A Study of Diplostomum Parasites Affecting Oreochromis niloticus in Chepkoilel Fish Farm and Two Dams in Eldoret-Kenya

The Diplostomum parasite completes its life-cycle in fish eating birds, but spends considerable time in the eye vitreous humor of many fresh water fishes. Its infection in fish causes severe ocular pathology, and leads to increased susceptibility to predation. A study on Diplostomum parasites was conducted at Chepkoilel University with an objective of assessing its parasitic indices and effects on O. niloticus. A total of 40 fish were collected from the fish farm and 155 from the dams between November 2010 and January, 2011. Fish were weighed and length measured to ascertain their condition factor. The fish were observed for the Diplostomum parasite to ascertain parasitic indices in the different habitats. The parasite abundance was related to fish size and condition factor to determine parasite’s effect on O. niloticus. Fish were found to have a parasitic prevalence (%) of 100, 84 and 66 in Kerita dam, Kesses dam and Chepkoilel fish farm. Parasite mean intensity was 12, 9 and 14 respectively.The wellbeing of the fish was not compromised by the parasites, as was seen in the correlation between condition factor and parasite abundance. There was a Pearson correlation of P = 0.357, 0.516 and 0.565 in Kerita dam, Kesses dam and Chepkoilel fish farm respectively. The dams and the fish farm did not pose significant difference in the parasitic indices, probably due to their proximity. There was seen equal abundance in both fish sexes, implying no sex preference in infection. Keywords: Diplostomum, Oreochromis niloticus, prevalence, Abundance, Mean intensity, Condition factor

Veterinary and public health aspects in tilapia (Oreochromis niloticus niloticus) aquaculture in Kenya, Uganda and Ethiopia.

SUMMARY - The European INCO-DEV BOMOSA Project (Integrating BOMOSA cage fish farming systems in reservoirs, ponds and temporary water bodies in Eastern Africa) intends to establish small scale fish farming in marginal water bodies in Kenya, Uganda and Ethiopia, creating rural aquaculture networks with the aim to economically integrate aquaculture with agriculture. In order to study veterinary and public health aspects in Bomosa fish farming systems, a parasitological survey on wild and cultured tilapias (Oreochromis niloticus niloticus) has been carried out from March 2007 to October 2008. A total of 982 tilapias - 685 from Kenya, 222 from Uganda and 75 from Ethiopia - were sampled and subjected to complete parasitological examination. During the survey, fish from different environments (258 from open water reservoirs, 445 from ponds and 279 from BOMOSA cages) were sampled in order to evaluate the factors which could influence the parasite diffusion and outbreak of diseases. Quantitative data, such as prevalence, intensity and abundance, and qualitative data are presented together with the main abiotic and biotic risk factors identified as relevant for veterinary and public health aspects in tilapia aquaculture. RIASSUNTO - Nell\u2019ambito del progetto europeo INCO-DEV \u201cIntegrating BOMOSA cage fish farming systems in reservoirs, ponds and temporary water bodied in Eastern Africa\u201d si \ue8 condotto uno studio sui fattori sanitari di carattere strettamente veterinario e di potenziale interesse in sanit\ue0 pubblica che possono interessare l\u2019allevamento della tilapia (Oreochromis niloticus niloticus) in Kenya, Uganda ed Etiopia. Sono state sottoposte ad esami necroscopici e parassitologici 982 tilapie - 685 dal Kenya, 222 dall\u2019Uganda e 75 dall\u2019Etiopia. Dei soggetti esaminati, 258 provenivano da acque libere, 445 erano allevati in bacini in terra e 279 in gabbie galleggianti approntate secondo il sistema \u201cBOMOSA\u201d, sperimentato nell\u2019ambito del progetto al fine di garantire un migliore sfruttamento di risorse idriche marginali e temporanee e una gestione semplificata da parte delle comunit\ue0 locali. Vengono presentati i risultati quantitativi (prevalenza, intensit\ue0, abbondanza) e qualitativi delle indagini parassitologiche, unitamente alla descrizione dei fattori di rischio abiotici e biotici individuati in relazione agli aspetti veterinari e di sanit\ue0 pubblica che possono interessare le tilapie allevate nei sistemi acquatici presi in considerazione