Histopathological Studies on Experimentally Eimeria tenella-Infected Broiler Chicken

Abstract Background: Coccidiosis is an important intestinal parasitic disease of chickens, caused by Eimeria spp. and leads to high mortality and morbidity rates for poultry industry throughout the world. This work was planned to determine the histopathological changes in the ileum, caecum, and bursa of Fabricius of broilers experimentally infected with the coccidian parasite; Eimeria tenella. Animals and methods: Sixty newly hatched commercial broiler chicks were divided randomly into four equal groups of 15 chicks each. The first group remained as a control group, while the other three were the infected groups. After the first week, group one (infected1) was inoculated orally with 40000 viable sporulated oocysts of the E. tenella laboratory strain. The second group (infected 2) was infected after the second week, but the third group (Infected 3) was infected after the third week. One week after each infection, the birds were dissected and the tissue samples of the ileum, caecum, and bursa were processed for histopathological examination under a light microscope. Results: Histopathological examinations of the affected ileum showed marked decrease of villi length. The caecum showed an excessive tissue damage, hemorrhage, presence of numeral coccidian oocysts in the tissue and the lumen. In addition, the crypt cells were highly invaded with the developmental stages of E. tenella schizonts. E. tenella infection also induced obvious harmful morphological changes in the bursa of Fabricius (BF) demonstrated by decrease in cell volumes, irregular arrangement, and enlargement of the intercellular space.