Trypanosoma rhodesiense
Disease. Rhodesian trypanosomiasis, East-African sleeping sickness
Geographic distribution. The disease is endemic among the cattle-raising tribes of East Africa. Present in Zimbabwe, Zambia, Malayi, Mozambique, Tanzania, and eastern Uganda.
Infection rate. The incidence of Rhodesian trypanosomiasis is lower and epidemics are less frequent than in the Gambian disease.
Life cycle. Antelopes and possibly other wild game and domesticated cattle are reservoir hosts. The main insect vectors are the woodland tsetse flies of Glossina spp. T. rhodesiense is transmitted from animals to humans by the bite of an infected tsetse fly.
Morphology. T. rhodesiense exists in human as a trypomastigote form. It is morphologically indistinguishable from T. gambiense.
Pathology and clinical symptoms. Rhodesian trypanosomiasis runs a more rapid and fatal course than the Gambian disease does, often terminating within a year. The pathologic changes are similar to those of Gambian sleeping sickness, but the febrile paroxysms are more frequent and severe. Edema, myocarditis and emaciation are more prominent. Chronic lesions in the central nervous system are less frequently encountered since death intervene before marked cerebrospinal changes occur.
Diagnosis. A definite laboratory diagnosis is made by finding the trypanosomes in the blood, lymph nodes, and bone marrow or spinal fluid. The methods include a direct microscopical examination, cultivation and animal inoculation.
Prevention. The prevention involves constant supervision to detect new cases, to keep track of the old, and regulate agriculture. Contact between humans and tsetse flies may be broken by the removal of the inhabitants from fly-infested areas to open country. Chemoprophylaxis, repellents, and nets may give some protection to the individual.
Tai Soon Yong