Helminth infection risk associated with the use of wastewater in Urban Agriculture in Kumasi, Ghana

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In many cities across developing countries wastewater is largely untreated and ends up being used for urban vegetable farming. The practice has many benefits but can also lead to significant health risks if not undertaken in a safe manner. The main aim of this study was to assess the helminth risk associated with the use of wastewater for irrigation in the Kumasi Metropolitan Area in the Ashanti Region of Ghana. The specific objectives were; a) to assess the occurrence and seasonality of helminth parasite in wastewater used for irrigation and in wastewater contaminated soil. b) to assess the helminths infection risk for urban farmers using wastewater for irrigation; and c) to assess the helminth infection risk for consumers of wastewater irrigated vegetables. Helminth egg concentration was determined using the Modified EPA Protocol. Four types of helminth eggs were identified in both the irrigation water and soil. These were, Ascaris lumbricoides, hookworm, Trichuris trichuira and Taenia spp. Schistosomaspp eggs were also found only in irrigation water, with A. lumbricoides being the most abundant in the irrigation water and farm soil. There was seasonal variation in the concentration of these helminths, however A. lumbricoides had the highest concentration across both seasons. A. lumbricoides and hookworm were the only helminth eggs identified in salad foods in the study area. The annual risk of infection with A. lumbricoides for vegetable farmers was found to be 0.85 ×10-1, higher than the tolerable risk of A. lumbricoides infection for farmers using wastewater for irrigation (1.2×10-2). Consumers of wastewater irrigated vegetables were equally at risk of A. lumbricoides infection with about the same magnitude as the farmers (2.6 ×10-1). To reduce the risk of A. lumbricoides infection it is recommended that simple, practical and inexpensive interventions such as the practice of drip irrigation, the use of stabilization ponds be introduced on the farms so as to reduce the concentration of these helminths in the irrigation water and soil. It is hope that these interventions would also include measures that reduce the risk of infection to the farmers as well. Education on disinfection practices should be introduced to further reduce the risk of A. lumbricoides infection to consumers
A thesis submitted to the Department of Theoretical And Applied Biology, College of Science, Kwame Nkrumah University of Science and Technology, in partial fulfilment of the requirements for the degree of Master of Philosophy (Parasitology)