The most important disease for the traveller to avoid and for physicians to suspect in travellers is malaria. All tropical Africa and most tropical areas in the East and Far East are now malarious. The infection has returned in recent years to India and several other parts of the East and Far East from which it had been almost eradicated. Travellers to those regions should, therefore, take appropriate malarial prophylactics and malaria should be the cause first suspected among those with fever who have recently visited malarious areas. The emergence of malarial strains resistant to chloroquine poses problems both for prophylaxis and treatment of the established disease.

The recognition in 1969 of Lassa fever has introduced a new problem in managing those with fever who have been to West Africa within the preceding three weeks.

Travellers to game parks in Africa have greatly increased in number within the last decade and are exposed to trypanosomiasis. Several cases resulting from such exposure are known. They cause special diagnostic problems.

Hepatic amoebiasis may be unsuspected until a considerable amount of pus has collected and the risk of complications developed. Its clinical features need to be borne in mind.

Helminthic infections are ubiquitous in the tropics. Schistosomiasis, ascariasis and strongyloidiasis are of special importance and practitioners in developed countries need to be familiar with their characteristics.

Awareness of the possible presence of tropical infections is the keynote to success both in avoiding them and in managing them among those whose precautions have been deficient.