Epidemiology of African animal Trypanosomiasis in transhumant herds of the sub-humid zone of Nigeria
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Nigeria recently became the leading economy in Sub-Saharan Africa with a total GDP of 522.64 billion of US dollars (Tradingeconomics.com). As GDP increases, population rises and food demand intensifies. Within this context it is of critical importance to achieve food security. However, Nigeria heavily relies in exportations in order to meet the growing food demand, especially of meat products, a situation which is not desirable. The livestock industry, although one of the largest in Sub-Saharan Africa, still constrained by several endemic livestock diseases which result in annual economic loses for value of 140 million of US dollars (Fadiga et al., 2013). Within this group, bovine and porcine trypasosomiasis alone has been estimated to be responsible for 50 million of US dollars in economic loses in Nigeria (Fadiga et al., 2013). However, the real epidemiological situation, and hence the possibility of developing a rational control programme, remains largely unknown across the country due to the absence of large epidemiological studies. Majority of the trypanosomiasis research studies in Nigeria employ the Haematocrit technique or the Buffy coat technique and Giemsa stain as a diagnostic method. These techniques possess a high specificity but a much lower sensitivity than the molecular method employed in this research study. In fact, better epidemiological studies employing molecular techniques have been conducted in recent times such (Majekodumni et al., 2013a; Takeet et al., 2013) and results displayed much higher trypanosomiasis prevalence than previously detected by microscopy. In many sub-Saharan countries the majority of national livestock herds are owned by mobile communities; however, the trypanosome status of cattle owned by mobile pastoralist communities have been less thoroughly studied when compared to those of sedentary livestock keepers. In this doctoral work, the epidemiology of trypanosomiasis was studied, in transhumant herds located in two different Nigerian enclaves: the Kachia grazing reserve and the Jos Plateau, both located in North-central Nigeria. Within Kachia, the ecology appears to determine the presence of infection with a spatially differentiated distribution of the detected trypanosome species being observed across the reserve that appears not to be related to the migration of livestock. While upon the Jos Plateau, the current reduction in trypanosome prevalence suggests an abrupt change in the trypanosome infection rates in this part of the country. The hypothesis established in this doctoral work is that these epidemiologically different scenarios are the result of land pressures that have ultimately resulted in the habitat destruction of the vector. Longitudinal data was also collected in order to assess the effectivity of different formulations of synthetic pyrethroids for the combined control of trypanosomiasis and tick-borne diseases. Insecticide treated cattle represents at the moment the best long-term and cost-effective method for the control of the vector responsible for the transmission of trypanosomiasis, the tsetse fly. Since no data exist about the efficacy of the insecticide or the compliance of the pastoralist population with its application under migratory conditions, its performance was assessed in this doctoral work. In addition, animal health outcomes were monitored to stablish the possible relationship between clinical symptoms and disease outcome and socio-economic data relevant for the dynamics of disease such as migration trends, husbandry practices, awareness and administered treatment has been also analysed. The compiled information of this data will establish the risk associated with contracting the disease and provide further indications for the control of African bovine trypanosomiasis in the specific context of transhumant pastoral systems of sub-humid sub-Saharan African.