Mechanical Transmission Of Trypanosoma Evansi Steel By Stomoxys Calcitrans Linnaeus

Abstract

Mechanical transmission studies of Trypanosoma evansi using the stablefly, Stomoxys calcitrans as the insect vector and mice as hosts (for T. evansi ) were carried out to determine if S. calcitrans could transmit T. evansi mechanically. So calcitrans transmitted T. evansi mechanically but the rate of transmission was low, being only 1.6% according to the technique employed in this study. Factors affecting mechanical transmission such as the contamination rate of the fly (S. calcitrans) mouthparts with the parasites (T. evansi) and the longevity of the parasites in the fly mouthparts were also determined. To do this fly mouthparts were dissected and examined microscopically after the flies had fed on T. evansi infected mice. Fly mouthparts were also innoculated into non-infected mice after the flies had fed on T. evansi infected mice and the non-infected mice checked subsequently for To evansi infection. According to the results of this study the parasites survived for as long as 15 minutes in the fly mouthparts according to the dissection technique and 20 minutes according to the innoculation technique. The contamination rates of the fly mouthparts 1 - 5 minutes, 5 10 minutes, 10 - 20 minutes and 20 25 minutes after the infective blood meal by the flies were 42%, 24%, 2% and 0% respectively according to the innoculation technique and 21%, 12)%, 2%and 0% according to the dissection technique. The results of this study indicated that S. calcitrans could transmit T. evansi under laboratory conditions and suggest that these flies probably play a role in the mechanical transmission of Trypanosomes in nature.