A cluster of malaria cases has been reported in United Kingdom (UK) travellers who have recently returned from a holiday in the Gambia. Five people (four men and one woman), aged from 16 to 74 years, who stayed at Kololi, a coastal resort 15 kilometres west of Banjul (the capital and airport), were admitted to hospitals in the north west of England between 25 and 28 November 2003, where each was diagnosed with falciparum malaria. Three had a hyperparasitaemia in excess of ten per cent and were gravely ill. Of those, one required renal dialysis, one a blood transfusion after a gastrointestinal bleed, and the other one suffered from severe haemolysis. None have died. Only two of the cases had taken antimalarial chemoprophylaxis and they had taken chloroquine, which is now largely ineffective in the Gambia. Although their holidays had varied in length from one to three weeks and they had returned to the UK between 13 and 21 November, all five were admitted to hospital within four days of each other, suggesting they might have been infected during a short period. The occurrence of this cluster underlines the necessity for travellers to West Africa to take full precautions against malaria, including chemoprophylaxis and mosquito avoidance measures.

The Gambia is a popular winter holiday destination for UK and other European travellers, with last minute offers of low prices holidays now commonplace (in 1999, Gambia recorded 40 588 arrivals of UK nationals at its borders, 25 393 of German nationals,and 9625 of Dutch nationals. Source: World Tourism Organization). West Africa is, however, one of the most malarious regions in the world. Between 1997 and 2002, the Gambia was the source of 385 cases of malaria in the UK including eight deaths, a case fatality rate of 2%. This is around 4% of all imported cases of falciparum malaria in the UK, and over two and a half times the overall case fatality rate of falciparum malaria reported in the UK. The Gambia, a very small country, is therefore the source of almost 12% of all deaths from malaria that occur in the UK. This appears to be because most visitors to the Gambia are non-immune holidaymakers, who may be unaware of the potential severity of malaria. Malaria transmission varies seasonally in the Gambia, and people who have visited in the less intense transmission season may therefore have escaped infection and mistakenly assume that the risk is low on a subsequent holiday.

Unless taking appropriate chemoprophylaxis, which is one of atovaquone/proguanil (Malarone), doxycycline, or mefloquine (Lariam), non-immune travellers to West Africa are at a high risk of contracting malaria. The use of mosquito repellents and mosquito nets when sleeping is also important, especially during the period of heaviest transmission in the second half of the year. Full details are given in the recently issued UK malaria guidelines (1).

There is a difficulty for last minute travellers, as the three effective chemoprophylactic options are all prescription only medicines. Such travellers need to be made aware of malaria (and yellow fever) risks, and encouraged to seek appropriate pre-travel medical advice, including the prescription of appropriate antimalarials.