The topographic distribution of Necator americanus and Ancylostoma duodenale in the human intestine.

During an investigation in Dar es Salaam, Tanzania, 28 human intestinal tracts were systematically inspected on the presence of hookworms. In total, 643 hookworms (508 Necator americanus and 135 Ancylostoma duodenale) were isolated from 19 intestinal tracts. The localization of these hookworms was determined. N. americanus worms were concentrated in the duodenum and jejunum, whereas A. duodenale worms rather prefer the jejunum and proximal ileum. Some preference of hookworms for the antimesenteric site of the intestinal wall was found. The relative distance between adjoining worms in the observed hookworm populations was 3.8 cm on the average for Necator and 5.5 cm for Ancylostoma. The distribution of the sexes in the worm-population revealed no monosexual or bisexual prevalence of the hookworms.