The World Access clinic in Phnom Penh recently confirmed two cases of hepatitis A
(infectious hepatitis) in expatriates.
Hepatitis A is a viral infection of the liver and is very common in areas where personal
hygiene and sanitation is poor.
More than 10 million clinical cases occur worldwide yearly. The disease is transmitted
by ingestion of contaminated water or uncooked food like salads or shellfish. It
is highly infectious and transmission is common by personal contact, particularly
in families.
The picture in developing countries is quite different from countries like Australia,
New Zealand, North America and Europe. In developing countries most children are
exposed to the virus at an early age, usually under 5 years. They experience a short,
usually minor illness which often goes unnoticed. In Cambodia it is likely that 90
percent of 5 year olds are immune and will remain so for life.
Most industrialized countries today had a similar experience during the early 1900s
and this is now reflected in high levels of immunity in those over 50 years.
The situation is different in younger age groups. Recent surveys in Adelaide, Australia
and other places with long established good public health now show that fewer than
12 percent under 30 years old are immune.
This is certainly a concern, as the disease in adults is more severe. The majority
become jaundiced and suffer from weight loss and lethargy. The average working time
lost is 30 days. Although the mortality rate is low, it does increase with age.
Individuals can be protected in two ways:
- Passive immunization with normal human immunoglobulin (gammaglobulin)
- Active immunization with the recently released hepatitis (Harvix)
Gammaglobulin has been used for many years and is about 85 percent protective.
The major disadvantage is its short duration of effectiveness which necessitates
frequent booster doses. This affects compliance because often after the first six
months people neglect obtaining boosters.
The hepatitis A vaccine, on the other hand, provides long term protection through
stimulation of antibody production in the recipient. Evidence to date suggests it
is more than 95 percent protective. A primary course of two doses of the vaccine
given two to four weeks apart will provide protection of at least a year. A booster
dose given from six months to a year is expected to extend that protection for at
least 10 years.
Apart from travellers and residents abroad the vaccine is recommended for foodhandlers,
hospital workers, day care center workers and the military.
Hepatitis A is a major concern to expatriates resident in Cambodia and protection
with the vaccine or gammaglobulin is strongly recommended.
