Definition

 • Infection of the liver by hepatitis A, B, C, or e, lasting less than 6 months.

Epidemiology

 • Hepatitis A virus (HAV) is especially common in Africa and India. Hepatitis B virus (HBV) is especially common in Africa and Asia.

 • Hepatitis C virus (HCV), Hepatitis D virus (HDV) and Hepatitis E virus (HEV) are common worldwide.

 • All ages may be affected.

Virology

 • HAV is a positive- sense, single- stranded ribonucleic acid (RNA) picornavirus transmitted orally by faecal contamination of food or water.

 • HBV is a partially double- stranded DNA hepadnavirus transmitted through contaminated needles, sexual contact, or vertically from an infected mother to her baby.

• HCV is a positive- sense, single- stranded RNA hepacivirus transmitted from contaminated needles, mostly through intravenous drug abuse.

 • HEV is positive- sense, single- stranded RNA hepevirus transmitted orally by faecal contamination of food or water.

Immunopathogenesis

 • the viruses localize to the liver. After a variable incubation period, a specific t- lymphocyte response to the virus is mounted.

• the necro- inflammatory activity in the liver causes an episode of acute hepatitis.

Presentation

 • Many cases are clinically silent or cause a non- specific, flu- like illness.

 • Clinically apparent cases cause nausea, vomiting, malaise, and jaundice.

 Serology

 • Presence of serum anti- hepatitis IgM antibodies confirms a recent infection.

Macroscopy

 • the liver may be swollen and discoloured with bile.

Histopathology

 • Liver lobules are infiltrated by mononuclear inflammatory cells.

• Hepatocyte injury is manifested morphologically by swelling (‘swelling’) or shrinkage and pyknosis (apoptotic/ acidophil bodies).

• Severe cases show confluent areas of hepatocyte necrosis and parenchymal collapse: ‘spotty necrosis’.

* Note these histological changes are not specific to viral hepatitis and may be seen in acute liver injury from other causes.

Prognosis

• Acute HAV never progresses to chronic infection.

 • Acute HBV progresses to chronic infection in ~10% of cases.

 • Acute HCV progresses to chronic infection in ~90% of cases.