Overview
Hepatitis E is a liver infection caused by the hepatitis E virus (HEV), an RNA virus belonging to the Hepeviridae family. HEV is primarily transmitted through the faeco-oral route and is commonly found in the stool of infected individuals. It is a food- and waterborne disease and represents a major public health concern in regions with poor sanitation and limited access to clean drinking water.
HEV infection is generally acute and self-limiting, with most individuals recovering completely without long-term complications. However, the disease can be severe in certain populations, particularly pregnant women and immunocompromised individuals. In developing countries, hepatitis E outbreaks are commonly linked to contaminated water supplies, while in developed countries, sporadic cases have been associated with consumption of raw or undercooked pork, venison, wild boar meat, or shellfish. HEV (Hepatitis E Virus)
Symptoms
Clinical presentation of hepatitis E varies widely. Many infected individuals, especially young children, remain asymptomatic. When symptoms occur, they are similar to those seen in other forms of acute viral hepatitis.
Common symptoms include fatigue, poor appetite, nausea, abdominal pain, and jaundice. Fever and malaise may also be present. The illness usually resolves spontaneously, but symptoms can be more severe in adults. Clinically, hepatitis E cannot be reliably distinguished from other acute viral hepatitis infections based on symptoms alone.
Causes
Hepatitis E is caused by ingestion of the hepatitis E virus, most commonly through contaminated water. Poor sanitation, unsafe drinking water, and inadequate sewage disposal play a major role in disease transmission.
In developed regions, zoonotic transmission has been documented. Genotypes 3 and 4 of HEV are transmitted from animals such as pigs, deer, and wild boar to humans, usually through consumption of undercooked meat or environmental exposure. Vertical transmission from mother to child and transmission through blood transfusion have also been reported.
Risk Factors
Individuals living in or traveling to endemic regions with poor sanitation are at increased risk of HEV infection. Populations in Asia, Africa, the Middle East, and parts of Latin America are particularly affected by waterborne outbreaks associated with genotypes 1 and 2.
Pregnant women, especially in the third trimester, are at significantly higher risk of severe disease and mortality. Immunocompromised individuals are also at increased risk, including those with HIV infection, organ transplant recipients, and patients receiving immunosuppressive therapy. In these groups, hepatitis E may progress to chronic infection.
Epidemiology
Hepatitis E has a global distribution and is endemic in many developing regions. Genotypes 1 and 2 are responsible for large waterborne outbreaks in Asia, Africa, and Latin America.
Genotypes 3 and 4 cause sporadic cases in developed countries and are associated with zoonotic transmission. HEV is also transmitted vertically and through blood transfusion. High mortality rates are observed among pregnant women and immunocompromised patients, making hepatitis E a significant public health concern.
Diagnosis
Definitive diagnosis of hepatitis E infection is usually based on the detection of specific anti-HEV immunoglobulin M (IgM) antibodies in blood. Anti-HEV IgM indicates acute or recent infection, while anti-HEV IgG suggests past exposure or immunity.
Additional diagnostic tests include reverse transcriptase polymerase chain reaction (RT-PCR), which detects HEV RNA in blood or stool. RT-PCR is particularly useful during the early phase of infection, including the window period before antibodies become detectable, and in immunocompromised patients.
Methods of Detection
Several laboratory methods are used for HEV detection. Rapid tests provide qualitative detection of anti-HEV IgM and IgG antibodies and are useful for screening.
Enzyme-linked immunosorbent assays (ELISA) and chemiluminescent immunoassays (CLIA) are commonly used for antibody detection with higher sensitivity. RT-PCR is the most sensitive method and confirms active infection by detecting viral RNA.
Clinical Significance
Anti-HEV IgM is a marker of acute or recent infection, while anti-HEV IgG indicates past infection or immunity. Detection of HEV RNA confirms active infection and is particularly important in early diagnosis and in chronic infection among immunocompromised individuals.
Liver function tests, including ALT, AST, and bilirubin levels, provide supportive evidence of liver injury but are not specific for hepatitis E. Combined interpretation of serology, molecular testing, and clinical findings is essential for accurate diagnosis.
Complications
Most cases of hepatitis E resolve without complications. However, severe outcomes can occur. Acute viral hepatitis and, rarely, fulminant hepatic failure may develop.
Pregnant women, particularly in the third trimester, face a markedly increased risk of fulminant hepatitis, maternal mortality, preterm labor, stillbirth, and neonatal death. In immunocompromised patients, hepatitis E can become chronic, leading to progressive fibrosis and cirrhosis.
Extrahepatic complications include acute pancreatitis, aplastic anemia, Guillain–Barré syndrome, neuralgic amyotrophy, encephalitis, glomerulonephritis, and cryoglobulinemia.
