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
- 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
- Other non-specific symptoms – including distaste for cigarettes!
- 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
- 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.
- 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
Hepatitis A vaccine is recommended for travellers before they visit:
- Indian subcontinent
- 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