When planning a trip abroad, check with your doctor or the Health Department early (preferably six to eight weeks in advance) about travel immunisations and advice.

The shots you may require depend on the type of tour as well as the destination, i.e., package tour or camping, backpacking type holiday.

Malaria This disease is caused by a parasite. It may start like a flu-like illness or fever with chills and rigours (shivering). It may cause life threatening complications. The malaria parasite is carried from an infected person to another via a carrier (vector) which is the anopheles mosquito. The parasite multiplies in large numbers and enters the salivary glands of the mosquito.

The mosquito bite causes entry of the malaria parasite to another person. No vaccine is yet available for general use.

All precautions should be taken to prevent mosquito bites. Here are a few suggestions for how to avoid them: 1. Use an "extra strength'' and long lasting ("twelve hour'') insect repellent containing DEET.

2. Sleep in a screened (wire meshed) room, or with air conditioning. If these are not available, use a mosquito net (bed net) treated with a nontoxic repellent.

Malaria prevention pills vary with your destination and your health.

Mefloquine is widely used if the parasite is resistant to the previously used medicine, chloroquine.

Alternatives such as doxycycline, chloroquine plus proguanil are given if mefloquine cannot be given, for example, in certain chronic medical conditions. The doctor prescribing malaria prevention pills must be made aware of the traveller's current medication and health status.

It is essential to start all once-a-week malaria pills one week before reaching the infected area, and once-daily pills one day before reaching the area of risk. The World Health Organisation recommends continuing to use all medications for four weeks after leaving the malarial area.

If you have an unexplained fever after your return from holiday, request a test for malaria. This has to be diagnosed by examining a blood sample under the microscope, specifically looking for malaria parasites.

If diagnosed and treated early, malaria is a curable disease.

Yellow Fever This disease is transmitted by mosquitoes. It occurs in parts of Africa and South America. It is a viral haemorrhagic fever which causes liver damage and is life threatening.

A yellow fever vaccination certificate is required for some countries and is valid ten days after the immunisation for the next ten years.

Rabies Rabies is a rare but deadly disease that is transmitted by animal bites which introduce the rabies virus through the wound. Do not approach wild or stray animals. If bitten by a domestic animal, check to make sure it is known to be up to date on anti-rabies shots. Wash the wound immediately with large amounts of soap and running water. A post exposure anti-rabies vaccine may be required. Contact the local embassy and health authorities immediately. Also contact your own physician and Health Department as soon as possible. Bermuda, Great Britain, Australia, New Zealand and parts of Scandinavia, are among countries considered free of rabies.

Diseases carried by contaminated food and water Typhoid, cholera and hepatitis A are transmitted this way. Immunisations are available. However, there are other diarrhoeal diseases for which vaccines are not available.

How to prevent bowel infections If in doubt; 1. Drink only bottled water from a reputed brand. If bottled water is not available, drink boiled water. Use sterilising tablets in the water (even for gargling and after brushing teeth).

2. Avoid ice in drinks. Avoid milk in coffee.

3. Avoid raw food. Eat only well-cooked meat, fish and vegetables. Avoid shellfish.

4. Do not eat salads. Peel fruits yourself before eating.

5. Beware of ice cream (milk may be contaminated).

6. Wash hands thoroughly with soap and water after using toilets and before handling food.

If you become ill with diarrhoea, stop solid food and drink plenty of fluids to prevent dehydration. Preferably, drink "Oral Rehydration Solution'' (ORS).

This is available as a powder in sachets (different brands are available) which should be dissolved in the recommended amount of clean water.

Taken liberally, ORS replaces the water and salt loss and prevents weakness and fatigue. Seek medical advice if symptoms continue.

Be up-to-date on your tetanus shots. (Effectively lasts for ten years.) Be conscious of risks of HIV from casual sexual contacts and unsterile medical procedures.

Make sure you have comprehensive travel health insurance.

Check about other immunisations, such as diphtheria, meningitis, hepatitis B or polio in certain circumstances.

DR. L. ANANDAGODA Medical Officer Department of Health