Intestinal Disaccharidase and Peroxidase Deficiencies during <i>Eimeria nieschulzi</i> Infections in Rats*

Abstract

SYNOPSIS Experiments were designed to study intestinal pathophysiologic changes associated with coccidial infections in mammalian hosts. Pairs of male Sprague‐Dawley rats were killed at various times postinoculation (PI) with 10 4 or 10 6 sporulated occysts of Eimeria nieschulzi. The small intestine from each rat was removed, weighed, measured, and divided into thirds. From the middle 11 cm of each third, one cm was fixed for histologic examination. Mucosa was scraped from the remaining 10 cm and was assayed for protein content and for peroxidase, sucrase and trehalase activities. Infection with E. nieschulzi was associated with increased mass of the small bowel. Histologically, crypt depth throughout the small bowel was significantly greater ( P ≤ 0.005) in infected rats than in non‐infected ones on PI days 8 and 16. Villus height did not change drastically during low‐dose infections (10 4 oocysts) and varied during high‐dose infections (10 6 oocysts). As a result of these morphologic changes in the mucosa, crypt/villus ratios were usually significantly greater ( P ≤ 0.005) in all infected rats throughout the small bowel. In general, increased gut weight and changes in crypt and villus dimensions became evident by PI day 2, were most pronounced at PI day 8, and began to return to control values by PI day 16. Peroxidase, sucrase, and trehalase levels equaled or were slightly higher than in controls on PI day 2, dropped significantly below controls ( P ≤ 0.05) by PI day 8, and returned to, or exceeded control levels by PI day 16. The intensity of all changes was directly dose‐dependent.