PREVALENCE OF PARASITIC INFECTIONS OF FARMED TILAPIA (Oreochromis niloticus) AND CATFISH (Clarias gariepinus) IN NYERI COUNTY, KENYA

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1 PREVALENCE OF PARASITIC INFECTIONS OF FARMED TILAPIA (Oreochromis niloticus) AND CATFISH (Clarias gariepinus) IN NYERI COUNTY, KENYA KVA ANNUAL SCIENTIFIC CONFERENCE 27TH-29 TH APRIL, 2016 PRESENTER: Dr Stephen K. Mavuti (BVM, MSc. UoN) (Currently PhD Student, UoN)

2 S.K. Mavuti 1 *, R.M. Waruiru 2, P.G. Mbuthia 2, J.G. Maina 3, J.M. Mbaria 4, R.O. Otieno 2 1 Directorate of Veterinary Services, Ministry of Agriculture, Livestock and Fisheries, Kenya 2 Department of Veterinary Pathology, Microbiology and Parasitology, 3 Department of Animal Production, 4 Department of Public Health, Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Nairobi, P.O. Box , Kangemi Nairobi. *Corresponding author: stekitong@yahoo.com

3 INTRODUCTION Fish farming in warm water ponds began in Kenya in the 1920s using tilapia species while common carp and African catfish were introduced thereafter. Aquaculture has since then continued to remain at subsistence level in the Country (Ngugi and Manyala, 2004; Coche et al., 2008; Mbugua, 2008a). The Eat More Fish campaigns by the Government have popularized rural fish farming

4 Eat more fish campaign (8 Jan 2014, Othaya)

5 Introduction (Cont d...) The explosive interest in fish farming stimulated by the ESP poses new challenges -Environmental pollution -Management practices -Biosecurity -The spread of fish diseases/parasites

6 Study Objective To determine the prevalence of fish parasites in farmed tilapia and catfish in two sub-counties of Nyeri County, Kenya

7 Materials and Methods The study was carried out in Tetu and Nyeri Central sub-counties of Nyeri County Tetu and Nyeri sub-counties were purposively selected because fish farming is becoming an important enterprise in the region. Fish farmers own ponds funded by the Economic Stimulus Programme (ESP), others are self-funded Farmers rear tilapia and catfish although other fish species e.g. trout are reared

8 Figure 1: Nyeri County in Kenya and its sub-counties

9 Cont d.. A list of fish farmers (self and ESP funded) was obtained from the Fisheries officers in Nyeri County Fig. 2: Tilapia fish purchased from a farmer in Tetu sub-county A total of 366 live fish (89 catfish and 277 tilapia) were purchased from 15 fish farmers between August 2014 and November, 2015

10 Cont d.. Eyes, skins, gills, muscles, stomachs and intestines were examined for parasites in-situ and at Kabete Campus using dissecting and compound microscopes Fig. 3: Dr. Mavuti collecting specimens from a tilapia for ectoparasite idetification The parasites were processed using standard parasitological techniques and identified as described by Noga (2010) and the Commonwealth Institute for Helminthology, UK

11 Results 31.4% (115/366) of the fish were infected with one species of ecto- or endo-parasite in the gills, skin, muscle, eye or gastro-intestinal tract Overall parasitic infection rate was significantly higher (p < 0.05) in tilapia (67.8%; 78/115) relative to catfish (32.2%; 37/115) There was no significant difference (p > 0.05) in overall fish parasite infestation rates between earthen (52.2%; 60/115) and liner (48.8%; 55/155) ponds

12 Cont d.. The prevalence of liner pond parasitic infection was relatively similar between catfish (56.4%; 31/55) and tilapia (43.6%; 24/55) However, in earthen ponds, there were significant differences (p<0.05) between tilapia (90%; 54/60) and catfish (10%; 6/60) parasitic infection rates

13 Cont d. Nearly 15% (57/366) of fish examined had gill monogenean flukes (Dactylogyrus spp.) Fig. 4:Anterior end of Dactylogyrus spp. anchored in the gills of a tilapia fish showing a scalloped head (arrow)

14 Cont d. 8.2% (30/366) tilapia fish had metacercariae nodules of the digenean fluke, Clinostomum spp. in the muscles Fig. 5: Cystic lesions on the skin of a tilapia infected with Clinostomum spp.

15 Cont d. 1.9% had Diplostomum spp. in the eyes Figure 6: A Diplostomum spp. metacercariae isolated from the vitreous humour of a tilapia fish from Nyeri County (arrow)

16 Cont d. Other parasites identified included: Leeches (ectoparasites of the skin) - 2.7% Trichodina spp. (protozoa) -1.4% Acanthocephala spp. (helminth) - 0.8% Contracaecum spp. and Paracamallanus spp. (nematodes) 0.5% Gyrodactylus spp. (monogenean fluke) - 0.5%

17 Cont d. D C Figure 7. Round shaped Trichodinid spp from a catfish from Nyeri County showing cilia (C) and denticle (D)

18 Cont d. Figure 8: Anterior end of an Acanthocephalan spp from a tilapia fish from Nyeri County showing a spined proboscis (arrow)

19 Cont d. B A C Figure 9. A Paracamallanus species from tilapia fish from Nyeri County showing the vertical chitinoid plates (A) and the buccal cavity divided into two levels:- the upper smaller (B) and lower larger parts (C)

20 Cont d. Figure 10. Skin monogenean fluke (Gyrodactylid spp) from the skin of a catfish showing a V-shaped head an opisthohaptor (posterior end) anchored on the skin

21 Conclusions This study reports the prevalence of: Monogenean and digenean flukes The protozoa Trichodina spp. Leeches Nematodes and Acanthocephala spp. in farmed fish in Nyeri County These parasites may affect the health and quality of fish leading to condemnation at inspection

22 Recommendations Further research is indicated to determine: Risk factors Pathophysiology Control of fish parasites in farmed tilapia and catfish in Kenya

23 Acknowledgements Dr. J.G. Maina s PEER Science Project for offering the scholarship USAID for funding UON DVS County Director of Fisheries, Nyeri County Fish farmers in Nyeri Central and Tetu sub-counties

24 Thank you for listening 24