Hepatitis A

Original article by Tom Leach | Last updated on 22/6/2016
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Aetiology and Epidemiology

  • The most common hepatitis virus. It is often seen in epidemics (usually in children), and most commonly occurs in the autumn
  • Often found in communities with overcrowding
  • Commonly found in water – partiuclarly beware salads washed in contaminated water  - often patient may have had recent travel abroad
  • Very common, particularly in developing world. In some countries, 100% of the population has been infected by the age 10 – but the disease is often asymptomatic in children and so may go unnoticed
  • In the developed world, 5-40% of the population have had the infection
  • There are sometimes 'mini-epidemics' in children in nursey / day-care centres
  • Often found after flooding
  • Shellfish have also been implicated in transmission – possibly due to human sewage reaching their habitat
  • There isn’t a carrier state
  • The virus can be killed by boiling water for 10 minutes.
  • Vaccination provides immunity for 10 years

Pathology

  • Incubation 2-6 weeks
  • Oro-faecal transmission. Viral shedding occurs in the faeces at about the time of the onset of symptoms
  • RNA virus

Signs and Symptoms

  • Many patients are asymptomatic. They may never know they have had the disease
  • Very rarely it can be lifethreatening (mortality 0.3-2%)
  • Symptoms depend on age:
    • < 4 years - 90% anicteric
    • 15 years – 40 – 70% icteric
  • May be a prodromal phase
  • Jaundice, malaise, abdominal pain, nausea & fever – usually lasting around 2 weeks
    • Jaundice may occur 1-2 weeks after other symptoms. As the jaundice worsens, other symptoms may subside, but the urine may become dark and the stools pale, due to intrahepatic cholestasis (i.e. the intrahepatic bile ducts get blocked)
    • 10% of patients get splenomegaly resulting in a palpable spleen
  • Other non-specific symptoms – including distaste for cigarettes!

 

Investigations

  • Only one antigen has been found – HAV. However, it is not tested for as levels vary during the course of an infection. Instead we test for anit-HAV – the levels of which are more predictable.
    • You can see IgM in the blood for the first 6 weeks, then IgG after that.
  • Diagnosis – abnormal LFTs / +ve IgM anti-HAV
    • ALT > AST
    • AST may be > 1000
  • IgM HAV antibody may be positive for up to 6 months after clinical feautres subside
  • IgG antibody positive indicates past exposure
  • Prognosis - can be determined by INR

Treatment

  • Usually self limiting. Does not usually require hospital admission in uncomplicated cases.
  • Rest and dietary modification seem to have little effect – basically, you just have to sit it out!
  • In most people, the severity of the virus peaks 4 weeks after infection, and symptoms will be virtually gone 2 weeks later.

 Complications

  • Acute fulminant liver failure is rare – 0.1 to 0.4%
  • Not associated with chronic liver disease
  • The mortality rate is low – around 0.3%, increasing to 2% with age and other co-morbities.
  • Extra-hepatic complications are very rare, but include arthritis, myocarditis and renal failure.
  • 10% of patient’s will have a relapse before recovery.
  • Some patients may ‘feel ill’ for months after the disease – this is known as post hepatitis syndrome and it is a functional disease that is treated by reassurance

Prophylaxis

Hepatitis A vaccine is recommended for travellers before they visit:

  • Indian subcontinent
  • Africa
  • Central & South America
  • The Far East
  • Eastern Europe

Hepatitis A vaccine schedule:

  • Initial dose 4-6 weeks before travel
  • Booster at 6-12 months later
  • Provides immunity for 10 years