Prevalence, intensity and lesions associated with gastro-intestinal parasites of indigenous chickens in Kenya
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Indigenous chickens constitute over 74.0 % of poultry in Kenya and account for 75.0 % of the total poultry meat and 54.0 % of eggs produced in the country. Gastro-intestinal parasites are of economic importance as they limit the production of these birds. Studies on the effects of parasites in commercial and experimentally infected birds are documented but very little is reported on parasitic effects in indigenous chickens. The aim of this study was to determine the prevalence, intensity and lesions associated with gastro-intestinal parasites of healthyappearing market indigenous chickens sold in markets in Nairobi. The study was conducted in the Department of Veterinary Pathology, Microbiology and Parasitology, University of Nairobi. Indigenous chickens were purchased from various openair markets in the city of Nairobi. The markets were at BurmalMaziwa (Jogoo road), Kariokor, Westlands and Nairobi South Band C trading centres. The birds originated from Machakos, Makueni, Kitui, Mwingi, Bomet, Kericho, Uasin Gishu, Sumba and Kisii districts. Thorough physical and post mortem examinations were performed on live chickens and carcasses at the market and in the laboratory, respectively. Worm egg and coccidial oocyst counts were performed on faecal materials from each bird. Worm identification and quantification was done on all worms isolated from the gastro-intestinal tracts (GIT). Tissues collected for histopathology were processed, examined and the severity of the lesions determined. The data obtained from these procedures were entered in Ms excel and analysed using i statistic, t-test and non-parametric one-way analysis of variance (ANOV A). Results showed that many chickens (90.0 %) had gastro-intestinal helminths, but only a few (13.9 %) of these had coccidial oocysts. Nematodes were the predominant helminths (89.0 %) followed by cestodes (51.5 %), and no trematodes were recovered in the study. The nematodes recovered from the OIT were: Heterakis isolonche (59.5 %), Subulura brumpti (36.0 %) Tetrameres species (32.0 %), Gongylonema ingluvicola (19.0 %), Ascaridia galli (19.8 %), Acuaria hamulosa (6.1 %), Heterakis gallinarum (5.3 %) and Capillaria species (2.3 %). The cestodes recovered were: Raillietina echinobothrida (37.7 %), Hymenolepis carioca (33.6 %), Davainea proglottina (6.9 %), Raillietina tetragona (6.1 %) and Raillietina cesticillus (2.3 %). Other endoparasites encountered were Syngamus trachea (4.0 %), which was identified in histological sections of lung tissues, Sarcocystis species (5.6 %), observed in the muscles surrounding the trachea (neck muscles) and Cytodite nudus (15.3 %), on the air sacs. The mean caecal worm counts in chickens were significantly different (p < 0.05) in various districts. However, there was no significant difference in the overall worm loads between sexes (p > 0.05). Seventy-six percent of the chickens harboured ectoparasites. These were stick tight fleas (Echidnophaga gallinacea, 56.0 %), lice in the genera Menopon, Goniocotes and Cuclotogaster (52.0 %), ticks (Argus persicus, 29.3 %) and scaly leg mites (Knemidocoptes mutans, 24.0 %). Gross lesions were observed in the following parts of the OIT: crops (2.7 %), proventriculi I (13.3 %), gizzard (4.0 %), duodenum and other parts of small intestines (5.3 %), large intestines (8.0 %) and caeca (2.7 %). Other organs with lesions were liver (16.0 %), lungs (8.0 %), heart (4.0 %), spleen (4.0 %) and the kidneys (2.7 %). The main gross lesions in the GIT that accompanied parasitic infestations were haemorrhagic enteritis, congestion and ulcerative patches. However, some parasites did not provoke obvious signs. There were more lesions seen on microscopic examination of these organs relative to gross observations (p < 0.05). The microscopic lesions observed were in the crops (21.3 %), proventriculi (61.3 %), gizzards (21.3 %), duodenums (84. 0 %), the rest of small intestines (73.3 %), large intestine (89.3 %) and caeca (74.7 %). Parasites in various organs caused lesions of variable severity. In the crops, G. ingluvicola worms were grossly observed in wavy tracts and microscopically comprised of parasitic sections in tunnels, pressure degeneration and necrosis of the stratified squamous epithelium. On the provetriculi, Tetrameres species were grossly seen as black spots beneath the serosal surfaces and histologically, the parasites caused pressure atrophy, fibroplasia and necrosis of the proventricular glands. In the crops and proventriculi, the , lesions were mild and significantly associated with the respective parasites (p < 0.05). Gizzards with A. hamulosa had several severe nodular lesions. Microscopically, these lesions were transformation of glandular epithelium, distension of glandular lumen with eosinophilic substance, sections of the parasite surrounded by numerous granulocytes and lymphocytes. This parasite was associated with severe pathological changes (p < 0.05). In the duodenum, the worms recovered were due to Ascaridia galli, H carioca and D. proglottina. The rest of the small intestines (jejunum and ileum) were infested with A. galli i and Raillietina spp. while the large intestines were infested by S. brumpti, Raillietina and Heterakis species. Grossly, the lesions observed were localized congestion, pinpoint haemorrhages and in a few cases, ulcerative lesions. Microscopically, there was epithelial desquamation, worm sections (some degenerating), villous matting and atrophy. There were also haemorrhages and cellular infiltrations with lymphocytes, plasma cells and granulocytes. The lesions observed in the intestines were mild and were not associated with the worms (p > 0.05). The caeca were infested with S. brumpti, Heterakis and Capillaria species. Pathological lesions observed were enlarged and haemorrhagic caecal tonsils. Petecchial haemorrhages were occasionally encountered in other parts of the caeca. Microscopically, there were cross sections of worms, epithelial desquamation, haemorrhages, lymphoid hyperplasia and infiltration with lymphocytes, plasma cells and granulocytes. The lesions observed were mild and were not associated with the worms (p> 0.05). In conclusion, the study has shown that both endo- and ecto-parasites are prevalent in the apparently healthy indigenous chickens in Kenya. The gastro-intestinal nematodes were , more prevalent than the cestodes, and most of the GIT parasites were associated with mild pathological lesions except A. hamulosa, which caused severe lesions in the gizzard. There is a need for more studies on parasite infections, their impact on productivity in various age groups of chickens and in other agroc1imatic zones of Kenya.