David S Boyle

PATH · Diagnostics Program

The typhoid conjugate vaccine is a safe and effective method for preventing Salmonella enterica serovar Typhi (typhoid) and the WHO’s guidance supports its use in locations with ongoing transmission. However, many countries lack a robust clinical surveillance system, making it challenging to determine where to use the vaccine. Environmental surveil...

Processing and storing blood samples for future analysis of biomarkers can be challenging in resource limited environments. The preparation of dried blood spots (DBS) from finger-stick collection of whole blood is a widely used and established method as DBS are biosafe, and allow simpler field processing, storage, and transport protocols than serum...

Over 71 million people are infected with hepatitis C virus (HCV) worldwide, and approximately 400,000 global deaths result from complications of untreated chronic HCV. Pan-genomic direct-acting antivirals (DAAs) have recently become widely available and feature high cure rates in less than 12 weeks of treatment. The rollout of DAAs is reliant on di...

Lipoarabinomannan (LAM), a component of the Mycobacterium tuberculosis (MTB) cell wall, is detectable in the urine of MTB infected patients with active tuberculosis (TB). LAM-specific antibodies (Igs) have been developed by a variety of traditional and recombinant methods for potential use in a rapid diagnostic test (RDT). We evaluated the analytic...

The relationship between N-antigen concentration and viral load within a specimen and across different specimens is essential for interpretation of rapid diagnostic tests (RDT) clinical performance in different use cases. A prospective study was conducted in Porto Velho, Brazil, to investigate RDT performance in different specimen types as a functi...

Rapid diagnostic tests (RDTs) that detect antigen indicative of SARS-CoV-2 infection can help in making quick health care decisions and regularly monitoring groups at risk of infection. With many RDT products entering the market, it is important to rapidly evaluate their relative performance. Comparison of clinical evaluation study results is chall...

Lipoarabinomannan (LAM), a component of the Mycobacterium tuberculosis (MTB) cell wall, is detectable in the urine of MTB infected patients with active tuberculosis (TB). LAM-specific antibodies (Igs) have been developed by a variety of traditional and recombinant methods for potential use in a rapid diagnostic test (RDT). We evaluated the analytic...

Current HIV antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP) therapy adherence monitoring relies on either patient self-reported adherence or monitored drug dispensing, which are not reliable. We report a proof-of-concept adherence monitoring assay which directly measures nucleotide reverse transcriptase inhibitor (NRTI) concentratio...

Objectives To assess performance of different swab types and specimen collection sites for SARS-CoV-2 testing, compared to reference standard RT-PCR and viral culture. Methods Symptomatic adults attending routine COVID-19 testing sites self-collected anterior nares and tongue specimens, using spun polyester and FLOQSwabs. We evaluated the anterior...

Eradication of poliovirus (PV) is a global public health priority, and as clinical cases decrease, the role of environmental surveillance becomes more important. Persistence of PV and the environmental factors that influence it (such as temperature and sample type) are an important part of understanding and interpreting positive environmental surve...

Inexpensive, simple, rapid diagnostics are necessary for efficient detection, treatment, and mitigation of COVID-19. Assays for SARS-CoV2 using reverse transcription polymerase chain reaction (RT-PCR) offer good sensitivity and excellent specificity, but are expensive, slowed by transport to centralized testing laboratories, and often unavailable....

Collecting, processing, and storing blood samples for future analysis of biomarkers can be challenging when performed in resource limited environments. The preparation of dried blood spots (DBS) from heel or finger stick collection of whole blood is a widely used and established method. DBS pose less risk of infection from blood borne pathogens, do...

A lack of comparative data across laboratories is often a barrier to the uptake and adoption of new technologies. Furthermore, data generated by different immunoassay methods may be incomparable due to a lack of harmonization. In this multicenter study, we describe validation experiments conducted in a single lab and cross-lab comparisons of assay...

The global COVID-19 pandemic has created an urgent demand for large numbers of inexpensive, accurate, rapid, point-of-care diagnostic tests. Analyte-based assays are suitably rapid and inexpensive and can be rapidly mass-produced, but for sufficiently accurate performance, they require highly optimized antibodies and assay conditions. We used an au...

Severe acute respiratory coronavirus-2 (SARS-CoV-2) is a novel viral pathogen and therefore a challenge to accurately diagnose infection. Asymptomatic cases are common and so it is difficult to accurately identify infected cases to support surveillance and case detection. Diagnostic test developers are working to meet the global demand for accurate...

Introduction. The typhoid conjugate vaccine is a safe and effective method for preventing Salmonella enterica serovar Typhi (typhoid) and the WHO's guidance supports its use in locations with ongoing transmission. However, many countries lack a robust clinical surveillance system, making it challenging to determine where to use the vaccine. Environ...

Micronutrient deficiencies are a significant public health problem affecting a large portion of the world’s population. Disproportionately affected populations—infants, young children, adolescents and women of reproductive age including pregnant women — are especially susceptible to the health consequences of insufficient micronutrient intakes. How...

The number of people living with HIV continues to increase with the current total near 38 million, of which about 26 million are receiving antiretroviral therapy (ART). These treatment regimens are highly effective when properly managed, requiring routine viral load monitoring to assess successful viral suppression. Efforts to expand access by dece...

The COVID-19 pandemic has put the spotlight on the urgent need for integrated nucleic acid tests (NATs) for infectious diseases, especially those that can be used near patient ("point-of-care", POC), with rapid results and low cost, but without sacrificing sensitivity or specificity of gold standard PCR tests. In the US, the Clinical Laboratory Imp...

Lipoarabinomannan (LAM) is a cell wall component of Mycobacterium tuberculosis that is excreted in the urine of persons with active tuberculosis (TB). Limited diagnostic sensitivity of LAM immunoassays has been due to selecting antibodies against LAM derived from in vitro cultured M. tuberculosis, rather than LAM purified from in vivo clinical urin...

Enteric viruses, such as poliovirus, are a leading cause of gastroenteritis, which causes 2–3 million deaths annually. Environmental surveillance of wastewater supplements clinical surveillance for monitoring enteric virus circulation. However, while many environmental surveillance methods require liquid samples, some at-risk locations utilize pit...

Background: Salmonella enterica remains a leading cause of food-borne diseases worldwide. Serotype information is important in food safety and public health activities to reduce the burden of salmonellosis. In the current study, two methods were used to determine serotypes of 111 strains of Salmonella isolated from poultry feces in Burkina Faso. Fi...

p>The number of people living with HIV continues to increase with the current total near 38 million, of which about 26 million are receiving antiretroviral therapy. These treatment regimens are highly effective when properly managed, requiring routine viral load monitoring to assess successful viral suppression. Efforts to expand access by decentra...

p> The global COVID-19 pandemic has created an urgent demand for large numbers of inexpensive, accurate, rapid, point-of-care diagnostic tests. Analyte-based assays are suitably inexpensive and can be rapidly mass-produced, but for sufficiently accurate performance they require highly optimized antibodies and assay conditions. We used an automated...

Current HIV antiretroviral (ART) or pre-exposure prophylaxis (PrEP) therapy adherence monitoring relies on either patient self-reported adherence or monitoring drug dispensing, which are not reliable. We propose an objective adherence monitoring assay which directly measures nucleotide reverse transcriptase inhibitor (NRTI) concentration using a re...

To facilitate treatment and limit transmission of tuberculosis (TB), new methods are needed to enable rapid and affordable diagnosis of the disease in high-burden low-resource settings. We have developed a prototype integrated nucleic acid testing device to detect Mycobacterium tuberculosis (M.tb) in sputum. The device consists of a disposable cart...

Environmental enteric dysfunction (EED) is an intestinal disorder common among children in low-resource settings and is associated with increased risk of growth stunting, cognitive deficits, and reduced oral vaccine immunogenicity. The Micronutrient and EED Assessment Tool (MEEDAT) is a multiplexed immunoassay that measures biomarkers previously as...

p>The spike glycoprotein of SARS-CoV-2 is a highly conserved surface protein and as such may represent a good target for immunoassay detection. We screened a variety of antibodies that were reactive to the S glycoprotein in a highly sensitive liquid immunoassay format and also on paper-based or lateral flow assay (LFA) to assess their analytical pe...

Severe acute respiratory coronavirus-2 (SARS-CoV-2) is a novel viral pathogen and therefore a challenge accurately diagnose infection. Asymptomatic cases are common and so it is difficult to accurately identify infected cases to support surveillance and case detection. Diagnostic test developers are working to meet the global demand for accurate an...

p> Inexpensive, simple, rapid diagnostics are necessary for efficient detection, treatment and mitigation of COVID‑19. Currently, the primary diagnostic tool being utilized is reverse transcription polymerase chain reaction (RT-PCR). RT-PCR delivers results with good sensitivity and excellent specificity, but is expensive, prone to access challeng...

Aims: This study compared the bag-mediated filtration system (BMFS) and standard WHO two-phase separation methods for poliovirus (PV) environmental surveillance, examined factors impacting PV detection, and monitored Sabin-like (SL) PV type 2 presence with withdrawal of oral polio vaccine type 2 (OPV2) in April 2016. Methods and results: Environ...

p> The global COVID-19 pandemic has created an urgent demand for large numbers of inexpensive, accurate, rapid, point-of-care diagnostic tests. Analyte-based assays are suitably inexpensive and can be rapidly mass-produced, but for sufficiently accurate performance they require highly optimized antibodies and assay conditions. We used an automated...

Background Salmonella enterica remains a leading cause of food-borne diseases worldwide. Serotype information is important in food safety and public health activities to reduce the burden of salmonellosis. In the current study, two methods were used to determine serotypes of 225 clinical, environmental, food and veterinary isolates of Salmonella fr...

The authors have withdrawn this preprint due to author disagreement.

The SARS-CoV-2 pandemic has created an unprecedented need for rapid diagnostic testing to enable the efficient treatment and mitigation of COVID-19. The primary diagnostic tool currently employed is reverse transcription polymerase chain reaction (RT-PCR), which can have good sensitivity and excellent specificity. Unfortunately, implementation cost...

p>The SARS-CoV-2 pandemic has created an unprecedented need for rapid diagnostic testing to enable the efficient treatment and mitigation of COVID-19. The primary diagnostic tool currently employed is reverse transcription polymerase chain reaction (RT-PCR), which can have good sensitivity and excellent specificity. Unfortunately, implementation co...

Objective: Micronutrient deficiencies are a significant public health. Vulnerable populations —infants, children, adolescents, pregnant and reproductive aged women—are especially susceptible to the health consequences of inadequate nutrition. However, direct assessment of micronutrient deficiencies is not routinely included in population surveys. T...

The bag-mediated filtration system (BMFS) was developed to facilitate poliovirus (PV) environmental surveillance, a supplement to acute flaccid paralysis surveillance in PV eradication efforts. From April to September 2015, environmental samples were collected from four sites in Nairobi, Kenya, and processed using two collection/concentration metho...

Objectives: Conduct time and temperature stability experiments on Nutritional Biomarkers (NBs) and inflammation markers extracted from ViveBio Dry Plasma Spots (DPS). Methods: Blood samples of 3 hematocrits (20, 30 and 45%) were created by combining purchased red blood cells (RBC) and sera. Blood samples of 35 µL were loaded onto ViveBio plasma...

The global public health community has set ambitious treatment targets to end the HIV/AIDS pandemic. With the notable absence of a cure, the goal of HIV treatment is to achieve sustained suppression of an HIV viral load, which allows for immunological recovery and reduces the risk of onward HIV transmission. Monitoring HIV viral load in people livi...

Nucleic acid amplification technologies (NAATs) are high-performance tools for rapidly and accurately detecting infectious agents. They are widely used in high-income countries to diagnose disease and improve patient care. The complexities associated with test methods, reagents, equipment, quality control and assurance require dedicated laboratorie...

Infectious disease nucleic acid amplification technologies (NAAT) have superior sensitivity, specificity, and rapid time to result compared to traditional microbiological methods. Recovery of concentrated, high quality pathogen nucleic acid (NA) from complex specimen matrices is required for optimal performance of several NA amplification/detection...

Enteric virus environmental surveillance via a highly sensitive method is critical, as many enteric viruses have low infectious doses and can persist in the environment for extended periods. This study determined the potential of the novel bag-mediated filtration system (BMFS) to recover human enteric viruses and pepper mild mottle virus (PMMoV) fr...

Effective surveillance of human enteric viruses is critical to estimate disease prevalence within a community and can be a vital supplement to clinical surveillance. This study sought to evaluate simple, effective, and inexpensive secondary concentration methods for use with ViroCap™ filter eluate for environmental surveillance of poliovirus. Waste...

Simplifying blood collection is often critical when collecting specimens in remote and/or austere settings. The use of dried blood spots (DBS) offers a practical collection method suitable for a wide variety of analytes. A small volume of whole blood can be obtained rapidly through a minimally invasive heel- or finger-stick using a disposable safet...

Introduction: Malaria rapid diagnostic tests (RDTs) detect primarily Plasmodium (P.) falciparum antigen histidine-rich protein 2 (HRP2) and the malaria–conserved antigen lactate dehydrogenase (LDH) for P. vivax and other malaria species. The performance of RDTs and their utility is dependent on circulating antigen concentration distributions in inf...

Poliovirus (PV) environmental surveillance (ES) plays an important role in the global eradication program and is crucial for monitoring silent PV circulation especially as clinical cases decrease. This study compared ES results using the novel bag-mediated filtration system (BMFS) with the current two-phase separation method. From February to Novem...

BMFS sample filtration time. (DOCX)

Chain of custody form tables. (XLSX)

BMFS sample processing and statistical analysis methods. (DOCX)

BMFS sample collection start time. (DOCX)

PV detection data tables. (XLSX)

Wild poliovirus type 1 isolates from BMFS and two-phase samples. (XLSX)

Nucleic acid amplification tests (NAATs) provide high diagnostic accuracy for infectious diseases and quantitative results for monitoring viral infections. The majority of NAATs require complex equipment, cold chain dependent reagents, and skilled technicians to perform tests. This largely confines NAATs to centralized laboratories and can signific...

Setting: New diagnostic tools for tuberculosis (TB) are urgently needed. To guide investment decisions, sufficient information regarding which test attributes are the most important for users and decision makers interested in introducing TB diagnostics should be made available. Objective: To rank test attributes in a target product profile (TPP)...

SETTING: New diagnostic tools for tuberculosis (TB) are urgently needed. To guide investment decisions, sufficient information regarding which test attributes are the most important for users and decision makers interested in introducing TB diagnostics should be made available. OBJECTIVE: To rank test attributes in a target product profile (TPP) i...

Environmental surveillance of poliovirus (PV) plays an important role in the global program for eradication of wild PV. The bag-mediated filtration system (BMFS) was first developed in 2014 and enhances PV surveillance when compared to the two-phase grab method currently recommended by the World Health Organization (WHO). In this study, the BMFS de...

Environmental surveillance of poliovirus (PV) and other non-enveloped viruses can help identify silent circulation and is necessary to certify eradication. The bag-mediated filtration system is an efficient method to filter large volumes of environmental waters at field sites for monitoring the presence of viruses. As filters may require long trans...

Environmental surveillance of waterborne pathogens is vital for monitoring the spread of diseases, and electropositive filters are frequently used for sampling wastewater and wastewater-impacted surface water. Viruses adsorbed to electropositive filters require elution prior to detection or quantification. Elution is typically facilitated by a peri...

Deficiencies of vitamin A, iron, and iodine are major public health concerns in many low- and middle-income countries, but information on their status in populations is often lacking due to high costs and logistical challenges associated with assessing micronutrient status. Accurate, user-friendly, and low-cost analytical tools are needed to allow...

Scatter plots, 7-Plex versus conventional immunoassay results for plasma samples from USA donor panel. Concentrations of each analyte as measured in the 7-Plex (x-axes) plotted against concentrations measured using conventional assays (y-axes) for 72 lithium heparin plasma specimens. Solid line is linear regression. AGP, α-1-acid glycoprotein; CRP,...

Sensitivity and specificity of 7-Plex assays using NiMaNu panel data. Receiver operating characteristic (ROC) curves plotting sensitivity (y-axis) against 1-specificity (x-axis) were generated from 7-Plex results of pregnant women participating in NiMaNu study to identify optimal threshold values for each analyte as measured in the 7-Plex to be use...

Summary statistics from the 7-Plex and conventional assays from USA donor training Panel and NiMaNu panel. (DOCX)

Bland-Altman analysis, 7-Plex results versus conventional immunoassay results for plasma samples from USA donor panel. Bland-Altman plots showing percent difference between 7-Plex and conventional assay results on the y-axes plotted against average concentration on the x-axes for 72 lithium heparin plasma specimens. Heavy horizontal line and light...