HEMATOLOGICAL-CHANGES IN SHEEP EXPERIMENTALLY INFECTED WITH TRYPANOSOMA-EVANSI

Sheep were infected with 2x10(6) Trypanosoma evansi TREU 2143 through the external jugular vein. The parasite kinetics as well as the effect s on body temperature, packed cell volume (PCV), erythrocyte counts an d total and differential white blood cell counts were monitored twice weekly for 3 months. The results showed that T. evansi produced a chro nic form of the disease in sheep characterised by low-level and often cryptic parasitaemia, with self-cure occurring in two cases; mild anae mia as evidenced by decreases in PCV and erythrocyte counts; and signi ficant (P<0.02) leucocytosis by day 22 post infection (p.i.). The leuc ocytosis was a result of marked lymphocytosis whose significant rises (P<0.02) parallelled the rises in total white blood cell (TWBC) counts . These changes were less obvious in the animals that underwent self-c ure. We conclude that T. evansi produces pathological changes in the p eripheral blood of sheep similar to those produced by its tsetse-trans mitted counterparts. It would thus appear that the sheep/T. evansi mod el is suitable for long-term study of the immunopathology of pathogeni c trypanosomes since the sheep is easily available, easy to handle and a natural host to all pathogenic trypanosomes.