MicrobiologyTier 2Medical Sciences concept

Viral hepatitis - transmission routes by type

Core concept

Virus	Route	Chronicity
Hep A	Faecal-oral	Never chronic
Hep B	Blood/body fluids, vertical, sexual	Chronic in ~5% adults, up to 90% neonates
Hep C	Blood-borne (IVDU, transfusion pre-1990s)	Chronic in ~75-85%
Hep D	Blood-borne, requires HBV co-infection	Chronic if HBV chronic
Hep E	Faecal-oral (waterborne; undercooked pork/shellfish in developed countries)	Usually self-limited; chronic if immunosuppressed

Key detail

Hep E genotype 1 (endemic - South/Central Asia, waterborne) - causes fulminant hepatitis with high mortality in pregnancy (~20-25% in the third trimester)
Hep E genotype 3 (developed countries, zoonotic - undercooked pork) - usually mild; can become chronic in solid organ transplant/immunosuppressed patients
Hep A and Hep E share the faecal-oral route but differ sharply in geography, pregnancy mortality, and chronicity risk

Clinical relevance

Returning traveller with jaundice and faecal-oral exposure -> Hep A or Hep E (often missed)
Pregnant traveller with acute hepatitis from an endemic area -> think Hep E, high fulminant risk
Solid organ transplant recipient with unexplained chronic hepatitis -> test Hep E RNA (serology unreliable when immunosuppressed)

Correlations

Hepatitis B serology interpretation
Needlestick and blood-borne virus exposure algorithms
Fulminant hepatic failure

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