Modes of entry of the first-stage larvae of Elaphostrongylus cervi (Nematoda: Protostrongylidae) into pulmonate snails Arianta arbustorum and Helix pomatia.

Experimental infection of the pulmonate snails Arianta arbustorum L. and Helix pomatia L. with first-stage larvae of protostrongylid nematode Elaphostrongylus cervi Cameron, 1931 was performed in order to determine modes of larval entry into the body of the snail intermediate host. Groups by four individuals of both snail species were examined histologically 30, 60, 90, and 120 minutes after the beginning of exposure and 1, 2, 4, and 7 days post infection. All 64 snails examined were found to be successfully infected. The superficial furrows of the sole were recognized as the most important site of larval entry into the snail organism. Larval penetration was observed to be accompanied by destruction of the superficial epithelium. The number of larvae found in the subepithelial connective tissue of the headfoot was significantly higher than that found in other tissues and organs. Larval counts in individual parts of the body of snails examined from 0 to 7 days p.i. did not fluctuate significantly. The present results indicate that only those protostrongylid larvae which actively penetrated the superficial epithelium of the snail sole play an important role in the life cycle.