Cyclically transmitted infections of Trypanosoma brucei, T. rhodesiense and T. Gambiense in chimpanzees

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Abstract
T. brucei, T. rhodesiense and T. gambiense were transmitted by Glossina palpalis to 3 chimpanzees; the strain of T. brucei was shown to be non-infective to man. High parasitaemias developed in the chimpanzee infected with T. brucei, and 14 days after the infective fly had fed trypanosomes were seen in the central nervous system. At this stage the animal was acutely ill and the erythrocyte sedimentation rate had increased; there was only a slight fall in the haemoglobin value. The chimpanzee appeared to be about to die but was cured by treatment with melarsen-oxide-Bal. The infection with T. rhodesiense showed a fluctuating parasitaemia and had no apparent ill effect upon the chimpanzee for about 1 month after the infective feed. The general condition of the animal then deteriorated, and 44 days after infection the erythrocyte sedimentation rate had increased considerably and there was a marked anaemia; trypanosomes had invaded the central nervous system. The chimpanzee died while being anesthetized. Large quantities of fluid containing trypanosomes were found post mortem in the pericar-dial sac and the thoracic cavity. The course of the infection with T. gambiense was mild, long lasting and did not appear to affect the chimpanzee unduly. The only noticeable change was an increase in the erythrocyte sedimentation rate. Trypanosomes were demonstrated in the cerebrospinal fluid on 2 occasions. The development of primary chancres and the invasion of the central nervous system by T. rhodesiense and T. gambiense emphasize the potential role of the chimpanzee in experimental studies on African trypanosomiasis. It is also suggested that the extremely virulent nature of T. brucei in the chimpanzee may be a means of distinguishing this species from T. rhodesiense. but more evidence is needed concerning other strains, host variations and the effect of intercurrent disease.