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Expert Group Confirms: Tsetse Fly Eradicated on Zanzibar


Vienna (Austria) - 28 November 1997 - Tsetse flies are a problem no more on Zanzibar Island, Tanzania. An independent expert group today confirmed that since September 1996 not a single wild fly has been captured in once heavily infested areas in the island (1600 km2) and that cattle are healthier than ever before.

Twenty-two species of tsetse fly infest 36 countries over an area of 10 million km2 in sub-Saharan Africa. They devastate livestock herds by transmitting a parasitic disease, trypanosomosis and spread "sleeping sickness" among people. Direct losses from bovine trypanosomosis in Africa are estimated to range from US$ 600 million to $ 1.2 billion per year.

"All the information strongly suggests that the tsetse fly has been eradicated on Zanzibar", states Dr. Linda Logan-Henfrey, National Program Leader for Animal Health from the US Department of Agriculture, who headed a team of distinguished independent experts that recently visited Zanzibar and mainland Tanzania to assess the eradication activities. "Further confirmation will come from ongoing monitoring", she adds. The expert team also concluded that re-infestation is highly unlikely.

This result marks the close of an intensive tsetse eradication campaign undertaken by the Vienna-based International Atomic Energy Agency (IAEA) and the Government of the United Republic of Tanzania. Further support came from the Rome-based International Fund for Agricultural Development (IFAD) and the Governments of Belgium, Canada, China, Sweden, the UK and the USA. A nuclear-related technology, known as Sterile Insect Technique (SIT), was employed to complete eradication of the tsetse fly. "Using SIT as a final component of an integrated area-wide approach on Zanzibar has been the right choice", the experts confirmed.

By early 1997, the incidence of trypanosomosis among sentinel animals had dropped to less than 0.1%. Previous surveys had shown that on average between 17 to 25% of the animals were infected with trypanosomes. In some herds, the disease prevalence was up to even 80%. Now plans by the Zanzibar authorities are underway to use the fertile fly-free land for dairy farming and crop production. The IAEA will provide technical assistance for these activities.

SIT is an insect birth control method and the most environmentally-friendly technology available. Tsetse are mass bred in a specially designed "fly factory". Male flies are then sterilized with low doses of gamma radiation and released by air over infested areas. When sterile males mate with wild females, no offspring is produced and the pest is steadily eliminated. The technology has been used successfully in many parts of the world against other insect pests, such as the Mediterranean Fruit Fly in Chile, Mexico and California, and the New World Screwworm in the USA, Central America and Libya.

"Zanzibar was an ideal setting to demonstrate the feasibility of integrating the SIT with conventional methods in an area-wide approach. The fact that only one species of tsetse, Glossina austeni, was present on the island and the isolated location of Zanzibar promised sustainable results", explains Dr. Udo Feldmann of Germany, Technical Project Officer of the Joint FAO/IAEA Division. Important is also the progress made in producing flies locally at reduced cost and in refining methods, including the aerial release of sterile males. The SIT will soon be an attractive component for tsetse control and eradication operations on the African mainland", he adds.

"The SIT campaign has been the final step in a decade long battle to rid Zanzibar of the fly, explains Dr. Paul Mkonyi, Tanzania's National Co-ordinator for the IAEA project. Eradication activities started in 1994 following intensive national efforts supported by FAO and UNDP aiming at eliminating the tsetse population by conventional methods. Tsetse mass breeding technology and procedures developed by the FAO/IAEA Agriculture and Biotechnology Laboratory in Seibersdorf, Austria, were transferred to the Tsetse and Trypanosomiasis Research Institute (TTRI) in Tanga, Tanzania, which now has the world's largest tsetse facility, with a female fly colony close to 1 million insects, and producing on average 70,000 sterile males per week.

"We have released almost 8 million sterile male flies in the course of this campaign, with an average rate of about 72,000 per week during 1996", explains Dr. Arnold Dyck, a Canadian entomologist and Project Director in Tanzania. "High overflooding ratios of sterile to wild males (ie more than 50:1) led to a population crash in early 1996, and the last wild fly was caught over a year ago", says Dr. Dyck. Island-wide monitoring of captured insects and cattle blood provided data on the progress towards tsetse eradication and elimination of the trypanosomosis problem.

SIT's potential for area-wide pest management has been successfully demonstrated on Zanzibar. The lessons from this pilot project will be of great value for future tsetse eradication efforts on mainland Africa. Already, the Ethiopian Government and the IAEA have joined forces in a tsetse eradication program which will expand into a 10-year multimillion dollar campaign. Its ultimate aim is to eliminate the fly from an 25,000 km2 area of the Southern Rift Valley, where tsetse transmitted trypanosomosis has extremely detrimental effects on farming. Eradication in this region will increase agricultural and livestock production, which means milk, meat, fertilizer and draught power for Ethiopia's impoverished rural population.

During the last 40 years the IAEA has delivered almost US$ 800 million in technical support to its developing Member States. These activities, financed entirely from voluntary contributions of developed and developing Member States, support efforts to meet people's basic needs - food, water, health and energy - through the peaceful application of nuclear technology. An objective of the Agency's Technical Co-operation (TC) Department is to become a "Partner in Development", a process to connect technology to the end-user and involve a broad community of interests to produce significant socio-economic impacts. "Model Projects" – contributing to problem-solving and fostering interactive development co-operation – were initiated in the 1990s. These projects respond to national and regional priority needs, require strong government commitments and employ nuclear technologies only when they have distinct advantages over others. IAEA-TC currently supports 15 Model Projects across the African continent.

For further information contact:
Dr. Udo Feldmann, Technical Officer, Insect and Pest Control Section
phone: +43 1 2060 Ext. 21629 (until 5 December and after 21 Dec. 1997)
e-mail: U.Feldmann@iaea.org (continuous)
Dr. Jorge Hendrichs, Head, Insect and Pest Control Section

Last update: 16 Feb 2018

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