Host resistance to Hymenolepis nana. II. Specificity of resistance to reinfection in the direct cycle

Abstract

The effect of prior infection with various helminths upon a challenge infection with eggs of Hymenolepis nana was studied in laboratory rodents. The nematodes, Capillaria hepatica, Ascaris lumbricoides, and Trichinella spiralis, were either without effect or produced transient changes in host reactivity to challenge with H. nana. In contrast, prior infection with the cestode species, Hydatigera taeniaeformis, Taenia crassiceps, Hymenolepis microstoma, and H. citelli enhanced resistance to H. nana to a variable degree. A single experiment with H. diminuta was inconclusive. The effects upon H. nana were persistent and appeared to be independent of survival of the primary cestodes. While cross-protection was marked in some experiments, the degree of host resistance elicited was not comparable to that evoked by light primary infections with eggs of H. nana, suggesting that a species-specific factor is important in acquired immunity to this parasite.