Thinking of going on an exotic holiday this year? Say the Caribbean, or South America, or the Far East?

Have you taken all the health possibilities into account, or do you think your holiday company will have taken these into account on your behalf?

For example, do you know all the insect-borne diseases that you might encounter in the places you will visit? And do you know the best ways of preventing them?

I've just been asked to give advice to two groups of people - a couple travelling up the Amazon on a luxury cruise ship, and two students backpacking across Peru, Bolivia, then into Chile, Argentina, then finally Brazil. It has taken quite a lot of puzzling out.

For example, I found out that there are advice sheets for doctors on common health risks to travellers that are not preventable by immunisation.

They cover the risks for different types of travellers - the list includes advice for backpackers, business travellers, expatriates, children, women, the elderly and those with disabilities. All these lists are updated regularly, sometimes at very short intervals, on the Foreign and Commonwealth Office Website.

To give one example from my own experience: until recently, people on cruise ships on the Amazon were not advised about malaria: it was very rare and only occurred occasionally, and then only in day trips to small villages in the jungle and small tributaries. So most cruisers' didn't bother about malaria protection.

They would be foolish to ignore malaria now. Itinerant workers from other parts of South America have brought two types of malaria with them, and there have been serious outbreaks in places, such as Manaus and Santarem, where cruise ships regularly dock.

So well before you take your cruise you should ask about taking anti-malarial drugs to cover the time your ship is in the river. For the moment, you will have a choice of three drugs - atovaquone/proguanil, doxycycline or mefloquine - and your local medical centre has information about all three.

Some have more side effects than others, and some have to be taken for longer than others, so you will be guided on what is best for you. You would be mad to try to do without - it just isn't worth the risk.

By the way, if you are cruising the Amazon, you mustn't forget your yellow fever vaccination. That's not just a technicality.

There is an outbreak of yellow fever in Brazil at the moment (as there is throughout the countries to the north and west of Brazil).

If you don't have a current yellow fever vaccine certificate you shouldn't be let off the ship at any of the Amazon ports.

In addition to malaria and yellow fever, backpackers have even more health risks to ponder. If you are going to be in close contact with the locals - say staying in villages - then you really must protect yourself beforehand against several diseases.

They even include diphtheria, an illness we have forgotten here, but that can still be lethal. Others are hepatitis A and typhoid, caught from contaminated food and water, tetanus (from wounds and scratches), rabies (from the saliva of infected animals, domestic or wild), and tuberculosis (from coughs and infected milk).

So what should you do about all these possible hazards? Obey the rules. Don't eat or drink if there is any doubt about the hygiene behind its presentation. Be scrupulous about your personal hygiene, although this can be difficult in places where there is no clean running water.

Always cover exposed skin with mosquito repellent, and cover up as much as possible - so long sleeves and trousers are a must. Use nets (preferably pre-treated with insect repellent or insecticide) at night.

If you do develop a fever, then see a doctor as soon as possible. A high temperature at least seven days after insect bites must be assumed to be malaria until proven otherwise.

Once you are back home, you are not free of risk. Malaria symptoms may not appear until up to a year later. So let the surgery know where you have been if you start to feel ill within the next year.

If we don't know that you have been to a high risk area, we may not suspect the illness, and you may not get the prompt treatment you need.

Enjoy your holiday...ever thought about staying in the UK? No, I thought not.