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Scientific Articles

Polymorphic markers for identification of parasite population in Plasmodium malariae

February 3, 2020 - 17:03 -- Open Access
Author(s): 
Vivek Bhakta Mathema, Supatchara Nakeesathit, Watcharee Pagornrat, Frank Smithuis, Nicholas J. White, Arjen M. Dondorp and Mallika Imwong
Reference: 
Malaria Journal 2020 19:48, 28 January 2020

Molecular genotyping in Plasmodium serves many aims including providing tools for studying parasite population genetics and distinguishing recrudescence from reinfection. Microsatellite typing, insertion-deletion (INDEL) and single nucleotide polymorphisms is used for genotyping, but only limited information is available for Plasmodium malariae, an important human malaria species. This study aimed to provide a set of genetic markers to facilitate the study of P. malariae population genetics.

Falciparum malaria from coastal Tanzania and Zanzibar remains highly connected despite effective control efforts on the archipelago

February 3, 2020 - 17:01 -- Open Access
Author(s): 
Andrew P. Morgan, Nicholas F. Brazeau, Jonathan J. Juliano, et al.
Reference: 
Malaria Journal 2020 19:47, 28 January 2020

Tanzania’s Zanzibar archipelago has made significant gains in malaria control over the last decade and is a target for malaria elimination. Despite consistent implementation of effective tools since 2002, elimination has not been achieved. Importation of parasites from outside of the archipelago is thought to be an important cause of malaria’s persistence, but this paradigm has not been studied using modern genetic tools.

Using health facility-based serological surveillance to predict receptive areas at risk of malaria outbreaks in elimination areas

February 3, 2020 - 16:38 -- Open Access
Author(s): 
Henry Surendra, Supargiyono, Chris Drakeley, et al.
Reference: 
BMC Med 18, 9 (2020)

In order to improve malaria burden estimates in low transmission settings, more sensitive tools and efficient sampling strategies are required. This study evaluated the use of serological measures from repeated health facility-based cross-sectional surveys to investigate Plasmodium falciparum and Plasmodium vivax transmission dynamics in an area nearing elimination in Indonesia.

Prevalence of Plasmodium falciparum field isolates with deletions in histidine-rich protein 2 and 3 genes in context with sub-Saharan Africa and India: a systematic review and meta-analysis

February 3, 2020 - 16:36 -- Open Access
Author(s): 
Loick P. Kojom and Vineeta Singh
Reference: 
Malaria Journal 2020 19:46, 28 January 2020

In 2017, nearly 80% of malaria morbidity and mortality occurred in sub-Saharan African (SSA) countries and India. Rapid diagnostic tests (RDTs), especially those targeting histidine-rich protein 2 (PfHRP2) of Plasmodium falciparum, have become an important diagnostic tool in these malaria-endemic areas. However, the chances of RDT-oriented successful treatment are increasingly jeopardized by the appearance of mutants with deletions in pfhrp2 and pfhrp3 genes. This systematic review and meta-analysis determines the prevalence of field P. falciparum isolates with deletion in pfhrp2 and/or pfhrp3 genes and their proportion among false-negative results in the PfHRP2-based RDTs in SSA and India.

African-centric TP53 variant increases iron accumulation and bacterial pathogenesis but improves response to malaria toxin

February 3, 2020 - 16:33 -- Open Access
Author(s): 
Kumar Sachin Singh, Julia I-Ju Leu, Farokh Dotiwala, et al.
Reference: 
Nat Commun. 2020; 11:473

A variant at amino acid 47 in human TP53 exists predominantly in individuals of African descent. P47S human and mouse cells show increased cancer risk due to defective ferroptosis. Here, we show that this ferroptotic defect causes iron accumulation in P47S macrophages. This high iron content alters macrophage cytokine profiles, leads to higher arginase level and activity, and decreased nitric oxide synthase activity. This leads to more productive intracellular bacterial infections but is protective against malarial toxin hemozoin. Proteomics of macrophages reveal decreased liver X receptor (LXR) activation, inflammation and antibacterial defense in P47S macrophages.

Lessons learned, challenges and outlooks for decision-making after a decade of experience monitoring the impact of indoor residual spraying in Benin, West Africa

February 3, 2020 - 16:31 -- Open Access
Author(s): 
Martin C. Akogbéto, Fortuné Dagnon, Germain G. Padonou, et al.
Reference: 
Malaria Journal 2020 19:45, 28 January 2020

Since 2008, Indoor Residual Spraying (IRS) has been performed in Benin in 19 districts, including 4 in southern Benin, 9 in Atacora, and 8 in Atacora, Alibori and Donga in northern Benin. However, Benin still struggles with questions about IRS cost–benefit and epidemiological impact. Lessons learned and challenges from 10 years of IRS in Benin to be shared with the stakeholders involved in vector control implementation for decision-making.

Assessing connectivity despite high diversity in island populations of a malaria mosquito

February 2, 2020 - 17:36 -- Open Access
Author(s): 
Christina M. Bergey, Martin Lukindu, Rachel M. Wiltshire, Michael C. Fontaine, Jonathan K. Kayondo, Nora J. Besansky
Reference: 
Evolutionary Applications, Volume13, Issue2, February 2020 Pages 417-431

Documenting isolation is notoriously difficult for species with vast polymorphic populations. High proportions of shared variation impede estimation of connectivity, even despite leveraging information from many genetic markers. We overcome these impediments by combining classical analysis of neutral variation with assays of the structure of selected variation, demonstrated using populations of the principal African malaria vector Anopheles gambiae. Accurate estimation of mosquito migration is crucial for efforts to combat malaria.

Pregnancy-specific malarial immunity and risk of malaria in pregnancy and adverse birth outcomes: a systematic review

February 2, 2020 - 17:33 -- Open Access
Author(s): 
Julia C. Cutts, Paul A. Agius, Zaw Lin, Rosanna Powell, Kerryn Moore, Bridget Draper, Julie A. Simpson, Freya J. I. Fowkes
Reference: 
BMC Medicine volume 18:14 (2020)

In endemic areas, pregnant women are highly susceptible to Plasmodium falciparum malaria characterized by the accumulation of parasitized red blood cells (pRBC) in the placenta. In subsequent pregnancies, women develop protective immunity to pregnancy-associated malaria and this has been hypothesized to be due to the acquisition of antibodies to the parasite variant surface antigen VAR2CSA. In this systematic review we provide the first synthesis of the association between antibodies to pregnancy-specific P. falciparum antigens and pregnancy and birth outcomes.

A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system

February 2, 2020 - 17:28 -- Open Access
Author(s): 
Shwu-Maan Lee, John M. Hickey, Kazutoyo Miura, Sangeeta B. Joshi, David B. Volkin, C. Richter King, Jordan L. Plieskatt
Reference: 
Scientific Reports volume 10:395 (2020)

The Plasmodium falciparum gametocyte surface protein, Pfs48/45, is a potential target for malaria transmission-blocking vaccines. However, due to its size and complexity, expression of the full-length protein has been difficult, leading to focus on the C-terminal six cysteine domain (6C) with the use of fusion proteins to facilitate expression and folding. In this study, we utilized the baculovirus system to evaluate the expression of three Pfs48/45 proteins including the full-length protein, the 6C domain fragment and the 6C domain mutant to prevent glycosylation.

The mosquito electrocuting trap as an exposure-free method for measuring human-biting rates by Aedes mosquito vectors

February 2, 2020 - 17:23 -- Open Access
Author(s): 
Leonardo D. Ortega-López, Emilie Pondeville, Alain Kohl, Renato León, Mauro Pazmiño Betancourth, Floriane Almire, Sergio Torres-Valencia, Segundo Saldarriaga, Nosrat Mirzai, Heather M. Ferguson
Reference: 
Parasites Vectors 2020; 13:31

Entomological monitoring of Aedes vectors has largely relied on surveillance of larvae, pupae and non-host-seeking adults, which have been poorly correlated with human disease incidence. Exposure to mosquito-borne diseases can be more directly estimated using human landing catches (HLC), although this method is not recommended for Aedes-borne arboviruses. We evaluated a new method previously tested with malaria vectors, the mosquito electrocuting trap (MET) as an exposure-free alternative for measuring landing rates of Aedes mosquitoes on people. Aims were to (i) compare the MET to the BG-sentinel (BGS) trap gold standard approach for sampling host-seeking Aedes vectors; and (ii) characterize the diel activity of Aedes vectors and their association with microclimatic conditions.

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