Mechanoreceptor--trypanosome interactions in the labrum of Glossina: fluid mechanics.

The fluid mechanics of the flow of blood through the labrum of Glossina is described in uninfected and trypanosome infected flies. The flow is characterised by the Reynolds number, and a frequency parameter for the pulsating flow and non-newtonian viscosity effects are considered. The effects of colonies of trypanosomes on the flow rate in the labrum and the interactions between colonies of Trypanosoma (Nannomonas) congolense and Trypanosoma (Trypanozoon) brucei and mechanoreceptors in the proximal third of the labrum are described. The direct association between trypanosomes and mechanoreceptors and the reduction in flow rate imposed by trypanosome colonies in the food canal distal to the mechanoreceptors will impair detection of stimuli by them. The epidemiological implications of these and earlier observations are discussed.