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https://www.readbyqxmd.com/read/28939159/marked-variation-in-prevalence-of-malaria-protective-human-genetic-polymorphisms-across-uganda
#1
Andrew Walakira, Stephen Tukwasibwe, Moses Kiggundu, Federica Verra, Patrick Kakeeto, Emmanuel Ruhamyankaka, Chris Drakeley, Grant Dorsey, Moses R Kamya, Samuel L Nsobya, Philip J Rosenthal
A number of human genetic polymorphisms are prevalent in tropical populations and appear to offer protection against symptomatic and/or severe malaria. We compared the prevalence of four polymorphisms, the sickle hemoglobin mutation (β globin E6V), the α-thalassemia 3.7kb deletion, glucose-6-phosphate dehydrogenase deficiency caused by the common African variant (G6PD A-), and the CD36 T188G mutation in 1344 individuals residing in districts in eastern (Tororo), south-central (Jinja), and southwestern (Kanungu) Uganda...
September 19, 2017: Infection, Genetics and Evolution
https://www.readbyqxmd.com/read/28931236/a-molecular-assay-to-quantify-male-and-female-plasmodium-falciparum-gametocytes-results-from-2-randomized-controlled-trials-using-primaquine-for-gametocyte-clearance
#2
Will Stone, Patrick Sawa, Kjerstin Lanke, Sanna Rijpma, Robin Oriango, Maureen Nyaurah, Paul Osodo, Victor Osoti, Almahamoudou Mahamar, Halimatou Diawara, Rob Woestenenk, Wouter Graumans, Marga van de Vegte-Bolmer, John Bradley, Ingrid Chen, Joelle Brown, Giulia Siciliano, Pietro Alano, Roly Gosling, Alassane Dicko, Chris Drakeley, Teun Bousema
Background: Single low-dose primaquine (PQ) reduces Plasmodium falciparum infectivity before it impacts gametocyte density. Here, we examined the effect of PQ on gametocyte sex ratio as a possible explanation for this early sterilizing effect. Methods: Quantitative reverse-transcription polymerase chain reaction assays were developed to quantify female gametocytes (targeting Pfs25 messenger RNA [mRNA]) and male gametocytes (targeting Pf3D7_1469900 mRNA) in 2 randomized trials in Kenya and Mali, comparing dihydroartemisinin-piperaquine (DP) alone to DP with PQ...
August 15, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28922357/analysis-of-nuclear-and-organellar-genomes-of-plasmodium-knowlesi-in-humans-reveals-ancient-population-structure-and-recent-recombination-among-host-specific-subpopulations
#3
Ernest Diez Benavente, Paola Florez de Sessions, Robert W Moon, Anthony A Holder, Michael J Blackman, Cally Roper, Christopher J Drakeley, Arnab Pain, Colin J Sutherland, Martin L Hibberd, Susana Campino, Taane G Clark
The macaque parasite Plasmodium knowlesi is a significant concern in Malaysia where cases of human infection are increasing. Parasites infecting humans originate from genetically distinct subpopulations associated with the long-tailed (Macaca fascicularis (Mf)) or pig-tailed macaques (Macaca nemestrina (Mn)). We used a new high-quality reference genome to re-evaluate previously described subpopulations among human and macaque isolates from Malaysian-Borneo and Peninsular-Malaysia. Nuclear genomes were dimorphic, as expected, but new evidence of chromosomal-segment exchanges between subpopulations was found...
September 18, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28831122/naturally-acquired-antibody-response-to-plasmodium-falciparum-describes-heterogeneity-in-transmission-on-islands-in-lake-victoria
#4
Zulkarnain Md Idris, Chim W Chan, James Kongere, Tom Hall, John Logedi, Jesse Gitaka, Chris Drakeley, Akira Kaneko
As markers of exposure anti-malaria antibody responses can help characterise heterogeneity in malaria transmission. In the present study antibody responses to Plasmodium falciparum AMA-1, MSP-119 and CSP were measured with the aim to describe transmission patterns in meso-endemic settings in Lake Victoria. Two cross-sectional surveys were conducted in Lake Victoria in January and August 2012. The study area comprised of three settings: mainland (Ungoye), large island (Mfangano) and small islands (Takawiri, Kibuogi, Ngodhe)...
August 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28764717/a-longitudinal-cohort-study-of-malaria-exposure-and-changing-serostatus-in-a-malaria-endemic-area-of-rural-tanzania
#5
Ryan A Simmons, Leonard Mboera, Marie Lynn Miranda, Alison Morris, Gillian Stresman, Elizabeth L Turner, Randall Kramer, Chris Drakeley, Wendy P O'Meara
BACKGROUND: Measurements of anti-malarial antibodies are increasingly used as a proxy of transmission intensity. Most serological surveys are based on the use of cross-sectional data that, when age-stratified, approximates historical patterns of transmission within a population. Comparatively few studies leverage longitudinal data to explicitly relate individual infection events with subsequent antibody responses. METHODS: The occurrence of seroconversion and seroreversion events for two Plasmodium falciparum asexual stage antigens (MSP-1 and AMA-1) was examined using three annual measurements of 691 individuals from a cohort of individuals in a malaria-endemic area of rural east-central Tanzania...
August 2, 2017: Malaria Journal
https://www.readbyqxmd.com/read/28758162/individual-level-factors-associated-with-the-risk-of-acquiring-human-plasmodium-knowlesi-malaria-in-malaysia-a-case-control-study
#6
Matthew J Grigg, Jonathan Cox, Timothy William, Jenarun Jelip, Kimberly M Fornace, Patrick M Brock, Lorenz von Seidlein, Bridget E Barber, Nicholas M Anstey, Tsin W Yeo, Christopher J Drakeley
BACKGROUND: The emergence of human malaria due to the monkey parasite Plasmodium knowlesi threatens elimination efforts in southeast Asia. Changes in land use are thought to be driving the rise in reported P knowlesi cases, but the role of individual-level factors is unclear. To address this knowledge gap we assessed human and environmental factors associated with zoonotic knowlesi malaria risk. METHODS: We did this population-based case-control study over a 2 year period in the state of Sabah in Malaysia...
June 9, 2017: The Lancet. Planetary health
https://www.readbyqxmd.com/read/28720113/evaluation-of-electric-nets-as-means-to-sample-mosquito-vectors-host-seeking-on-humans-and-primates
#7
Frances Hawkes, Benny Obrain Manin, Sui Han Ng, Stephen J Torr, Chris Drakeley, Tock H Chua, Heather M Ferguson
BACKGROUND: Plasmodium knowlesi is found in macaques and is the only major zoonotic malaria to affect humans. Transmission of P. knowlesi between people and macaques depends on the host species preferences and feeding behavior of mosquito vectors. However, these behaviours are difficult to measure due to the lack of standardized methods for sampling potential vectors attracted to different host species. This study evaluated electrocuting net traps as a safe, standardised method for sampling P...
July 18, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28719294/molecular-markers-for-sensitive-detection-of-plasmodium-falciparum-asexual-stage-parasites-and-their-application-in-a-malaria-clinical-trial
#8
RANDOMIZED CONTROLLED TRIAL
Fitsum G Tadesse, Kjerstin Lanke, Issa Nebie, Jodie A Schildkraut, Bronner P Gonçalves, Alfred B Tiono, Robert Sauerwein, Chris Drakeley, Teun Bousema, Sanna R Rijpma
Plasmodium falciparum parasite life stages respond differently to antimalarial drugs. Sensitive stage-specific molecular assays may help to examine parasite dynamics at microscopically detectable and submicroscopic parasite densities in epidemiological and clinical studies. In this study, we compared the performance of skeleton-binding protein 1 (SBP1), ring-infected erythrocyte surface antigen, Hyp8, ring-exported protein 1 (REX1), and PHISTb mRNA for detecting ring-stage trophozoite-specific transcripts using quantitative reverse transcriptase polymerase chain reaction...
July 2017: American Journal of Tropical Medicine and Hygiene
https://www.readbyqxmd.com/read/28619120/g6pd-deficiency-alleles-in-a-malaria-endemic-region-in-the-western-brazilian-amazon
#9
Jamille G Dombrowski, Rodrigo M Souza, Jonathan Curry, Laura Hinton, Natercia R M Silva, Lynn Grignard, Ligia A Gonçalves, Ana Rita Gomes, Sabrina Epiphanio, Chris Drakeley, Jim Huggett, Taane G Clark, Susana Campino, Claudio R F Marinho
BACKGROUND: Plasmodium vivax parasites are the predominant cause of malaria infections in the Brazilian Amazon. Infected individuals are treated with primaquine, which can induce haemolytic anaemia in glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals and may lead to severe and fatal complications. This X-linked disorder is distributed globally and is caused by allelic variants with a geographical distribution that closely reflects populations exposed historically to endemic malaria...
June 15, 2017: Malaria Journal
https://www.readbyqxmd.com/read/28595603/current-and-cumulative-malaria-infections-in-a-setting-embarking-on-elimination-amhara-ethiopia
#10
Woyneshet G Yalew, Sampa Pal, Pooja Bansil, Rebecca Dabbs, Kevin Tetteh, Caterina Guinovart, Michael Kalnoky, Belendia A Serda, Berhane H Tesfay, Belay B Beyene, Catherine Seneviratne, Megan Littrell, Lindsay Yokobe, Gregory S Noland, Gonzalo J Domingo, Asefaw Getachew, Chris Drakeley, Richard W Steketee
BACKGROUND: Since 2005, Ethiopia has aggressively scaled up malaria prevention and case management. As a result, the number of malaria cases and deaths has significantly declined. In order to track progress towards the elimination of malaria in Amhara Region, coverage of malaria control tools and current malaria transmission need to be documented. METHODS: A cross-sectional household survey oversampling children under 5 years of age was conducted during the dry season in 2013...
June 8, 2017: Malaria Journal
https://www.readbyqxmd.com/read/28541483/malaria-host-candidate-genes-validated-by-association-with-current-recent-and-historical-measures-of-transmission-intensity
#11
Nuno Sepúlveda, Alphaxard Manjurano, Susana G Campino, Martha Lemnge, John Lusingu, Raimos Olomi, Kirk A Rockett, Christina Hubbart, Anna Jeffreys, Kate Rowlands, Taane G Clark, Eleanor M Riley, Chris J Drakeley
Background: Human malaria susceptibility is determined by multiple genetic factors. It is unclear, however, which genetic variants remain important over time. Methods: Genetic associations of 175 high-quality polymorphisms within several malaria candidate genes were examined in a sample of 8096 individuals from northeast Tanzania using altitude, seroconversion rates, and parasite rates as proxies of historical, recent, and current malaria transmission intensity...
July 1, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28522690/resistance-to-malaria-through-structural-variation-of-red-blood-cell-invasion-receptors
#12
Ellen M Leffler, Gavin Band, George B J Busby, Katja Kivinen, Quang Si Le, Geraldine M Clarke, Kalifa A Bojang, David J Conway, Muminatou Jallow, Fatoumatta Sisay-Joof, Edith C Bougouma, Valentina D Mangano, David Modiano, Sodiomon B Sirima, Eric Achidi, Tobias O Apinjoh, Kevin Marsh, Carolyne M Ndila, Norbert Peshu, Thomas N Williams, Chris Drakeley, Alphaxard Manjurano, Hugh Reyburn, Eleanor Riley, David Kachala, Malcolm Molyneux, Vysaul Nyirongo, Terrie Taylor, Nicole Thornton, Louise Tilley, Shane Grimsley, Eleanor Drury, Jim Stalker, Victoria Cornelius, Christina Hubbart, Anna E Jeffreys, Kate Rowlands, Kirk A Rockett, Chris C A Spencer, Dominic P Kwiatkowski
The malaria parasite Plasmodium falciparum invades human red blood cells by a series of interactions between host and parasite surface proteins. By analyzing genome sequence data from human populations, including 1269 individuals from sub-Saharan Africa, we identify a diverse array of large copy-number variants affecting the host invasion receptor genes GYPA and GYPB We find that a nearby association with severe malaria is explained by a complex structural rearrangement involving the loss of GYPB and gain of two GYPB-A hybrid genes, which encode a serologically distinct blood group antigen known as Dantu...
June 16, 2017: Science
https://www.readbyqxmd.com/read/28441959/serological-measures-to-assess-the-efficacy-of-malaria-control-programme-on-ambae-island-vanuatu
#13
Zulkarnain Md Idris, Chim W Chan, Mubasher Mohammed, Morris Kalkoa, George Taleo, Klara Junker, Bruno Arcà, Chris Drakeley, Akira Kaneko
BACKGROUND: Seroepidemiology can provide evidence for temporal changes in malaria transmission and is an important tool to evaluate the effectiveness of control interventions. During the early 2000s, Vanuatu experienced an acute increase in malaria incidence due to a lapse in funding for vector control. After the distribution of subsidised insecticide-treated nets (ITNs) resumed in 2003, malaria incidence decreased in the subsequent years. This study was conducted to find the serological evidence supporting the impact of ITN on exposure to Anopheles vector bites and parasite prevalence...
April 26, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28431115/spatial-distribution-of-falciparum-malaria-infections-in-zanzibar-implications-for-focal-drug-administration-strategies-targeting-asymptomatic-parasite-carriers
#14
Anders Björkman, Jackie Cook, Hugh Sturrock, Mwinyi Msellem, Abdullah Ali, Weiping Xu, Fabrizio Molteni, Roly Gosling, Chris Drakeley, Andreas Mårtensson
Background: Optimal use of mass/targeted screen-and-treat or mass or focal drug administration as malaria elimination strategies remains unclear. We therefore studied spatial distribution of Plasmodium falciparum infections to compare simulated effects of these strategies on reducing the parasite reservoir in a pre-elimination setting. Methods: P. falciparum rapid diagnostic tests (RDTs) and molecular (polymerase chain reaction [PCR]) and serological (enzyme-linked immunosorbent assay) analyses were performed on finger-prick blood samples from a population-based survey in 3 adjacent communities...
May 1, 2017: Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America
https://www.readbyqxmd.com/read/28401903/impact-of-metric-and-sample-size-on-determining-malaria-hotspot-boundaries
#15
Gillian H Stresman, Emanuele Giorgi, Amrish Baidjoe, Phil Knight, Wycliffe Odongo, Chrispin Owaga, Shehu Shagari, Euniah Makori, Jennifer Stevenson, Chris Drakeley, Jonathan Cox, Teun Bousema, Peter J Diggle
The spatial heterogeneity of malaria suggests that interventions may be targeted for maximum impact. It is unclear to what extent different metrics lead to consistent delineation of hotspot boundaries. Using data from a large community-based malaria survey in the western Kenyan highlands, we assessed the agreement between a model-based geostatistical (MBG) approach to detect hotspots using Plasmodium falciparum parasite prevalence and serological evidence for exposure. Malaria transmission was widespread and highly heterogeneous with one third of the total population living in hotspots regardless of metric tested...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28369085/defining-the-next-generation-of-plasmodium-vivax-diagnostic-tests-for-control-and-elimination-target-product-profiles
#16
Xavier C Ding, Maria Paz Ade, J Kevin Baird, Qin Cheng, Jane Cunningham, Mehul Dhorda, Chris Drakeley, Ingrid Felger, Dionicia Gamboa, Matthias Harbers, Socrates Herrera, Naomi Lucchi, Alfredo Mayor, Ivo Mueller, Jetsumon Sattabongkot, Arsène Ratsimbason, Jack Richards, Marcel Tanner, Iveth J González
The global prevalence of malaria has decreased over the past fifteen years, but similar gains have not been realized against Plasmodium vivax because this species is less responsive to conventional malaria control interventions aimed principally at P. falciparum. Approximately half of all malaria cases outside of Africa are caused by P. vivax. This species places dormant forms in human liver that cause repeated clinical attacks without involving another mosquito bite. The diagnosis of acute patent P. vivax malaria relies primarily on light microscopy...
April 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/28359609/pregnant-women-an-overlooked-asset-to-plasmodium-falciparum-malaria-elimination-campaigns
#17
REVIEW
Bronner P Gonçalves, Patrick G Walker, Matthew Cairns, Alfred B Tiono, Teun Bousema, Chris Drakeley
Community chemotherapy campaigns to reduce malaria transmission often exclude pregnant women due to safety concerns related to the drugs. However, pregnant women might represent an important source of human-to-mosquito infection due to frequent parasite carriage with higher densities of parasites (often detectable by microscopy), attractiveness to mosquitoes, and modified sleeping behaviour. Accumulating evidence of the safety of artemisinin-based combination therapies for the treatment of malaria during gestation suggests that malaria elimination programmes should reconsider this exclusion...
July 2017: Trends in Parasitology
https://www.readbyqxmd.com/read/28345507/plasmodium-knowlesi-invasion-following-spread-by-infected-mosquitoes-macaques-and-humans
#18
Laith Yakob, Alun L Lloyd, Rowland R Kao, Heather M Ferguson, Patrick M Brock, Chris Drakeley, Michael B Bonsall
Plasmodium knowlesi is increasingly recognized as a major cause of malaria in Southeast Asia. Anopheles leucosphyrous group mosquitoes transmit the parasite and natural hosts include long-tailed and pig-tailed macaques. Despite early laboratory experiments demonstrating successful passage of infection between humans, the true role that humans play in P. knowlesi epidemiology remains unclear. The threat posed by its introduction into immunologically naïve populations is unknown despite being a public health priority for this region...
March 27, 2017: Parasitology
https://www.readbyqxmd.com/read/28289025/age-weight-and-cyp2d6-genotype-are-major-determinants-of-primaquine-pharmacokinetics-in-african-children
#19
Bronner P Gonçalves, Helmi Pett, Alfred B Tiono, Daryl Murry, Sodiomon B Sirima, Mikko Niemi, Teun Bousema, Chris Drakeley, Rob Ter Heine
Low-dose primaquine is recommended to prevent Plasmodium falciparum malaria transmission in areas threatened by artemisinin resistance and areas aiming for malaria elimination. Community treatment campaigns with artemisinin-based combination therapy in combination with the gametocytocidal primaquine dose target all age groups, but no studies thus far have assessed the pharmacokinetics of this gametocytocidal drug in African children. We recruited 40 children participating in a primaquine efficacy trial in Burkina Faso to study primaquine pharmacokinetics...
May 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28270152/a-systematic-review-on-malaria-sero-epidemiology-studies-in-the-brazilian-amazon-insights-into-immunological-markers-for-exposure-and-protection
#20
REVIEW
Pedro M Folegatti, André M Siqueira, Wuelton M Monteiro, Marcus Vinícius G Lacerda, Chris J Drakeley, Érika M Braga
BACKGROUND: Considerable success in reducing malaria incidence and mortality has been achieved in Brazil, leading to discussions over the possibility of moving towards elimination. However, more than reporting and counting clinical cases, elimination will require the use of efficient tools and strategies for measuring transmission dynamics and detecting the infectious reservoir as the primary indicators of interest for surveillance and evaluation. Because acquisition and maintenance of anti-malarial antibodies depend on parasite exposure, seroprevalence rates could be used as a reliable tool for assessing malaria endemicity and an adjunct measure for monitoring transmission in a rapid and cost-effective manner...
March 7, 2017: Malaria Journal
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