38 - Viral hepatitis

Summary

Viral hepatitis is a clinical diagnosis and presents as a systemic infection primarily affecting the liver or as part of a general systemic infection. Hepatitis A, B, C, D and E viruses are all hepatotropic viruses and primarily cause hepatic infection, whereas Epstein–Barr virus (EBV), cytomegalovirus (CMV) and other viruses may cause hepatitis as part of a more generalized systemic infection. The differential diagnosis should also include non-viral causes such as leptospirosis.

Clinical

The clinical features of hepatitis include nausea, vomiting, lack of appetite and dark urine, and these may be accompanied by pain in the right upper quadrant. This is normally preceded by prodromal symptoms, which may include fever, arthralgia, myalgia, headache and rash. Clinically it is not possible to distinguish the etiological agent, although there may be clues in the epidemiology (Table 38.1). The majority of cases of acute viral hepatitis, especially in children, may be asymptomatic e.g. not accompanied by clinical jaundice. About 50% of adults with acute hepatitis A (HAV) and B (HBV) virus infections and 70% with acute hepatitis C (HCV) virus infection develop an asymptomatic infection. Diagnosis is only made by chance or due to investigations of non-specific symptoms or during follow up after known exposure. The main abnormal finding is elevated liver function tests (LFTs) with peak alanine aminotransferase (ALT) levels of >1000 U/L, especially in hepatitis A and B virus infections. Peak ALT levels tend to be lower in acute hepatitis C virus infection.