Eighty healthy adult albino rats of both sexes weighing 180-200g were used in two experiments to study the effects of oral calcium chloride treatment on the pathogenicity of Trypanosoma congolense
infection. Experiment 1 was terminated at the peak of parasitaemia while experiment II was allowed to run a full course. In each experiment, forty rats were divided into four groups of 10 rats each, namely: A, uninfected untreated control; B, treated uninfected control; C, infected untreated and D, treated infected. Aqueous solution (10%) of CaCl2
was administered daily using stomach tube to each rat at 100mg/kg in groups B and D from 7 days before infection to the end of the study. Each rat in groups C and D was infected by intraperitoneal injection of 1x106
trypanosomes in phosphate buffered saline solution (pH 7.4) diluted donor rat blood. The infected untreated group exhibited higher (P< 0.05) parasitaemia, more severe anaemia and hepatic and renal damage than the infected treated group. In conclusion, oral calcium chloride treatment in rats seemed to reduce the pathogenicity of T. congolense
infection by delaying the onset of parasitaemia and reducing the levels of parasitaemia, accompanied anaemia as well as organ damage.