Effects of the intestinal flagellate, Cochlosoma anatis, on intestinal mucosal morphology and disaccharidase activity in Muscovy ducklings.

Newly hatched female Muscovy ducklings were randomly separated into 2 groups of 12 and 1 group of 13. Ducklings in the first 2 groups were each orally inoculated with 0.5 ml of sterile normal saline containing 0 and 3 x 10(6) trophozoites of Cochlosoma anatis, respectively. Birds in the third group were each orally inoculated with 3 x 10(6) trophozoites for 5 consecutive days. Birds were weighed daily for the first 5 days and then on days 7, 14 and 21 post-inoculation (p.i.). On days 6, 7, 8, 13, 14, 15, 20, 21 and 22 p.i., 1 bird from each group was killed and samples of intestine at 7 levels were taken for trophozoite counts, mucosal disaccharidase analyses and morphometric analysis. Body weights did not differ among treatment groups at any time during the experiment. Trophozoite numbers did not change over the period 6-22 days p.i. Trophozoite numbers were lowest in the anterior small intestine and increased distally, but very few were observed in the caecum. Crypt depth was greater in all regions of the small intestine in inoculated groups compared to uninoculated controls, and was significantly increased in the duodenum, proximal jejunum and mid-jejunum (P < 0.05). Villus height was greater in inoculated groups compared to controls at all levels of the intestine and was significantly increased in the duodenum, proximal jejunum and ileum (P < 0.05). Mucosal palatinase and maltase activity in the small intestine were reduced in inoculated groups compared to uninoculated controls; palatinase activities were significantly reduced in the proximal and mid-jejunum and maltase activities were significantly reduced in the mid-jejunum (P < 0.05). Sucrase activities were significantly increased at all levels of the small intestine in inoculated ducklings compared to uninoculated controls (P < 0.05). Although no clinical signs were evident, Cochlosoma infection significantly altered intestinal morphometrics and mucosal enzyme concentrations in ducklings, in several cases in a counter-intuitive direction.