CURRENT EPIDEMIOLOGICAL AND DIAGNOSTIC STUDIES OF AVIAN COCCIDIOSIS IN NIGERIA: REVIEW STUDY

Abstract

Diagnosis of Eimeria infections and differentiation between species is usually attempted by consideration of clinical signs, post mortem lesions and biological features of the parasite. Analysis of these characteristics is labour intensive and does not provide accurate data for identification of Eimeria species. Diagnostic laboratories are increasingly utilizing DNA based technologies for the specific identification of the parasite. Polymerase Chain Reaction (PCR) based assays have proved to be effective for the identification of all seven species of Eimeria in chickens. A number of approaches have also proved to be both specific and highly sensitive for analysis. An attractive genomic DNA target for PCR analysis is the Internal Transcribed Spacer 1 (ITS-1) and Internal Transcribed Spacer 2 (ITS-2) gene of ribosomal DNA. Epidemiological studies in Nigeria have established the importance of avian coccidiosis though in north western Nigeria, data are scarce and not up to date. The disease
occurs throughout the year in northern Nigeria but with higher prevalence rates from May to September. The prevalence of coccidial infection among adult birds has been put at 36.7% while that of the younger birds is 52.9%. It has been deduced that reliance on imported day old chicks could introduce different Eimeria species and strains into these environments. Also the usage of imported vaccines to prevent this disease though effective is expensive and targeted at specific strains and species thus making its application difficult for the poultry farmer. It is recommended that the molecular characterization of our local avian strains and species with view of vaccine formulations will go a long way in providing adequate information on the disease as well as addressing its control.