Diagnostics in Ebola Virus Disease in Resource-Rich and Resource-Limited Settings

Analysis and mapping of global research publications on point-of-care testing for infectious diseases

RATIONALE

This study presents the first comprehensive analysis and mapping of scientific research on point-of-care testing (POCT) in infectious diseases, filling a gap in understanding the evolving landscape of this field. The identification of research themes and global contributions offers valuable insights.

AIMS AND OBJECTIVES

This manuscript aims to analyse and map scientific research on POCT in the context of infectious diseases.

METHODS

The study employed a comprehensive search strategy using terms related to POCT and infectious diseases. The search was conducted on the Scopus database, refining results based on inclusion and exclusion criteria. The dataset of 1719 research articles was then subjected to descriptive analysis and mapping using VOSviewer.

RESULTS

The research findings indicate an exponential growth in POCT-related publications, with 46.8% published post the COVID-19 pandemic. Plos One journal led in publication frequency, and Biosensors and Bioelectronics received the highest citations per article. North America and Western Europe dominated contributions, with notable participation from China, South Africa, and India. The research landscape revealed the following research themes: detection technologies, human immunodeficiency virus (HIV)/sexually transmitted infection (STI) diagnosis, antibiotic optimisation, and schistosomiasis. Clinical trials focused on antibiotic prescribing, HIV, STIs, and specific infections. The findings suggest a shifting landscape towards POCT, emphasising the need for future planning and investment in healthcare systems. The research identifies areas for future exploration, such as the impact of POCT on antibiotic prescribing and its role in combating infectious diseases in low- and middle-income countries.

CONCLUSION

Implementation of POCT has the potential to revolutionise infectious disease management, improve patient outcomes, and reduce the global burden of diseases. Better public awareness, healthcare team management, and planning for POCT at entry points are crucial for societal benefit. Results demonstrated the evolving role of POCT in infectious disease management and prevention.

Utilising biosensor-based approaches for identifying neurotropic viruses

Neurotropic viruses, with their ability to invade the central nervous system, present a significant public health challenge, causing a spectrum of neurological diseases. Clinical manifestations of neurotropic viral infections vary widely, from mild to life-threatening conditions, such as HSV-induced encephalitis or poliovirus-induced poliomyelitis. Traditional diagnostic methods, including polymerase chain reaction, serological assays, and imaging techniques, though valuable, have limitations. To address these challenges, biosensor-based methods have emerged as a promising approach. These methods offer advantages such as rapid results, high sensitivity, specificity, and potential for point-of-care applications. By targeting specific biomarkers or genetic material, biosensors utilise technologies like surface plasmon resonance and microarrays, providing a direct and efficient means of diagnosing neurotropic infections. This review explores the evolving landscape of biosensor-based methods, highlighting their potential to enhance the diagnostic toolkit for neurotropic viruses.

Head-to-head comparison of diagnostic accuracy of four Ebola virus disease rapid diagnostic tests versus GeneXpert® in eastern Democratic Republic of the Congo outbreaks: a prospective observational study

BACKGROUND

Ebola virus disease (EVD) outbreaks have emerged in Central and West Africa. EVD diagnosis relies principally on RT-PCR testing with GeneXpert®, which has logistical and cost restrictions at the peripheral level of the health system. Rapid diagnostic tests (RDTs) would offer a valuable alternative at the point-of-care to reduce the turn-around time, if they show good performance characteristics. We evaluated the performance of four EVD RDTs against the reference standard GeneXpert® on stored EVD positive and negative blood samples collected between 2018 and 2021 from outbreaks in eastern Democratic Republic of the Congo (DRC).

METHODS

We conducted a prospective and observational study in the laboratory on QuickNavi-Ebola™, OraQuick® Ebola Rapid Antigen, Coris® EBOLA Ag K-SeT, and Standard® Q Ebola Zaïre Ag RDTs using left-over archived frozen EDTA whole blood samples. We randomly selected 450 positive and 450 negative samples from the EVD biorepositories in DRC, across a range of GeneXpert® cycle threshold values (Ct-values). RDT results were read by three persons and we considered an RDT result as "positive", when it was flagged as positive by at least two out of the three readers. We estimated the sensitivity and specificity through two independent generalized (logistic) linear mixed models (GLMM).

FINDINGS

476 (53%) of 900 samples had a positive GeneXpert Ebola result when retested. The QuickNavi-Ebola™ showed a sensitivity of 56.8% (95% CI 53.6-60.0) and a specificity of 97.5% (95% CI 96.2-98.4), the OraQuick® Ebola Rapid Antigen test displayed 61.6% (95% CI 57.0-65.9) sensitivity and 98.1% (95% CI 96.2-99.1) specificity, the Coris® EBOLA Ag K-SeT showed 25.0% (95% CI 22.3-27.9) sensitivity and 95.9% (95% CI 94.2-97.1) specificity, and the Standard® Q Ebola Zaïre Ag displayed 21.6% (95% CI 18.1-25.7) sensitivity and 99.1% (95% CI 97.4-99.7) specificity.

INTERPRETATION

None of the RDTs evaluated approached the "desired or acceptable levels" for sensitivity set out in the WHO target product profile, while all of the tests met the "desired level" for specificity. Nevertheless, the QuickNavi-Ebola™ and OraQuick® Ebola Rapid Antigen Test demonstrated the most favorable profiles, and may be used as frontline tests for triage of suspected-cases while waiting for RT-qPCR confirmatory testing.

FUNDING

Institute of Tropical Medicine Antwerp/EDCTP PEAU-EBOV-RDC project.

The diagnostic accuracy of rapid diagnostic tests for Ebola virus disease: a systematic review

BACKGROUND

Ebola virus disease (EVD) is a dangerous condition that can cause an epidemic. Several rapid diagnostic tests (RDTs) have been developed to diagnose EVD. These RDTs promise to be quicker and easier to use than the current reference standard diagnostic test, PCR.

OBJECTIVES

To assess the diagnostic accuracy of RDTs for EVD.

METHODS

A systematic review of diagnostic accuracy studies.

DATA SOURCES

The following bibliographic databases were searched from inception to present: MEDLINE (Ovid), Embase, Global Health, Cochrane Central Register of Controlled Trials, WHO Global Index Medicus database, Web of Science, PROSPERO register of Systematic Reviews, and Clinical Trials.Gov.

STUDY ELIGIBILITY CRITERIA

Diagnostic accuracy studies.

PARTICIPANTS

Patients presenting to the Ebola treatment units with symptoms of EVD.

INTERVENTIONS

RDTs; reference standard, RT-PCR.

ASSESSMENT OF RISK OF BIAS

Quality Assessment of Diagnostic Accuracy Studies-2 tool.

METHODS OF DATA SYNTHESIS

Summary estimates of diagnostic accuracy study were produced for each device type. Subgroup analyses were performed for RDT type and specimen material. A sensitivity analysis was performed to assess the effect of trial design and bias.

RESULTS

We included 15 diagnostic accuracy studies. The summary estimate of sensitivity for lateral flow assays was 86.1% (95% CI, 86-86.2%), with specificity of 97% (95% CI, 96.1-97.9%). The summary estimate for rapid PCR devices was sensitivity of 96.2% (95% CI, 95.3-97.9%), with a specificity of 96.8% (95% CI, 95.3-97.9%). Pre-specified subgroup analyses demonstrated that RDTs were effective on a range of specimen material. Overall, the risk of bias throughout the included studies was low, but it was high in patient selection and uncertain in the flow and timing domains.

CONCLUSIONS

RDTs possess both high sensitivity and specificity compared with RT-PCR among symptomatic patients presenting to the Ebola treatment units. Our findings support the use of RDTs as a 'rule in' test to expedite treatment and vaccination.

The Evolution of Medical Countermeasures for Ebola Virus Disease: Lessons Learned and Next Steps

The Ebola virus disease outbreak that occurred in Western Africa from 2013-2016, and subsequent smaller but increasingly frequent outbreaks of Ebola virus disease in recent years, spurred an unprecedented effort to develop and deploy effective vaccines, therapeutics, and diagnostics. This effort led to the U.S. regulatory approval of a diagnostic test, two vaccines, and two therapeutics for Ebola virus disease indications. Moreover, the establishment of fieldable diagnostic tests improved the speed with which patients can be diagnosed and public health resources mobilized. The United States government has played and continues to play a key role in funding and coordinating these medical countermeasure efforts. Here, we describe the coordinated U.S. government response to develop medical countermeasures for Ebola virus disease and we identify lessons learned that may improve future efforts to develop and deploy effective countermeasures against other filoviruses, such as Sudan virus and Marburg virus.

Sample-to-answer COVID-19 nucleic acid testing using a low-cost centrifugal microfluidic platform with bead-based signal enhancement and smartphone read-out

With its origin estimated around December 2019 in Wuhan, China, the ongoing SARS-CoV-2 pandemic is a major global health challenge. The demand for scalable, rapid and sensitive viral diagnostics is thus particularly pressing at present to help contain the rapid spread of infection and prevent overwhelming the capacity of health systems. While high-income countries have managed to rapidly expand diagnostic capacities, such is not the case in resource-limited settings of low- to medium-income countries. Aiming at developing cost-effective viral load detection systems for point-of-care COVID-19 diagnostics in resource-limited and resource-rich settings alike, we report the development of an integrated modular centrifugal microfluidic platform to perform loop-mediated isothermal amplification (LAMP) of viral RNA directly from heat-inactivated nasopharyngeal swab samples. The discs were pre-packed with dried n-benzyl-n-methylethanolamine modified agarose beads used to selectively remove primer dimers, inactivate the reaction post-amplification and allowing enhanced fluorescence detection via a smartphone camera. Sample-to-answer analysis within 1 hour from sample collection and a detection limit of approximately 100 RNA copies in 10 μL reaction volume were achieved. The platform was validated with a panel of 162 nasopharyngeal swab samples collected from patients with COVID-19 symptoms, providing a sensitivity of 96.6% (82.2-99.9%, 95% CI) for samples with Ct values below 26 and a specificity of 100% (90-100%, 95% CI), thus being fit-for-purpose to diagnose patients with a high risk of viral transmission. These results show significant promise towards bringing routine point-of-care COVID-19 diagnostics to resource-limited settings.

Ebola Virus IgG Seroprevalence in Southern Mali

Mali had 2 reported introductions of Ebola virus (EBOV) during the 2013–2016 West Africa epidemic. Previously, no evidence for EBOV circulation was reported in Mali. We performed an EBOV serosurvey study in southern Mali. We found low seroprevalence in the population, indicating local exposure to EBOV or closely related ebola viruses.

Ebola virus outbreak preparedness plan for developing Nations: Lessons learnt from affected countries

BACKGROUND

Ebola virus (EBOV); a public health emergency of international concern,is known to pose threat of global outbreaks. EBOV has spread in African continent and due to unchecked international travel, importation of cases has been reported in different countries. In this alarming scenario, developing countries need to evaluate and upgrade their preparedness plan to contain the spread of EBOV. The present review lays down the updated preparedness plan for developing countries to contain future EBOV outbreaks.

METHODS

The literature on EBOV outbreaks and preparedness strategies reported were searched on Pubmed and Google Scholar using the MeSH terms such as "Ebola virus disease, Epidemic, Outbreak, Imported case, Preparedness, Public health interventions" combined with Boolean operator (OR) for the period of 2011-2020. Additionally, World Health organization (WHO) and Centers for Disease Control & Prevention (CDC) websites were searched for the guidelines, reports, containment strategies, containment plan of countries, actions taken by countries and international partners, etc. RESULTS: The present review analyzed the EBOV outbreaks between 2011-2020 and containment strategies used by the affected countries. Based on the lessons learned from EBOV outbreaks and personal experience in infectious disease management, we have recommended a preparedness and response plan for EBOV containment in developing countries.

CONCLUSION

Developing countries are particularly vulnerable to major outbreaks of EBOV due to increased international travel and unchecked transmission. The recommended preparedness plan will help developing counties to contain EBOV outbreaks in future.

Molecular diagnosis of COVID-19: Current situation and trend in China (Review)

COVID-19 is caused by a novel coronavirus (2019-nCoV or SARS-CoV-2) and has become a global public health emergency. Rapid and accurate molecular diagnostic technologies are crucial for the screening, isolation, treatment, prevention and control of COVID-19. Currently, nucleic acid detection-based techniques and rapid diagnostic tests that detect antigens or antibodies specific to 2019-nCoV infections are the primary diagnostic tools. China National Medical Products Administration has opened a special channel for approval of new pharmaceuticals owing to urgent clinical needs, with 18 nucleic acid detection kits, 11 protein detection kits and 1 sequencing-related equipment and supporting software having been approved until April 23, 2020. The current review summarizes the application situation, advantages, disadvantages and associated technology improvement trends of molecular diagnostics for COVID-19 in China, identifies knowledge gaps and indicates future priorities for research in this field. The most effective way to prevent and control COVID-19 is early detection, diagnosis, isolation and treatment. In the clinical application of molecular diagnosis technology, it is necessary to combine pathogenic microbiology, immunology and other associated detection technologies, advocate the combination of multiple technologies, determine how they complement each other, enhance practicability and improve the ability of rapid and accurate diagnosis and differential diagnosis of COVID-19.

Meta-analysis of predictive symptoms for Ebola virus disease

INTRODUCTION

One of the leading challenges in the 2013-2016 West African Ebola virus disease (EVD) outbreak was how best to quickly identify patients with EVD, separating them from those without the disease, in order to maximise limited isolation bed capacity and keep health systems functioning.

METHODOLOGY

We performed a systematic literature review to identify all published data on EVD clinical symptoms in adult patients. Data was dual extracted, and random effects meta-analysis performed for each symptom to identify symptoms with the greatest risk for EVD infection.

RESULTS

Symptoms usually presenting late in illness that were more than twice as likely to predict a diagnosis of Ebola, were confusion (pOR 3.04, 95% CI 2.18-4.23), conjunctivitis (2.90, 1.92-4.38), dysphagia (1.95, 1.13-3.35) and jaundice (1.86, 1.20-2.88). Early non-specific symptoms of diarrhoea (2.99, 2.00-4.48), fatigue (2.77, 1.59-4.81), vomiting (2.69, 1.76-4.10), fever (1.97, 1.10-4.52), muscle pain (1.65, 1.04-2.61), and cough (1.63, 1.24-2.14), were also strongly associated with EVD diagnosis.

CONCLUSIONS

The existing literature fails to provide a unified position on the symptoms most predictive of EVD, but highlights some early and late stage symptoms that in combination will be useful for future risk stratification. Confirmation of these findings across datasets (or ideally an aggregation of all individual patient data) will aid effective future clinical assessment, risk stratification tools and emergency epidemic response planning.

Geospatial Hotspots Need Point-of-Care Strategies to Stop Highly Infectious Outbreaks

CONTEXT.—

Point-of-care testing (POCT), diagnostic testing at or near the site of patient care, is inherently spatial, that is, performed at points of need, and also intrinsically temporal, because it produces fast actionable results. Outbreaks generate geospatial "hotspots." POC strategies help control hotspots, detect spread, and speed treatment of highly infectious diseases.

OBJECTIVES.—

To stop outbreaks, accelerate detection, facilitate emergency response for epidemics, mobilize public health practitioners, enhance community resilience, and improve crisis standards of care.

DATA SOURCES.—

PubMed, World-Wide Web, newsprint, and others were searched until Coronavirus infectious disease-19 was declared a pandemic, the United States, a national emergency, and Europe, the epicenter. Coverage comprised interviews in Asia, email to/from Wuhan, papers, articles, chapters, documents, maps, flowcharts, schematics, and geospatial-associated concepts. EndNote X9.1 (Clarivate Analytics) consolidated literature as abstracts, ULRs, and PDFs, recovering 136 hotspot articles. More than 500 geospatial science articles were assessed for relevance to POCT.

CONCLUSIONS.—

POCT can interrupt spirals of dysfunction and delay by enhancing disease detection, decision-making, contagion containment, and safe spacing, thereby softening outbreak surges and diminishing risk before human, economic, and cultural losses mount. POCT results identify where infected individuals spread Coronavirus infectious disease-19, when delays cause death, and how to deploy resources. Results in national cloud databases help optimize outbreak control, mitigation, emergency response, and community resilience. The Coronavirus infectious disease-19 pandemic demonstrates unequivocally that governments must support POCT and multidisciplinary healthcare personnel must learn its principles, then adopt POC geospatial strategies, so that onsite diagnostic testing can ramp up to meet needs in times of crisis.

Metagenomic sequencing with spiked primer enrichment for viral diagnostics and genomic surveillance

Metagenomic next-generation sequencing (mNGS), the shotgun sequencing of RNA and DNA from clinical samples, has proved useful for broad-spectrum pathogen detection and the genomic surveillance of viral outbreaks. An additional target enrichment step is generally needed for high-sensitivity pathogen identification in low-titre infections, yet available methods using PCR or capture probes can be limited by high cost, narrow scope of detection, lengthy protocols and/or cross-contamination. Here, we developed metagenomic sequencing with spiked primer enrichment (MSSPE), a method for enriching targeted RNA viral sequences while simultaneously retaining metagenomic sensitivity for other pathogens. We evaluated MSSPE for 14 different viruses, yielding a median tenfold enrichment and mean 47% (±16%) increase in the breadth of genome coverage over mNGS alone. Virus detection using MSSPE arboviral or haemorrhagic fever viral panels was comparable in sensitivity to specific PCR, demonstrating 95% accuracy for the detection of Zika, Ebola, dengue, chikungunya and yellow fever viruses in plasma samples from infected patients. Notably, sequences from re-emerging and/or co-infecting viruses that have not been specifically targeted a priori, including Powassan and Usutu, were successfully enriched using MSSPE. MSSPE is simple, low cost, fast and deployable on either benchtop or portable nanopore sequencers, making this method directly applicable for diagnostic laboratory and field use.

This study describes a new method that improves the sensitivity of viral detection compared with next-generation sequencing and enables the detection of emerging flaviviruses not specifically targeted a priori. Metagenomic sequencing with spiked primer enrichment is simple, low cost, fast and deployable on either benchtop or portable nanopore sequencers, making it applicable for diagnostic laboratory and field use.

Geospatial Science and Point-of-Care Testing: Creating Solutions for Population Access, Emergencies, Outbreaks, and Disasters

Objectives: (a) To understand how to integrate geospatial concepts when implementing point-of-care testing (POCT); (b) to facilitate emergency, outbreak, and disaster preparedness and emergency management in healthcare small-world networks; (c) to enhance community resilience by using POCT in tandem with geographic information systems (GISs) and other geospatial tools; and (d) to advance crisis standards of care at points of need, adaptable and scalable for public health practice in limited-resource countries and other global settings.

Content: Visual logistics help integrate and synthesize POCT and geospatial concepts. The resulting geospatial solutions presented here comprise: (1) small-world networks and regional topography; (2) space-time transformation, hubs, and asset mapping; (3) spatial and geospatial care paths™; (4) GIS-POCT; (5) isolation laboratories, diagnostics isolators, and mobile laboratories for highly infectious diseases; (6) alternate care facilities; (7) roaming POCT—airborne, ambulances, space, and wearables; (8) connected and wireless POCT outside hospitals; (9) unmanned aerial vehicles; (10) geospatial practice—demographic care unit resource scoring, geographic risk assessment, and national POCT policy and guidelines; (11) the hybrid laboratory; and (12) point-of-careology.

Value: Small-world networks and their connectivity facilitate efficient and effective placement of POCT for optimal response, rescue, diagnosis, and treatment. Spatial care paths™ speed transport from primary encounters to referral centers bypassing topographic bottlenecks, process gaps, and time-consuming interruptions. Regional GISs position POCT close to where patients live to facilitate rapid triage, decrease therapeutic turnaround time, and conserve economic resources. Geospatial care paths™ encompass demographic and population access features. Timeliness creates value during acute illness, complex crises, and unexpected disasters. Isolation laboratories equipped with POCT help stop outbreaks and safely support critically ill patients with highly infectious diseases. POCT-enabled spatial grids can map sentinel cases and establish geographic limits of epidemics for ring vaccination.

Impact: Geospatial solutions generate inherently optimal and logical placement of POCT conceptually, physically, and temporally as a means to improve crisis response and spatial resilience. If public health professionals, geospatial scientists, and POCT specialists join forces, new collaborative teamwork can create faster response and higher impact during disasters, complex crises, outbreaks, and epidemics, as well as more efficient primary, urgent, and emergency community care.

International Biological Reference Preparations for Epidemic Infectious Diseases

Recent years have seen unprecedented investment in research and development for countermeasures for high-threat pathogens, including specific and ambitious objectives for development of diagnostics, therapeutics, and vaccines. The inadequate availability of biological reference materials for these pathogens poses a genuine obstacle in pursuit of these objectives, and the lack of a comprehensive and equitable framework for developing reference materials is a weakness. We outline the need for internationally standardized biological materials for high-threat pathogens as a core element of global health security. We also outline the key components of a framework for addressing this deficiency.

A molecular based diagnosis of positive blood culture in the context of viral haemorrhagic fever: proof of concept

OBJECTIVES

The aim of this study was to evaluate the possibility of using a PCR-based panel to identify bacterial and fungal bloodstream infections in the setting of suspected or confirmed viral haemorrhagic fever.

METHODS

The accuracy of the FilmArray® Blood Culture Identification Panel (BCID) assay was assessed to identify the common bacterial and fungal pathogens associated with bloodstream infections after positive blood culture inactivation using a guanidinium thiocyanate containing buffer lysis that is commonly used for viral haemorrhagic fever molecular diagnostics.

RESULTS

The FilmArray® BCID panel assay detected 95% (19/20) of the pathogens analysed in this study by using both protocols with and without inactivation. Absolute consistency (100%) was observed in all isolates with phenotypes compatible with the presence of the antibiotic resistance genes mecA, vanA, vanB and blaKPC.

CONCLUSIONS

The FilmArray® BCID panel assay coupled to inactivation using a guanidinium thiocyanate containing buffer lysis represents a convenient, sensitive and specific diagnostic tool to detect some of the most pathogens associated with bloodstream infections in the context of a suspected or confirmed viral haemorrhagic fever.

Diagnostics for filovirus detection: impact of recent outbreaks on the diagnostic landscape

Ebolaviruses and Marburg virus (MARV) both belong to the family Filoviridae and cause severe haemorrhagic fever in humans. Due to high mortality rates and potential for spread from rural to urban regions, they are listed on the WHO R&D blueprint of high-priority pathogens. Recent ebolavirus outbreaks in Western and Central Africa have highlighted the importance of diagnostic testing in epidemic preparedness for these pathogens and led to the rapid development of a number of commercially available benchtop and point-of-care nucleic acid amplification tests as well as serological assays and rapid diagnostic tests. Despite these advancements, challenges still remain. While products approved under emergency use licenses during outbreak periods may continue to be used post-outbreak, a lack of clarity and incentive surrounding the regulatory approval pathway during non-outbreak periods has deterred many manufacturers from seeking full approvals. Waning of funding and poor access to samples after the 2014–2016 outbreak also contributed to cessation of development once the outbreak was declared over. There is a need for tests with improved sensitivity and specificity, and assays that can use alternative sample types could reduce the need for invasive procedures and expensive equipment, making testing in field conditions more feasible. For MARV, availability of diagnostic tests is still limited, restricted to a single ELISA test and assay panels designed to differentiate between multiple pathogens. It may be helpful to extend the target product profile for ebolavirus diagnostics to include MARV, as the viruses have many overlapping characteristics.

Detection of unique Ebola virus oligonucleotides using fluorescently-labeled phosphorodiamidate morpholino oligonucleotide probe pairs

Here we identify a low-cost diagnostic platform using fluorescently-labeled phosphorodiamidate morpholino oligonucleotide (PMO) probe pairs, which upon binding target oligonucleotides undergo fluorescence resonance energy transfer (FRET). Using a target oligonucleotide derived from the Ebola virus (EBOV), we have derivatized PMO probes with either Alexa Fluor488 (donor) or tetramethylrhodamine (acceptor). Upon EBOV target oligonulceotide binding, observed changes in FRET between PMO probe pairs permit a 25 pM lower limit of detection; there is no off-target binding within a complex mixture of nucleic acids and other biomolecules present in human saliva. Equivalent levels of FRET occur using PMO probe pairs for single or double stranded oligonucleotide targets. High-affinity binding is retained under low-ionic strength conditions that disrupt oligonucleotide secondary structures (e.g., stem-loop structures), ensuring reliable target detection. Under these low-ionic strength conditions, rates of PMO probe binding to target oligonucleotides are increased 3-fold relative to conventional high-ionic strength conditions used for nucleic acid hybridization, with half-maximal binding occurring within 10 min. Our results indicate an ability to use PMO probe pairs to detect clinically relevant levels of EBOV and other oligonucleotide targets in complex biological samples without the need for nucleic acid amplification, and open the possibility of population screening that includes assays for the genomic integration of DNA based copies of viral RNA.

Novel surveillance methods for the control of Ebola virus disease

The unprecedented scale of the 2013-2016 West African Ebola virus disease (EVD) outbreak was in a large part due to failings in surveillance: contacts of confirmed cases were not systematically identified, monitored and diagnosed early, and new cases appearing in previously unaffected communities were similarly not rapidly identified, diagnosed and isolated. Over the course of this epidemic, traditional surveillance methods were strengthened and novel methods introduced. The wealth of experience gained, and the systems introduced in West Africa, should be used in future EVD outbreaks, as well as for other communicable diseases in the region and beyond.

EBOLA Ag K-SeT rapid test: field evaluation in Sierra Leone

OBJECTIVES

Efficient interruption of Ebola virus disease (EVD) transmission chains critically depends on reliable and fast laboratory diagnosis. We evaluated the performance of the EBOLA Virus Antigen Detection K-SeT (EBOLA Ag K-SeT), a new rapid diagnostic antigen test in field settings.

METHODS

The study was conducted in a field laboratory located in Freetown (Sierra Leone) by the Italian National Institute for Infectious Diseases 'L. Spallanzani' and the EMERGENCY Onlus NGO. The EBOLA Ag K-SeT was tested on 210 residual plasma samples (EVD prevalence 50%) from patients hospitalized at the EMERGENCY Ebola treatment center in Goderich (Freetown), comparing the results with quantitative real-time PCR.

RESULTS

Overall, the sensitivity of EBOLA Ag K-SeT was 88.6% (95% confidence interval (CI), 82.5-94.7), and the corresponding specificity was 98.1% (95% CI, 95.5-100.7). The positive and negative predictive values were 97.9% (95% CI, 95.0-100.8) and 89.6% (95% CI, 84-95.2), respectively. The sensitivity strongly increased up to 98.7% (95% CI, 96.1-101.2) for those samples with high virus load (≥6.2 log RNA copies/mL).

CONCLUSIONS

Our results suggest that EBOLA Ag K-SeT could represent a new effective diagnostic tool for EVD, meeting a need for resource-poor settings and rapid diagnosis for individuals with suspected EVD.

How to treat Ebola virus infections? A lesson from the field

The reported case fatality ratios (CFR) of Ebola virus disease (EVD) have been as high as 90% in previous outbreaks. While the cumulative CFR among patients medically evacuated and treated in Western countries was inferior to 20%, it peaked to approximately 75% between September and December 2014 in West Africa, thereafter decreasing to less than 40% (May 2015) without current evidence of major virus mutations capable to alter virus pathogenicity over the course of the epidemic. Therefore, the observed diminution of CFR is likely to reflect improvement of EVD patient care. Here, we summarize major lessons learned, that is, progresses and knowledge gaps, about the clinical management of patients in West African settings during the 2014-2016 outbreak.