Mating of Ancylostoma caninum in Relation to Blood Loss in the Host

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Abstract
By oral inoculation of juvenile or adult worms, unisexual or bisexual Ancylostoma caninum infections were established in 39 young dogs. Less than 100 adult females caused rapid blood loss and anemia in two dogs at the time when the worms began laying infertile eggs. Equally heavy all-male or balanced male-female infections did not cause detectable anemia. A higher percentage of males remained in recipient dogs when transferred with (62%), than without (49%), females, but females became established equally well with or without males (average 55%). The average rate of laceration (per 100 worms) was greatest in all-female (147) and unbalanced infections (97 and 134), least in all-male infections (21), and relatively low but highly variable in balanced infections (57, range 3 to 122). Laceration rate was not related to overall population density, but when worms were very unequally distributed as they often were in all-female infections, or bunched as they were when males congregated around receptive females, the focal laceration rates were high. Blood in the worm''s intestine was evident more frequently in females than in males, being seen in 53, 64, and 80% of females in balanced, unisexual, and unbalanced infections, respectively. The corresponding rates for males were 26, 9, and 37%. More than half of the worms of both sexes were unattached to the intestinal mucosa when observed 15 to 30 min after death of the host through Nembutal injection into the heart. The observations suggest that the female of A. caninum normally mates at intervals of 3 weeks or less, that mating behavior is attendant with laceration of the intestinal mucosa, especially when the sexes are highly unbalanced, and that mating may rank high among those activities of the hookworm which cause blood loss and anemia in the host.