ROME, 10 May 2002 -- Nearly 10
million square kilometres of Africa are infested by tsetse fly.
Part of this large area is composed of fertile land that is left
uncultivated -- a so-called green desert abandoned by humans and
cattle. Eradicating the tsetse -- and with it trypanosomiasis,
the disease it carries -- would allow rural Africans to reclaim
areas of their continent and greatly increase food production.
The biting tsetse fly transmits a deadly
parasite, trypanosome, that attacks the blood and nervous system
of its victims. It causes trypanosomiasis, known as nagana in
livestock and sleeping sickness in humans.
Trypanosomiasis is one of the most devastating
diseases in sub-Saharan Africa, killing 80 percent of infected
victims. It affects an estimated total of 500 000 people. The
disease kills 3 million livestock animals each year and reduces
the productivity of sick animals. About 50 million animals are
at risk from nagana, and sleeping sickness threatens around 60
million people, mainly in rural areas.
At the root of poverty
Of the 37 countries infested with tsetse, 32 are among
the poorest in the world. Further compounding these
countries' economic burden, between US$600 million and
US$1.2 billion are lost each year in attempts to control the
disease and in direct losses in meat and milk production.
"Tsetse is a poverty
fly," says Jorge Hendrichs, an FAO expert in insect and
pest control. "It keeps people poor by preventing them
from producing the food they need to survive." In
fact, tsetse and trypanosomiasis are major impediments to the
development of sustainable agricultural systems in the region,
hitting the poorest of the poor -- rural people in the most
indebted countries in Africa.
million cattle in sub-Saharan Africa, 155 million are in
tsetse-free areas, such as the highlands or the semi-arid Sahel
zone, leading to overgrazing by animals and overuse of land by
people for food production.
cycle of poverty and hunger must therefore incorporate decisive
action against trypanosomiasis, according to Mr Hendrichs.
"If we want to achieve the World Food Summit goal of
halving hunger by 2015, addressing this unique African problem
is an important precondition."
Tsetse and trypanosomiasis are often forgotten because
their victims, rural Africans, have no voice at the
international level, points out Mr Hendrichs. But that is
changing. In October 2001, at the request of African Heads of
State, the Organization of African Unity launched the Pan
African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC)
to tackle the problem. FAO, the World Health Organization and
the International Atomic Energy Agency have agreed to actively
support this initiative. National authorities, in collaboration
with PATTEC, will begin work soon to develop tsetse-free zones
in three areas of sub-Saharan Africa - the cotton belt in West
Africa, the Southern Rift Valley of Ethiopia and Botswana.
Stopping the spread with sterile
One method that has
proved successful in combating the tsetse is the sterile insect
technique. Male flies are sterilized through radiation and then
released into the tsetse-infested area, where they mate. But
while the sterile males transfer sperm, the eggs in the wild
female do not develop. With continuous release of sterile males,
the reproductive rate of the whole population rapidly declines,
leading to extinction. The technique, used in combination with
traditional methods, such as traps and insecticide, was
successful in ridding the Tanzanian island of Zanzibar of the
tsetse in 1997.
According to Mr Hendrichs,
these efforts to eliminate tsetse have no persistent side
effects on the ecosystem. "The only thing that really
depends on the tsetse is the disease," he says.
"Parasite transmission cannot be sustained without the
Mattioli, an FAO animal health specialist, points out that the
presence oftsetse flies and the diseases they transmit influence
where people decide to live, how they manage their livestock and
the intensity of crop agriculture. The combined effects result
in changes in land use and exploitation of natural resources and
environment, affect human welfare and increase the vulnerability
of agricultural activity. All of these factors must be
considered when designing tsetse intervention strategies,
including eradication programmes, in order to generate
sustainable agricultural development. FAO's strategy to
combat tsetse and trypanosomiasis includes considerations of
human well-being, poverty reduction, food security and improved
The integrated approach --
the application of the sterile insect technique along with other
methods -- seems costly, considering the poverty of sub-Saharan
Africa, the large surfaces to be eventually covered and
therefore the large number of sterile flies needed.
"The question is not how much this integrated
approach costs to eliminate the tsetse," says Mr
Hendrichs, "but rather how much living with the tsetse
costs." And living with the tsetse fly is very
expensive. Traditional control methods have to be repeated
regularly and never achieve total elimination of the pest in an
environmentally friendly way.
advantage of the sterile insect technique is that, unlike
traditional methods, it is most effective at low population
levels in dealing with the last remaining flies. When applied in
broad areas against larger populations, the integrated approach
is the most cost-effective due to the resulting economies of
scale. The sterile insect technique package (sterile males
released once a week over a period of 18 months) requires an
investment similar to the cost of applying conventional methods
over two to eight years.
appropriate target areas have to be identified before any
large-scale eradication operation is undertaken to ensure
cost-effectiveness and sustainability. Infested regions
unsuitable for agriculture or cattle should not be given high
priority. FAO promotes action in selected areas where the
disease constrains mixed farming systems, involving cattle and
food production, and where there is potential for raising
agricultural productivity. The sterile insect technique, like
any other, has to be used in a way that maximizes its impact
while minimizing its cost.
successful campaign to establish tsetse-free areas, communities,
governments and the private sector should all contribute to the
effort, according to Mr Hendrichs. Without strong commitment and
sustained financial support over decades, a regional initiative
such as PATTEC cannot succeed.