The sheep (Ovis aries) as an experimental model for African trypanosomiasis. I. Clinical study.

Sheep were used as an experimental model to study trypanosomiasis. Twelve animals were infected with Trypanosoma brucei brucei, and the clinical evolution of the disease in the sheep corresponded closely to that described in human patients. The main clinical signs of the experimental infection were hyperthermia, anaemia, loss of weight and behavioural disturbances. Death occurred in all cases after a mean time of 75 days. Trypanosomes were detected in blood films nine to 15 days after inoculation, and the parasitaemia was usually mild and irregular. Changes in the cerebrospinal fluid--increase in leucocyte counts and the presence of trypanosomes--appeared after about 45 days. This model would provide a valuable way of testing the effectiveness of new therapeutic drugs.