Prevalence of parasitic infection in farmed Nile tilapia and factors associated with transmission in Kiambu County, Kenya
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Date
2017
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Sokoine University of Agriculture
Abstract
The current study was undertaken between October 2016 and March 2017 to
determine the prevalence of fish parasites infesting farmed Tilapia and the associated
risk factors in Kiambu County, Kenya. A total of 148 questionnaires supplemented
with direct observations were administered to fish farmers to assess the status of fish
farming and management practices that could influence the occurrence of fish
parasites in the farms. A total of 260 fish were purchased from farmers and examined
for ecto-and endo-parasites. Most of the farmers were males, over 50 years of age,
had been in fish farming for more than five years and were involved in farming of
fish, crops and livestock as their main occupation. In majority (60.8%) of the farms,
Tilapia (Oreochromis niloticus) was the main species farmed under semi intensive
farming system in earthen ponds. Farm owners (66.7%) were responsible for day to
day management of the farms and most had attained secondary school education. The
management practices identified as possible risk factors for occurrence of fish
parasites included: use of rivers as sources of fish pond water, earthen ponds with
overgrown vegetation in and around them, stocking with fingerlings from non
certified sources, failure to change water within a production cycle, lack of pond
draining, cleaning and treatment after harvesting and lack of or infrequent
fertilization of ponds. Others were: use of poor quality feeds and lack of feeding or
improper feeding, sharing of fishing nets among farmers and between ponds in the
same farm, failure to clean and disinfect fishing nets, lack of knowledge on signs of
fish diseases in general and parasitism in particular and presence of predators
especially, predatory birds. The mean weight, total length and standard length of the
fish collected were 110.2g (±83.7), 17.6 cm (±4.1) and 14.3 cm (±3.5), respectively
while, the mean condition factor was 1.8 (± 0.4). Of the fish sampled, 68 (26.2%)
were found to be infested by one or more species of parasites. Fish from earthen
ponds (31%) were more parasitized relative to those from liner ponds (3.3%). More
fish from ponds with overgrown vegetation (30.3%) were parasitized as opposed to
those ponds whose vegetation around the pond was well trimmed (9.7%). Fish
parasites recovered and their prevalence were: digenean trematodes, Diplostomum
spp. (8.5%), and Clinostomum spp. (3.5%), monogenean trematodes, Dactylogyrus
spp. (3.5%), Gyrodactylus spp. (0.4%) and the thorny headed worm,
Acanthocephalus spp. (10.4%). Among the parasites recovered Clinostomum spp.
and Diplostomum spp. have been reported to be zoonotic and therefore, more
research is required to characterize them and determine their zoonotic importance.
The prevalence and intensities of the parasites recovered were low and majority of
infested fish were in good body condition. For profitable fish farming in Kiambu
County, awareness in fish health and farm management practices among farmers,
fisheries and veterinary extension workers, researchers and all other relevant
stakeholders is indicated.
Description
Masters Thesis
Keywords
Parasitic infection, Farmed Nile tilapia, Nile tilapia, Transmission, Kiambu County, Kenya