Acute
Hepatitis E is an acute, self-limited hepatitis caused by hepatitis E virus (HEV). Although the disease is rarely diagnosed in industrialized countries, including the United States, hepatitis E is the most likely cause of acute hepatitis in adults worldwide and is highly endemic in Southeast Asia. On the basis of viral genetic and epidemiological features, the disease is divided into two forms, epidemic and autochthonous:
Outbreaks and sporadic cases of epidemic hepatitis E are common in developing countries and are caused by HEV genotypes 1 and 2. The epidemic form is associated with waterborne and fecal-oral transmission, with humans as the exclusive hosts. The epidemic form is rarely imported to the United States via travel.
In contrast, autochthonous hepatitis E is caused by genotypes 3 and 4, and pigs are the natural reservoir. Sporadic cases occur in developed countries when humans become accidental hosts. Rarely, transfusion-related HEV infection has occurred.
Acute hepatitis E may be asymptomatic, marked only by a rise in AST or ALT levels, or symptomatic (with or without jaundice). Asymptomatic infections are likely 10-30 times more common than symptomatic infections. Rare cases may have a subfulminant or fulminant course. Acute infection can be protracted and cholestatic, lasting for several weeks. Fulminant hepatic failure, defined as severe liver failure in the presence of encephalopathy that develops within 8 weeks of the onset of symptoms, is characterized by severe sudden liver cell dysfunction leading to encephalopathy, ascites, and coagulopathy in people with no underlying liver disease. Pregnant individuals are at increased risk for severe illness from HEV infection.
Codes
ICD10CM: B17.2 – Acute hepatitis E
SNOMEDCT: 78475006 – Hepatitis E Virus
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
Hepatitis E cannot be differentiated from other types of viral hepatitis (A, B, C, D) on the basis of clinical presentation. Moreover, a number of diverse disorders enter into the differential diagnosis of "acute hepatitis." These include:
Acute Budd-Chiari syndrome – Associated primarily with aminotransferase elevations, not alkaline phosphatase, and increased lactate dehydrogenase levels.
Wilson's disease – This metabolic disorder rarely mimics acute viral hepatitis. Look for Kayser-Fleischer rings and history of psychiatric disorder.
Acute fatty liver of pregnancy – It is potentially fatal and most common in third trimester. Liver biopsy shows characteristic steatosis.
The syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome) – Common in third trimester; presents with eclampsia, right upper quadrant pain, hypertension, and edema.
