The Lethal Effect of Eimeria tenella Extracts on Rabbits

Abstract

Recent observations on host-parasite relations in cecal coccidiosis indicate that this disease is manifested by diverse histo-pathological and early physiological changes in the chicken (Bertke, 1955; Levine and Herrick, 1954; Schildt and Herrick, 1955). Bertke suggested that the changes seen in organs far from the site of the primary infection might be due to a toxic substance released by or through the action of the parasite. A search for toxic substances released during Eimeria tenella infections was undertaken in conjunction with studies on immunity in this disease. One approach in the investigation was an attempt to induce the formation of coccidial antibodies in rabbits by injecting them with extracts prepared from cecal contents of infected chickens. The injection of relatively small amounts of this material intravenously or intraperitoneally into laboratory rabbits resulted in the death of the animals in 16 to 24 hours. This is a report on initial studies of extracts from Eimeria tenella and their toxic effect on rabbits. The possible significance of this toxin in the coccidiosis syndrome is discussed.