Friday, March 05, 2004

The Mighty Tsetse Fly

It's easy to downplay the importance of accidents of geography to the wealth and poverty of nations, but one geographically-restricted creature that has had, and still has, a tremendously detrimental effect to agricultural productivity in Africa is the tsetse fly. If there were ever a living creature eminently deserving of full-fledged hatred, this would be it, with only the mosquito in the competitive stakes for the deadliest insect of all time.

The tsetse infests 37 sub-Saharan African countries, including 32 of the 42 most heavily indebted poor countries in the world. Much of the tsetse-infested areas where the land is suitable for mixed farming lies uncultivated, while the tsetse-free areas face collapse from overuse. Out of a population of 260 million people in this area, 60 million are at risk from sleeping sickness. In some parts of Africa, such as in the war-torn Democratic Republic of the Congo, renewed outbreaks are killing more people than any other communicable disease, including HIV/AIDS, says the World Health Organization. Only 3 million to 4 million of those at risk are being screened, and the total number of cases may be as high as 500,000. In the absence of effective screening, “most people with sleeping sickness - an estimated 80 per cent - die before they can ever be diagnosed”, says WHO.

The tsetse fly - carrier of the trypanosome parasite - has been spreading sleeping sickness and killing 3 million livestock each year, turning much of Africa’s fertile landscape into an uninhabited area.


The economic impact of sleeping sickness is significant due to the dramatic reduction in the labour force and the resulting decrease in economic productivity, and because it can reduce cattle production by 20 to 40 per cent. The United Kingdom’s Department for International Development has estimated that the tsetse flies’ annual cost to agriculture in Africa totals $4.5 billion.

According to experts, in the absence of the tsetse fly, there would be more even distribution of livestock and a marked shift to more productive breeds. Although efforts are under way to promote the use of cattle breeds that are less susceptible to nagana, only low productive native breeds, which are being maintained by drugs to which trypanosome parasites are becoming resistant, can survive in tsetse-infested regions. With many breeds of cattle, when infected, cows abort much of the time and bulls become infertile and their growth is stunted. Because of the tsetse, horses and other beasts of burden are conspicuously absent from the African tsetse fly regions. A UN-commissioned study in Zimbabwe found that farmers who were able to use animal traction generated 25 to 45 per cent more income per unit of land and 140 to 143 per cent more per unit of labour than farmers who cultivated by hand.

Scientists have been unable to develop a vaccine and drugs for humans or cattle that can prevent the onset of sleeping sickness, and the drugs available to treat it are highly toxic or difficult to administer. (emphases added)

Here's another article that gives an indication of just how big an impediment this loathsome insect has been to the efforts of Africa's farmers.

It has been more than six years since the last tsetse fly was seen in Zanzibar. Routine blood samples taken from cattle have tested negative for the trypanosome parasites that are spread by the flies. As a result, milk production has tripled, local beef production has doubled and the use of animal manure for crop farming has increased five-fold, according to the Ministry of Agriculture of the island, which is part of Tanzania.

This creature is one major reason why agricultural productivity is so low in Africa - the near complete absence of draught animals of any sort is a major impediment to farmers' output. It also goes some way to explaining the absence of wheeled transport in much of the continent before the arrival of Europeans - what advantage was there to it when the only beasts of burden available were one's fellow men?