The Effect of Cecal Coccidiosis on the Blood Cells of the Domestic Fowl

ONE of the more noticeable manifestations of cecal coccidiosis is the hemorrhage that results when chickens become severely infected with the disease. Because the disease has such pronounced effect on the chickens, various studies have been carried out to explain the physiological changes that occur in the infected animal. Edgar (1944) in his study on the life cycle of the sporozoan parasite, Eimeria tenella, the causal organism, substantiated the findings of Tyzzer (1929) and others who observed that the hemorrhage begins in the infected cecal mucosa when the second-generation merozoites approach maturity. Edgar (1944) suggests that the hemorrhage is the result of the pinching off of mucosal capillaries by pressure resulting from the enlargement of epithelial cells in which the intracellular parasitic development (schizogony) has been taking place. Late in the fourth day and during the fifth day of infection, the second-generation merozoites are discharged from the infected epithelial …