Evaluation of a new point-of-care test to determine prior dengue infection for potential use in pre-vaccination screening

ObjectiveVaccination with the first licensed dengue vaccine is recommended only for those who have had previous infection with dengue virus (DENV). A point-of-care test with the desired sensitivity of 95% and specificity of 98% could facilitate pre-vaccination screening. We evaluated a newly developed, automated dengue immunoglobulin fluorescence immunoassay for determining dengue serostatus.MethodsWe used serum samples collected just prior to a mass dengue vaccination in Cebu, Philippines. Healthy children residing in Bogo and Balamban who would be 9–14 years old at the time of the mass dengue vaccination were eligible to participate. We evaluated the ichroma? II dengue fluorescence immunoassay (Boditech Med Incorporated, Gang-won-do, Republic of Korea) using a neutralization test (NT) as the reference assay.ResultsWe enrolled 2996 children (mean age 10.39 years, 51.7% female) in the cohort and included a subsample of 1000 (mean age 10.56 years, 54.4% female) in this study. Of the 1000 children, 86/1000 (8.6%) tested seronegative and 914/1000 (91.4%) seropositive for DENV antibodies by neutralization testing. Compared with the NT, the dengue IgG fluorescence immunoassay had an overall specificity of 90.7% (95%CI: 82.5–95.9%) and a sensitivity of 91.8% (95%CI: 89.8–93.5%) for determining dengue seropositivity. The sensitivity declined to 51.2% (42.3–61.0%) for the detection of the subset with a monotypic dengue profile.ConclusionThe insufficient specificity and sensitivity (particularly in the detection of a previous monotypic dengue infection) would render the test, in its current state, inadequate for pre-vaccination screening. Considering its user-friendly interphase and possibility of point-of-care use, the test could be further developed and validated to improve its performance characteristics.     

Rapid diagnostic tests for infectious diseases in the emergency department

BackgroundRapid diagnostic tests (RDTs) for infectious diseases, with a turnaround time of less than 2 hours, are promising tools that could improve patient care, antimicrobial stewardship and infection prevention in the emergency department (ED) setting. Numerous RDTs have been developed, although not necessarily for the ED environment. Their successful implementation in the ED relies on their performance and impact on patient management.ObjectivesThe aim of this narrative review was to provide an overview of currently available RDTs for infectious diseases in the ED.SourcesPubMed was searched through August 2019 for available studies on RDTs for infectious diseases. Inclusion criteria included: commercial tests approved by the US Food and Drug Administration (FDA) or Conformité Européenne (CE) in vitro diagnostic devices with data on clinical samples, ability to run on fully automated systems and result delivery within 2 hours.ContentA nonexhaustive list of representative commercially available FDA- or CE-approved assays was categorized by clinical syndrome: pharyngitis and upper respiratory tract infection, lower respiratory tract infection, gastrointestinal infection, meningitis and encephalitis, fever in returning travellers and sexually transmitted infection, including HIV. The performance of tests was described on the basis of clinical validation studies. Further, their impact on clinical outcomes and anti-infective use was discussed with a focus on ED-based studies.ImplicationsClinicians should be familiar with the distinctive features of each RDT and individual performance characteristics for each target. Their integration into ED work flow should be preplanned considering local constraints of given settings. Additional clinical studies are needed to further evaluate their clinical effectiveness and cost-effectiveness.     

Comparative Evaluation of 11 Commercialized Rapid Diagnostic Tests for Detecting Trypanosoma cruzi Antibodies in Serum Banks in Areas of Endemicity and Nonendemicity

Chagas disease is one of the main public health issues in Latin America. Increasingly during the past few decades, Trypanosoma cruzi infection has been detected in North America, Europe, and the Western Pacific, mainly as a result of population movement. The limited availability of rapid serological diagnostic tests hinders rapid diagnosis and early treatment in areas of endemicity and nonendemicity. In collaboration with 11 national reference laboratories (NRLs) from different geographical areas, we evaluated the performances of commercialized serological rapid diagnostic tests (RDT) for T. cruzi infection. Eleven commercialized T. cruzi infection RDTs were evaluated on a total of 474 samples extensively tested with at least three different techniques for Chagas disease, maintained at controlled low temperatures, and stored in the serum banks of the 11 NRLs. We measured the sensitivity, specificity, and concordance of each RDT and provided an additional questionnaire to evaluate its ease of use. The selected RDTs in this study were performed under controlled laboratory conditions. Out of the 11 RDTs, we found 8 of them to be useful, with the cassette format favored over the strip. We did not observe significant differences in RDT performances in the different regions. Overall, the performance results were lower than those disclosed by the manufacturers. The results of this evaluation validate the possibility of using RDTs to diagnose Chagas disease, thereby decreasing the time to treatment at a primary health care facility for patients who are willing to be treated. Further studies should be conducted in the laboratory and in the field to confirm these data, expressly to evaluate reproducibility in resource-limited settings, or using whole blood in clinical settings in areas of endemicity and nonendemicity.     

Molecular and serological techniques to detect co-circulation of DENV,ZIKV and CHIKV in suspected dengue-like syndrome patients

BackgroundArboviruses are important emerging viruses worldwide. The signs and symptoms of Zika virus (ZIKV) infection are similar to those presented by infections with dengue virus (DENV) and chikungunya virus (CHIKV). Furthermore, diagnosis of ZIKV infection is particularly challenging in dengue endemic regions and with co-circulation of DENV, CHIKV, and ZIKV, making diagnosis based solely on clinical and epidemiological data unreliable. As these three viral infections share similar clinical manifestations, differential diagnosis is crucial.ObjectivesIn this study, diagnoses of ZIKV, CHIKV and DENV infections were investigated in 30 patients with suspected dengue fever residing in the area of co-circulation of these three arboviruses.Study designThe study included whole blood and/or serum samples obtained from 30 patients with suspected dengue fever. All patients were tested for DENV infection as well as for CHIKV and ZIKV infections. Assays for detecting anti-DENV IgM and DENV RNA by semi-nested RT-PCR and ZIKV and CHIKV RNA by real-time RT-PCR were performed.ResultsDENV RNA was not detectable in any of the clinical samples, whereas ZIKV RNA was detectable in 17 samples (56.7%). Co-infection by ZIKV and CHIKV was documented in one case. Of the 17 ZIKV-positive individuals, 8 showed reactivity for anti-DENV IgM, which suggested recent DENV infection, cross-reactivity or co-infection.ConclusionOur findings confirm that accurate laboratory testing is of paramount importance for differential diagnosis in areas of simultaneous transmission of different arboviruses with similar clinical presentations.     

Sensitivity of 8 CE (European Community)-approved rapid disposable tests for anti-HIV antibody detection during and after seroconversion

We evaluated the sensitivity for the anti-HIV antibody detection of the 8 rapid disposable tests (RDTs) EC approved in 2008.MethodsA panel of 100 native serum samples collected from HIV-1 subtype B or non-B, HIV-1 group O or HIV-2-infected patient and 3 commercial seroconversion panels were tested. 50 sera from HIV-negative patients were included to blind reading and RDT specificity.ResultsAll native samples HIV-1 subtype B were reactive; an HIV-1 non-B subtype gave false-negative results with 3 of the 8 tests. False-negative results on HIV-1 group O samples were observed with one RDT. All the HIV-2 samples were detected. Seroconversion sample reactivity ranged from 60 to 86.7% according to the tests.ConclusionDespite their lower performances relative to ELISA tests during the HIV seroconversion period, RDT may be of interest in case of chronic infection.     

Accuracy of cholera rapid diagnostic tests: a systematic review and meta-analysis

BackgroundCholera is an acute diarrheal disease caused by Vibrio cholerae O1 or O139. Cholera rapid diagnostic tests (RDTs) are widely used to screen for cholera cases. However, their accuracy has not been systematically reviewed.ObjectivesTo evaluate the diagnostic accuracy of cholera RDTs.MethodsSystematic review and meta-analysis.Data sourcesMedline, EMBASE and Web of science through to November 2020; references of included studies and a technical guidance on cholera RDTs. This review is registered with PROSPERO (CRD42021233124).Study eligibility criteriaCross-sectional studies comparing the performance of cholera RDTs either to stool culture or PCR.ParticipantsIndividuals with clinically suspected cholera.Data extractionTwo authors independently extracted data and assessed the quality using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) criteria.ResultsEighteen studies were included in the systematic review of which 17 were used for meta-analysis. Crystal VC was the most frequently used RDT (13 studies), followed by Cholkit and Institut Pasteur cholera dipstick (three studies each), SD Bioline (two studies), Artron (one study) and Smart (one study). Using direct testing (n = 12 627 specimens), the bivariate random-effects model yielded a pooled sensitivity and specificity of 91% (95% CI 87%–94%) and 80% (95% CI 74%–84%), respectively. However, through alkaline peptone water (APW) enrichment (n = 3403 specimens), the pooled sensitivity and specificity were 89% (95% CI 79%–95%) and 98% (95% CI 95%–99%), respectively.ConclusionCholera RDTs, especially when enriched with APW, have moderate sensitivity and specificity. Although less useful for clinical management, the current generation of RDTs have clear utility for surveillance efforts if used in a principled manner. Enrichment of stool specimens in APW before using cholera RDTs reduces the possibility of obtaining false-positive results, despite the few cholera cases that go undetected. It is noteworthy that APW-enriched cholera RDTs are not necessarily rapid tests, and are not listed in the Global Task Force on Cholera Control/WHO target product profile.     

Antibody and memory B cell responses to the dengue virus NS1 antigen in individuals with varying severity of past infection

To further understand the role of NS1-specific antibodies (Abs) in disease pathogenesis, we compared neutralizing antibody levels (Nabs), NS1-Ab levels, IgG antibody subclass profiles and NS1-specific memory B-cell responses (Bmems) in individuals, with varying severity of past dengue. Nabs (Neut50 titres) were assessed using the Foci Reduction Neutralization Test (FRNT) and in-house ELISAs were used to assess NS1-Abs and NS1-Ab subclasses for all four DENV serotypes in individuals with past DF (n = 22), those with past DHF (n = 14) and seronegative (SN) individuals (n = 7). B-cell ELISpot assays were used to assess NS1-specific Bmem responses. 15/22 (68.18%) individuals with past DF and 9/14 (64.29%) individuals with past DHF had heterotypic infections. Neut50 titres were found to be significantly higher for DENV1 than DENV2 (p = 0.0006) and DENV4 (p = 0.0127), in those with past DHF, whereas there was no significant difference seen in titres for different DENV serotypes in those with past DF. Overall NS1-Ab to all serotypes and NS1-specific IgG1 responses for DENV1, 2 and 4 serotypes were significantly higher in those with past DHF than individuals with past DF. Those with past DHF also had higher IgG1 than IgG3 for DENV1 and DENV3, whereas no differences were seen in those with past DF. Over 50% of those with past DF or DHF had NS1-specific Bmem responses to >2 DENV serotypes. There was no difference in the frequency of Bmem responses to any of the DENV serotypes between individuals with past DF and DHF. Although the frequency of Bmem responses to DENV1 correlated with DENV1-specific NS1-Abs levels (Spearman r = 0.35, p = 0.02), there was no correlation with other DENV serotypes. We found that those with past DF had broadly cross-reactive Nabs, while those with past DHF had higher NS1-Ab responses possibly with a different functionality profile than those with past DF. Therefore, it would be important to further evaluate the functionality of NS1-specific antibody and Bmem responses to find out the type of antibody repertoire that is associated with protection against severe disease.     

Re-evaluation of routine dengue virus serology in travelers in the era of Zika virus emergence

BackgroundDiagnostic requests for both Zika virus (ZIKV) and dengue virus (DENV) infections in returning travelers have significantly increased during the recent ZIKV outbreak in the Americás. These flaviviruses have overlapping clinical syndromes and geographical distribution, but diagnostic differentiation is important because of different clinical consequences. As flaviviruses are known to have a short viremic period, diagnostics often rely on serological methods, which are challenging due to extensive cross-reactive antibodies.ObjectiveTo re-evaluate the performance of DENV serological assays in laboratory confirmed ZIKV-infected travelers.Study designThe extent of cross-reactivity of the DENV NS1 antigen, IgM and IgG ELISA was analyzed in 152 clinical blood samples collected from 69 qRT-PCR and 24 virus neutralization titer (VNT) confirmed ZIKV-infected travelers.ResultsThe majority of travelers in the presented cohort returned to the Netherlands from Suriname and presented with symptoms of fever and rash. Twenty-three percent of the female travelers were pregnant. None of the 39 ZIKV RNA positive blood samples were cross-reactive in the DENV NS1 antigen ELISA. The rates of cross-reactivity of the DENV IgM and IgG ELISÁs were 31% and 54%, respectively, after excluding travelers with (potential) previous DENV exposure.ConclusionsAlthough the DENV NS1 antigen assay was highly specific in this cohort of laboratory confirmed ZIKV-infected travelers, we demonstrate high percentages of cross-reactivity of DENV IgM and IgG ELISÁs of which diagnostic laboratories should be aware. In addition, the high rate of DENV IgG background of >25% complicates a proper serological diagnosis in this group.     

Rapid diagnostic tests for non-malarial febrile illness in the tropics

The recent roll-out of rapid diagnostic tests (RDTs) for malaria has highlighted the decreasing proportion of malaria-attributable illness in endemic areas. Unfortunately, once malaria is excluded, there are few accessible diagnostic tools to guide the management of severe febrile illnesses in low resource settings. This review summarizes the current state of RDT development for several key infections, including dengue fever, enteric fever, leptospirosis, brucellosis, visceral leishmaniasis and human African trypanosomiasis, and highlights many remaining gaps. Most RDTs for non-malarial tropical infections currently rely on the detection of host antibodies against a single infectious agent. The sensitivity and specificity of host-antibody detection tests are both inherently limited. Moreover, prolonged antibody responses to many infections preclude the use of most serological RDTs for monitoring response to treatment and/or for diagnosing relapse. Considering these limitations, there is a pressing need for sensitive pathogen-detection-based RDTs, as have been successfully developed for malaria and dengue. Ultimately, integration of RDTs into a validated syndromic approach to tropical fevers is urgently needed. Related research priorities are to define the evolving epidemiology of fever in the tropics, and to determine how combinations of RDTs could be best used to improve the management of severe and treatable infections requiring specific therapy.     

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

BackgroundEbola 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.ObjectivesTo assess the diagnostic accuracy of RDTs for EVD.MethodsA systematic review of diagnostic accuracy studies.Data sourcesThe 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 criteriaDiagnostic accuracy studies.ParticipantsPatients presenting to the Ebola treatment units with symptoms of EVD.InterventionsRDTs; reference standard, RT-PCR.Assessment of risk of biasQuality Assessment of Diagnostic Accuracy Studies-2 tool.Methods of data synthesisSummary 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.ResultsWe 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.ConclusionsRDTs 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.     

Characterization of type I interferon responses in dengue and severe dengue in children in Paraguay

BackgroundInfection with dengue virus (DENV) produces a wide spectrum of clinical illness ranging from asymptomatic infection to mild febrile illness, and to severe forms of the disease. Type I interferons (IFNs) represent an initial and essential host defense response against viruses. DENV has been reported to trigger a robust type I IFN response; however, IFN-α/β profile in the progression of disease is not well characterized.Objectives and study designIn this context, we conducted a retrospective study assessing the circulating serum levels of type I IFNs and related cytokines at different phases of illness in children during the 2011 outbreak of DENV in Paraguay. Demographic, clinical, laboratory and virological data were analyzed.ResultsDuring defervescence, significantly higher levels of IFN-β, IL-6 and MIP-1β, were detected in severe vs. non-severe dengue patients. Additionally, a significant positive correlation between INF-α and viremia was detected in children with severe dengue. A significant positive correlation was also observed between IFN-β serum levels and hematocrit during the febrile phase, whereas IFN-α levels negatively correlated with white blood cells during defervescence in severe dengue patients. Furthermore, previous serologic status of patients to DENV did not influence type I IFN production.ConclusionsThe distinct type I IFN profile in children with dengue and severe dengue, as well as its association with viral load, cytokine production and laboratory manifestations indicate differences in innate and adaptive immune responses that should be investigated further in order to unveil the association of immunological and physiological pathways that underlie in DENV infection.     

A simple one-step real-time RT-PCR for diagnosis of dengue virus infection

Dengue is the most important arbovirus disease in tropical and sub-tropical countries, and can be caused by infection with any of the four-dengue virus (DENV) serotypes. Infection with DENV can lead to a broad clinical spectrum, ranging from sub-clinical infection or an influenza-like disease known as dengue fever (DF) to a severe, sometimes fatal, disease characterized by hemorrhage and plasma leakage that can lead to shock, known as dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). The diagnosis of dengue is routinely accomplished by serologic assays, such as IgM and IgG ELISAs, as well as HI tests, analyzing serum samples obtained from patients with at least 7 days of symptoms onset. These tests cannot be used for diagnosis during the early symptomatic phase. In addition, antibodies against dengue are broad reactive with other flaviviruses. Therefore, a specific diagnostic method for acute DENV infection is of great interest. In that sense, the real-time RT-PCR has become an important tool that can be used for early and specific detection of dengue virus genome in human serum samples. This study describes a simple, specific, and sensitive real-time RT-PCR for early diagnosis of dengue virus infection.     

Central nervous system and muscle involvement in dengue patients: A study from a tertiary care center

BackgroundNeurological involvement in dengue virus (DENV) infection is being increasingly reported. There is paucity of studies evaluating the relative frequency of central nervous system (CNS) and muscle involvement in dengue.ObjectivesTo evaluate the frequency and prognosis of neurological and muscle involvement in dengue, and correlate these with dengue subtypes.Study designConsecutive dengue patients were included, and their clinical features, laboratory investigations and cerebrospinal fluid (CSF) findings were recorded. Cranial MRI was done in unconscious patients and electromyography and nerve conduction study in patients with flaccid weakness. Patients were categorized into encephalopathy, encephalitis, immune mediated and dengue associated muscle dysfunction (DAMD). Outcome at 1 month and its predictors were evaluated.Results116 patients aged 5–70 years were included; 82 had dengue fever (DF), 18 had dengue hemorrhagic fever (DHF), and 16 had dengue shock syndrome (DSS). Neurological manifestations were present in 92 (79%); encephalopathy in 17 (15%), encephalitis in 22 (19%), transverse myelitis in 1 (1%) and DAMD in 52 (45%) patients. Central nervous system (CNS) involvement was commoner in DHF/DSS compared to DF (44% vs 26%). 10 patients with CNS involvement died versus 1 with DAMD. The patients in the CNS group had more frequent hypotension, renal dysfunction and respiratory failure compared to the DAMD group, and had worse outcome. DENV2 and DENV3 were the commonest serotypes, but serotypes did not differ between CNS and DAMD groups.ConclusionsDAMD is commoner than CNS involvement in dengue. CNS involvement however, is associated with more serious illness and predicts poorer outcome.     

Impact on blood safety of the last arboviruses outbreaks in French Polynesia (2012–2018)

BackgroundSeveral successive arbovirus outbreaks have affected French Polynesia (FP) in the recent past years due to different dengue serotypes (DENV) present for several decades, Zika (ZIKV) (2013–2014) and chikungunya (CHIKV) (2014–2015) viruses with a potential impact on blood safety and blood supply due to the geographical isolation of these islands. This study reports an assessment of the impact of these outbreaks on blood products supply and infectious safety in FP and discuss the effectiveness of implemented preventive measures.MethodsTo ensure the infectious safety of blood products during outbreaks, several measures have successively been introduced as the selection of donors suspected of infection, the nucleic acid testing (NAT) and the pathogen reduction of platelets and plasmas.ResultsThe donor deferral rate increased by 6% between 2012 and 2014 without changes in the number of collected donations. NAT excluded five blood donations reactive for DENV RNA, 42 for ZIKV and 34 for CHIKV. As Zika screening could not been implemented before the third month of the outbreak, 36 blood products from ZIKV-infected donors were transfused to 26 recipients. However, no transfusion-transmitted arbovirus has been reported.ConclusionThe last past arboviruses outbreaks did not have a significant impact on blood supply in FP. The measures introduced to prevent arbovirus transmission by transfusion were able to maintain infectious safety for all blood products without impairing self-sufficiency.     

Optimal use of Rapid Diagnostics in Infection Control and Prevention

Clinical laboratories have implemented rapid diagnostic tests (RDTs) for the identification of bacterial pathogens, with subsequent improvements in antimicrobial stewardship, but these tests may also have a role in infection prevention. Early identification of pathogens by RDTs should allow faster implementation of infection prevention strategies with the goal of reducing transmission. In this review, we assess the use of RDTs as an infection control tool by exploring their role in screening, as well as diagnosis, of methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant gram-negative organisms, Clostridium difficile, and Mycobacterium tuberculosis. This assessment highlights the fact that implementation of RDTs to improve infection prevention will require ongoing collaboration between clinical laboratory personnel, infection prevention departments, and clinicians.     

Prospective evaluation of the SD BIOLINE Dengue Duo rapid test during a dengue virus epidemic

Dengue virus is endemic in French Guiana with occurrence of cyclical outbreaks. There is a need for rapid tests allowing dengue laboratory diagnosis in healthcare centers scattered throughout this wide Amazonian territory. Our objective was to evaluate the real-life performance of the SD BIOLINE Dengue Duo (IgG/IgM + NS1 Ag) rapid test (RDT) during the 2012–2013 dengue epidemics. The RDT was evaluated in parallel with routine laboratory tests, PlateliaTM Dengue NS1 Ag and Focus Diagnostics Dengue Fever Virus IgM Capture DxSelect. A total of 3,347 patients with suspected dengue acute infection were evaluated. The diagnostic performances of the SD BIOLINE NS1 Ag were equivalent to Platelia NS1, 471 patients (14.1%) were NS1 Ag positive with the RDT and 14.2% with Platelia. The Cohen’s Kappa coefficient was 0.86 [95%CI: 0.83–0.88], indicating an almost perfect agreement. Moreover, the sensitivity of SD BIOLINE NS1 Ag relative to the RT-PCR method was 87% [95%CI: 80–93%] and the specificity was 92% [95% CI: 87–97%]. However, the SD BIOLINE IgM test was found positive in 6.3% of the samples in comparison to 10.7% with Dx Select IgM. The Cohen’s Kappa coefficient was 0.53 [95%CI: 0.47–0.58] indicating a moderate agreement. This raised concern about the SD BIOLINE IgM for the diagnostic of dengue in endemic areas. When considering only NS1 Ag results and not IgM, the RDT could be a viable solution to manage dengue outbreaks in healthcare centers where no laboratory services are available, in the early phase of the disease.