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

Background. The hookworms, Ancylostoma duodenale and Necator americanus, cause significant gastrointestinal blood loss. In clinical studies, greater blood losses have been reported with A. duodenale. However, there has been no evidence that endemic A. duodenalp infection has greater impact than N. americanus infection on the iron status of populations. Methods. In a sample of 525 school children in Pemba Island, Tanzania, we compared the degree of anaemia and iron deficiency associated with the two hookworm species at the individual and community (i.e. school) levels. Multiple regression was used to control for infection intensiiies and other child characteristics. Results. In the 492 children with hookworm positive faecal cultures, haemoglobin and ferritin concentrations decreased wilh increasing proportions of A. duodenale. Among children with only N. americanus larvae, the prevalence of anaemia was 60.5% and the prevalence of ferritin < 12 μg/l was 33.1%, while in children with ≤ 50% A. duodenale larvae, the respective prevaiences were 80.6% and 58.9%. When children were grouped by the prevalence of A. driodnmle at the school level, children from high prevalence (≤ 20%) schools had signficantly worse iron deficiency and anaemia than children from low prevalence schools. The species of hookworm being transmitted in a community influences the burden of iron deficiency anaemia in the community and should be considered in prioritizing and planning programmes for hookworm and anaemia control.