RESUMO
Background: Eimeria is a parasitic organism causing coccidiosis, an enteric disease of major economic importance in poultry. The conventional methods for species identification of Eimeria have major limitations. Methods: Fresh fecal samples were randomly collected from 50 small and large-scale commercial broiler farms located in Adama, Bishoftu, Dukem, and Mojo towns. Polymerase chain reaction (PCR)-based assay was used for the differentiation of Eimeria species circulating among study sites and broiler farms. DNA was extracted from Eimeria oocytes using a DNeasy Tissue Kit. The extracted DNA templates and the genus-specific primers (Invitrogen) were used for the amplification of the ITS-1 region from seven Eimeria species of chicken. Descriptive statistical analysis and t-test were used to summarize and analyze the data. Results: The PCR result confirms that all the seven species of Eimeria were detected in both small and large-scale broiler farms. Prevalence variation was found among broiler farms and between study sites. The frequency of E. brunetti (P<0.006) and E. tenella (P<0.04) in the small-scale broiler farms was significantly higher compared to that of in large-scale farms. A significantly higher frequency of E. acervulina (P<0.03) and E. brunetti (P<0.03) was detected in broiler farms of Dukem and Mojo compared to the broiler farms in Bishoftu. The study also revealed that multiple infections of Eimeria species per sample are common in most farms. Among the evaluated small-scale broiler farms of Bishoftu, 80% showed up to 5 mixed species. In addition, about 33% of large-scale and 20% of small-scale broiler farms showed 6-7 mixed species. Conclusion: This study characterized all the seven Eimeria species and revealed that multiple infections of Eimeria species per sample are common in most of the evaluated farms. The current findings might be useful for future anticoccidial vaccine development and for effective chemoprophylactic and control strategies.
RESUMO
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.
