By: Charles Ebikeme
“Trypanosomiasis has kept Africa green”
The quote above comes from a book I can’t remember by an author whose name escapes me. In essence, it alludes to the inextricable relationship and balance that exists between all things on our planet, particularly the relationship between man and his environment. For a long time, we have known about the influence diseases can have on us, but we are only now beginning to realise its full extent.
The delicate relationship and inter-connected influence between human populations, climate, and the ecology of disease (vector-borne or otherwise) has unfolded over evolutionary time.
Genetically, some populations are predisposed to particular diseases. A Science last year, showed African-Americans have higher rates of kidney disease than European-Americans. The reason, as postulated by the researchers, was due to variants of a gene (APOL1), common in African chromosomes but absent from European chromosomes. The gene codes for a serum factor that lyses (or harms) trypanosomes. It seems the evolution of a critical survival factor in Africa now contributes to the high rates of kidney disease in African-Americans.
Changes in African climate in the last 5-6 million years are thought to have mediated important modifications in the African environment and in the animals that live there. As the rivers changed, and as plant and animal species adapted to a changing climate, disease was brought to areas where it wasnt before. These phenomena have marked important milestones in the evolution of humans and their predecessors. Read more: Trypanosomes, climate change and evolution; past and present