Figure 6.
Intradermal infection with 102 Trypanosoma congolense, clone TC13, renders mice more susceptible to an intradermal reinfection with T. congolense, clone TC14. Mice were infected intradermally in a hind footpad with 102 T. congolense, clone TC13, 3 times at weekly intervals. These mice did not develop any detectable parasitemia during this period of low-dose exposure. Ten days after the last infection, the preexposed mice and unexposed control mice were infected intradermally in a hind footpad with T. congolense, clone TC14. Parasitemia and survival time (in BALB/c mice) was monitored after infection with T. congolense, clone TC14. A, 6 control BALB/c mice were infected intradermally in a hind footpad with 103 T. congolense TC14. B, 10 BALB/c mice were preexposed to 102 T. congolense TC13 and challenged with 103 T. congolense TC14. C, Survival times in control and preexposed mice challenged with 103 T. congolense TC14; the survival time in the preexposed mice was significantly (P < .02) shorter than that in the control mice. D, C57BL/6 control mice were infected with 104 T. congolense, TC14. E, Eight C57BL/6 mice preexposed to 102 T. congolense TC13 and challenged with 104 T. congolense TC14. *