Advanced studies on coccidiosis in broiler chicken flocks with special reference to methods of diagnosis, prevention and control

Abstract

Twenty-eight broiler chicken farms from 16 to 70 days of age were examined clinically for suspected outbreaks of coccidiosis in eight governorates in Egypt. Flock history, clinical signs, dropping score and lesion score were recorded at time of examination. Fecal as well as intestinal samples (from different intestinal portions) were examined for coccidiosis using direct wet smear. Positive samples were subjected to DNA extraction followed by amplification of internal transcribed spacer 1(ITS1) region of Eimeria genome with species specific primers of E. tenella, E. necatrix, E. maxima and E. acervulina for detection of these species using conventional PCR. The ITS1 region of ribosomal DNA (rDNA) from highly positive samples of single infection with E. tenella was sequenced and compared with sequence of ITS1 region of E. tenella strain in coccivac-B Vaccine .Results revealed that, the highest mortality rate (2.49%) was recorded in cobb breed in Dakahlia governorate while the lowest mortality (0.5%) was recorded in avian species in Dakahlia and Damitte governorates. Higher prevalence rate (89.28%) was observed in young birds (16-42days) than growing birds (10.72%) (50-70 days of age). Cobb breed proved to be more susceptible to infection (42.85%) than other breeds (14.28% in Balady breed, 10.71% in both Sasso and Hubbard breeds, 7.14% in Avian 48 breed and 3.57% in Arbor acres breed). Higher prevalence of mixed infection with different Eimeria species was 26 out of 28 farm (92.8%) while single infection with Eimeria tenella was 2 out of 28 farm (7.2%). Mean lesion score revealed that higher score in different types of chickens attributed to cecal portion (0.6-3.3) and lower score observed in other portions as follows; (0-0.9) in jejunal portion and (0-0.6) in illiual portion. Results of PCR results revealed detection of Eimeria tenella in a rate of 100%