Variations in Response to Filariform Larvae of Ancylostoma caninum in the Skin of Man

Reports on the reaction of the skin of man to penetration by filariform larvae of Ancylostoma caninum (Ercolani, 1859) Hall, 1913, have been in conflict on several points, particularly with regard to the subsequent behavior and fate of the worms. White and Dove (1929) described a transient papular dermatitis, clearly distinct from the clinical appearance of burrows that follow penetration by larvae of Ancylostoma braziliense de Fairo, 1910. Heydon (1929) and Fiilleborn (1930), however, reported a more prolonged reaction, apparently produced by deep penetration and an ensuing aimless migration or creeping eruption of the parasites through the superficial tissues. These reports raised the following questions: (1) are there separate strains of A. caninum, possessing variable abilities to invade the skin of man? or (2) does the human subject vary constitutionally in his ability to arrest the invasion of a parasite which may be considered uniform within its species ? The following work, carried out with a single culture of A. caninum larvae, presents evidence which would answer the latter question in the affirmative.