TRICHOSTRONGYLUS-COLUBRIFORMIS INFECTION IN RABBITS - PERSISTENCE OF THE DISTAL ADAPTIVE RESPONSE TO PARASITISM AFTER ANTHELMINTIC TREATMENT

Mucosal changes associated with anthelmintic treatment in Trichostrong ylus colubriformis-infected rabbits were assessed along the entire len gth of the small intestine. The following groups, each of five rabbits , were compared: infected (group I); infected and treated on day 21 wi th fenbendazole (group IT); uninfected but given fenbendazole on day 2 1 (group C, controls). All animals were killed on day 28. In the proxi mal part of the small intestine of group I rabbits, the worms were ass ociated with shortening of the villi and a significant depletion in al kaline phosphatase activity, which differed significantly from the fin dings in groups C and IT. In the same region, no difference was found between groups C and IT. In the distal small intestine, hypertrophy of villi and crypts (an adaptive response to the infection), coupled wit h an increase in enzymic activity, were present in both groups I and I T, in contrast to group C.These results suggest that a complete mucosa l restoration occurred within 7 days of anthelmintic treatment in the parasitized part of the intestine. In contrast, the adaptive response observed beyond the main site of parasitism was not abolished by treat ment. The functional significance of these findings is discussed in re lation to the compensatory growth commonly observed after anthelmintic treatment in ruminants. (C) 1995 Academic Press Limited