Working Together:
UN Agencies Battle Tsetse ... and Rural Poverty
By Erika Reinhardt, for the Chronicle

A new campaign in Africa to control the deadly tsetse fly, the carrier of sleeping sickness, has been launched by the Organization of African Unity (OAU). The control programme is initially being conducted in the valleys of Ethiopia, the cotton belt in West Africa, and a region in southern Africa, beginning with the Okavango Delta. In Burkina Faso in 2001, OAU inaugurated the Pan African Tsetse and Trypanosomosis Eradication Campaign (PATTEC), based on the successful Zanzibar programme (see box). FAO, WHO and IAEA are supporting the campaign. The United Nations Economic and Social Council has acknowledged that creating tsetse-free zones will be a valuable step towards reducing rural poverty. Under PATTEC, tsetse control is accompanied by thorough land-use planning to guide environmentally responsible use of natural resources in tsetse-free areas.

Photo: WHO/TDR/Fisher The island of Zanzibar in the United Republic of Tanzania was declared free of the tsetse in 1997, after the use of conventional methods to reduce its numbers and the release of hundreds of thousands of infertile male flies into the wild. This breakthrough was achieved using the sterile insect technique (SIT), in combination with applying insecticide to the backs of cattle and setting insecticide traps to reduce the tsetse population. The sterile male flies are introduced into the breeding population of a target region. They are able to mate and produce sperm, but the eggs do not develop in the female. The flies are bred in special centres and the males, after birth, are exposed to a short burst of gamma radiation from a cobalt-60 source, which is strong enough to inhibit the fertility of the sperm. They are then released into the atmosphere from a specially outfitted plane over the target area. SIT, in conjunction with other control methods, can establish fly-free areas without the need for further control, according to Peter Salema, Deputy Director of the Vienna-based joint Food and Agriculture Organization of the United Nations (FAO)/International Atomic Energy Agency (IAEA) Division of Nuclear Techniques in Food and Agriculture. SIT has been successful in controlling the Mediterranean fruit fly, the melon fly and in the eradication of the New World Screwworm.

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.

Usually, less than 5 per cent of the flies carry the parasite, yet even small numbers are known to be efficient vectors. They become the host for the parasite after feeding on the blood of an infected mammal. The parasite takes 12 to 21 days before it can enter a new host. It attacks the blood and nervous system, causing sleeping sickness in humans and nagana in livestock. 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. Major pharmaceutical companies and United States foundations are committing funds to assist WHO in combating this disease and the PATTEC public partners have recently been invited by a pharmaceutical company to identify their needs to fight the tsetse fly and nagana.

Links:
Speech announcing launch of PATTEC campaign
FAO: Fighting tsetse -- a scourge to African farmers