Diseases are part and package of any exotic foreign travel. And there are some worrying trends, as Jonathan Gregson discovers
EVERY summer thousands of adventure-seeking travellers set out for tropical climates. And every year a few of them return with serious illnesses or harbouring diseases with hidden symptoms. When these do appear, your local GP or hospital may not recognise them, particularly if you don't own up to all the places you have visited.

That's what happened to a back-packing acquaintance of mine who recently returned from India. He went to his GP with flu-like symptoms, but forgot to mention he had previously been in Sumatra. The GP told him to come back in three days if there was no improvement. He ended up checking into the Hospital for Tropical Diseases in London, where he was discovered to be suffering from a serious cocktail of giardia and pancreatitis.

Of all the potential problems facing travellers to the tropics malaria is the most serious. Each year, an average of 2,000 people return to the UK with malaria, of whom around 10 will die. "Deaths are almost exclusively from the plasmodium falciparum type of malaria,"says Dr Sharon Welby, clinical lecturer at Liverpool's School of Tropical Medicine, "which is contracted in Africa or south Asia."

"Malaria cases account for between a quarter and a third of all patients here," comments Dr Ron Behrens, who is a consultant at the Hospital for Tropical Diseases and director of its travel clinic. "If you've been to a malarious country and have the typical symptoms - fever, diarrhoea, back pain or joint pain - then you should immediately seek a blood test and, if it is positive, be admitted to hospital for further treatment."

Speed is essential when dealing with tropical diseases as they can develop with alarming rapidity. "Those deaths from malaria that have occurred are mostly people who delayed coming in for treatment," says Dr Behrens. However, he is as concerned about prevention as cure. "If you're going to a malarial country you need to ensure you have the right information about what prophylactics you should take. Your travel agent, your GP or a travel clinic should advise you, but it is the individual's responsibility to follow that up."

Those who ignore that advice do so at their peril. Perhaps half or more of the people who die of malaria during one year turn out not to have bothered to take any prophylaxis whatsoever. And while there is controversy about taking mefloquine and its possible side-effects, Dr Behrens points out: "You shouldn't forget that malaria is a fatal illness or that in many parts of the world there are now strains resistant to other drugs."

This is especially true of sub-Saharan Africa. Even travellers who conscientiously take their pills while in a malarial zone often stop when they return to more temperate climates. "A lot of people do not continue their course for the recommended four weeks afterwards," says Dr Welby.

Other common complaints are "traveller's diarrhoea" and fever, often caused by unknown things. As Dr Behrens explains: "Sometimes we have to deal with illnesses we can't put a name to." These can range from the life-threatening ones to those bordering on the absurd - for example,my wife returned from Irian Jaya with a tropical ulcer on one leg and a coral growth inside the other foot. The coral-in-the-foot was sufficiently unusual for the consultant to bring with him a group of trainee doctors who giggled uncontrollably when she explained the infection had started in a town called Fak Fak.

When she added that we had visited the MacCluer Gulf the consultant grew interested, for the area is notorious for unusual tropical diseases. Its mushroom-shaped islets may be absurdly picturesque, but the opaque waters around them are a breeding ground for all manner of organisms. The pearl- divers we had met there complained of eye infections and problems with even the smallest grazes.

Fresh water, particularly lakes and river shallows in sub-Saharan Africa, holds the menace of bilharzia, which is a condition that is difficult to diagnose, but is seen with increasing frequency in returning travellers. There have also been more cases of skin rashes and blistering caused by the larva of the dog hookworm among visitors to the Caribbean.

But the most worrying trend is the growing number of people returning from tropical destinations who are HIV positive. Although not specifically a tropical disease, statistics show that 79 per cent of heterosexually transmitted HIV cases seen in the UK are acquired abroad. In other words, whether you're out in the bush or cruising the clubs, it's best to play safe under tropical skies.


1 Accidents

The most common serious health problems encountered on holiday result from accidents, ranging from road traffic to sporting. This is usually due to people attempting activities on holiday that they would not dream of doing at home. Over indulgence in alcohol plays a big part.

2 Malaria

One of the most serious infections that travellers are likely to encounter when travelling to certain destinations. Watch out for any flu like illness up to a year after returning home.

3 Diarrhoea

Definitely the most common problem. Ordinary travellers' diarrhoea should resolve in a few days. Any diarrhoea lasting more than 10 days could be something more serious like dysentery. Best advice for travellers' diarrhoea is to keep well hydrated by drinking plenty of fluid, ideally in the form of oral rehydration salts.

4 Sexually transmitted diseases

Another example of how people ten to throw caution to the wind while on holiday. Safe sex is vitally important wherever you are in the world.

5 Dengue

Malaria apart, most tropical diseases are quite unusual in holidaymakers, but dengue is definitely on the increase in the tropics. This is not usually fatal in adults but results in an extremely nasty infection which is guaranteed to ruin your holiday.

Larry Goodyer