Studies on the biology of the life-cycle of Trichuris suis Schrank, 1788

The biology of the life-cycle ofTrichuris suisof the pig is described and discussed together with aspects of the hosi-parasite relationship. Development of the infective L. 1 larval stage within the egg was shown to be influenced by temperature. Following ingestion of infective ova by the pig, all subsequent larval development to the adult stage occurred in the mucosa of the caecum and colon. Eggs hatched in the distal region of the small intestine and throughout the large intestine. Larvae then penetrated the caecum and colonic mucosa via the crypts of Lieberkühn, where they entered the cells lining the crypts. The ensuing histotrophic phase lasted 13 days, during which time a gradual larval migration occurred from the deeper regions of the lamina propria to areas immediately beneath the surface mucosal epithelium. Luminal development was initially seen on day 16 when the posterior extremities of larvae were protruded into the gut lumen; from day 20 the entire posterior body region was exposed, while only the filamentous anterior region of the parasite remained embedded in the mucosal surface. The prepatent period varied from 41 to 47 days. Four moults were observed during development within the host and these occurred on days 10, 16, 20, 32 and 37 (to form the L. 2, L. 3, L. 4 and L. 5 or adult stage respectively). It is suggested that althoughT. suismay not be an important pathogen in its own right, its activities in the caecal and colonic mucosa may cause sufficient damage to enable secondary pathogenic invaders to become established.

A cryptic infection of an appendix with the whipworm, Trichuris trichiura in Britain

A case of infection of an appendix with a whipworm, Trichuris trichiura is described. Only the thin pharyngeal part of the worm imbedded in the mucosa was observed in the sections, and whipworm eggs were not found in the patient's stools or appendiceal faeces.