% effective and two doses are 87% effective at preventing the disease.
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