Malaria News |
Control of pyrethroid and DDT-resistant Anopheles gambiae by application of indoor residual spraying or mosquito nets treated with a long-lasting organophosphate insecticide, chlorpyrifos-methyl 
Scaling up of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) with support from the Global Fund and President's Malaria Initiative is providing increased opportunities for malaria control in Africa. The most cost-effective and longest-lasting residual insecticide DDT is also the most environmentally persistent. Alternative residual insecticides exist, but are too short-lived or too expensive to sustain.
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Control of pyrethroid and DDT-resistant Anopheles gambiae by application of indoor residual spraying or mosquito nets treated with a long-lasting organophosphate insecticide, chlorpyrifos-methyl
Background:
Scaling up of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) with support from the Global Fund and President's Malaria Initiative is providing increased opportunities for malaria control in Africa. The most cost-effective and longest-lasting residual insecticide DDT is also the most environmentally persistent. Alternative residual insecticides exist, but are too short-lived or too expensive to sustain.
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Malaria Elimination: When the Tools Are Great but Implementation Falters 
In the current issue of the American Journal of Tropical Medicine and Hygiene, Silas Majambere and colleagues report the outcome of a trial to control malaria in rural parts of The Gambia through larval source management (LSM). In response to the increased uptake of treated bed nets and indoor residual spraying across Africa, various integrated programs that include LSM have been, or are being implemented, in line with the World Health Organization's (WHO) advocacy of integrated vector management (IVM). Area-wide larviciding thus seemed an attractive integral component for IVM along the Gambia River where annual flooding produces numerous breeding sites in the first kilometer of landward edges of the river. Parallel to this study, several authors were also engaged in a similar trial in West Kenya, the results of which were published recently, which showed unequivocally that larval control significantly enhanced the impact of bed net use only. Regretfully, in The Gambia the trial failed, with no reduction in clinical malaria, parasite prevalence, or anemia. This trial failed despite a massive 88% reduction in apparent larval densities. What went wrong?
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New malaria vaccine is safe and protective in children, scientists find 
A new vaccine to prevent the deadly malaria infection has shown promise to protect the most vulnerable patients -- young children -- against the disease, according to an international team of researchers. The vaccine seems to replicate in children the natural protective immunity that adults develop after years of intense exposure to malaria. A child dies of malaria every 30 seconds, according to the WHO.
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A Non-Radioactive DAPI-based High-Throughput In Vitro Assay to Assess Plasmodium falciparum Responsiveness to Antimalarials—Increased Sensitivity of P. falciparum to Chloroquine in Senegal
The spread of Plasmodium falciparum drug resistance is outpacing new antimalarial development and compromising effective malaria treatment. Combination therapy is widely implemented to prolong the effectiveness of currently approved antimalarials. To maximize utility of available drugs, periodic monitoring of drug efficacy and gathering of accurate information regarding parasite-sensitivity changes are essential. We describe a high-throughput, non-radioactive, field-based assay to evaluate in vitro antimalarial drug sensitivity of P. falciparum isolates from 40 Senegalese patients. Compared with earlier years, we found a significant decrease in chloroquine in vitro and in genotypic resistances (> 50% and > 65%, respectively, in previous studies) with only 23% of isolates showing resistance. This is possibly caused by a withdrawal of chloroquine from Senegal in 2002. We also found a range of artemisinin responses. Prevalence of drug resistance is dynamic and varies by region. Therefore, the implementation of non-radioactive, robust, high-throughput antimalarial sensitivity assays is critical for defining region-specific prophylaxis and treatment guidelines.
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Geographic Structure of Plasmodium vivax: Microsatellite Analysis of Parasite Populations from Sri Lanka, Myanmar, and Ethiopia
Genetic diversity and population structure of Plasmodium vivax parasites can predict the origin and spread of novel variants within a population enabling population specific malaria control measures. We analyzed the genetic diversity and population structure of 425 P. vivax isolates from Sri Lanka, Myanmar, and Ethiopia using 12 trinucleotide and tetranucleotide microsatellite markers. All three parasite populations were highly polymorphic with 3–44 alleles per locus. Approximately 65% were multiple-clone infections. Mean genetic diversity (HE) was 0.7517 in Ethiopia, 0.8450 in Myanmar, and 0.8610 in Sri Lanka. Significant linkage disequilibrium was maintained. Population structure showed two clusters (Asian and African) according to geography and ancestry. Strong clustering of outbreak isolates from Sri Lanka and Ethiopia was observed. Predictive power of ancestry using two-thirds of the isolates as a model identified 78.2% of isolates accurately as being African or Asian. Microsatellite analysis is a useful tool for mapping short-term outbreaks of malaria and for predicting ancestry.
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Community-based interventions to reduce maternal mortality 
Community programmes such as those suggested by Pagel and colleagues need to incorporate effective screening, prevention, and treatment measures for malaria, tuberculosis, bacterial sepsis, and HIV/AIDS, and operational studies will be required to delineate the factors that will determine acceptance by women and health officers in rural communities, and to evaluate effectiveness and cost-effectiveness.
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Burden of Malaria during Pregnancy at the Time of IPTp/SP Implementation in Gabon
The new recommendations to prevent malaria in pregnant women have recently been implemented in Gabon. There is little information on the pregnancy indicators that are useful for their evaluation. A cross-sectional study for the assessment of the prevalence of peripheral, placental, and cord malaria and anemia among delivering women was performed at the largest public hospital of Gabon. Malaria prevalence was 34.4%, 53.6%, and 18.2% for maternal peripheral, placental, and cord blood respectively, with no difference between primigravidae and multigravidae. Submicroscopic infections were frequent and concerned all the positive cord samples. Maternal peripheral, late placental, and cord infections were all associated with a reduced mean birth weight in primigravidae (P = 0.02). Anemia prevalence was 53%, low birth rate was 13%, and prematurity was 25%. The use of intermittent preventive treatment with sulfadoxine-pyrimethamine (greater than or equal to one dose) combined with bed net was associated with a reduction in infection only in multigravidae and with a reduced risk of maternal anemia.
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