- 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.
Hepatitis E virus infection
B17.2 – Acute hepatitis E
7111000119109 – Viral hepatitis type E
Differential Diagnosis & Pitfalls
- Epstein-Barr virus
- Herpes simplex virus
- Varicella virus
- Coxsackie virus
- Alcoholic hepatitis – Serum AST levels rarely rise above 300 units/L, and typically serum AST levels exceed serum ALT levels.
- Drug-induced hepatotoxicity – Careful medication history should be obtained.
- Ischemic hepatitis ("shock liver") – Usually in the setting of cardiogenic or septic shock (see bacterial sepsis).
- Severe autoimmune chronic active hepatitis – Young females; positive auto-antibodies and other systemic auto-immune manifestations.
- 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.