EIMERIA-TENELLA OR EIMERIA-ADENOEIDES - INDUCTION OF MORPHOLOGICAL-CHANGES AND INCREASED RESISTANCE TO SALMONELLA-ENTERITIDIS INFECTION IN LEGHORN CHICKS

The effect of either low doses of the chicken coccidium, Eimeria tenel la (ET) or high doses of the turkey coccidium, Eimeria adenoeides (EA) on Salmonella enteritidis (SE) organ invasion, as well as histologica l and morphometric changes in the ceca of Leghorn chicks, was investig ated. In these studies, chicks were inoculated orally with either sali ne solution (control) or one of three doses of sporulated oocysts of e ither ET or EA at 1 d of age. Five days later, 10(4) cfu of SE were ad ministered per os to all chickens. Chicks were killed and organs cultu red for SE 6 d following bacterial challenge. A clear relationship of decreased SE organ invasion was observed by increasing the dose of spo rulated oocysts of either ET or EA. Furthermore, the increased resista nce to organ infectivity in both experiments was matched with an incre ase in lamina propria thickness based on morphometric analysis (P < .0 5), probably due to a marked infiltration of inflammatory cells in the cecal mucosa. In both trials, a significant correlation was found (r = -.98 for ET; r = -.99 for EA) between the rate of bacterial organ in fectivity and lamina propria thickness of the cecum. These data indica te that the increased resistance to SE organ invasion following subcli nical coccidial infections were associated with morphological changes in the ceca of Leghorn chicks.