1 - African trypanosomes and their VSGs

Summary

Time has fallen asleep in the afternoon sun.

A Boy's Dream, Alexander Smith (1830–1867)

Lyons (1992) describes sleeping sickness as a “classical disease of the savannah and transitional savannah around river systems where tsetse flies and people are forced into close contact by their shared need for water, especially during dry seasons. It has also been labeled a disease of frontier zones as it more generally occurs on the edges of human settlements where transition from the sylvan, or wild, ecosystem to the domesticated ecosystem of man is in progress.” One can thus easily view sleeping sickness as a ‘pastoral’ problem, which it is. It is certainly not an urban disease.

However, when most of us think of a pastoral setting, we probably conjure up a vision of rolling countrysides, green pastures, and a certain sort of tranquility, if you will. This is as true in sub-Saharan Africa as it is in Kansas, where I grew up as a boy. However, lurking in many of these peaceful African locales are tsetse flies and, as a result, anything but tranquility for humans and their domesticated ungulates. The problem is trypanosomiasis: more specifically, sleeping sickness for humans and nagana for the latter.

When we speak of trypanosomiasis, we are actually talking about a wide range of diseases in mammals caused by several species of Trypanosoma. Included among these diseases are surra, which affects horses, mules, and camels in India and North Africa.