Alternative Complement Pathway Activity in Experimental Surra

Abstract

Haemolytic complement activity in dromedary camels Infected with Trypanosoma evansi was assayed under alternative pathway conditions. Complement fixing antibody titres and circulating trypanosomal antigen levels were also monitored throughout the infection period. A rapid initial increase (47%) in mean alternative pathway haemolytic complement (ACH5o) level occurred during the first week of infection. ACH50 levels later decreased significantly in infected camels and recovered only after drug treatment was started. The mean ACH 50 units of un-infected control camels showed only slight variations throughout the study and were significantly higher than those of infected camels (p<O.05). Complement fixing (CF) antibody titres and circulating trypanosomal antigens rose considerably following infection and decreased only when treatment was started. It IS concluded that complement depletion occurs In T. evansi infected camels. The observed depletion in complement level was probably due to complement activation and may have several important implications in both the pathogenesis of trypanosomiasis and pathology in the dromedary camel.