Effect of time of treatment on the efficacy of trypanocides in rats experimentally infected with Trypanosoma brucei brucei

The effect of treatment time on the efficacy of trypanocides in rats experimentally infected with Trypanosoma brucei brucei was assessed. The thirty albino rats utilized in this study were divided into six groups, each with five rats. Group 1 rats were uninfected while those in groups 2 - 6 were inoculated intraperitoneally with 106 trypanosomes. Group 2 rats were left untreated while groups 3 - 6 rats were treated respectively on days 5, 8, 11 and 14 post infection (PI) with 1.0 mg/kg Securidium® (brand of isometamidium chloride) intraperitoneally. Level of parasitaemia, rectal temperature, clinical signs, haematological indices (packed cell volume and total leucocyte count) and survivability were used to evaluate the treatment time on the efficacy of Securidium®. Pre-patent period was 4 - 5 days. On days 4, 5, and 11 following the treatments (PT), the parasites were eliminated in the treated groups 3 - 6 respectively. Also, two rats relapsed in group 3 from 37 days PT with 20% mortality, whereas groups 4 - 6 rats relapsed from days 19, 16 and 21 PT respectively. Groups 4 - 6 rats had 40%, 60% and 80% mortalities respectively. The mean PCV and TLC showed a striking drop (p<0.05) PI, however, group 3 had a better result PT compared to other infected-treated groups. In conclusion, it is safe to say that treatment time is a significant determinant of therapeutic efficacy in trypanosomosis, as early treatment group had better overall indices of therapeutic efficacy than the late treatment groups.