Clinical features

Symptoms do not occur in all people. (1)

• children <5 years - 80-95% of infections are asymptomatic
• in adults - 70-95% of infections result in clinical illness
• severity of symptoms also increases with age

The course of acute hepatitis A can be typically divided into four clinical phases (1,2,3):

• incubation phase or pre clinical period (during which time the virus replicates in the liver and is shed into the faeces)
  • average incubation period is 28 days (range of 15-50 days)
  • patient is asymptomatic but transmissibility is of greatest concern
• prodromal or pre-icteric phase
  • may last from several days to couple of weeks
  • typically, there are non-specific flu like symptoms (malaise, myalgia, fatigue) and mild fever. There can be non-specific gastrointestinal symptoms like loss of appetite, fatigue, abdominal pain, nausea and vomiting
  • other symptoms like cough, pharyngitis, constipation, diarrhoea
• icteric phase
  • jaundice develops (with associated anorexia, nausea and fatigue)
  • usually lasts 1-3 weeks, in a minority of patients with cholestatic symptoms (itching and deep jaundice) - may last for 12 or more weeks
  • dark urine and pale stools (before onset of jaundice)
  • tender hepatomegaly
  • pruritus
  • fever is not present during this phase
  • fulminant hepatitis may occur rarely (<1%)
• convalescent period
  • resolution of the disease occurs
  • malaise, tenderness and minor abnormalities of hepatic function may persist

The hepatitis is usually mild. In children, it is frequently, sub-clinical and only 10% of infected children develop jaundice. Adults tend to experience more serious and prolonged disease.

Faecal excretion of the virus declines once infection becomes asymptomatic.

Reference:

1. Castaneda D, Gonzalez AJ, Alomari M, et al; From hepatitis A to E: A critical review of viral hepatitis. World J Gastroenterol. 2021 Apr 28;27(16):1691-1715.
2. Committee on Infectious Diseases, American Academy of Pediatrics; Kimberlin D, Barnett E, Lynfield R, et al. Hepatitis A. In: Red Book: 2021–2024 report of the Committee on Infectious Diseases. 32nd ed. Elk Grove Village, IL: American Academy of Pediatrics; 2021.
3. World Health Organization. Hepatitis A. July 2023 [internet publication].