Hepatitis A virus (HAV) is one of the hepatotrophic viruses, which cause viral hepatitis.
Endemic in developing countries, with exposure in early childhood being common and adults universally immune. In developed countries, most cases are sporadic and the numbers are declining.
ssRNA enterovirus of the picorna group. HAV is transmitted by the faecal–oral route (especially in seafood) and has an incubation period of 2–6 weeks. It is infectious from 2 weeks before clinical symptoms until a few days after the onset of jaundice. The mechanism of hepatocyte necrosis is unclear; the virus is not cytopathic in tissue culture.
Exposure and infection in early childhood is usually asymptomatic. Symptoms and severity increase with age. A history of contact/travel abroad may be found, although many asymptomatic cases occur. Patients present with a prodromal phase (malaise, anorexia, nausea, aversion to fatty foods and cigarettes) lasting about a week. Jaundice appears after the prodromal phase and lasts about 2 weeks. The liver may be palpably enlarged and tender.
Intrahepatic cholestasis resulting in dark urine and pale stools. Rarely, aplastic anaemia in children, which has a high mortality. Very occasionally fulminant hepatic failure occurs.
Diagnosed by the finding of HAV-specific IgM. IgG anti-HAV appears as IgM, disappears over the following months and persists for years, giving immunity.
Treatment is supportive. Prevention by HAV vaccination, a killed whole virus vaccine.
Case fatality rate less than 1 per 1000. No long-term carrier state.