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Prevalence and molecular characterisation of Eimeria species in Ethiopian village chickens.

Luu L, Bettridge J, Christley RM, Melese K, Blake D, Dessie T, Wigley P, Desta TT, Hanotte O, Kaiser P, Terfa ZG, Collins M, Lynch SE - BMC Vet. Res. (2013)

Bottom Line: Eimeria oocysts were detected significantly more frequently in October (248/384, 65%, 95% CI 60-69%), following the main rainy season, compared to May (179/383, 47%, 95% CI 42-52%, p < 0.001).Eimeria oocyst positivity in May did not significantly affect the likelihood of detecting Eimeria oocyst five months later perhaps suggesting infection with different species or immunologically distinct strains.Although there was no evidence of a difference in the prevalence of oocysts in faecal samples between study regions, there was evidence of variation in the prevalence of some species, perhaps suggesting regional differences in exposure to risk factors associated with the birds, their management and/or location-specific environmental and ecological factors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom. robc@liverpool.ac.uk.

ABSTRACT

Background: Coccidiosis, caused by species of the apicomplexan parasite Eimeria, is a major disease of chickens. Eimeria species are present world-wide, and are ubiquitous under intensive farming methods. However, prevalence of Eimeria species is not uniform across production systems. In developing countries such as Ethiopia, a high proportion of chicken production occurs on rural smallholdings (i.e. 'village chicken production') where infectious diseases constrain productivity and surveillance is low. Coccidiosis is reported to be prevalent in these areas. However, a reliance on oocyst morphology to determine the infecting species may impede accurate diagnosis. Here, we used cross-sectional and longitudinal studies to investigate the prevalence of Eimeria oocyst shedding at two rural sites in the Ethiopian highlands.

Results: Faecal samples were collected from 767 randomly selected chickens in May or October 2011. In addition, 110 chickens were sampled in both May and October. Eimeria oocysts were detected microscopically in 427 (56%, 95% confidence interval (95% CI) 52-59%) of the 767 faecal samples tested. Moderate clustering of positive birds was detected within households, perhaps suggesting common risk factors or exposure pathways. Seven species of Eimeria were detected by real time PCR in a subset of samples further analysed, with the prevalence of some species varying by region. Co-infections were common; 64% (23/36, 95% CI 46-79%) of positive samples contained more than one Eimeria spp. Despite frequent infection and co-infection overt clinical disease was not reported. Eimeria oocysts were detected significantly more frequently in October (248/384, 65%, 95% CI 60-69%), following the main rainy season, compared to May (179/383, 47%, 95% CI 42-52%, p < 0.001). Eimeria oocyst positivity in May did not significantly affect the likelihood of detecting Eimeria oocyst five months later perhaps suggesting infection with different species or immunologically distinct strains.

Conclusions: Eimeria spp oocysts may be frequently detected in faecal samples from village chickens in Ethiopia. Co-infection with multiple Eimeria spp was common and almost half of Eimeria positive birds had at least one highly pathogenic species detected. Despite this, all sampled birds were free of overt disease. Although there was no evidence of a difference in the prevalence of oocysts in faecal samples between study regions, there was evidence of variation in the prevalence of some species, perhaps suggesting regional differences in exposure to risk factors associated with the birds, their management and/or location-specific environmental and ecological factors.

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Co-occurrence of Eimeria spp. Faecal samples were collected from 47 chickens from two regions of Ethiopia in May 2011. Each row represents one sample. Red boxes indicated samples from Horro, blue indicate samples from Jarso. Light and dark shading indicates each of the pairs of villages within each region.
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Figure 1: Co-occurrence of Eimeria spp. Faecal samples were collected from 47 chickens from two regions of Ethiopia in May 2011. Each row represents one sample. Red boxes indicated samples from Horro, blue indicate samples from Jarso. Light and dark shading indicates each of the pairs of villages within each region.

Mentions: Of the 47 samples where Eimeria oocysts were detected, 36 were known to be collected from individual birds, the rest included fresh chicken faeces sampled from the environment and may have included faeces from more than one bird. Of these 36 samples, more than one Eimeria spp was detected in 64% (23/36, 95% CI 46-79%). Species frequencies in co-infection are presented in Table 1. Eimeria praecox was the most common species and detected in 46% of single infections and 74% of co-infections in this study. The frequency of species presence in mixed infections was strongly correlated with overall prevalence of that species (Spearman r = 0.82, p = 0.03) suggesting that there was no species predilection for co-infection, except that due to prevalence. There was evidence for spatial clustering of patterns of co-infection within each of the two study regions (Figure 1), however, this was less obvious when E. mitis and E. praecox were excluded from the analysis (data not shown), suggesting much of the spatial variation in patterns of co-occurrence was due to the different prevalence of E. mitis and E. praecox between the two regions.


Prevalence and molecular characterisation of Eimeria species in Ethiopian village chickens.

Luu L, Bettridge J, Christley RM, Melese K, Blake D, Dessie T, Wigley P, Desta TT, Hanotte O, Kaiser P, Terfa ZG, Collins M, Lynch SE - BMC Vet. Res. (2013)

Co-occurrence of Eimeria spp. Faecal samples were collected from 47 chickens from two regions of Ethiopia in May 2011. Each row represents one sample. Red boxes indicated samples from Horro, blue indicate samples from Jarso. Light and dark shading indicates each of the pairs of villages within each region.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852846&req=5

Figure 1: Co-occurrence of Eimeria spp. Faecal samples were collected from 47 chickens from two regions of Ethiopia in May 2011. Each row represents one sample. Red boxes indicated samples from Horro, blue indicate samples from Jarso. Light and dark shading indicates each of the pairs of villages within each region.
Mentions: Of the 47 samples where Eimeria oocysts were detected, 36 were known to be collected from individual birds, the rest included fresh chicken faeces sampled from the environment and may have included faeces from more than one bird. Of these 36 samples, more than one Eimeria spp was detected in 64% (23/36, 95% CI 46-79%). Species frequencies in co-infection are presented in Table 1. Eimeria praecox was the most common species and detected in 46% of single infections and 74% of co-infections in this study. The frequency of species presence in mixed infections was strongly correlated with overall prevalence of that species (Spearman r = 0.82, p = 0.03) suggesting that there was no species predilection for co-infection, except that due to prevalence. There was evidence for spatial clustering of patterns of co-infection within each of the two study regions (Figure 1), however, this was less obvious when E. mitis and E. praecox were excluded from the analysis (data not shown), suggesting much of the spatial variation in patterns of co-occurrence was due to the different prevalence of E. mitis and E. praecox between the two regions.

Bottom Line: Eimeria oocysts were detected significantly more frequently in October (248/384, 65%, 95% CI 60-69%), following the main rainy season, compared to May (179/383, 47%, 95% CI 42-52%, p < 0.001).Eimeria oocyst positivity in May did not significantly affect the likelihood of detecting Eimeria oocyst five months later perhaps suggesting infection with different species or immunologically distinct strains.Although there was no evidence of a difference in the prevalence of oocysts in faecal samples between study regions, there was evidence of variation in the prevalence of some species, perhaps suggesting regional differences in exposure to risk factors associated with the birds, their management and/or location-specific environmental and ecological factors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom. robc@liverpool.ac.uk.

ABSTRACT

Background: Coccidiosis, caused by species of the apicomplexan parasite Eimeria, is a major disease of chickens. Eimeria species are present world-wide, and are ubiquitous under intensive farming methods. However, prevalence of Eimeria species is not uniform across production systems. In developing countries such as Ethiopia, a high proportion of chicken production occurs on rural smallholdings (i.e. 'village chicken production') where infectious diseases constrain productivity and surveillance is low. Coccidiosis is reported to be prevalent in these areas. However, a reliance on oocyst morphology to determine the infecting species may impede accurate diagnosis. Here, we used cross-sectional and longitudinal studies to investigate the prevalence of Eimeria oocyst shedding at two rural sites in the Ethiopian highlands.

Results: Faecal samples were collected from 767 randomly selected chickens in May or October 2011. In addition, 110 chickens were sampled in both May and October. Eimeria oocysts were detected microscopically in 427 (56%, 95% confidence interval (95% CI) 52-59%) of the 767 faecal samples tested. Moderate clustering of positive birds was detected within households, perhaps suggesting common risk factors or exposure pathways. Seven species of Eimeria were detected by real time PCR in a subset of samples further analysed, with the prevalence of some species varying by region. Co-infections were common; 64% (23/36, 95% CI 46-79%) of positive samples contained more than one Eimeria spp. Despite frequent infection and co-infection overt clinical disease was not reported. Eimeria oocysts were detected significantly more frequently in October (248/384, 65%, 95% CI 60-69%), following the main rainy season, compared to May (179/383, 47%, 95% CI 42-52%, p < 0.001). Eimeria oocyst positivity in May did not significantly affect the likelihood of detecting Eimeria oocyst five months later perhaps suggesting infection with different species or immunologically distinct strains.

Conclusions: Eimeria spp oocysts may be frequently detected in faecal samples from village chickens in Ethiopia. Co-infection with multiple Eimeria spp was common and almost half of Eimeria positive birds had at least one highly pathogenic species detected. Despite this, all sampled birds were free of overt disease. Although there was no evidence of a difference in the prevalence of oocysts in faecal samples between study regions, there was evidence of variation in the prevalence of some species, perhaps suggesting regional differences in exposure to risk factors associated with the birds, their management and/or location-specific environmental and ecological factors.

Show MeSH
Related in: MedlinePlus