EPIDEMIOLOGY OF IRON-DEFICIENCY ANEMIA IN ZANZIBARI SCHOOLCHILDREN - THE IMPORTANCE OF HOOKWORMS

Anemia is estimated to affect one-half of school-age children in devel oping countries. The school years are an opportune time to intervene, and interventions must be based on sound epidemiologic understanding o f the problem in this age group. We report on the distribution of iron deficiency and anemia across age, sex, anthropometric indexes, and pa rasitic infections in a representative sample of 3595 schoolchildren f rom Pemba Island, Zanzibar. Iron status was assessed by hemoglobin ery throcyte protoporphyrin (EP), and serum ferritin concentrations from a venous blood sample. Overall, 62.3% of children were anemic (hemoglob in < 110 g/L), and 82.7% of anemia was associated with iron deficiency . The overall prevalence of iron-deficient erythropoiesis (EP > 90 mu mol/mol heme) was 48.5%, and the prevalence of exhausted iron stores ( serum ferritin < 12 mu g/L) was 41.3%. In bivariate analyses, iron sta tus was slightly better in girls than in boys, and was better in child ren aged 7-11 y than in those older or younger. Hemoglobin but not EP or serum ferritin concentrations were lower in stunted children. Infec tion with malaria, Trichuris trichiura, Ascaris lumbricoides, and hook worms were all associated with worse iron status; the association with hookworms was strongest by far. In multivariate analyses, hookworm in fection intensity was the strongest explanatory variable for hemoglobi n, EP, and serum ferritin. Sex, malarial parasitemia, A. lumbricoides infection, and stunting were also retained in the multivariate model f or hemoglobin. Twenty-five percent of all anemia, 35% of iron deficien cy anemia, and 73% of severe anemia were attributable to hookworm infe ction; < 10% of anemia was attributable to A. lumbricoides, malaria in fection, or stunting. We conclude that anthelminthic therapy is an ess ential component of anemia control in schoolchildren in whom hookworms are endemic, and should be complemented with school-based iron supple mentation.