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 tenella (ET) or high doses of the turkey coccidium, Eimeria adenoeides (EA) on Salmonella enteritidis (SE) organ invasion, as well as histological and morphometric changes in the ceca of Leghorn chicks, was investigated. In these studies, chicks were inoculated orally with either saline solution (control) or one of three doses of sporulated oocysts of either ET or EA at 1 d of age. Five days later, 10(4) cfu of SE were administered per os to all chickens. Chicks were killed and organs cultured for SE 6 d following bacterial challenge. A clear relationship of decreased SE organ invasion was observed by increasing the dose of sporulated oocysts of either ET or EA. Furthermore, the increased resistance to organ infectivity in both experiments was matched with an increase in lamina propria thickness based on morphometric analysis (P < .05), 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 infectivity and lamina propria thickness of the cecum. These data indicate that the increased resistance to SE organ invasion following subclinical coccidial infections were associated with morphological changes in the ceca of Leghorn chicks.