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EY Lukianova-Hleb et al. Hemozoin-generated vapor nanobubbles for transdermal reagent- and needle-free detection of malaria. Proc Natl Acad Sci U S A

High Impact Journal from Malaria Portal - 31 December 2014 - 12:00am
Successful diagnosis, screening, and elimination of malaria critically depend on rapid and sensitive detection of this dangerous infection, preferably transdermally and without sophisticated reagents or blood drawing. . . .
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KJ Vogel et al. Phylogenetic investigation of Peptide hormone and growth factor receptors in five dipteran genomes. Front Endocrinol (Lausanne)

High Impact Journal from Malaria Portal - 31 December 2014 - 12:00am
Peptide hormones and growth factors bind to membrane receptors and regulate a myriad of processes in insects and other metazoans. . . .
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J Rydzak et al. Human erythrocyte glycophorin C as the receptor for EBA-140 Plasmodium falciparum merozoite ligand. Postepy Hig Med Dosw (Online)

High Impact Journal from Malaria Portal - 31 December 2014 - 12:00am
Erythrocyte invasion by the blood-stage Plasmodium falciparum parasites is a multistep process involving specific interactions between parasites and red blood cells. . . .
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R Sundararajan et al. Barriers to Malaria Control among Marginalized Tribal Communities: A Qualitative Study. PLoS One

High Impact Journal from Malaria Portal - 30 December 2014 - 12:00am
Malaria infection accounts for over one million deaths worldwide annually. . . .
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DV Canyon et al. Insights in public health: systems thinking: basic constructs, application challenges, misuse in health, and how public health leaders can pave the way forward. Hawaii J Med Public Health

High Impact Journal from Malaria Portal - 30 December 2014 - 12:00am
The strengthening of health systems is fundamental to improving health outcomes, crisis preparedness, and our capacity to meet global challenges, such as accelerating progress towards the Millennium Development Goals, reducing maternal and child mortality, combating HIV, malaria and other diseases, limiting the effects of a new influenza pandemic, and responding appropriately to climate change. . . .
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Low genetic diversity in the locus encoding the Plasmodium vivax P41 protein in Colombia's parasite population

Malaria Journal - 30 September 2014 - 12:00am
Background: The development of malaria vaccine has been hindered by the allele-specific responses produced by some parasite antigens' high genetic diversity. Such antigen genetic diversity must thus be evaluated when designing a completely effective vaccine. Plasmodium falciparum P12, P38 and P41 proteins have red blood cell binding regions in the s48/45 domains and are located on merozoite surface, P41 forming a heteroduplex with P12. These three genes have been identified in Plasmodium vivax and share similar characteristics with their orthologues in Plasmodium falciparum. Plasmodium vivax pv12 and pv38 have low genetic diversity but pv41 polymorphism has not been described. Methods: The present study was aimed at evaluating the P. vivax p41 (pv41) gene's polymorphism. DNA sequences from Colombian clinical isolates from pv41 gene were analysed for characterising and studying the genetic diversity and the evolutionary forces that produced the variation pattern so observed. Results: Similarly to other members of the 6-Cys family, pv41 had low genetic polymorphism. pv41 3[prime]-end displayed the highest nucleotide diversity value; several substitutions found there were under positive selection. Negatively selected codons at inter-species level were identified in the s48/45 domains; p41 would thus seem to have functional/structural constraints due to the presence of these domains. Conclusions: In spite of the functional constraints of Pv41 s48/45 domains, immune system pressure seems to have allowed non-synonymous substitutions to become fixed within them as an adaptation mechanism; including Pv41 s48/45 domains in a vaccine should thus be carefully evaluated due to these domains containing some allele variants.
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Spatial clustering and risk factors of malaria infections in Ratanakiri Province, Cambodia

Malaria Journal - 30 September 2014 - 12:00am
Background: Malaria incidence worldwide has steadily declined over the past decades. Consequently, increasingly more countries will proceed from control to elimination. The malaria distribution in low incidence settings appears patchy, and local transmission hotspots are a continuous source of infection. In this study, species-specific clusters and associated risk factors were identified based on malaria prevalence data collected in the north-east of Cambodia. In addition, Plasmodium falciparum genetic diversity, population structure and gene flows were studied.MethodIn 2012, blood samples from 5793 randomly selected individuals living in 117 villages were collected from Ratanakiri province, Cambodia. Malariometric data of each participant were simultaneously accumulated using a standard questionnaire. A two-step PCR allowed for species-specific detection of malaria parasites, and SNP-genotyping of P. falciparum was performed. SaTScan was used to determine species-specific areas of elevated risk to infection, and univariate and multivariate risk analyses were carried out.Result: PCR diagnosis found 368 positive individuals (6.4%) for malaria parasites, of which 22% contained mixed species infections. The occurrence of these co-infections was more frequent than expected. Specific areas with elevated risk of infection were detected for all Plasmodium species. The clusters for Falciparum, Vivax and Ovale malaria appeared in the north of the province along the main river, while the cluster for Malariae malaria was situated elsewhere. The relative risk to be a malaria parasite carrier within clusters along the river was twice that outside the area. The main risk factor associated with three out of four malaria species was overnight stay in the plot hut, a human behaviour associated with indigenous farming. Haplotypes did not show clear geographical population structure, but pairwise Fst value comparison indicated higher parasite flow along the river.DiscussionSpatial aggregation of malaria parasite carriers, and the identification of malaria species-specific risk factors provide key insights in malaria epidemiology in low transmission settings, which can guide targeted supplementary interventions. Consequently, future malaria programmes in the province should implement additional specific policies targeting households staying overnight at their farms outside the village, in addition to migrants and forest workers.
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Humanized HLA-DR4.RagKO.IL2RgammacKO.NOD (DRAG) mice sustain the complex vertebrate life cycle of Plasmodium falciparum malaria

Malaria Journal - 30 September 2014 - 12:00am
Background: Malaria is a deadly infectious disease affecting millions of people in tropical and sub-tropical countries. Among the five species of Plasmodium parasites that infect humans, Plasmodium falciparum accounts for the highest morbidity and mortality associated with malaria. Since humans are the only natural hosts for P. falciparum, the lack of convenient animal models has hindered the understanding of disease pathogenesis and prompted the need of testing anti-malarial drugs and vaccines directly in human trials. Humanized mice hosting human cells represent new pre-clinical models for infectious diseases that affect only humans. In this study, the ability of human-immune-system humanized HLA-DR4.RagKO.IL2RgammacKO.NOD (DRAG) mice to sustain infection with P. falciparum was explored. Methods: Four week-old DRAG mice were infused with HLA-matched human haematopoietic stem cells (HSC) and examined for reconstitution of human liver cells and erythrocytes. Upon challenge with infectious P. falciparum sporozoites (NF54 strain) humanized DRAG mice were examined for liver stage infection, blood stage infection, and transmission to Anopheles stephensi mosquitoes. Results: Humanized DRAG mice reconstituted human hepatocytes, Kupffer cells, liver endothelial cells, and erythrocytes. Upon intravenous challenge with P. falciparum sporozoites, DRAG mice sustained liver to blood stage infection (average 3-5 parasites/microlitre blood) and allowed transmission to An. stephensi mosquitoes. Infected DRAG mice elicited antibody and cellular responses to the blood stage parasites and self-cured the infection by day 45 post-challenge. Conclusions: DRAG mice represent the first human-immune-system humanized mouse model that sustains the complex vertebrate life cycle of P. falciparum without the need of exogenous injection of human hepatocytes/erythrocytes or P. falciparum parasite adaptation. The ability of DRAG mice to elicit specific human immune responses to P. falciparum parasites may help deciphering immune correlates of protection and to identify protective malaria antigens.
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Spatial and temporal epidemiology of clinical malaria in Cambodia 2004-2013

Malaria Journal - 30 September 2014 - 12:00am
Background: Artemisinin-resistant Plasmodium falciparum malaria has recently been identified on the Thailand-Cambodia border and more recently in parts of Thailand, Myanmar and Vietnam. There is concern that if this resistance were to spread, it would severely hamper malaria control and elimination efforts worldwide. Efforts are currently underway to intensify malaria control activities and ultimately eliminate malaria from Cambodia. To support these efforts, it is crucial to have a detailed picture of disease burden and its major determinants over time. Methods: An analysis of spatial and temporal data on clinical malaria in Cambodia collected by the National Centre for Parasitology, Entomology and Malaria Control (CNM) and the Department of Planning and Health Information, Ministry of Health Cambodia from 2004 to 2013 is presented. Results: There has been a marked decrease of 81% in annual cases due to P. falciparum since 2009 coinciding with a rapid scale-up in village malaria workers (VMWs) and insecticide-treated bed nets (ITNs). Concurrently, the number of cases with Plasmodium vivax has greatly increased. It is estimated that there were around 112,000 total cases in 2012, 2.8 times greater than the WHO estimate for that year, and 68,000 in 2013 (an annual parasite incidence (API) of 4.6/1000). With the scale-up of VMWs, numbers of patients presenting to government facilities did not fall and it appears likely that those who saw VMWs had previously accessed healthcare in the private sector. Malaria mortality has decreased, particularly in areas with VMWs. There has been a marked decrease in cases in parts of western Cambodia, especially in Pailin and Battambang Provinces. In the northeast, the fall in malaria burden has been more modest, this area having the highest API in 2013. Conclusion: The clinical burden of falciparum malaria in most areas of Cambodia has greatly decreased from 2009 to 2013, associated with roll-out of ITNs and VMWs. Numbers of cases with P. vivax have increased. Possible reasons for these trends are discussed and areas requiring further study are highlighted. Although malaria surveillance data are prone to collection bias and tend to underestimate disease burden, the finding of similar trends in two independent datasets in this study greatly increased the robustness of the findings.
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Mosquito magnet(R) liberty plus trap baited with octenol confirmed best candidate for Anopheles surveillance and proved promising in predicting risk of malaria transmission in French Guiana

Malaria Journal - 26 September 2014 - 12:00am
Background: In French Guiana, Mosquito Magnet(R) Liberty Plus trap baited with octenol (MMoct) has been proposed for sampling Anopheles darlingi after comparison with CDC light trap and Human landing catch (HLC). However, other available lures were not tested. The current study compared MMoct and MM baited with LurexTM (MMlur) to HLC, and analysed entomological data from MMoct collection with malaria cases to facilitate malaria surveillance. Methods: Two independent experiments were conducted during 2012 and 2013 in Saint-Georges town, French Guiana. The first experiment used Latin square design to compare MMoct and MMlur to HLC between 18:30 to 22:30 and 05:00 to 07:00. Parity rate was determined for An. darlingi from each sampling system. In the second experiment, a 24:00 hour collection was done for four consecutive days during the first week of each month and every four days for the rest of the month using MMoct. Portion of the 24 hour collection was dissected for parity rate. All anophelines were screened for Plasmodium infection by PCR. Data for number of malaria cases was analysed for association with density of An. darlingi. Results: In the first experiment, 3,721 anopheline mosquitoes were collected over 21 nights. Of these, 95.7% was identified morphologically to five species and An. darlingi contributed 98.4%, mainly from HLC (75.1%, CI95% [73.2-77.0]) than MMoct (14.1%, CI95% [12.6-15.7]) and MMlur (10.8%, CI95% [9.4-12.2]). Species richness was highest in HLC meanwhile species diversity index was greatest in MMoct. MMoct collected more parous An. darlingi than HLC (p < 0.0001) and MMlur (p = 0.0021). The second experiment amounted to 2035 females, 60.8% belonging to 10 species. Anopheles darlingi constituted 85.0% of the species and had parity rate of 52.3%. Specimens were uninfected with Plasmodium. Density of An. darlingi best correlated with malaria cases observed six weeks later (p = 0.0016; r = 0.4774). Conclusion: Though MMoct and MMlur performed well in sampling An. darlingi, MMoct captured more species and, therefore, would be useful for surveillance. Even if it collected mostly parous mosquitoes, MMoct proved useful in collecting entomological data required for predicting malaria emergence. It is a potential replacement for HLC.
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Association between malaria control and paediatric blood transfusions in rural Zambia: an interrupted time-series analysis

Malaria Journal - 26 September 2014 - 12:00am
Background: Blood transfusions can reduce mortality among children with severe malarial anaemia, but there is limited evidence quantifying the relationship between paediatric malaria and blood transfusions. This study explores the extent to which the use of paediatric blood transfusions is affected by the number of paediatric malaria visits and admissions. It assesses whether the scale-up of malaria control interventions in a facility catchment area explains the use of paediatric blood transfusions. Methods: The study was conducted at a referral hospital for 13 rural health centres in rural Zambia. Data were used from facility and patient records covering all paediatric malaria admissions from 2000 to 2008. An interrupted time series analysis using an autoregression-moving-average model was conducted to assess the relationship between paediatric malaria outpatient visits and admissions and the use of paediatric blood transfusions. Further investigation explored whether the use of paediatric blood transfusions over time was consistent with the roll out of malaria control interventions in the hospital catchment area. Results: For each additional paediatric malaria outpatient visit, there were 0.07 additional paediatric blood transfusions (95% CI 0.01-0.13; p < 0.05). For each additional paediatric admission for severe malarial anaemia, there were 1.09 additional paediatric blood transfusions (95% CI 0.95-1.23; p < 0.01). There were 19.1 fewer paediatric blood transfusions per month during the 2004-2006 malaria control period (95% CI 12.1-26.0; p < 0.01), a 50% reduction compared to the preceding period when malaria control was relatively limited. During the 2007-2008 malaria control period, there were 27.5 fewer paediatric blood transfusions per month (95% CI 14.6-40.3; p < 0.01), representing a 72% decline compared to the period with limited malaria control. Conclusions: Paediatric admissions for severe malarial anaemia largely explain total use of paediatric blood transfusions. The reduction in paediatric blood transfusions is consistent with the timing of the malaria control interventions. Malaria control seems to influence the use of paediatric blood transfusions by reducing the number of paediatric admissions for severe malarial anaemia. Reduced use of blood transfusions could benefit other areas of the health system through greater blood availability, particularly where supply is limited.
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Transcriptome sequencing and analysis of Plasmodium gallinaceum reveals polymorphisms and selection on the apical membrane antigen-1

Malaria Journal - 26 September 2014 - 12:00am
Background: Plasmodium erythrocyte invasion genes play a key role in malaria parasite transmission, host-specificity and immuno-evasion. However, the evolution of the genes responsible remains understudied. Investigating these genes in avian malaria parasites, where diversity is particularly high, offers new insights into the processes that confer malaria pathogenesis. These parasites can pose a significant threat to birds and since birds play crucial ecological roles they serve as important models for disease dynamics. Comprehensive knowledge of the genetic factors involved in avian malaria parasite invasion is lacking and has been hampered by difficulties in obtaining nuclear data from avian malaria parasites. Thus the first Illumina-based de novo transcriptome sequencing and analysis of the chicken parasite Plasmodium gallinaceum was performed to assess the evolution of essential Plasmodium genes. Methods: White leghorn chickens were inoculated intravenously with erythrocytes containing P. gallinaceum. cDNA libraries were prepared from RNA extracts collected from infected chick blood and sequencing was run on the HiSeq2000 platform. Orthologues identified by transcriptome sequencing were characterized using phylogenetic, ab initio protein modelling and comparative and population-based methods. Results: Analysis of the transcriptome identified several orthologues required for intra-erythrocytic survival and erythrocyte invasion, including the rhoptry neck protein 2 (RON2) and the apical membrane antigen-1 (AMA-1). Ama-1 of avian malaria parasites exhibits high levels of genetic diversity and evolves under positive diversifying selection, ostensibly due to protective host immune responses. Conclusion: Erythrocyte invasion by Plasmodium parasites require AMA-1 and RON2 interactions. AMA-1 and RON2 of P. gallinaceum are evolutionarily and structurally conserved, suggesting that these genes may play essential roles for avian malaria parasites to invade host erythrocytes. In addition, host-driven selection presumably results in the high levels of genetic variation found in ama-1 of avian Plasmodium species. These findings have implications for investigating avian malaria epidemiology and population dynamics. Moreover, this work highlights the P. gallinaceum transcriptome as an important public resource for investigating the diversity and evolution of essential Plasmodium genes.
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Optimized Whole-Genome Amplification Strategy for Extremely AT-Biased Template

CiteULike malaria tags - 25 September 2014 - 10:37am
DNA Research (19 September 2014), doi:10.1093/dnares/dsu028

Pathogen genome sequencing directly from clinical samples is quickly gaining importance in genetic and medical research studies. However, low DNA yield from blood-borne pathogens is often a limiting factor. The problem worsens in extremely base-biased genomes such as the AT-rich Plasmodium falciparum. We present a strategy for whole-genome amplification (WGA) of low-yield samples from P. falciparum prior to short-read sequencing. We have developed WGA conditions that incorporate tetramethylammonium chloride for improved amplification and coverage of AT-rich regions of the genome. We show that this method reduces amplification bias and chimera formation. Our data show that this method is suitable for as low as 10 pg input DNA, and offers the possibility of sequencing the parasite genome from small blood samples.
Samuel Oyola, Magnus Manske, Susana Campino, Antoine Claessens, William Hamilton, Mihir Kekre, Eleanor Drury, Daniel Mead, Yong Gu, Alistair Miles, Bronwyn MacInnis, Chris Newbold, Matthew Berriman, Dominic Kwiatkowski
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A Polishko et al. PuFFIN - a parameter-free method to build nucleosome maps from paired-end reads. BMC Bioinformatics

High Impact Journal from Malaria Portal - 25 September 2014 - 12:00am
We introduce a novel method, called PuFFIN, that takes advantage of paired-end short reads to build genome-wide nucleosome maps with larger numbers of detected nucleosomes and higher accuracy than existing tools. . . .
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S Biswas et al. Assessment of Humoral Immune Responses to Blood-Stage Malaria Antigens following ChAd63-MVA Immunization, Controlled Human Malaria Infection and Natural Exposure. PLoS One

High Impact Journal from Malaria Portal - 25 September 2014 - 12:00am
The development of protective vaccines against many difficult infectious pathogens will necessitate the induction of effective antibody responses. . . .
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S Konzuch et al. Binding modes of reverse fosmidomycin analogs towards the antimalarial target IspC. J Med Chem

High Impact Journal from Malaria Portal - 25 September 2014 - 12:00am
1-Deoxy-D-xylulose 5-phosphate reductoisomerase of Plasmodium falciparum (PfIspC), believed to be the rate-limiting enzyme of the non-mevalonate pathway of isoprenoid biosynthesis (MEP pathway), is a clinically validated antimalarial target. . . .
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E Numminen et al. Two-phase importance sampling for inference about transmission trees. Proc Biol Sci

High Impact Journal from Malaria Portal - 25 September 2014 - 12:00am
There has been growing interest in the statistics community to develop methods for inferring transmission pathways of infectious pathogens from molecular sequence data. . . .
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Antibody response against three Plasmodium falciparum merozoite antigens in Mamuju District, West Sulawesi Province, Indonesia

Malaria Journal - 25 September 2014 - 12:00am
Background: Malaria endemicity in the archipelago of Indonesia varies substantially across regions. Following the government's plan for a malaria elimination programme in Indonesia, baseline malaria surveys were conducted in Mamuju District, West Sulawesi Province, Indonesia to re-assess the malaria situation prior to the establishment of an evidence-based malaria elimination programme in the area. The present study aims to determine the antibody response to three merozoite antigens among the inhabitants of the district. Methods: Antibodies were measured following elution from filter-paper blood spots collected during cross-sectional surveys in the dry and wet season in 2010. Enzyme-linked immunosorbent assays using three merozoite antigens, MSP2, EBA175 and PfRh2a were conducted. A positivity threshold was determined by samples from unexposed individuals and the difference in antibody level against each antigen and correlation of antibody level in different age groups and seasons were statistically analysed. Results: A total of 497 subjects, 248 in dry and 249 in wet season, aged between 0.6 and 78 years were included. The prevalence of positive antibody responses to MSP2, EBA175 and PfRh2a antigens in dry season were 27.82, 27.42 and 25.81%, respectively. In wet season, the antibody prevalences were 64.26, 64.66 and 61.45%. The antibody levels to the three antigens were all higher in older age groups and also significantly higher in the wet season. The antibody levels also correlated positively with the Plasmodium falciparum infection status of the subjects. Conclusion: MSP2, EBA175 and PfRh2a induce antibody responses among the subjects in Mamuju District, and the prevalence is significantly higher in wet season. The level of antibody also correlates significantly with age and malaria positivity. The overall results indicate the antigens might be used as a target for vaccines against P. falciparum infection and as markers for malaria exposure.
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