Epidemiological evidence for a differential effect of hookworm species, Ancylostoma duodenale or Necator americanus, on iron status of children

Hookworms infect 1.3 billion people annually. Iron-deficiency anemia caused or exacerbated by intestinal blood loss is the major feature of hookworm infection with such loss caused by the feeding of hookworms upon the intestinal mucosa. The hookworms Ancylostoma duodenale and Necator americanus cause major gastrointestinal blood loss. While relatively greater blood loss has been reported in clinical studies due to infection with A. duodenale there has been no evidence that endemic A. duodenale infection has a greater impact than N. americanus infection upon the iron status of populations. The authors compared the degree of anemia and iron deficiency associated with these 2 hookworm species at the individual and community levels using a sample of 525 school children in grades 1-4 in Pemba Island Tanzania and controlling for infection intensities and other child characteristics through multiple regression. In the 492 children with hookworm-positive fecal cultures hemoglobin and ferritin concentrations decreased with increasing proportions of A. duodenale. Among children with only N. americanus larvae the prevalence of anemia was 60.5% and the prevalence of ferritin under 12 mcg/l was 33.1%. In children with 50% or higher proportions of A. duodenale larvae the respective prevalences were 80.6% and 58.9%. Children from schools with high prevalences of A. duodenale infection had significantly worse iron deficiency and anemia than did children from low prevalence schools.