scholarly journals Community-based molecular and serological surveillance of subclinical malaria in Myanmar

BMC Medicine ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Katherine O’Flaherty ◽  
Win Han Oo ◽  
Sophie G. Zaloumis ◽  
Julia C. Cutts ◽  
Kyaw Zayar Aung ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Quantitative Polymerase Chain Reaction ◽  
Dried Blood Spots ◽  
Molecular Testing ◽  
Sample Collection ◽  
Malaria Surveillance ◽  
Surveillance Network ◽  
Targeted Interventions ◽  
Residual Malaria Transmission ◽  
Serological Surveillance

Abstract Background In the Greater Mekong Subregion (GMS), current malaria surveillance strategies rely on a network of village health volunteers (VHVs) reporting the results of rapid diagnostic tests (RDTs), known to miss many asymptomatic infections. Integration of more sensitive diagnostic molecular and serological measures into the VHV network may improve surveillance of residual malaria transmission in hard-to-reach areas in the region and inform targeted interventions and elimination responses. However, data on residual malaria transmission that would be captured by these measures in the VHV-led testing and treatment surveillance network in the GMS is unknown. Methods A total of 114 VHVs were trained to collect dried blood spots from villagers undergoing routine RDTs as part of VHV-led active and passive case detection from April 2015 to June 2016. Samples were subjected to molecular testing (quantitative polymerase chain reaction [qPCR]) to determine Plasmodium falciparum and P. vivax infection and serological testing (against P. falciparum and P. vivax antigens) to determine exposure to P. falciparum and P. vivax. Results Over 15 months, 114 VHVs performed 32,194 RDTs and collected samples for molecular (n = 13,157) and serological (n = 14,128) testing. The prevalence of molecular-detectable P. falciparum and P. vivax infection was 3.2% compared to the 0.16% prevalence of Plasmodium spp. by RDT, highlighting the large burden of infections undetected by standard surveillance. Peaks in anti-P. falciparum, but not P. vivax, merozoite IgG seroprevalence coincided with seasonal P. falciparum transmission peaks, even in those with no molecularly detectable parasites. At the individual level, antibody seropositivity was associated with reduced odds of contemporaneous P. falciparum (OR for PfCSP 0.51 [95%CI 0.35, 0.76], p = 0.001, PfAMA1 0.70 [95%CI 0.52, 0.93], p = 0.01, and PfMSP2 0.81 [95%CI 0.61, 1.08], p = 0.15), but not P. vivax infection (OR PvAMA1 1.02 [95%CI 0.73, 1.43], p = 0.89) indicating a potential role of immunity in protection against molecular-detectable P. falciparum parasitaemia. Conclusions We demonstrated that integration and implementation of sample collection for molecular and serological surveillance into networks of VHV servicing hard-to-reach populations in the GMS is feasible, can capture significant levels of ongoing undetected seasonal malaria transmission and has the potential to supplement current routine RDT testing. Improving malaria surveillance by advancing the integration of molecular and serological techniques, through centralised testing approaches or novel point-of-contact tests, will advance progress, and tracking, towards malaria elimination goals in the GMS.

scholarly journals Assessment of Plasmodium antigens and CRP in dried blood spots with multiplex malaria array

2021 ◽  
Author(s):  
Ihn Kyung Jang ◽  
Sara Aranda ◽  
Rebecca Barney ◽  
Andrew Rashid ◽  
Muhammad Helwany ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Whole Blood ◽  
Dried Blood Spots ◽  
Careful Consideration ◽  
Clinical Samples ◽  
Sample Type ◽  
Sample Collection ◽  
Malaria Surveillance ◽  
Inflammatory Biomarker ◽  
Blood Spots

AbstractDried blood spots (DBS) typically prepared on filter papers are an ideal sample type for malaria surveillance by offering easy and cost-effective methods in terms of sample collection, storage, and transport. The objective of this study was to evaluate the applicability of DBS with a commercial multiplex malaria assay, developed to concurrently measure Plasmodium antigens, histidine-rich protein 2 (HRP2), Plasmodium lactate dehydrogenase (pLDH), and a host inflammatory biomarker, C-reactive protein (CRP), in whole blood. The assay conditions were optimized for DBS, and thermal stability for measurement of Plasmodium antigens and CRP in dried blood were determined. Performance of the multiplex assay on matched DBS and whole blood pellet samples was also evaluated using the clinical samples. The results indicate the acceptable performance in multiplex antigen detection using DBS samples. At cutoff levels for DBS, with a diagnostic specificity with a lower 95% confidence bound > 92%, diagnostic sensitivities against polymerase chain reaction (PCR)–confirmed malaria for HRP2, Pf LDH, Pv LDH, and Pan LDH were 93.5%, 80.4%, 21.3%, and 55.6%, respectively. The half-life of pLDH was significantly less than that of HRP2 in thermal stability studies. Results with DBS samples collected from Peru indicate that the uncontrolled storage conditions of DBS can result in inaccurate reporting for infection with P. falciparum parasites with hrp2/3 deletions. With careful consideration that minimizing the unfavorable DBS storage environment is essential for ensuring integrity of heat-labile Plasmodium antigens, DBS samples can be used as an alternative to liquid whole blood to detect P. falciparum with hrp2/3 deletions in malaria surveillance.

scholarly journals Asymptomatic Plasmodium falciparum malaria prevalence among adolescents and adults in Malawi, 2015–2016

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hillary M. Topazian ◽  
Austin Gumbo ◽  
Sydney Puerto-Meredith ◽  
Ruth Njiko ◽  
Alexis Mwanza ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Quantitative Polymerase Chain Reaction ◽  
Household Survey ◽  
Plasmodium Falciparum Malaria ◽  
Parasite Prevalence ◽  
Dried Blood Spots ◽  
Asymptomatic Infection ◽  
Bed Net ◽  
Previous Night ◽  
Targeted Interventions

Abstract Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. While children report the highest rates of clinical disease, adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection. The 2015–2016 Malawi Demographic and Health Survey was a nationally representative household survey which collected dried blood spots from 15,125 asymptomatic individuals ages 15–54 between October 2015 and February 2016. We performed quantitative polymerase chain reaction on 7,393 samples, detecting an overall P. falciparum prevalence of 31.1% (SE = 1.1). Most infections (55.6%) had parasitemias ≤ 10 parasites/µL. While 66.2% of individuals lived in a household that owned a bed net, only 36.6% reported sleeping under a long-lasting insecticide-treated net (LLIN) the previous night. Protective factors included urbanicity, greater wealth, higher education, and lower environmental temperatures. Living in a household with a bed net (prevalence difference 0.02, 95% CI − 0.02 to 0.05) and sleeping under an LLIN (0.01; − 0.02 to 0.04) were not protective against infection. Our findings demonstrate a higher parasite prevalence in adults than published estimates among children. Understanding the prevalence and distribution of asymptomatic infection is essential for targeted interventions.

scholarly journals Antibody responses to a suite of novel serological markers for malaria surveillance demonstrate strong correlation with clinical and parasitological infection across seasons and transmission settings in The Gambia

BMC Medicine ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Lindsey Wu ◽  
Julia Mwesigwa ◽  
Muna Affara ◽  
Mamadou Bah ◽  
Simon Correa ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Clinical Malaria ◽  
The Gambia ◽  
Antibody Responses ◽  
Serological Markers ◽  
Malaria Surveillance ◽  
Diverse Range ◽  
Targeted Interventions ◽  
River Region ◽  
The Individual

Abstract Background As malaria transmission declines, sensitive diagnostics are needed to evaluate interventions and monitor transmission. Serological assays measuring malaria antibody responses offer a cost-effective detection method to supplement existing surveillance tools. Methods A prospective cohort study was conducted from 2013 to 2015 in 12 villages across five administrative regions in The Gambia. Serological analysis included samples from the West Coast Region at the start and end of the season (July and December 2013) and from the Upper River Region in July and December 2013 and April and December 2014. Antigen-specific antibody responses to eight Plasmodium falciparum (P. falciparum) antigens—Etramp5.Ag1, GEXP18, HSP40.Ag1, Rh2.2030, EBA175 RIII-V, PfMSP119, PfAMA1, and PfGLURP.R2—were quantified using a multiplexed bead-based assay. The association between antibody responses and clinical and parasitological endpoints was estimated at the individual, household, and population level. Results Strong associations were observed between clinical malaria and concurrent sero-positivity to Etramp5.Ag1 (aOR 4.60 95% CI 2.98–7.12), PfMSP119 (aOR 4.09 95% CI 2.60–6.44), PfAMA1 (aOR 2.32 95% CI 1.40–3.85), and PfGLURP.R2 (aOR 3.12, 95% CI 2.92–4.95), while asymptomatic infection was associated with sero-positivity to all antigens. Village-level sero-prevalence amongst children 2–10 years against Etramp5.Ag1, HSP40.Ag1, and PfMSP119 showed the highest correlations with clinical and P. falciparum infection incidence rates. For all antigens, there were increased odds of asymptomatic P. falciparum infection in subjects residing in a compound with greater than 50% sero-prevalence, with a 2- to 3-fold increase in odds of infection associated with Etramp5.Ag1, GEXP18, Rh2.2030, PfMSP119, and PfAMA1. For individuals residing in sero-positive compounds, the odds of clinical malaria were reduced, suggesting a protective effect. Conclusions At low transmission, long-lived antibody responses could indicate foci of malaria transmission that have been ongoing for several seasons or years. In settings where sub-patent infections are prevalent and fluctuate below the detection limit of polymerase chain reaction (PCR), the presence of short-lived antibodies may indicate recent infectivity, particularly in the dry season when clinical cases are rare. Serological responses may reflect a persistent reservoir of infection, warranting community-targeted interventions if individuals are not clinically apparent but have the potential to transmit. Therefore, serological surveillance at the individual and household level may be used to target interventions where there are foci of asymptomatically infected individuals, such as by measuring the magnitude of age-stratified antibody levels or identifying areas with clustering of above-average antibody responses across a diverse range of serological markers.

scholarly journals Antibody responses to a suite of novel serological markers for malaria surveillance demonstrate strong correlation with clinical and parasitological infection across seasons and transmission settings in The Gambia

2020 ◽  
Author(s):  
Lindsey Wu ◽  
Julia Mwesigwa ◽  
Muna Affara ◽  
Mamadou Bah ◽  
Simon Correa ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Fold Increase ◽  
Clinical Malaria ◽  
Incidence Rates ◽  
The Gambia ◽  
Antibody Responses ◽  
Malaria Surveillance ◽  
Targeted Interventions ◽  
River Region ◽  
The Individual

AbstractBackgroundAs malaria transmission declines, sensitive diagnostics are needed to evaluate interventions and monitor transmission. Serological assays measuring malaria antibody responses offer a cost-effective detection method to supplement existing surveillance tools.MethodsA prospective cohort study was conducted from 2013 to 2015 in 12 villages across five administrative regions in The Gambia. Serological analysis included samples from the West Coast Region at the start and end of the season (July and December 2013) and from the Upper River Region in July and December 2013, and April and December 2014. Antigen-specific antibody responses to eight Plasmodium falciparum (P.falciparum) antigens – Etramp5.Ag1, GEXP18, HSP40.Ag1, Rh2.2030, EBA175 RIII-V, PfMSP119, PfAMA1, PfGLURP.R2 - were quantified using a multiplexed bead-based assay. The association between antibody responses and clinical and parasitological endpoints was estimated at the individual, household, and population level.ResultsStrong associations were observed between clinical malaria and concurrent sero-positivity to Etramp5.Ag1 (aOR 4.60 95%CI 2.98 - 7.12), PfMSP119 (aOR 4.09 95%CI 2.60 - 6.44), PfAMA1 (aOR 2.32 95%CI 1.40 - 3.85) and PfGLURP.R2 (aOR 3.12, 95%CI 2.92 – 4.95), while asymptomatic infection was associated with sero-positivity to all antigens. Village-level sero-prevalence amongst children 2-10 years against Etramp5.Ag1, HSP40.Ag1, and PfMSP119 showed the highest correlations with clinical and P.falciparum infection incidence rates. For all antigens, there was increased odds of asymptomatic P.falciparum infection in subjects residing in a compound with greater than 50% sero-prevalence, with a 2- to 3-fold increase in odds of infection associated with Etramp5.Ag1, GEXP18, Rh2.2030, PfMSP119 and PfAMA1. For individuals residing in sero-positive compounds, the odds of clinical malaria were reduced, suggesting a protective effect.ConclusionsAt low transmission, long-lived antibody responses could indicate foci of malaria transmission that have been ongoing for several seasons or years. In settings where sub-patent infections are prevalent and fluctuate below the detection limit of polymerase chain reaction (PCR), the presence of short- lived antibodies may indicate recent infectivity, particularly in the dry season when clinical cases are rare. Serological responses may reflect a persistent reservoir of infection, warranting community- targeted interventions if individuals are not clinically apparent but have the potential to transmit. Therefore, serological surveillance at both the individual and household level may be used to target interventions where there are foci of asymptomatically infected individuals.

scholarly journals Back to school: use of Dried Blood Spot for the detection of SARS-CoV-2‐specific immunoglobulin G (IgG) among schoolchildren in Milan, Italy.

2020 ◽  
Author(s):  
Antonella Amendola ◽  
Silvia Bianchi ◽  
Maria Gori ◽  
Lucia Barcellini ◽  
Daniela Colzani ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Dried Blood Spots ◽  
Elisa Test ◽  
Sample Collection ◽  
Venous Sampling ◽  
Serum Samples ◽  
School Activities ◽  
Specific Immunoglobulin ◽  
Serological Surveillance ◽  
Blood Spot

Abstract Serological surveillance is necessary to the reestablishment of school activities in safe conditions and to avoid school-related outbreaks. In this study, DBS (Dried Blood Spots) have proven to be a simple, rapid and reliable sample collection tool for detecting antibodies against SARS-CoV-2 by ELISA test compared to matched serum samples from venous sampling (R2=0.9553; Pearson's coefficient=0.98; Cohen's unweighted k=0.93; overall agreement=96.2%). This approach may facilitate sample collection from schoolchildren for serological surveys useful to an adequate risk-assessment.

scholarly journals Liquid Biopsy Analysis in Clinical Practice: Focus on Lung Cancer

2021 ◽  
Vol 2 (3) ◽  
pp. 241-254
Author(s):  
Pasquale Pisapia ◽  
Francesco Pepe ◽  
Antonino Iaccarino ◽  
Roberta Sgariglia ◽  
Mariantonia Nacchio ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Liquid Biopsy ◽  
Treatment Options ◽  
Molecular Testing ◽  
Specific Information ◽  
Sample Collection ◽  
Timely Manner ◽  
Oncology Practice ◽  
Nsclc Patients ◽  
To Receive

Lung cancer is the leading cause of cancer death worldwide. Despite the emergence of highly effective targeted therapies, up to 30% of advanced stage non-small cell lung cancer (NSCLC) patients do not undergo tissue molecular testing because of scarce tissue availability. Liquid biopsy, on the other hand, offers these patients a valuable opportunity to receive the best treatment options in a timely manner. Indeed, besides being much faster and less invasive than conventional tissue-based analysis, it can also yield specific information about the genetic make-up and evolution of patients’ tumors. However, several issues, including lack of standardized protocols for sample collection, processing, and interpretation, still need to be addressed before liquid biopsy can be fully incorporated into routine oncology practice. Here, we reviewed the most important challenges hindering the implementation of liquid biopsy in oncology practice, as well as the great advantages of this approach for the treatment of NSCLC patients.

scholarly journals N-protein presents early in blood, dried blood and saliva during asymptomatic and symptomatic SARS-CoV-2 infection

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dandan Shan ◽  
Joseph M. Johnson ◽  
Syrena C. Fernandes ◽  
Hannah Suib ◽  
Soyoon Hwang ◽  
...  
Keyword(s):  
Single Molecule ◽  
High Performance ◽  
Point Of Care ◽  
Capillary Blood ◽  
Molecular Testing ◽  
Sample Collection ◽  
Protein Assay ◽  
N Protein ◽  
Protein Levels ◽  
Percent Agreement

AbstractThe COVID-19 pandemic continues to have an unprecedented impact on societies and economies worldwide. There remains an ongoing need for high-performance SARS-CoV-2 tests which may be broadly deployed for infection monitoring. Here we report a highly sensitive single molecule array (Simoa) immunoassay in development for detection of SARS-CoV-2 nucleocapsid protein (N-protein) in venous and capillary blood and saliva. In all matrices in the studies conducted to date we observe >98% negative percent agreement and >90% positive percent agreement with molecular testing for days 1–7 in symptomatic, asymptomatic, and pre-symptomatic PCR+ individuals. N-protein load decreases as anti-SARS-CoV-2 spike-IgG increases, and N-protein levels correlate with RT-PCR Ct-values in saliva, and between matched saliva and capillary blood samples. This Simoa SARS-CoV-2 N-protein assay effectively detects SARS-CoV-2 infection via measurement of antigen levels in blood or saliva, using non-invasive, swab-independent collection methods, offering potential for at home and point of care sample collection.

Patterns of human exposure to early evening and outdoor biting mosquitoes and residual malaria transmission in Ethiopia

Acta Tropica ◽  
2021 ◽  
Vol 216 ◽  
pp. 105837
Author(s):  
Teshome Degefa ◽  
Andrew K. Githeko ◽  
Ming-Chieh Lee ◽  
Guiyun Yan ◽  
Delenasaw Yewhalaw
Keyword(s):  
Malaria Transmission ◽  
Human Exposure ◽  
Early Evening ◽  
Outdoor Biting ◽  
Residual Malaria Transmission

scholarly journals Anopheles ecology, genetics and malaria transmission in northern Cambodia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Amélie Vantaux ◽  
Michelle M. Riehle ◽  
Eakpor Piv ◽  
Elise J. Farley ◽  
Sophy Chy ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Mosquito Species ◽  
Rubber Tree ◽  
Amplicon Sequencing ◽  
Forest Sites ◽  
Baited Traps ◽  
Residual Malaria Transmission ◽  
Mosquito Ecology ◽  
Forested Areas ◽  
Greater Mekong Subregion

AbstractIn the Greater Mekong Subregion, malaria cases have significantly decreased but little is known about the vectors or mechanisms responsible for residual malaria transmission. We analysed a total of 3920 Anopheles mosquitoes collected during the rainy and dry seasons from four ecological settings in Cambodia (villages, forested areas near villages, rubber tree plantations and forest sites). Using odor-baited traps, 81% of the total samples across all sites were collected in cow baited traps, although 67% of the samples attracted by human baited traps were collected in forest sites. Overall, 20% of collected Anopheles were active during the day, with increased day biting during the dry season. 3131 samples were identified morphologically as 14 different species, and a subset was also identified by DNA amplicon sequencing allowing determination of 29 Anopheles species. The investigation of well characterized insecticide mutations (ace-1, kdr, and rdl genes) indicated that individuals carried mutations associated with response to all the different classes of insecticides. There also appeared to be a non-random association between mosquito species and insecticide resistance with Anopheles peditaeniatus exhibiting nearly fixed mutations. Molecular screening for Plasmodium sp. presence indicated that 3.6% of collected Anopheles were positive, most for P. vivax followed by P. falciparum. These results highlight some of the key mechanisms driving residual human malaria transmission in Cambodia, and illustrate the importance of diverse collection methods, sites and seasons to avoid bias and better characterize Anopheles mosquito ecology in Southeast Asia.

scholarly journals Accuracy of quantitative polymerase chain reaction in samples of frozen and paraffin-embedded healthy skin for the diagnosis of canine visceral leishmaniasis

2017 ◽  
Vol 69 (6) ◽  
pp. 1443-1450 ◽  
Author(s):  
M.P. Campos ◽  
M.F. Madeira ◽  
D.A. Silva ◽  
M.S. Solcà ◽  
O.M. Espíndola ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Quantitative Polymerase Chain Reaction ◽  
Healthy Skin ◽  
Sample Collection ◽  
Chain Reaction ◽  
Dna Recovery ◽  
Ffpe Samples ◽  
Fresh Frozen ◽  
Polymerase Chain ◽  
Commercial Kits

ABSTRACT The purpose of the present work was to evaluate the accuracy of quantitative polymerase chain reaction (qPCR) performed on samples of fresh frozen tissue (FT) and formalin-fixed, paraffin-embedded (FFPE) healthy skin. This is a validation study conducted with samples from 46 dogs from an endemic area in Brazil. After sample collection, DNA extractions were conducted using commercial kits and qPCR was oriented to kinetoplast DNA (kDNA) targets of the Leishmania infantum species. The results obtained for the FFPE samples showed 63.6% sensitivity and 77.1% specificity, whereas those obtained for the FT samples showed 100% and 48.6%, respectively. Poor agreement was observed for the results of the qPCR technique with FT and FFPE samples. Our results suggest freezing as the most suitable conservation method for the formation of sample databases considering DNA recovery

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