Reduced risk for placental malaria in iron deficient women

Edward L Senga,Gregory Harper,Bernard J Brabin,Peter N Kazembe,Gibby Koshy

doi:10.1186/1475-2875-10-47

Abstract

BackgroundNutritional iron deficiency may limit iron availability to the malaria parasite reducing infection risk, and/or impair host immunity thereby increasing this risk. In pregnant women, there is evidence of an adverse effect with iron supplementation, but the few reported studies are strongly confounded.MethodsA case control study in pregnant Malawian women was undertaken in Chikhwawa southern Malawi in order to describe iron status in relation to placental malaria controlling for several confounding factors. Pregnancy characteristics were obtained and a blood sample at delivery. A full blood count was performed and serum ferritin and transferrin receptor quantified by enzyme-linked immunoassay. DNA analysis was used to identify genetic polymorphisms for ABO phenotype, hemoglobin HbS, and glucose -6 phosphate dehydrogenase deficiency. Placental tissue was obtained and malaria histology classified as active, past or no malaria infection.Results112 cases with placental malaria were identified and 110 women with no evidence of placental infection. Iron deficiency was less frequent in women with placental Plasmodium falciparum infection. In those with acute, chronic or past placental infections the odds ratio for iron deficiency was 0.4, 95% CI 0.2-0.8, p = 0.01; for acute and chronic infections 0.4, 0.2-0.8, p = 0.006; for acute infection 0.3, 0.1-0.7, p = 0.001. The association was greater in multigravidae.ConclusionWomen with either acute, or acute and chronic placental malaria were less likely to have iron deficiency than women without placental malaria infection There is a priority to establish if reversing iron deficiency through iron supplementation programs either prior to or during pregnancy enhances malaria risk.

Highlights

Nutritional iron deficiency may limit iron availability to the malaria parasite reducing infection risk, and/or impair host immunity thereby increasing this risk
Between February-June 2004 and January-July 2005 a total of 112 infected cases were identified who were compared with the first 110 women identified with no evidence of placental infection
There were no significant differences between cases and controls for the following parameters: mean age and parity, proportion with low mid-upper arm circumference (< 23 cm), marital or literacy status, adolescents, frequency of use of insecticide treated bed nets or uptake of IPTp-SP during pregnancy. 44.1% of cases and 42.5% of controls were anaemic (Hb < 11g/dl), There were no differences between cases and controls in prevalence of severe anaemia (Hb < 8 g/dl, mean 5.9%), glucose -6-phosphate dehydrogenase deficiency (G6PD)

Summary

Introduction

Nutritional iron deficiency may limit iron availability to the malaria parasite reducing infection risk, and/or impair host immunity thereby increasing this risk. There is evidence of an adverse effect with iron supplementation, but the few reported studies are strongly confounded. A recent Cochrane analysis of 68 trials of iron supplementation observed an increased risk of malaria with iron in trials that did not provide malaria surveillance and treatment [3]. Two uncontrolled studies reported parenteral iron given to severely anaemic women was associated with higher risk of P. falciparum malaria at delivery [8,9], one of which reported the association in primiparae, but not multiparae [9] As these women receiving parenteral iron all had severe antenatal anaemia, they would be the more likely to have malaria at the time of treatment and delivery independent of iron prescription. A single crosssectional study at delivery reported iron deficiency was associated with decreased the risk of placental parasitaemia especially in the first pregnancy [10]

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Conclusion