International travel and health

Trypanosomiasis

1. African trypanosomiasis (sleeping sickness)

Cause

Protozoan parasites Trypanosoma brucei gambiense and T. b. rhodesiense.

Transmission

Infection occurs through the bite of infected tsetse flies. Humans are the main reservoir host for T. b. gambiense. Domestic cattle and wild animals, including antelopes, are the main animal reservoir of T. b. rhodesiense.

Nature of the disease

T. b. gambiense causes a chronic illness with onset of symptoms after a prolonged incubation period of weeks or months. T. b. rhodesiense causes a more acute illness, with onset a few days or weeks after the infected bite; often, there is a striking inoculation chancre. Initial clinical signs include severe headache, insomnia, enlarged lymph nodes, anaemia and rash. In the late stage of the disease, there is progressive loss of weight and involvement of the central nervous system. Without treatment, the disease is invariably fatal.

Geographical distribution

T. b. gambiense is present in foci in the tropical countries of western and central Africa. T. b. rhodesiense occurs in eastern Africa, extending south as far as Botswana.

Risk for travellers

In rural areas of countries or areas at risk.

Prophylaxis

None.

Precautions

Travellers in countries or areas at risk should, as far as possible, avoid any contact with tsetse flies. However, bites are difficult to avoid because tsetse flies can bite through clothing. Travellers should be warned that tsetse flies bite during the day and are not repelled by available insect-repellent products. The bite is painful, which helps to identify its origin, and travellers should seek medical attention promptly if symptoms develop subsequently.

2. American trypanosomiasis (Chagas disease)

Cause

Protozoan parasite Trypanosoma cruzi.

Transmission

Infection is transmitted by blood-sucking triatomine bugs (“kissing bugs”). Oral transmission by ingestion of unprocessed freshly squeezed sugar cane in areas where the vector is present has also been reported. During feeding, infected bugs excrete trypanosomes, which can then contaminate the conjunctiva, mucous membranes, abrasions and skin wounds including the bite wound. Transmission also occurs by blood transfusion when blood has been obtained from an infected donor. Congenital infection is possible, due to parasites crossing the placenta during pregnancy. T. cruzi infects many species of wild and domestic animals as well as humans.

Nature of the disease

In adults, T. cruzi causes a chronic illness with progressive myocardial damage leading to cardiac arrhythmias and cardiac dilatation, and gastrointestinal involvement leading to mega-oesophagus and megacolon. T. cruzi causes acute illness in children, which is followed by chronic manifestations later in life.

Geographical distribution

American trypanosomiasis occurs in Mexico and in central and South America (as far south as central Argentina and Chile). The vector is found mainly in rural areas where it lives in the walls of poorly-constructed housing.

Risk for travellers

In countries or areas at risk, when trekking, camping or using poor-quality accommodation.

Precautions

Avoid exposure to blood-sucking bugs. Residual insecticides can be used to treat housing. Exposure can be reduced by the use of bednets in houses and camps.

Share