| dc.description.abstract | The objective of the present study was to establish the prevalence, intensity and pathology
associated with helminths infections in three age groups and sexes of free range indigenous
chickens from farms and markets in Kiambu and Nairobi Counties. A total of 108 indigenous
chickens were purchased from the farms and 48 from the markets. The farm birds were from
three agroecological zones (AEZ), namely; Lower highland I (LH1) in Kiambu West District,
Lower midland 4 (LM4) in Thika West District, both in Kiambu County and Lower midland
5 (LMS) in Embakasi District, Nairobi County. Market birds were from Kasarani, Jogoo road
(Burma), Uthiru and Lirnuru. On necropsy examination of the chickens, worms were
recovered from various parts of the gastro intestinal tract, quantified and identified. Tissues
for histopathology were processed, examined and severity of lesions determined.
Overall the prevalence rates of helminths were 89.8 % and 95.8 % in farm and market
chickens, respectively (p>O.OS). Farm chickens had nematodes (87 %) with Heterakis
gallinarum (SI.9 %) being the most prevalent followed by Ascaridia galli (47.2 %) and
Tetramere species (21.3 %) while the cestodes (S4.6 %) were Raillietina echinobothrida
(30.3 %) as the most prominent followed by Hymenolepis species (20.4 %). Market chickens
had Heterakis gallinarurn (S2.1%), Heterakis isolonche (31.3 %) and Ascaridia galli (31.3 %)
as the most prevalent nematodes (93.8 %) while Raillietina echinobothrida (43.8 %) and
Hymenolepis species (29.2 %) were most prevalent cestodes (70.8 %). Echinostoma
revolutum (6.3 %), a trematode was found in market chickens for the first time in Kenya.
Among the age groups in farm chickens, adults and-growers had equal and higher prevalence
rate of nematodes (97.2 %) compared to chicks (75 %) (p<0.05), while in market chickens, all
adults (100 %) and 91.7 % of growers examined were infected (p<0.05). Between the sexes,
88.9 % of males and 85.2 % of females of the farm chickens were infected (p>0.05) while in
the market chickens, 83.3 % of males and all females were infected (p<0.05). For the
cestodes, the prevalence rate in adults (69.4 %) was highest in farm chickens followed by
growers (61.1 %) and chicks (33.3 %). The difference was statistically significant between
the chicks and the other ages of chickens (p < 0.05). For the market chickens, adults (87.5 %)
were higher than grower birds (54.2 %). Infection rate by cestodes was 63 % and 52 % for the
male and female farmed chickens, respectively, while it was 75.0 % and 66.7 % in male and
female marketed chickens.
Nematode infections were most prevalent in the LH1 (97.2 %), followed by LM4 (94.4 %)
and LM5 (77.8 %). Lower midland 4 had the highest prevalence ofcestodes (86.1 %)
followed by LHI (63.9 %) and LM5 (36.1 %). The difference_was statistically significant
between the LM5 and the other AEf.{p·< 0.05). The cool climat~ in LH1 could promote the
presence of intermediate hosts for the helminths leading to the highest prevalence rate.
Among the age groups, adults and growers have reached equilibrium for most of the
infections and the prevalence rate of infection is either equal or the difference is not
significant (p> 0.05). The intensities of nematodes ranged from 0 - 875 worms with an
average of212 worms per chicken in farm chickens while in the market chickens, the range
was from 0 - 550 worms and an average of 73 worms per chicken.
The gross lesions observed in farm and market chickens were 74.1 % and 72.9 %,
respectively (p>0.05). In farm chickens, the gross lesions in chicks, growers and adults were
27.5 %,37.5 % and 35 % (p>0.05), respectively while between the sexes; females had a
higher prevalence of 52.5 % than males, 47.5 % (p>0.05). Among the agro ecological zones,
both LHI and LM5 had higher and equal prevalence of35.0% than LM4, 30 % (p>0.05). In
market chickens, the prevalence in growers and adults were 54.3 %and 45.7 %(p>O.05),
respectively while males had a higher prevalence of 54.3 % than females, 45.7 % (p>O.05).
The gross lesions found were oedema, thickening and obstruction ofthe proventriculus which
was associated with the female Tetrameres species infection. There was also destruction of
the proventricular glands and petechial haernorrhages in chickens infected with Dispharynx
nasuta. Acuaria hamulosa were found embedded in nodules in the gizzards of the infected
chickens.
The occurrence of microscopic lesions was higher in growers among the age groups in both
farm and market birds while between sexes, females in farm chickens had a higher prevalence
of occurrence of microscopic lesions than males in all gut sections examined. In market
chickens, males had higher prevalence rates of microscopic lesions than females in gut
sections. The lesions observed included pressure atrophy of glandular epithelium resulting to
necrosis and cross sections of females of Tetramere species in the proventriculi of the
infected chickens. The lesions were more severe with extensive mucosal ulcerations and
glandular destruction in cases where Dispharynx nasuta was isolated. In farm chickens,
35.2% of the proventriculi had lesions of which 55.3% were attributed to parasites while in
market chickens, 54.2% had lesions with 42.3% being attributed to parasites. The parasites
were associated with both severe and mild pathological lesions in both farm and market
chickens (p<O.05).
The microscopic lesions in gizzards of chickens infected with D. nasuta and A. hamulosa,
were mononuclear cell infiltration and sections of the parasites surrounded by granulocytes
and lymphocytes. The lesions were seen in 5.6 % of the gizzards from farm birds and 40 %
was associated with the parasites. For the market chickens, 12.5% had lesions with 16.7%
being associated to A. hamulosa. Most of the lesions in both farm and market chickens were
mild and statistically associated with the presence of parasites (p<O.05).
The microscopic lesions seen in caeca were cross section of worms in the caecal lumen and
lamina propria. There were also cellular infiltrations mainly mononuclear cells and
granulocytes. Other changes were epithelial desquamation, haemorrhages and infiltration into
lamina propria by plasma cells. In farm chickens, 71.3 % of the caeca had lesions and 85.9%
had parasites while 79 % of market chickens had lesions with 86.8% having parasites.
Pathological lesions were mild in both farm and market chickens but only statistically
associated to parasites in farm chickens (p<0.05)
A total of 60.2 % of the farm Chicken were infested with ectoprasites while market birds
had a prevalence of 77.1 %. Most of the birds had mixed infestations. The most prevalent
ectoparasite was Echidnophaga gallinacea (41.7 %) followed by Knemidocoptes mutans
(27.8 %). Other ectoparasites isolated were fowl tick (Argas persicus) and lice.
In conclusion, this study established that indigenous chickens in the three agro-ecological
zones and markets have high prevalence of helminths. The prevalence rates varied according
to the age, sex of the chickens and agro-ecological zone. Among the helminths, nematodes
were most prevalent followed by cestodes and trematodes. The helminths infections were
associated with gross and Inicroscopic lesions which may affect the health and productivity of
the chicken. There is need for further investigation 'on the impact of helminth infections in the
indigenous chickens of various agro - ecological zones in Kenya. | en |
