Clinical features

Symptoms do not occur in all people.

• 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 (1)

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

• 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) (1)
  • patient is asymptomatic but transmissibility is of greatest concern (2)
• 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 (3)
• 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 (4)
  • dark urine and pale stools (before onset of jaundice)
  • tender hepatomegaly (4)
  • pruritus
  • fever is not present during this phase (4)
  • fulminant hepatitis may occur rarely (<1%) (1,2)
• convalescent period
  • resolution of the disease occurs (2)
  • malaise, tenderness and minor abnormalities of hepatic function may persist

The hepatitis is usually mild. In children, it is frequently, sub-clinical. Adults tend to experience more serious and prolonged disease.

Faecal excretion of the virus declines once infection becomes asymptomatic.

Reference:

• (1) Health Protection Agency (HPA) 2009. Guidance for the prevention and control of hepatitis A infection
• (2) World Health Organization (WHO) 2003. Department of Communicable Disease Surveillance and Response. Hepatitis A vaccine
• (3) World Health Organization (WHO) 2009. The global prevalence of hepatitis A virus infection and susceptibility: a systematic review
• (4) British Association for Sexual Health and HIV (BASHH) 2008. United Kingdom national guideline on the management of the viral hepatitides A, B & C 2008