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Viral Hepatitis
ALF occurs in less than 5% of hepatitis viral infections, and HBV accounts for the majority of cases. Hepatitis E virus-induced ALF is uncommon in western countries, but accounts for sporadic and major epidemics of viral hepatitis in underdeveloped nations (India, Pakistan, Mexico, Central Asia, Southeast Asia, Russia, and North Africa) and in travelers returning from these areas. Other viruses causing ALF include herpes simplex virus (HSV), varicella zoster virus, cytomegalovirus, Epstein–Barr virus, parvovirus B19, and yellow-fever virus. These viruses generally lead to ALF in the setting of immune compromise or pregnancy, but cases in immunocompetent individuals have been reported.