Effects of Crowding and of Superinfection on Habitat Selection and Egg Production in Ancylostoma caninum

Abstract

Twelve dogs were infected with single graded doses of Ancylostoma caninum infective larvae and 4 were superinfected with 4 graded doses of larvae per os given at weekly intervals. The egg production was determined daily and, approximately 2 months after inoculation, the number of adults and their position in the intestine were observed. The data collected indicated that, both in the super-infected animals and in those with single infections, as the worm burden and the consequent degree of crowding increased, the number of eggs produced per female worm decreased. Superinfection apparently had no influence on the rate of egg output. A greater proportion of adults was found in the jejunum in 9 of the animals and in the ileum in the remaining 7. However, the most densely populated area was the duodenum in 2 of the animals, the jejunum in 10, and the ileum in 4. The concentration of worms in a particular region could not be correlated with an increase or decrease in the rate of egg production. The percentage of larvae developed into adult worms decreased as the number of inoculated larvae increased above 100. Relatively fewer larvae developed into adults in superinfected than in singly infected animals.