Field Validation of the ReEBOV Antigen Rapid Test for Point-of-Care Diagnosis of Ebola Virus Infection

Embedding treatment in stronger care systems

A key lesson from the west Africa (2014-16) Ebola disease epidemic was that outbreak responses fail when they respond to patients through a narrow clinical lens without considering the broader community and social context of care. Here, in the second of two Series papers on the modern landscape of Ebola disease, we review progress made in the last decade to improve patient-centred care. Although the biosafety imperatives of treating Ebola disease remain, recent advances show how to mitigate these so that patients are cared for in a safe and dignified manner that encourages early treatment-seeking behaviour and provides support after the return of patients to their communities. We review advances in diagnostics, including faster Ebola disease detection via real-time RT-PCR, and consider design improvements in Ebola disease treatment units that enhance patient safety and dignity. We also review advances in care provision, such as the integration of palliative care and mobile communication into routine care, and address how greater access to research is possible through harmonised clinical trials. Finally, we discuss how strengthened community engagement and psychosocial programmes are addressing stigma and providing holistic support for survivors.

Systematic review and meta-analysis of antigen rapid diagnostic tests to detect Zaire ebolavirus

We conducted a systematic review and meta-analysis of studies and reports comparing the performance of antigen rapid diagnostic tests (Ag RDT) for diagnosing Ebola disease (EVD). We searched PubMed, EMBASE, and Web of Science for diagnostic studies published between 1976 and 2023, evaluating them with QUADAS-2. Using a bivariate random-effects model, we estimated the pooled sensitivity and specificity of Ag RDTs. Of 64 eligible full studies and reports, 16 met the inclusion criteria. Pooled sensitivity and specificity were 82.1% (95%CI: 75.2 - 88.0) and 97.0% (95%CI: 95.1-98.2), respectively. We conducted subgroup analysis on 4 Ag RDTs, 3 RT-PCR tests, and 4 sample types, showing varied performance. The high specificity and positive predictive value of Ag RDTs support their use to "rule-in" patients with EVD. However, high-sensitivity RDTs suitable for field settings and capable of detecting multiple ebolavirus species are needed.

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.

Rapid diagnostic tests versus RT-PCR for Ebola virus infections: a systematic review and meta-analysis

Objective

To evaluate the clinical accuracy of rapid diagnostic tests for the detection of Ebola virus.

Methods

We searched MEDLINE®, Embase® and Web of Science for articles published between 1976 and October 2021 reporting on clinical studies assessing the performance of Ebola virus rapid diagnostic tests compared with reverse transcription polymerase chain reaction (RT-PCR). We assessed study quality using the QUADAS-2 criteria. To estimate the pooled sensitivity and specificity of these rapid diagnostic tests, we used a bivariate random-effects meta-analysis.

Findings

Our search identified 113 unique studies, of which nine met the inclusion criteria. The studies were conducted in the Democratic Republic of the Congo, Guinea, Liberia and Sierra Leone and they evaluated 12 rapid diagnostic tests. We included eight studies in the meta-analysis. The pooled sensitivity and specificity of the rapid tests were 86% (95% confidence interval, CI: 80-91) and 95% (95% CI: 91-97), respectively. However, pooled sensitivity decreased to 83% (95% CI: 77-88) after removing outliers. Pooled sensitivity increased to 90% (95% CI: 82-94) when analysis was restricted to studies using the RT-PCR from altona Diagnostics as gold standard. Pooled sensitivity increased to 99% (95% CI: 67-100) when the analysis was restricted to studies using whole or capillary blood specimens.

Conclusion

The included rapid diagnostic tests did not detect all the Ebola virus disease cases. While the sensitivity and specificity of these tests are moderate, they are still valuable tools, especially useful for triage and detecting Ebola virus in remote areas.

Technologies for Frugal and Sensitive Point-of-Care Immunoassays

Immunoassays are a powerful tool for sensitive and quantitative analysis of a wide range of biomolecular analytes in the clinic and in research laboratories. However, enzyme-linked immunosorbent assay (ELISA)-the gold-standard assay-requires significant user intervention, time, and clinical resources, making its deployment at the point-of-care (POC) impractical. Researchers have made great strides toward democratizing access to clinical quality immunoassays at the POC and at an affordable price. In this review, we first summarize the commercially available options that offer high performance, albeit at high cost. Next, we describe strategies for the development of frugal POC assays that repurpose consumer electronics and smartphones for the quantitative detection of analytes. Finally, we discuss innovative assay formats that enable highly sensitive analysis in the field with simple instrumentation.

Ultrasensitive point-of-care immunoassay for secreted glycoprotein detects Ebola infection earlier than PCR

Ebola virus (EBOV) hemorrhagic fever outbreaks have been challenging to deter due to the lack of health care infrastructure in disease-endemic countries and a corresponding inability to diagnose and contain the disease at an early stage. EBOV vaccines and therapies have improved disease outcomes, but the advent of an affordable, easily accessed, mass-produced rapid diagnostic test (RDT) that matches the performance of more resource-intensive polymerase chain reaction (PCR) assays would be invaluable in containing future outbreaks. Here, we developed and demonstrated the performance of a new ultrasensitive point-of-care immunoassay, the EBOV D4 assay, which targets the secreted glycoprotein of EBOV. The EBOV D4 assay is 1000-fold more sensitive than the U.S. Food and Drug Administration-approved RDTs and detected EBOV infection earlier than PCR in a standard nonhuman primate model. The EBOV D4 assay is suitable for low-resource settings and may facilitate earlier detection, containment, and treatment during outbreaks of the disease.

Boosting understanding of Lassa Fever virus epidemiology: Field testing a novel assay to identify past Lassa Fever virus infection in blood and oral fluids of survivors and unexposed controls in Sierra Leone

BACKGROUND

Despite identification 50 years ago, the true burden of Lassa Fever (LF) across Africa remains undefined for reasons including research focus on hospitalised patients, lack of validated field-feasible tools which reliably identify past infection, and the fact that all assays require blood samples making large-scale surveys difficult. Designated a priority pathogen of epidemic potential requiring urgent research by the World Health Organisation, a better understanding of LF sero-epidemiology is essential to developing and evaluating new interventions including vaccines. We describe the first field testing of a novel species-neutral Double Antigen Binding Assay (DABA) designed to detect antibodies to LF in plasma and oral fluid.

METHODOLOGY/PRINCIPAL FINDINGS

Paired plasma and oral fluid were collected in Sierra Leone from survivors discharged from Kenema Government Hospital Lassa Fever Unit between 1980 and 2018, and from controls recruited in Freetown in 2019. Epidemiological sensitivity and specificity of the DABA measured against historical diagnosis in survivors and self-declared non-exposed controls was 81.7% (95% CI 70.7%- 89.9%) and 83.3% (72.7%- 91.1%) respectively in plasma, and 71.8% (60.0%- 81.9%) and 83.3% (72.7%- 91.1%) respectively in oral fluid. Antibodies were identified in people infected up to 15 years and, in one case, 40 years previously. Participants found oral fluid collection easy and painless with 80% happy to give an oral fluid sample regularly.

CONCLUSIONS/SIGNIFICANCE

Given the difficulties of assay validation in a resource-limited setting, including unexpected exposures and diagnostics of varying accuracy, the new assay performed well in both plasma and oral fluid. Sensitivity and specificity are expected to be higher when case/control ascertainment is more definitive and further work is planned to investigate this. Even at the performance levels achieved, the species-neutral DABA has the potential to facilitate the large-scale seroprevalence surveys needed to underpin essential developments in LF control, as well as support zoonotic investigations.

Antibodies from Sierra Leonean and Nigerian Lassa fever survivors cross-react with recombinant proteins representing Lassa viruses of divergent lineages

Lassa virus (LASV) is the causative agent of Lassa fever, an often-fatal hemorrhagic disease that is endemic in West Africa. Seven genetically distinct LASV lineages have been identified. As part of CEPI's (Coalition for Epidemic Preparedness Innovations) Lassa vaccine development program, we assessed the potential of the human immune system to mount cross-reactive and cross-protective humoral immune responses to antigens from the most prevalent LASV lineages, which are lineages II and III in Nigeria and lineage IV in Sierra Leone. IgG and IgM present in the blood of Lassa fever survivors from Nigeria or Sierra Leone exhibited substantial cross-reactivity for binding to LASV nucleoprotein and two engineered (linked and prefusion) versions of the glycoproteins (GP) of lineages II-IV. There was less cross-reactivity for the Zinc protein. Serum or plasma from Nigerian Lassa fever survivors neutralized LASV pseudoviruses expressing lineage II GP better than they neutralized lineage III or IV GP expressing pseudoviruses. Sierra Leonean survivors did not exhibit a lineage bias. Neutralization titres determined using LASV pseudovirus assays showed significant correlation with titres determined by plaque reduction with infectious LASV. These studies provide guidance for comparison of humoral immunity to LASV of distinct lineages following natural infection or immunization.

50 Years of Lassa Fever Research

Lassa fever was first described as a clinical entity fifty years ago. The causative agent Lassa virus was isolated from these first known cases. This chapter reviews the key publications on Lassa fever research that appeared in the scientific literature at that time and over the ensuing decades.

Early detection of Ebola virus proteins in peripheral blood mononuclear cells from infected mice

Background

Detection of viral ribo-nucleic acid (RNA) via real-time polymerase chain reaction (RT-PCR) is the gold standard for the detection of Ebola virus (EBOV) during acute infection. However, the earliest window for viral RNA detection in blood samples is 48–72 h post-onset of symptoms. Therefore, efforts to develop additional orthogonal assays using complementary immunological and serological technologies are still needed to provide simplified methodology for field diagnostics. Furthermore, unlike RT-PCR tests, immunoassays that target viral proteins and/or early host responses are less susceptible to sequence erosion due to viral genetic drift. Although virus is shed into the bloodstream from infected cells, the wide dynamic range of proteins in blood plasma makes this a difficult sample matrix for the detection of low-abundant viral proteins. We hypothesized that the isolation of peripheral blood mononuclear cells (PBMCs), which are the first cellular targets of the Ebola virus (EBOV), may provide an enriched source of viral proteins.

Methods

A mouse infection model that employs a mouse-adapted EBOV (MaEBOV) was chosen as a proof-of-principal experimental paradigm to determine if viral proteins present in PBMCs can help diagnose EBOV infection pre-symptomatically. We employed a liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) platform to provide both high sensitivity and specificity for the detection and relative quantitation of viral proteins in PBMCs collected during MaEBOV infection. Blood samples pooled from animals at the post-infection time-points were used to determine the viral load by RT-PCR and purify PBMCs.

Results

Using quantitative LC-MS/MS, we detected two EBOV proteins (vp40 and nucleoprotein) in samples collected on Day 2 post-infection, which was also the first day of detectable viremia via RT-PCR. These results were confirmed via western blot which was performed on identical PBMC lysates from each post-infection time point.

Conclusions

While mass spectrometry is not currently amenable to field diagnostics, these results suggest that viral protein enrichment in PBMCs in tandem with highly sensitive immunoassays platforms, could lead to the development of a rapid, high-throughput diagnostic platform for pre-symptomatic detection of EBOV infection.

Diagnostic Laboratories' Capacities and Preparedness for Emerging Viral Diseases in Guinea and Mali

The 2014-2016 Ebola epidemic in Guinea highlighted the need for more extensive evaluation of laboratories diagnostic capacities and preparedness in anticipation of future emerging viral disease outbreaks. We developed a questionnaire to assess the diagnostic capacities and preparedness of the four major medical laboratories in Guinea and Mali that are responsible for the provision of Ebola, Lassa, and Dengue diagnostics. The questionnaire inquired about the current state and need for equipment and reagents and adequacy of equipment and training received. In Guinea, all three diagnostic laboratories have the capacity and are well-prepared to perform Ebola diagnostics, however, only two have the capacity and trained staff to diagnose Lassa and none are currently prepared to diagnose Dengue infection. In Mali, the University Clinical Research Center (UCRC) laboratory, which was in charge of Ebola diagnostics during the last epidemic, currently has the capacity and is prepared to diagnose Ebola, Lassa, and Dengue infections. Combined, Guinea and Mali appear to have complementary capacity and preparedness to diagnose these Category A Priority Pathogens. While, the equipment, reagents and training efforts should be maintained, the gap in Dengue diagnostic capability in Guinea should be addressed with further equipping and training of additional district laboratories to strengthen the public health response for all viral diseases in these high-risk, yet, low-resource settings.

Status, quality and specific needs of Ebola virus diagnostic capacity and capability in laboratories of the two European preparedness laboratory networks EMERGE and EVD-LabNet

From December 2013 to March 2016, West Africa experienced the largest Ebola virus (EBOV) outbreak to date, leading to a European-wide activation of laboratory preparedness and response. At the end of the outbreak, laboratories associated with the two European preparedness networks of expert laboratories EMERGE JA and EVD-LabNet were invited to participate in an assessment of the response of European laboratories to the EBOV outbreak, to identify learning points and training needs to strengthen future outbreak responses. Response aspects assessed included diagnostics, biorisk management and quality assurance. The overall coverage of EBOV diagnostics in the European Union/European Economic Area (EU/EEA) was found to be adequate although some points for quality improvement were identified. These included the need for relevant International Organization for Standardization (ISO) accreditation, the provision of EBOV external quality assessments (EQA) in periods where there is no emergency, facilitating access to controls and knowledge, biorisk management without compromising biosafety and a rapid public health response, and the need for both sustained and contingency funding for preparedness and response activities.

Development of Mobile Laboratory for Viral Hemorrhagic Fever Detection in Africa

Background

A mobile laboratory transportable on commercial flights was developed to enable local response to viral hemorrhagic fever outbreaks.

Methods

The development progressed from use of mobile real-time reverse-transcription polymerase chain reaction to mobile real-time recombinase polymerase amplification. In this study, we describe various stages of the mobile laboratory development.

Results

A brief overview of mobile laboratory deployments, which culminated in the first on-site detection of Ebola virus disease (EVD) in March 2014, and their successful use in a campaign to roll back EVD cases in Conakry in the West Africa Ebola virus outbreak are described.

Conclusions

The developed mobile laboratory successfully enabled local teams to perform rapid disgnostic testing for viral hemorrhagic fever.

Recent advances in the development and evaluation of molecular diagnostics for Ebola virus disease

INTRODUCTION

The 2014-16 outbreak of ebola virus disease (EVD) in West Africa resulted in 11,308 deaths. During the outbreak only 60% of patients were laboratory confirmed and global health authorities have identified the need for accurate and readily deployable molecular diagnostics as an important component of the ideal response to future outbreaks, to quickly identify and isolate patients. Areas covered: Currently PCR-based techniques and rapid diagnostic tests (RDTs) that detect antigens specific to EVD infections dominate the diagnostic landscape, but recent advances in biosensor technologies have led to novel approaches for the development of EVD diagnostics. This review summarises the literature and available performance data of currently available molecular diagnostics for ebolavirus, identifies knowledge gaps and maps out future priorities for research in this field. Expert opinion: While there are now a plethora of diagnostic tests for EVD at various stages of development, there is an acute need for studies to compare their clinical performance, but the sporadic nature of EVD outbreaks makes this extremely challenging, demanding pragmatic new modalities of research funding and ethical/institutional approval, to enable responsive research in outbreak settings. Retrospective head-to-head diagnostic comparisons could also be implemented using biobanked specimens, providing this can be done safely.

Diagnostics for Lassa fever virus: a genetically diverse pathogen found in low-resource settings

Lassa fever virus (LASV) causes acute viral haemorrhagic fever with symptoms similar to those seen with Ebola virus infections. LASV is endemic to West Africa and is transmitted through contact with excretions of infected Mastomys natalensis rodents and other rodent species. Due to a high fatality rate, lack of treatment options and difficulties with prevention and control, LASV is one of the high-priority pathogens included in the WHO R&D Blueprint. The WHO LASV vaccine strategy relies on availability of effective diagnostic tests. Current diagnostics for LASV include in-house and commercial (primarily research-only) laboratory-based serological and nucleic acid amplification tests. There are two commercially available (for research use only) rapid diagnostic tests (RDTs), and a number of multiplex panels for differential detection of LASV infection from other endemic diseases with similar symptoms have been evaluated. However, a number of diagnostic gaps remain. Lineage detection is a challenge due to the genomic diversity of LASV, as pan-lineage sensitivity for both molecular and immunological detection is necessary for surveillance and outbreak response. While pan-lineage ELISA and RDTs are commercially available (for research use only), validation and external quality assessment (EQA) is needed to confirm detection sensitivity for all known or relevant strains. Variable sensitivity of LASV PCR tests also highlights the need for improved validation and EQA. Given that LASV outbreaks typically occur in low-resource settings, more options for point-of-care testing would be valuable. These requirements should be taken into account in target product profiles for improved LASV diagnostics.

Diagnostics for Nipah virus: a zoonotic pathogen endemic to Southeast Asia

Nipah virus (NiV) is an emerging pathogen that, unlike other priority pathogens identified by WHO, is endemic to Southeast Asia. It is most commonly transmitted through exposure to saliva or excrement from the Pteropus fruit bat, or direct contact with intermediate animal hosts, such as pigs. NiV infection causes severe febrile encephalitic disease and/or respiratory disease; treatment options are limited to supportive care. A number of in-house diagnostic assays for NiV using serological and nucleic acid amplification techniques have been developed for NiV and are used in laboratory settings, including some early multiplex panels for differentiation of NiV infection from other febrile diseases. However, given the often rural and remote nature of NiV outbreak settings, there remains a need for rapid diagnostic tests that can be implemented at the point of care. Additionally, more reliable assays for surveillance of communities and livestock will be vital to achieving a better understanding of the ecology of the fruit bat host and transmission risk to other intermediate hosts, enabling implementation of a ‘One Health’ approach to outbreak prevention and the management of this zoonotic disease. An improved understanding of NiV viral diversity and infection kinetics or dynamics will be central to the development of new diagnostics, and access to clinical specimens must be improved to enable effective validation and external quality assessments. Target product profiles for NiV diagnostics should be refined to take into account these outstanding needs.

A Smartphone-Based Rapid Telemonitoring System for Ebola and Marburg Disease Surveillance

We have developed a digital and multiplexed platform for the rapid detection and telemonitoring of infections caused by Ebola and Marburg filoviruses. The system includes a flow cell assay cartridge that captures specific antibodies with microarrayed recombinant antigens from all six species of filovirus, and a smartphone fluorescent reader for high-performance interpretation of test results. Multiplexed viral proteins, which are expandable to include greater numbers of probes, were incorporated to obtain highest confidence results by cross-correlation, and a custom smartphone application was developed for data analysis, interpretation, and communication. The smartphone reader utilizes an opto-electro-mechanical hardware attachment that snaps at the back of a Motorola smartphone and provides a user interface to manage the operation, acquire test results, and communicate with cloud service. The application controls the hardware attachment to turn on LEDs and digitally record the optically enhanced images. Assay processing time is approximately 20 min for microliter amounts of blood, and test results are digitally processed and displayed within 15 s. Furthermore, a secure cloud service was developed for the telemonitoring of test results generated by the smartphone readers in the field. Assay system results were tested with sera from nonhuman primates that received a live attenuated EBOV vaccine. This integrated system will provide a rapid, reliable, and digital solution to prevent the rapid overwhelming of medical systems and resources during EVD or MVD outbreaks. Further, this disease-monitoring system will be useful in resource-limited countries where there is a need for dispersed laboratory analysis of recent or active infections.

Tracking virus outbreaks in the twenty-first century

Emerging viruses have the potential to impose substantial mortality, morbidity and economic burdens on human populations. Tracking the spread of infectious diseases to assist in their control has traditionally relied on the analysis of case data gathered as the outbreak proceeds. Here, we describe how many of the key questions in infectious disease epidemiology, from the initial detection and characterization of outbreak viruses, to transmission chain tracking and outbreak mapping, can now be much more accurately addressed using recent advances in virus sequencing and phylogenetics. We highlight the utility of this approach with the hypothetical outbreak of an unknown pathogen, ‘Disease X’, suggested by the World Health Organization to be a potential cause of a future major epidemic. We also outline the requirements and challenges, including the need for flexible platforms that generate sequence data in real-time, and for these data to be shared as widely and openly as possible.

This Review Article describes how recent advances in viral genome sequencing and phylogenetics have enabled key issues associated with outbreak epidemiology to be more accurately addressed, and highlights the requirements and challenges for generating, sharing and using such data when tackling a viral outbreak.

Analysis of CD8+ T cell response during the 2013-2016 Ebola epidemic in West Africa

The recent Ebola epidemic exemplified the importance of understanding and controlling emerging infections. Despite the importance of T cells in clearing virus during acute infection, little is known about Ebola-specific CD8⁺ T cell responses. We investigated immune responses of individuals infected with Ebola virus (EBOV) during the 2013-2016 West Africa epidemic in Sierra Leone, where the majority of the >28,000 EBOV disease (EVD) cases occurred. We examined T cell memory responses to seven of the eight Ebola proteins (GP, sGP, NP, VP24, VP30, VP35, and VP40) and associated HLA expression in survivors. Of the 30 subjects included in our analysis, CD8⁺ T cells from 26 survivors responded to at least one EBOV antigen. A minority, 10 of 26 responders (38%), made CD8⁺ T cell responses to the viral GP or sGP. In contrast, 25 of the 26 responders (96%) made response to viral NP, 77% to VP24 (20 of 26), 69% to VP40 (18 of 26), 42% (11 of 26) to VP35, with no response to VP30. Individuals making CD8⁺ T cells to EBOV VP24, VP35, and VP40 also made CD8⁺ T cells to NP, but rarely to GP. We identified 34 CD8⁺ T cell epitopes for Ebola. Our data indicate the immunodominance of the EBOV NP-specific T cell response and suggest that its inclusion in a vaccine along with the EBOV GP would best mimic survivor responses and help boost cell-mediated immunity during vaccination.

Field validation of recombinant antigen immunoassays for diagnosis of Lassa fever

Lassa fever, a hemorrhagic fever caused by Lassa virus (LASV), is endemic in West Africa. It is difficult to distinguish febrile illnesses that are common in West Africa from Lassa fever based solely on a patient’s clinical presentation. The field performance of recombinant antigen-based Lassa fever immunoassays was compared to that of quantitative polymerase chain assays (qPCRs) using samples from subjects meeting the case definition of Lassa fever presenting to Kenema Government Hospital in Sierra Leone. The recombinant Lassa virus (ReLASV) enzyme-linked immunosorbant assay (ELISA) for detection of viral antigen in blood performed with 95% sensitivity and 97% specificity using a diagnostic standard that combined results of the immunoassays and qPCR. The ReLASV rapid diagnostic test (RDT), a lateral flow immunoassay based on paired monoclonal antibodies to the Josiah strain of LASV (lineage IV), performed with 90% sensitivity and 100% specificity. ReLASV immunoassays performed better than the most robust qPCR currently available, which had 82% sensitivity and 95% specificity. The performance characteristics of recombinant antigen-based Lassa virus immunoassays indicate that they can aid in the diagnosis of LASV Infection and inform the clinical management of Lassa fever patients.

Ebola virus disease: Biological and diagnostic evolution from 2014 to 2017

The Ebola virus disease outbreak observed in West Africa from March 2014 to June 2016 has led to many fundamental and applied research works. Knowledge of this virus has substantially increased. Treatment of many patients in epidemic countries and a few imported cases in developed countries led to developing new diagnostic methods and to adapt laboratory organization and biosafety precautions to perform conventional biological analyses. Clinical and biological monitoring of patients infected with Ebola virus disease helped to determine severity criteria and bad prognosis markers. It also contributed to showing the possibility of viral sanctuaries in patients and the risk of transmission after recovery. After a summary of recent knowledge of environmental and clinical viral persistence, we aimed to present new diagnostic methods and other biological tests that led to highlighting the pathophysiological consequences of Ebola virus disease and its prognostic markers. We also aimed to describe our lab experience in the care of Ebola virus-infected patients, especially technical and logistical changes between 2014 and 2017.

Evaluation of a rapid and sensitive RT-qPCR assay for the detection of Ebola Virus

BACKGROUND

The 2013-2016 Ebola virus disease (EVD) outbreak showed a lack of diagnostic point-of-care methods. Currently, EBOV diagnosis relies on quantitative reverse-transcription-PCR (RT- qPCR), highly specific and sensitive, but requiring skilled personnel and well-equipped laboratories. In field settings, these factors and others, such as samples' time of collection and transportation, determine a prolonged turnaround-time to final results. In outbreak scenarios, a rapid and transportable method could eliminate issues of cohorting suspected and actual EVD patients for lack of diagnostic certainty. The aim of this study was the field evaluation of the new fast, easy-to-use and reliable RT-qPCR assay and platform for EBOV detection, developed in the framework of the EbolaMoDRAD project by CLONIT S.r.l. and STMicroelectronics S.r.l.

STUDY DESIGN

We evaluated its performance during the outbreak and in further studies in the EVD laboratory at the Princess Christian Maternity Hospital (PCMH) in Freetown (Sierra Leone) run by Emergency NGO and the Italian National Institute for Infectious Diseases (INMI). The assay was tested on residual aliquots of clinical specimens from EBOV-positive or -negative patients (n=116, EVD prevalence 37%).

RESULTS AND CONCLUSION

Overall, the test was very easy-to-use and the instrument was robust and reliable in field-settings. The sensitivity of the assay was 100% and the specificity was 98.63% (95%CI: 96.34-100.92%). The positive and negative predictive values were 97.73 (95%CI:94.77-100.68%) and 100%, respectively. The high sensitivity and specificity of this new assay indicate that it is promising for laboratory diagnosis, especially in resource-limited settings.

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.

Metabolomics analyses identify platelet activating factors and heme breakdown products as Lassa fever biomarkers

Lassa fever afflicts tens of thousands of people in West Africa annually. The rapid progression of patients from febrile illness to fulminant syndrome and death provides incentive for development of clinical prognostic markers that can guide case management. The small molecule profile of serum from febrile patients triaged to the Viral Hemorrhagic Fever Ward at Kenema Government Hospital in Sierra Leone was assessed using untargeted Ultra High Performance Liquid Chromatography Mass Spectrometry. Physiological dysregulation resulting from Lassa virus (LASV) infection occurs at the small molecule level. Effects of LASV infection on pathways mediating blood coagulation, and lipid, amino acid, nucleic acid metabolism are manifest in changes in the levels of numerous metabolites in the circulation. Several compounds, including platelet activating factor (PAF), PAF-like molecules and products of heme breakdown emerged as candidates that may prove useful in diagnostic assays to inform better care of Lassa fever patients.

Lassa fever afflicts tens of thousands of people in West Africa each year. The disease progresses rapidly, but there are no tests available to determine which patients are at high risk for dying. We measured the levels of small molecules in the blood of febrile patients with and without infection by LASV that presented to Kenema Government Hospital in Sierra Leone using Ultra High Performance Liquid Chromatography Mass Spectrometry (LCMS), which identifies compounds based on their precise mass. Computational analyses were used to identify compounds that differed in patients with an acute LASV infection, patients with evidence of prior exposure to LASV and patients with fever, but who did not have evidence of exposure to LASV. Several serum metabolites, including factors that are involved in blood clotting and breakdown products of heme, were identified that may prove useful in diagnostic assays that will inform better care of Lassa fever patients or development of therapeutic interventions.

Global Emergency Medicine: A Review of the Literature From 2016

OBJECTIVES

The Global Emergency Medicine Literature Review (GEMLR) conducts an annual search of peer-reviewed and gray literature relevant to global emergency medicine (EM) to identify, review, and disseminate the most important new research in this field to a global audience of academics and clinical practitioners.

METHODS

This year 13,890 articles written in four languages were identified by our search. These articles were distributed among 20 reviewers for initial screening based on their relevance to the field of global EM. An additional two reviewers searched the gray literature. All articles that were deemed appropriate by at least one reviewer and approved by their editor underwent formal scoring of overall quality and importance. Two independent reviewers scored all articles.

RESULTS

A total of 716 articles met our inclusion criteria and underwent full review. Fifty-nine percent were categorized as emergency care in resource-limited settings, 17% as EM development, and 24% as disaster and humanitarian response. Nineteen articles received scores of 18.5 or higher out of a maximum score of 20 and were selected for formal summary and critique. Inter-rater reliability testing between reviewers revealed Cohen's kappa of 0.441.

CONCLUSIONS

In 2016, the total number of articles identified by our search continued to increase. The proportion of articles in each of the three categories remained stable. Studies and reviews with a focus on infectious diseases, pediatrics, and the use of ultrasound in resource-limited settings represented the majority of articles selected for final review.

Responding to ever-changing epidemiological dynamics of Ebola virus disease

With the incidence and mortality rates of Ebola virus disease (EVD) in Guinea, Liberia and Sierra Leone now at zero and reports of the largest and most complex EVD outbreak in history no longer on the front pages of newspapers worldwide, the urgency of that crisis seems to have subsided. During this lull after the storm and before the next one, the international community needs to engage in a 'lessons-learned' exercise with respect to our collective scientific, clinical and public health preparedness. This engagement must identify pragmatic, innovative mechanisms at multinational, national and community levels that allow research and development of next generation diagnostics and therapeutics, the safe and effective practice of medicine, and the maintenance of public health to keep pace with the rapid epidemiological dynamics of EVD and other deadly infectious diseases.

Epidemiology and Management of the 2013-16 West African Ebola Outbreak

The 2013-16 West African Ebola outbreak is the largest, most geographically dispersed, and deadliest on record, with 28,616 suspected cases and 11,310 deaths recorded to date in Guinea, Liberia, and Sierra Leone. We provide a review of the epidemiology and management of the 2013-16 Ebola outbreak in West Africa aimed at stimulating reflection on lessons learned that may improve the response to the next international health crisis caused by a pathogen that emerges in a region of the world with a severely limited health care infrastructure. Surveillance efforts employing rapid and effective point-of-care diagnostics designed for environments that lack advanced laboratory infrastructure will greatly aid in early detection and containment efforts during future outbreaks. Introduction of effective therapeutics and vaccines against Ebola into the public health system and the biodefense armamentarium is of the highest priority if future outbreaks are to be adequately managed and contained in a timely manner.