Center for Human Nutrition and Division of Disease Control, Department of International Health, The Johns Hopkins University, Schistosomiasis and Intestinal Parasites Unit, Division of Tropical Diseases, World Health Organization, Ministry of Health, Division of Nutrition, Centers for Disease Control and Prevention, Baltimore, Maryland, Switzerland
Iron deficiency remains the most prevalent form of human malnutrition, and current interventions to control it have not decreased the global prevalence. Hookworm control activities are becoming more widely implemented, but the importance of these efforts to prevent anemia in populations is not well-defined. We studied the relationships among hookworm infection, intestinal blood loss, and iron status of 203 Zanzibari school children. Helminth infection intensity was quantified by fecal egg counts, and iron deficiency anemia was defined by low hemoglobin and serum ferritin concentrations. Intestinal blood loss was quantified by measuring fecal heme and heme breakdown products as porphyrin, a noninvasive method that has not been used previously to assess hookworm blood loss. Intestinal blood loss was strongly and linearly related to hookworm egg counts. The degree of degradation of fecal heme indicated that blood loss occurred in the upper gastrointestinal tract, compatible with the behavior of hookworms. Trichuris trichiura and Ascaris lumbricoides infections were also common, but did not contribute significantly to intestinal blood loss in this population. The prevalence of iron deficiency anemia increased steadily as hookworm infection intensity and intestinal blood loss increased. In the context of a poor diet, as exists in Zanzibar and many tropical countries, hookworm-related blood loss contributes dramatically to anemia. In such contexts, hookworm control is a feasible and essential component of anemia control. Determination of fecal heme is relatively simple and noninvasive and may be a useful tool for measuring the impact of hookworm control activities.