Published online by Cambridge University Press: 06 April 2009
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 (≤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 4days 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 worms' entry into the bile duct which occurs 3–4 days after infection.