title: Hymenolepis microstoma: a change in susceptibility to resistance with increasing age of the parasite.
abstract: Hymenolepis microstoma from secondary infections in mice were found to grow initially more slowly than H. microstoma from primary infections. Eventually a similar rate of growth was attained by both kinds of worm. After transplantation, young worms (less than or equal to 4 days old) grew more slowly in previously infected than in naive mice. In contrast, 10-day-old worms grew equally well in naive or resistant mice. The administration of cortisone to mice during a secondary infection of H. microstoma inhibited the stunting of growth in young worms which were able to grow as well as those in a primary infection. The effects of the cortisone persisted for less than 4 days. Worms in a secondary infection given 4 days after cortisone treatment were stunted in growth. These experiments suggest that the susceptibility of the worms to the resistance of the mouse applies to the first 4 days within the host. The loss or reduction of this susceptibility might be associated with the worm's entry into the bile duct which occurs 3--4 days after infection.
mesh_terms: D000818:Animals; D002589:Cestoda / Q000254:growth & development*; D003348:Cortisone / Q000494:pharmacology; D006925:Hymenolepiasis / Q000276:immunology* / Q000469:parasitology; D006926:Hymenolepis / Q000187:drug effects / Q000254:growth & development*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013997:Time Factors
chemical_list: D003348:Cortisone