Studies on the distribution and site location of<i>Nippostrongylus brasiliensis</i>within the small intestine of laboratory rats

Abstract

The distribution of N. brasiliensis within the small intestine of rats, following a primary infection, is described. The fourth stage larvae were found to inhabit the sections later parasitized by the adult population. Both the larval and adult worms were found to be confined to the anterior half of the small intestine. This aggregation is believed to be under the influence of stimuli (factor(s) 1), present in the lumen of the host gut. The adult worms also clumped within the already confined worm population. This behaviour is thought to be due to intrinsic behaviour patterns of the worm, sexual attraction and thigmokinesis. Larval and adult worms were surgically transferred to points, at varying distance from the ‘normally’ inhabited region, in the small intestine of fresh recipient rats. The resulting migratory behaviour of the worms was studied. The worm populations resulting from both the larval and the adult transfers showed the ability to recognize that they were in the wrong position of the small intestine and to be able to orientate, migrate and locate the ‘normal’ site.