ENDOHELMINTHS OF Oreochromis niloticus baringoensis (Trewavas, 1983) AT RIVER MOLO INLET IN LAKE BARINGO, KENYA

Abstract

Endohelminths infections in fish cause production and economic losses through direct fish mortality, reduction in growth and condition, reproduction, energy loss, increase in the susceptibility to disease and predation. A study on endohelminths of Oreochromis niloticus baringoensis (Baringo tilapia) at the inlet of River Molo in Lake Baringo was conducted during the dry and wet seasons between August and December 2015 to investigate the impact of water quality on their prevalence and mean intensities. Fishing was done weekly each month. Dissolved Oxygen, temperature, turbidity and pH of the water were measured in-situ. Fish samples were collected and immediately transported to the laboratory for examination and parasite identification using standard parasitological techniques. Out of 447 fish, 340 were infected with endohelminth parasites of three classes and six parasitic species: Nematoda (Contracaecum), Cestoda (Amirthalingamia), Trematoda (Tylodelphys, Apharyngostrigea, Clinostomum and Euclinostomum). Prevalence levels of Tylodelphys, Clinostomum, Amirthalingamia, Contracaecum, Euclinostomum and Apharyngostrigea were 57.7, 20.8, 19.7, 12.4, 11.7 and 1.4% respectively. Mean intensities of infections by Amirthalingamia, Tylodelphys, Euclinostomum, Clinostomum, Apharyngostrigea, and Contraceacum were 45.6, 6.0, 3.8, 3.4, 2.2 and 1.5 respectively. Overall, Amirthalingamia had the highest mean intensities for either sex or season (χ2=19.800, p<0.001). The relative condition factor (Kn) for the infected and non-infected fish were 1.06 and 1.07 respectively. Only the Contracaecum sp. had significant relationship with fish condition factor (F=13.08, p< 0.0001). Amirthalingamia, Tylodelphys and Euclinostomum sp. were inversely related to the fish condition suggesting they were pathogenic to the host. Correspondence analysis showed that turbidity and Dissolved Oxygen had strong negative relationship with the intensity of Amirthalingamia and Tylodelphys, whereas the intensity of Contracaecum, Clinostomum and Euclinostomum were strongly positively related to temperature and pH. However, Apharyngostrigea were not affected by any of the water quality parameters. Consumers are advised to cook fish properly as a precautionary measure due to the zoonotic nature of Contracaecum, Euclinostomum and Clinostomum parasites. More attention is needed to address water pollution control since the study reveals that variations in physico- chemical parameters have influence on parasitic infections of fish