Rapid Diagnostic Tests

While equipment-free visual interpretation is a benefit of lateral-flow assays, automating the reading of rapid diagnostic tests promotes proper test performance, interpretation and reporting of the results. We have created a target product profile that describes the minimal and optimal characteristics of various rapid diagnostic test readers. The product profile is intended to promote the development of effective, useful, sustainable rapid diagnostic test readers in support of health programmes worldwide. These readers may be custom hardware or software-only running on a general-purpose mobile device, for professional or lay use, and for medical or non-medical purposes. During the development of the product profile, the World Health Organization and FIND convened a development group of 40 leading scientists, experts, public health officials and regulators. We held a public consultation to which 27 individuals or organizations responded. The product profile calls for rapid diagnostic test readers that at minimum should: (i) interpret colorimetric tests with at least 95% agreement with expert visual interpretation; and (ii) automatically report results and associated data for the health programme. Optimally, readers should: (i) provide at least 98% agreement; (ii) operate with multiple models of rapid diagnostic tests; (iii) assist the user in performing each rapid diagnostic test according to the test instructions; and (iv) offer multiple configurations, operating modes and languages to suit the needs of diverse users, settings and health programmes.

BackgroundChagas disease is a public health challenge in Colombia, where only an estimated 1.2% of people at risk have accessed diagnosis, while less than 0.5% of affected people have obtained treatment. The development of simplified diagnostic algorithms would enable progress in access to diagnosis; however, the current diagnostic algorithm relies on at least two laboratory-based tests that require qualified personnel, processing equipment, and infrastructure, which are still generally lacking at the primary care level. Rapid diagnostic tests (RDTs) for Chagas disease could simplify diagnosis, but their performance in the epidemiological context of Colombia is not well known.MethodologyA retrospective analytical observational study of RDTs was performed to estimate the operational characteristics of 11 commercially available RDTs designed for in vitro detection of anti-T. cruzi IgG antibodies. The study was performed under controlled laboratory conditions using human serum samples.Principal findingsEleven RDTs were assessed, ten using 585 serum samples and one using 551 serum samples. Employing the current national diagnostic algorithm as a reference standard for serological diagnosis of chronic infection, the sensitivity of the assessed RDTs ranged from 75.5% to 99.0% (95% CI 70.5-100), while specificity ranged from 70.9% to 100% (95% CI 65.3-100). Most tests (7/11, 63.6%) had sensitivity above 90%, and almost all (10/11, 90.9%) had specificity above 90%. Five RDTs had both sensitivity and specificity above 90%.Conclusions/significanceThe evaluation of these 11 commercially available RDTs under controlled laboratory conditions is a first step in the assessment of the diagnostic performance of RDTs in Colombia. As a next step, field studies will be conducted on available RDTs with sensitivity and specificity greater than 90% in this study, to evaluate performance in real world conditions, with the final goal to allow simplified diagnostic algorithms.

BackgroundPoint-of-care-tests (POCTs) have been advocated to optimise care in patients with infections but their actual use varies. This study aimed to estimate the variability in the adoption of current POCTs by paediatricians across Europe, and to explore the determinants of variability.Methods and findingsA cross-sectional survey was conducted of hospital and primary care paediatricians, recruited through professional networks. Questions focused on the availability and use of currently available POCTs. Data were analysed descriptively and using Median Odds Ratio (MOR) to measure variation between countries. Multilevel regression modelling using changes in the area under the receiver operating characteristic curve of models were used to assess the contribution of individual or workplace versus country level factors, to the observed variation. The commonest POCT was urine dipsticks (UD) which were available to >80% of primary care and hospital paediatricians in 68% (13/19) and 79% (23/29) countries, respectively. Availability of all POCTs varied between countries. In primary care, the country (MOR) varied from 1.61 (95%CI: 1.04-2.58) for lactate to 7.28 (95%CI: 3.04-24.35) for UD. In hospitals, the country MOR varied from 1.37 (95%CI:1.04-1.80) for lactate to 11.93 (95%CI:3.35-72.23) for UD. Most paediatricians in primary care (69%, 795/1154) and hospital (81%, 962/1188) would use a diagnostic test in the case scenario of an infant with undifferentiated fever. Multilevel regression modelling showed that the country of work was more important in predicting both the availability and use of POCTs than individual or workplace characteristics.ConclusionThere is substantial variability in the adoption of POCTs for the management of acute infections in children across Europe. To inform future implementation of both existing and innovative tests, further research is needed to understand what drives the variation between countries, the needs of frontline clinicians, and the role of diagnostic tests in the management of acute childhood infections.

Lassa fever is a high-risk viral disease endemic to West Africa for which rapid and reliable diagnosis is essential for outbreak control. Here, we describe the development of a lateral flow-based rapid diagnostic test (RDT) targeting the Lassa virus nucleoprotein using newly generated monoclonal antibody pairs. The analytical performance of the assay was evaluated using human serum and plasma specimens as well as inactivated Lassa virus strains and compared with a commercially available antigen test. The final RDT (Pair 2; 1P-44-7/9B-28) demonstrated high analytical sensitivity and 100% specificity across 60 human samples and detected multiple genetically diverse Lassa virus strains, with lineage-dependent differences in analytical sensitivity. In direct analytical comparisons using recombinant antigen, the assay was approximately 64-fold more sensitive than the ReLASV Pan-Lassa Antigen Rapid Test. The RDT provides a rapid visual readout, remains stable at ambient temperatures, and is suitable for decentralized testing workflows, features aligned with key aspects of the World Health Organization (WHO) REASSURED framework. These results indicate that the developed RDT offers a robust and broadly reactive platform for Lassa virus antigen detection and has potential utility for surveillance and outbreak response in resource-limited settings.IMPORTANCELassa fever remains a significant public health concern in West Africa, where diagnostic capacity is often limited in endemic regions. This study describes the development of a broad-lineage Lassa virus rapid diagnostic test informed by the World Health Organization (WHO) REASSURED framework. The assay demonstrates high analytical sensitivity and broad lineage coverage in a field-deployable format, supporting its potential utility for early case detection and decentralized surveillance in endemic settings.