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Anemia is common in women of child-bearing age in the Democratic Republic of the Congo (DRC). As part of the 2007 DRC Demographic and Health Survey (DHS), 4638 women of childbearing age (including 526 pregnant women) were tested for HIV and had the hemoglobin content of their blood recorded. We used the leftover dried blood spots to assess malaria prevalence using PCR assays. The DHS provided extensive information on individuals, as well as the geographic coordinates of household clusters which enabled us to derive several variables that characterize the spatial context of these clusters. Multilevel analyses were conducted to determine individual and contextual risk factors for anemia. Prevalence varied geographically; the odds of anemia were associated with both one's ethnic group and the amount and type of nearby agriculture. The odds were not affected by HIV or malaria status., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A real-time PCR assay was developed to detect the K76T point mutation in the Plasmodium falciparum putative chloroquine resistance transporter gene. The assay was used with malaria positive clinical isolates from Rutshuru in the eastern part of the Democratic Republic of the Congo (DRC) and from Malawi. The K76T mutation was found in 52/56 (93%) clinical isolates from the DRC, where chloroquine resistance is high, but in none of the 12 isolates tested from Malawi where chloroquine is now rarely used. Sixteen percent of specimens from the DRC had detectable levels of both wild-type and mutant alleles. The real-time PCR results were compared to results from a nested allele-specific PCR assay and from direct DNA sequencing. Using allele-specific PCR as the reference method, the new assay is 100% sensitive and specific towards the mutant allele. In addition to its low per-test cost, the new assay is fast, easily automated, sensitive and well-suited to large-scale epidemiological studies.

Background: HIV infection increases the risk of malaria infection in pregnant women. Antibodies to variant surface antigens (VSA) on infected erythrocytes might protect against malaria in pregnancy. We postulated that HIV-induced impairment of humoral immunity to VSA mediates the increased susceptibility to malaria., Methods: We compared serum concentrations of antibodies to VSA by flow cytometry or agglutination, and to merozoite proteins AMA-1 and MSP119 by ELISA, in 298 pregnant Malawian women, and related the findings to malaria and HIV infection, CD4-positive T-cell count, and HIV-1 viral load., Findings: Concentrations of IgG to placental type VSA were lower in HIV-infected women than in HIV-uninfected women (median 8 units [IQR 4-23] vs 20 [12-30]; p<0.0001), among women with malaria (p=0.009) and those without malaria (p=0.0062). The impairment was greatest in first pregnancy. Agglutinating antibodies to placental VSA were present in a lower proportion of HIV-infected than HIV-uninfected women (58 [35.1%] of 165 vs 50 [53.8%] of 93, p<0.001). The degree of antibody binding by flow cytometry was correlated with CD4-positive T-cell count (r=0.16, p=0.019) and inversely with HIV-1 viral load (r=-0.16, p=0.030). Concentrations of antibodies to AMA-1 were lower in HIV infection (p<0.0001) but were not correlated with CD4-positive T-cell count or viral load. Responses to MSP119 were little affected by HIV infection. In multivariate analyses, HIV was negatively associated with amount of antibody to both VSA and AMA-1 (p<0.001 for each) but not MSP119., Interpretation: HIV infection impairs antimalarial immunity, especially responses to placental type VSA. The impairment is greatest in the most immunosuppressed women and could explain the increased susceptibility to malaria seen in pregnant women with HIV infection.

Malaria infections in pregnant women cause poor birth outcomes. Malaria pigment (haemozoin) accumulates in the placenta within macrophages and extracellularly, but its pathological significance is not understood. In order to study the potential role of haemozoin in malaria pathogenesis, we enrolled primigravid women at a Malawian government antenatal clinic and followed them through delivery. One hundred and thirteen women (71 per cent) out of 159 women followed through delivery were parasitaemic at least once. Mean placental haemozoin concentrations were significantly higher in women with delivery parasitaemias (223 ng/mg protein) than in women who never had a detectable parasitaemia (43 ng/mg protein; P<0.05), but were not significantly higher in women who were parasitaemic only during the antenatal period (67 ng/mg protein). Haemozoin was not associated with preterm delivery (PTD) or intrauterine growth retardation (IUGR) (P -values, 0.307-0.787). Thus, placental haemozoin is associated with malaria infection at the time of delivery and does not seem to be associated with poor birth outcome., (Copyright 2000 Harcourt Publishers Ltd.)

Artemisinin derivatives are endoperoxide antimalarials widely used to treat falciparum malaria in areas where drug resistance is common. In Plasmodium falciparum-infected erythrocytes, radiolabeled artemisinin derivatives have been shown to react with malarial proteins, one of which is the Translationally Controlled Tumor Protein (TCTP). The P. falciparum TCTP was found by immunofluorescence to be located in both the cytoplasm and food vacuoles. Immunoelectron microscopy shows that it is present in the parasite cytoplasm as well as in its food vacuolar and limiting membranes. Like other TCTPs, the P. falciparum protein binds to calcium. Further studies on the physiological role of TCTP may aid in understanding the mechanism of action of endoperoxide antimalarials.

Artemisinin (qinghaosu) and its derivatives are endoperoxide-containing compounds that are an important new class of antimalarial drugs. Tritiated dihydroartemisinin is taken up and concentrated by isolated red cell membranes but not by intact erythrocytes. More than half of the membrane-associated drug can be released by treatment with phospholipase A2 followed by extraction with ethyl acetate. The remaining drug appears to be bound to the major red cell membrane proteins. There is no association of the drug with either the membrane or cytoplasm of intact red cells. Thus dihydroartemisinin appears to be taken up by isolated membranes, where it associates with proteins but not via intact red cells.

A number of quinones have been shown to be effective antimalarials. In addition some have been shown to have oxidant effects on glucose-6-phosphate dehydrogenase-deficient red cells. To clarify the mechanism of this oxidant effect and to determine whether it is a general property of antimalarial quinones, the effects of five compounds on red cells were studied. Two, 5-hydroxy-6-demethyl pentaquine (5H6DP) and menadione, caused marked methemoglobin production and the insertion of heme into the red-cell membrane. The other three, atovaquone, daphnetin, and menoctone, did not. The insertion of heme into membranes caused diminished deformability, and this might account for the hemolytic effects. Redox potentials of all five compounds were measured. The two quinones that caused heme release, menadione and 5H6DP, had redox potentials of -141 +/- 12 and -97 +/- 25 mV, respectively, which are similar to the reported redox potentials for hemoglobin. The other three quinones had redox potentials that were either significantly higher or lower. Thus only quinones of the appropriate redox potentials are likely to be toxic to red cells.

Qinghaosu, a potent antimalarial agent, has recently been shown to act via oxidative mechanisms. Hence, we have investigated what effect qinghaosu has on cellular oxidation in normal and oxidant-sensitive red blood cells (RBCs). At 500 mumol/L, qinghaosu was found to directly alter red cell deformability (DI) in both normal (hemoglobin AA) and abnormal (hemoglobins SS, AE, and EE) RBCs, with the maximum DI being 70% to 80% of that of untreated RBCs. Although concentrations of less than or equal to 200 mumol/L qinghaosu had a minimal effect on the maximum DI, qinghaosu was found to act as an efficient prooxidant at these concentrations. Cellular deformability was lost more rapidly in response to exogenous oxidants in the qinghaosu-treated RBCs than in control cells. Hemoglobin SS and EE RBCs pretreated with qinghaosu demonstrated a much more rapid decrease in cellular deformability than did the control RBCs in response to exogenous oxidants. Additionally, qinghaosu resulted in a dose-dependent increase in red cell lysis and methemoglobin generation while decreasing reduced glutathione concentration. As a consequence of qinghaosu challenge, a decrease in unsaturated fatty acids was noted. Deoxyqinghaosu, which lacks the endoperoxide bridge and is pharmacologically inactive, did not affect cellular deformability and did not function as a prooxidant. Additionally, deoxyqinghaosu had no effect on fatty acid composition, red cell lysis, methemoglobin generation, or reduced glutathione concentration. In conclusion, although the oxidative effects of qinghaosu on uninfected erythrocytes were only seen at concentrations much greater than that necessary for antimalarial activity, these results confirm the proposition that qinghaosu may act via oxidative mechanisms. Furthermore, qinghaosu-mediated oxidation was significantly increased in erythrocytes characterized by enhanced oxidant sensitivity caused by unstable hemoglobins.

Plasmodium berghei, a murine malaria, lacks endogenous superoxide dismutase (SOD). Instead it appears to take up and concentrate SOD from its host cell, the erythrocyte. We now demonstrate that the adopted host enzyme is localized in granules which are probably lysosomes. In addition, isolated P. berghei parasites contain only low levels of catalase, probably as a result of contamination of the preparation with host cell material. Thus, the cytosol of this organism appears to be deficient in enzymes which protect against damage by activated oxygen.