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Accueil du site → Doctorat → Allemagne → 2020 → Impact of irrigation expansion on the inter-epidemic and between-season transmission of Rift Valley fever in Bura Sub-County, Tana River County, Kenya

Freie Universität Berlin (2020)

Impact of irrigation expansion on the inter-epidemic and between-season transmission of Rift Valley fever in Bura Sub-County, Tana River County, Kenya

Mbotha, Deborah R. Nyakwea

Titre : Impact of irrigation expansion on the inter-epidemic and between-season transmission of Rift Valley fever in Bura Sub-County, Tana River County, Kenya

Auswirkungen des Ausbaus von Bewässerungssystemen auf die Übertragung des Rift Valley-Fiebers zwischen Epidemien und Jahreszeiten im Bura Sub-County, Tana River County, Kenia

Auteur : Mbotha, Deborah R. Nyakwea

Université de soutenance : Freie Universität Berlin

Grade : PhD in Biomedical Sciences 2020

Résumé
The government of Kenya has prioritized food production through revitalized and sustained agricultural expansion as a means of achieving food security for the rapidly growing population, uplifting the living standards of rural communities by providing them with livelihood opportunities as well as jumpstarting overall economic growth for employment and wealth creation through the export of excess produce and by products. Key among several policy directives issued in this regard was the harnessing of the country’s vast irrigation potential, through the expansion of existing irrigation schemes as well as establishment of new ones along the Tana and Athi river basins as well as along the shoreline of Lake Victoria. The development of these schemes however has the potential to alter local environmental and ecological conditions that may influence the risk of RVF disease transmission. Given that a thorough understanding of the risk factors precipitating the occurrence of any infectious disease is vital for its effective control, this study aimed to investigate whether these land-use changes associated with the development of irrigation schemes had any impact on the transmission dynamics of RVF virus. This study involved the spatio-temporal evaluation and comparison of the abundance, distribution and species diversity of potential vectors of RVF virus across three villages with differing ecological habitats in Bura, Tana River County, Kenya. These included the irrigated ecosystem represented by Bura irrigation scheme located near Bura township, the riverine ecosystem represented by Husingo village that is adjacent to Tana River and the dry, pastoral ecosystem represented by Chifiri village which is located further inland, away from both the irrigated and riverine ecosystems. A concurrent longitudinal study was also undertaken to measure and compare the risk of RVF on the local population of sheep and goats kept by households, and between the three ecosystems. Representative samples of mosquitoes were collected from all ecosystems and morphologically identified using taxonomic keys. The sources of blood meals were also examined in order to identify the host spectrum of engorged females while sampling of sentinel animals for RVF antibodies was undertaken as a direct measure of risk. Comparative and multivariable analysis between these ecosystems revealed that the irrigated and riverine ecosystems were similar in terms of mosquito abundance and seasonality, despite one being naturally occurring while the other being man-made

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