What does it take to control malaria?

Walther, Brigitte; Walther, Michael

doi:10.1179/136485907x229013

Cited by 12 publications

(14 citation statements)

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“…Overall, 109 countries are endemic for malaria; 45 of these are in Africa [1]. While work continues toward a malaria vaccine, prompt diagnosis and effective treatment remain, in addition to vector control measures, mainstays of malaria control [2]. Unfortunately, disease control is strongly compromised by the emergence of resistance to commonly used drugs [3].…”

Section: Introductionmentioning

confidence: 99%

Plasmodium falciparum isolates from Angola show the StctVMNT haplotype in the pfcrt gene

Gama

Pereira-Carvalho

Kosi

et al. 2010

Malar J

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BackgroundEffective treatment remains a mainstay of malaria control, but it is unfortunately strongly compromised by drug resistance, particularly in Plasmodium falciparum, the most important human malaria parasite. Although P. falciparum chemoresistance is well recognized all over the world, limited data are available on the distribution and prevalence of pfcrt and pfmdr1 haplotypes that mediate resistance to commonly used drugs and that show distinct geographic differences.MethodsPlasmodium falciparum-infected blood samples collected in 2007 at four municipalities of Luanda, Angola, were genotyped using PCR and direct DNA sequencing. Single nucleotide polymorphisms in the P. falciparum pfcrt and pfmdr1 genes were assessed and haplotype prevalences were determined.Results and DiscussionThe most prevalent pfcrt haplotype was StctVMNT (representing amino acids at codons 72-76). This result was unexpected, since the StctVMNT haplotype has previously been seen mainly in parasites from South America and India. The CVIET, CVMNT and CVINT drug-resistance haplotypes were also found, and one previously undescribed haplotype (CVMDT) was detected. Regarding pfmdr1, the most prevalent haplotype was YEYSNVD (representing amino acids at codons 86, 130, 184, 1034, 1042, 1109 and 1246). Wild haplotypes for pfcrt and pfmdr1 were uncommon; 3% of field isolates harbored wild type pfcrt (CVMNK), whereas 21% had wild type pfmdr1 (NEYSNVD). The observed predominance of the StctVMNT haplotype in Angola could be a result of frequent travel between Brazil and Angola citizens in the context of selective pressure of heavy CQ use.ConclusionsThe high prevalence of the pfcrt SVMNT haplotype and the pfmdr1 86Y mutation confirm high-level chloroquine resistance and might suggest reduced efficacy of amodiaquine in Angola. Further studies must be encouraged to examine the in vitro sensitivity of pfcrt SVMNT parasites to artesunate and amodiaquine for better conclusive data.

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Section: Introductionmentioning

confidence: 99%

Plasmodium falciparum isolates from Angola show the StctVMNT haplotype in the pfcrt gene

Gama

Pereira-Carvalho

Kosi

et al. 2010

Malar J

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“…Malaria is one of the most prevalent infections in the world and constitutes one of the main causes of death in much of the tropics (Walther and Walther 2007; Rowe et al 2007). Plasmodium falciparum is increasingly resistant to available antimalarial agents, and so, the identification of new compounds that are active against the parasite is an urgent priority.…”

Section: Introductionmentioning

confidence: 99%

Antiplasmodial volatile extracts from Cleistopholis patens Engler & Diels and Uvariastrum pierreanum Engl. (Engl. & Diels) (Annonaceae) growing in Cameroon

et al. 2010

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In a search for alternative treatment for malaria, plant-derived essential oils extracted from the stem barks and leaves of Cleistopholis patens and Uvariastrum pierreanum (Annonaceae) were evaluated in vitro for antiplasmodial activity against the W2 strain of Plasmodium falciparum. The oils were obtained from 500 g each of stem barks and leaves, respectively, by hydrodistillation, using a Clevenger-type apparatus with the following yields: 0.23% and 0.19% for C. patens and 0.1% and 0.3% for U. pierreanum (w/w relative to dried material weight). Analysis of 10% (v/v) oil in hexane by gas chromatography and mass spectrometry identified only terpenoids in the oils, with over 81% sesquiterpene hydrocarbons in C. patens extracts and U. pierreanum stem bark oil, while the leaf oil from the latter species was found to contain a majority of monoterpenes. For C. patens, the major components were α-copaene, δ-cadinene, and germacrene D for the stem bark oil and β-caryophyllene, germacrene D, and germacrene B for the leaf oil. The stem bark oil of U. pierreanum was found to contain mainly β-bisabolene and α-bisabolol, while α-and β-pinenes were more abundant in the leaf extract. Concentrations of oils obtained by diluting 1-mg/mL stock solutions were tested against P. falciparum in culture. The oils were active, with IC 50 values of 9.19 and 15.19 μg/mL for the stem bark and leaf oils, respectively, of C. patens and 6.08 and 13.96 μg/mL, respectively, for those from U. pierreanum. These results indicate that essential oils may offer a promising alternative for the development of new antimalarials. IntroductionA multitude of biological activities have been described for essential oils. The physicochemical properties of these substances, including ready diffusion across cell membranes (acting as drug transport enhancers; Cornwell and Barry 1994) and other specific actions on parasite metabolism, e.g., modulators of P-glycoprotein drug efflux activity (Calcabrini et al. 2004;Munoz-Martinez et al. 2004) and protein isoprenylation (Moura et al. 2001), are likely to explain their biological activities.Malaria is one of the most prevalent infections in the world and constitutes one of the main causes of death in much of the tropics (Walther and Walther 2007;Rowe et al. 2007). Plasmodium falciparum is increasingly resistant to available antimalarial agents, and so, the identification of new compounds that are active against the parasite is an urgent priority.Nonvolatile natural products have been widely investigated for antiplasmodial activity, with encouraging results F. F. Boyom (*) : V. Ngouana : E. A. M. Kemgne :

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“…Despite the availability of appropriate tools to control malaria and recently strengthened efforts to employ them efficiently [1], the latest estimates still consider 3.3 billion people at risk of acquiring malaria each year. In 2006, 247 million malaria cases were reported, causing almost one million deaths [2].…”

Section: Introductionmentioning

confidence: 99%

Placental Malaria is associated with reduced early life weight development of affected children independent of low birth weight

Walther

Miles

Crozier

et al. 2010

Malar J

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BackgroundInfection with Plasmodium falciparum during pregnancy contributes substantially to the disease burden in both mothers and offspring. Placental malaria may lead to intrauterine growth restriction or preterm delivery resulting in low birth weight (LBW), which, in general, is associated with increased infant morbidity and mortality. However, little is known about the possible direct impact of the specific disease processes occurring in PM on longer term outcomes such as subsequent retarded growth development independent of LBW.MethodsIn an existing West-African cohort, 783 healthy infants with a birth weight of at least 2,000 g were followed up during their first year of life. The aim of the study was to investigate if Plasmodium falciparum infection of the placenta, assessed by placental histology, has an impact on several anthropometric parameters, measured at birth and after three, six and 12 months using generalized estimating equations models adjusting for moderate low birth weight.ResultsIndependent of LBW, first to third born infants who were exposed to either past, chronic or acute placental malaria during pregnancy had significantly lower weight-for-age (-0.43, 95% CI: -0.80;-0.07), weight-for-length (-0.47, 95% CI: -0.84; -0.10) and BMI-for-age z-scores (-0.57, 95% CI: -0.84; -0.10) compared to infants born to mothers who were not diagnosed with placental malaria (p = 0.019, 0.013, and 0.012, respectively). Interestingly, the longitudinal data on histology-based diagnosis of PM also document a sharp decline of PM prevalence in the Sukuta cohort from 16.5% in 2002 to 5.4% in 2004.ConclusionsIt was demonstrated that PM has a negative impact on the infant's subsequent weight development that is independent of LBW, suggesting that the longer term effects of PM have been underestimated, even in areas where malaria transmission is declining.

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What does it take to control malaria?

Cited by 12 publications

References 65 publications

Plasmodium falciparum isolates from Angola show the StctVMNT haplotype in the pfcrt gene

Plasmodium falciparum isolates from Angola show the StctVMNT haplotype in the pfcrt gene

Antiplasmodial volatile extracts from Cleistopholis patens Engler & Diels and Uvariastrum pierreanum Engl. (Engl. & Diels) (Annonaceae) growing in Cameroon

Placental Malaria is associated with reduced early life weight development of affected children independent of low birth weight

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