Zinc erythrocyte protoporphyrin as marker of malaria risk in pregnancy - a retrospective cross-sectional and longitudinal study.

BACKGROUND: The effects of iron interventions and host iron status on infection risk have been a recurrent clinical concern, although there has been little research on this interaction in pregnant women. METHODS: Cross-sectional and longitudinal analyses were undertaken to determine the association of whole blood zinc erythrocyte protoporphyrin (ZPP) with malaria parasitaemia in pregnant women attending antenatal and delivery care at Montfort and Chikwawa Hospitals, Shire Valley, Malawi. Prevalence of antenatal, delivery and placental malaria was assessed in relation to maternal ZPP levels. The main outcome measures were prevalence of peripheral and placental Plasmodium falciparum parasitaemia and odds ratios of malaria risk. RESULTS: A total of 4,103 women were evaluated at first antenatal visit, of whom at delivery 1327 were screened for peripheral and 1285 for placental parasitaemia. Risk of malaria at delivery (peripheral or placental) was higher in primigravidae (p < 0.001), and lower (peripheral) with use of intermittent preventive anti-malarials during pregnancy (p < 0.001). HIV infection was associated with increased malaria parasitaemia (p < 0.02, peripheral or placental). Parasitaemia prevalence was lower in women with normal ZPP levels compared to those with raised concentrations at both first antenatal visit (all gravidae, p = 0.048, and at delivery (all gravidae, p < 0.001; primigravidae, p = 0.056). Between first antenatal visit and delivery women who transitioned from raised (at first antenatal visit) to normal ZPP values (at delivery) had lower peripheral parasitaemia prevalence at delivery compared to those who maintained normal ZPP values at both these visits (all gravidae: 0.70, 95%CI 0.4-1.1; primigravidae: 0.3, 0.1-0.8). In regression analysis this difference was lost with inclusion of HIV infection in the model. CONCLUSIONS: Raised ZPP concentrations in pregnancy were positively associated with P. falciparum parasitaemia and were probably secondary to malaria inflammation, rather than indicating an increased malaria risk with iron deficiency. It was not possible from ZPP measurements alone to determine whether iron deficiency or repletion alters malaria susceptibility in pregnancy.

Reduced risk for placental malaria in iron deficient women.

BACKGROUND: Nutritional 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. METHODS: A 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. RESULTS: 112 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. CONCLUSION: Women 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.