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Tsetse flies are present in 34 African countries, according to a new atlas published by Food and Agriculture Organization of the United Nations (FAO).
Tsetse flies (genus Glossina) transmit trypanosomes, which are unicellular parasites that cause sleeping sickness in humans. They are also linked to nagana in African livestock, resulting in annual agricultural losses estimated in the billions of dollars.
Sleeping sickness is no longer deemed a public health issue, with annual human cases falling below 2,000. However, the parasites continues to have a significant impact on livestock in Africa.
Efforts to manage and eradicate trypanosomiasis in livestock necessitate decisions grounded in reliable evidence. However, the most recent comprehensive map of tsetse fly distribution across Africa was created over 50 years ago, and there are currently no existing maps of tsetse fly presence in Africa.
The new FAO atlas is the first significant step in filling such data gaps. Its data on tsetse distribution is based on 669 scientific papers spanning 31 years (from 1990 to 2020).
It combines Google Earth geolocation data with entomological fieldwork, including fixed and mobile trapping. In this atlas, a total of 7.386 sites across Africa were analysed.
The collected data confirmed the presence of Glossina species in 34 countries, ranging from Northern Senegal (around 15 degrees north) to South Africa (Kwazulu-Natal province at 28.5 degrees south).
Ethiopia’s National Institute for Control and Eradication of Tsetse and Trypanosomosis, through this initiative, aims to establish a reference for the distribution of tsetse flies and African animal trypanosomosis in western Ethiopia.
No published data on tsetse flies were found in the five countries in sub-Saharan Africa — Burundi, Guinea-Bissau, Liberia, Sierra Leone and Somalia. They, however, can still be considered affected by tsetse flies, according to FAO.
Information is relatively limited for Angola, Congo, Democratic Republic of Congo and South Sudan, according to FAO. The map does not consider countries in North Africa that have historically been free of tsetse flies.
Using available data, FAO has developed continental and national maps for 26 of the 31 recognised species and subspecies of tsetse flies. The species with the widest geographical distribution are Glossina palpalis and Glossina tachinoides in west Africa, Glossina fuscipes in central Africa and Glossina morsitans and Glossina pallidipes in east and southern Africa.
The collected data will aid veterinary practitioners and policymakers in affected countries and assist international organisations like the World Health Organization in the fight against sleeping sickness and animal trypanosomiasis.