EPIDEMIOLOGIC EVIDENCE FOR A DIFFERENTIAL EFFECT OF HOOKWORM SPECIES,ANCYLOSTOMA-DUODENALE OR NECATOR-AMERICANUS, ON IRON STATUS OF CHILDREN

Background The hookworms, Ancylostama duodenale and Necator americanus , cause significant gastrointestinal blood loss. Ln clinical studies, greater blood losses have been reported with A. duodenale. However, th ere has been no evidence that endemic A. duodenale infection has great er impact than N. americanus infection on the iron status of populatio ns. Methods In a sample of 525 school children in Pemba Island, Tanzan ia, we compared the degree of anaemia and iron deficiency associated w ith the two hookworm species at the individual and community (i.e. sch ool) levels. Multiple regression was used to control for infection int ensities and other child characteristics. Results In the 492 children with hookworm positive faecal cultures, haemoglobin and ferritin conce ntrations decreased with increasing proportions of A. duodenale. Among children with only N. americanus larvae, the prevalence of anaemia wa s 60.5% and the prevalence of ferritin <12 mu g/l was 33.1%, while in children with greater than or equal to 50% A. duodenale larvae, the re spective prevalences were 80.6% and 58.9%. When children were grouped by the prevalence of A. duodenale at the school level, children from h igh prevalence (greater than or equal to 20%) schools had significantl y worse iron deficiency and anaemia than children from low prevalence schools. Conclusions The species of hookworm being transmitted in a co mmunity influences the: burden of iron deficiency anaemia in the commu nity, and should be considered in prioritizing and planning programmes for hookworm and anaemia central.