Hepatitis A is an acute inflammation of the liver caused by infection with hepatitis A virus. It is spread through the " fecal-oral " route i.e. through by ingestion of food contaminated by faeculent material. The period between ingestion and manifestation of illness (incubation period) is 28 days.
Some infected patients may not suffer any illmess, especially children. Symptoms and signs include :
- Loss of appetite and vomiting
- Abdominal discomfort
- Dark urine, yellowing of skin and eyes ( jaundice )
Most people recover in under 2 months, but in a few, the illness may persist up to 6 months. Some patients may experience a symptomatic relapse 2 - 3 months after the initial illness.
Hepatitis A is a self-limiting disease. However, in less than 1% of patients, largely in the elderly, the disease may progress to acute liver failure (fulminant hepatitis ) and death. Unlike hepatitis B and C, long term complications does not occur with the hepatitis A.
How is Hepatitis A transmitted?
Hepatitis A is prevalent in areas where there are poor sanitary conditions. Most infections are spread by food or drinks contaminated by faeculent materials, either through poor personal hygiene or by sewage eg. contaminated raw shell fish. Rarely hepatitis A can be transmitted by intravenous drug usage, blood products and amongst practising homosexual men
Hepatitis A is a self-limiting disease. There is no specific treatment. Symptomatic treatment and rest are all that is required.
The patient should observe good personal hygiene to prevent spread to others. Admission to hospital is indicated if the patient's symptoms become worse ( eg intractable vomiting, dehydration and signs of impending liver failure ).
Besides observing good personal hygiene, and avoidance of eating raw seafood and water contaminated with sewage, a more specific measure would be immunization. Such general measures would apply especially if one is travelling or living in areas where hepatitis A is endemic like Southeast Asia ( including Singapore ), Mexico, Caribbean, South & Central America, Africa and Eastern Europe.
There are 2 methods of immunisation for hepatitis A:
Passive Immunisation by immune globulin which is a preparation of antibodies collected from blood of persons who have been exposed to the hepatitis A. This method of immunization is getting obsolete because of the short supply of immune globulin and the potential risk of transmission of other infection through blood products.
Active immunisation with hepatitis A vaccine. Hepatitis A vaccine consists of the virus in an inactivated form. It is given in 2 doses, with the second dose being given 6 - 12 months later. Immunity after hepatitis A lasts for 10 - 20 years. Protection against hepatitis A begins 4 weeks after vaccination. We are however, not sure if the hepatitis A vaccine is completely safe in pregnancy and lactation because of the theoretical risk to the developing foetus. It can however be used in immunocompromised patients eg persons on hemodialysis or persons with AIDS.
Who should receive the hepatitis A vaccine?
- Persons travelling to or working in countries that have high or intermediate rates of hepatitis A. This essentially applies to travellers from a low risk environment who enter an endemic area
- Persons who work with hepatitis A virus infected primates or with hepatitis A virus in a research laboratory should be vaccinated.
- Persons with chronic liver disease eg. chronic hepatitis B carriers as these patients have been reported to have a higher mortality.
Hepatitis A vaccination could be useful also for:
- Sewerage workers
- Food service workers
- Healthcare workers
- Day-care attendees.
- Hepatitis A & Travellers
Travellers from low risk regions visiting endemic areas should observe scrupulous personal and food hygiene.
For protection, travellers can be immunised using hepatitis A vaccines. Vaccines may be administered 2 weeks prior to departure, followed by a booster 6 - 12 months later. Frequent or long-term travellers should consider this option as such immunity lasts for 10 - 20 years.