PARASITOLOGICAL, BIOCHEMICAL AND CLINICAL OBSERVATIONS IN PONIES EXPERIMENTALLY INFECTED WITH Trypanosoma evansi

Abstract

The present investigation aimed to study the parasitological, biochemical and clinical alterations in ponies during the course of Trypanosoma evansi experimental infection. Six female ponies were experimentally infected sub-cutaneously with mice adapted 2x106 T. evansi parasites, isolated from naturally infected horse, while two ponies were maintained as uninfected healthy controls. All six ponies became parasitologically positive between 5-7 days post infection (DPI) tested by standard parasitological detection method (SPDM) by blood smear examination showing varying degree of parasitaemia and two prominent peaks during the course of infection. The main clinical signs observed were intermittent fever, weakness, emaciation, anaemia, anorexia and incoordination in hind quarters leading to significant weight loss at terminal stage of infection. All the infected ponies developed sub-acute to acute disease within 56 days and reached to recumbency stage. Of them, four ponies died at different stages of infection and few of them showing neurological signs at terminal stage of infection. The present investigation also revealed that horse ponies are more susceptible than donkeys in experimental infection of T. evansi. Haematological studies showed a gradual fall in the levels of haemoglobin (Hb), hematocrit (HCT) and red blood cell (RBC) count from 10.57 to 4.83 (g/dl), 32.81 to 16.33 (%) and 8.53 to 3.33 (x1012 cells/l) respectively, in infected animals over the study period. Serum urea, uric acid, triglyceride, cholesterol, bilirubin indirect (BID) and total bilirubin (BIT) contents increased, while albumin contents significantly decreased in T. evansi infected ponies at different stages indicating impairment of liver and kidney functions. However, no changes in parasitological and biochemical responses were observed in the healthy controls.