Diagnostics have proven to be crucial to the COVID-19 pandemic response. There are three major methods for the detection of SARS-CoV-2 infection and their role has evolved during the course of the ...pandemic. Molecular tests such as PCR are highly sensitive and specific at detecting viral RNA, and are recommended by WHO for confirming diagnosis in individuals who are symptomatic and for activating public health measures. Antigen rapid detection tests detect viral proteins and, although they are less sensitive than molecular tests, have the advantages of being easier to do, giving a faster time to result, of being lower cost, and able to detect infection in those who are most likely to be at risk of transmitting the virus to others. Antigen rapid detection tests can be used as a public health tool for screening individuals at enhanced risk of infection, to protect people who are clinically vulnerable, to ensure safe travel and the resumption of schooling and social activities, and to enable economic recovery. With vaccine roll-out, antibody tests (which detect the host's response to infection or vaccination) can be useful surveillance tools to inform public policy, but should not be used to provide proof of immunity, as the correlates of protection remain unclear. All three types of COVID-19 test continue to have a crucial role in the transition from pandemic response to pandemic control.
WHO recommends a minimum of 80% sensitivity and 97% specificity for antigen-detection rapid diagnostic tests (Ag-RDTs), which can be used for patients with symptoms consistent with COVID-19. However, ...after the acute phase when viral load decreases, use of Ag-RDTs might lead to high rates of false negatives, suggesting that the tests should be replaced by a combination of molecular and serological tests. When the likelihood of having COVID-19 is low, such as for asymptomatic individuals in low prevalence settings, for travel, return to schools, workplaces, and mass gatherings, Ag-RDTs with high negative predictive values can be used with confidence to rule out infection. For those who test positive in low prevalence settings, the high false positive rate means that mitigation strategies, such as molecular testing to confirm positive results, are needed. Ag-RDTs, when used appropriately, are promising tools for scaling up testing and ensuring that patient management and public health measures can be implemented without delay.
To improve case detection among symptomatic individuals, Boum and colleagues used their data to evaluate a diagnostic algorithm combining use of antigen rapid diagnostic tests with PCR confirmation ...of samples negative at antigen rapid diagnostic tests.1 In week one, 60% of symptomatic patients tested positive by PCR and 54% of symptomatic patients tested positive by antigen-based rapid diagnostic test. ...after the first week post-symptom onset, although use of antigen-based rapid diagnostic testing improves the sensitivity of case detection, it is limited by low specificity, which translates into high numbers of false-positive samples that require PCR confirmation. ...timing is everything: the reduced costs and quicker turnaround time of this diagnostic algorithm should prompt decision makers to encourage people to present for testing earlier. For triaging of those who can return to school, work, attend mass gatherings, or travel, it is important that antigen-based rapid diagnostic tests has a high negative predictive value, so that those who test negative are truly negative.2 When used instead for case-finding among, for example, contacts of cases, as in Boum and colleagues' study,1 it is important that individuals identified as antigen-based rapid diagnostic test-positive are truly infected with SARS-CoV-2, meaning a high positive predictive value.
Mobile health, or 'mHealth', is the application of mobile devices, their components and related technologies to healthcare. It is already improving patients' access to treatment and advice. Now, in ...combination with internet-connected diagnostic devices, it offers novel ways to diagnose, track and control infectious diseases and to improve the efficiency of the health system. Here we examine the promise of these technologies and discuss the challenges in realizing their potential to increase patients' access to testing, aid in their treatment and improve the capability of public health authorities to monitor outbreaks, implement response strategies and assess the impact of interventions across the world.
Stigma, discrimination, lack of privacy, and long waiting times partly explain why six out of ten individuals living with HIV do not access facility-based testing. By circumventing these barriers, ...self-testing offers potential for more people to know their sero-status. Recent approval of an in-home HIV self test in the US has sparked self-testing initiatives, yet data on acceptability, feasibility, and linkages to care are limited. We systematically reviewed evidence on supervised (self-testing and counselling aided by a health care professional) and unsupervised (performed by self-tester with access to phone/internet counselling) self-testing strategies.
Seven databases (Medline via PubMed, Biosis, PsycINFO, Cinahl, African Medicus, LILACS, and EMBASE) and conference abstracts of six major HIV/sexually transmitted infections conferences were searched from 1st January 2000-30th October 2012. 1,221 citations were identified and 21 studies included for review. Seven studies evaluated an unsupervised strategy and 14 evaluated a supervised strategy. For both strategies, data on acceptability (range: 74%-96%), preference (range: 61%-91%), and partner self-testing (range: 80%-97%) were high. A high specificity (range: 99.8%-100%) was observed for both strategies, while a lower sensitivity was reported in the unsupervised (range: 92.9%-100%; one study) versus supervised (range: 97.4%-97.9%; three studies) strategy. Regarding feasibility of linkage to counselling and care, 96% (n = 102/106) of individuals testing positive for HIV stated they would seek post-test counselling (unsupervised strategy, one study). No extreme adverse events were noted. The majority of data (n = 11,019/12,402 individuals, 89%) were from high-income settings and 71% (n = 15/21) of studies were cross-sectional in design, thus limiting our analysis.
Both supervised and unsupervised testing strategies were highly acceptable, preferred, and more likely to result in partner self-testing. However, no studies evaluated post-test linkage with counselling and treatment outcomes and reporting quality was poor. Thus, controlled trials of high quality from diverse settings are warranted to confirm and extend these findings. Please see later in the article for the Editors' Summary.
The collapse of global cooperation and a failure of international solidarity have led to many low-income and middle-income countries being denied access to molecular diagnostics in the COVID-19 ...pandemic response. Yet the scarcity of knowledge on the dynamics of the immune response to infection has led to hesitation on recommending the use of rapid immunodiagnostic tests, even though rapid serology tests are commercially available and scalable. On the basis of our knowledge and understanding of viral infectivity and host response, we urge countries without the capacity to do molecular testing at scale to research the use of serology tests to triage symptomatic patients in community settings, to test contacts of confirmed cases, and in situational analysis and surveillance. The WHO R&D Blue Print expert group identified eight priorities for research and development, of which the highest is to mobilise research on rapid point-of-care diagnostics for use at the community level. This research should inform control programmes of the required performance and utility of rapid serology tests, which, when applied specifically for appropriate public health measures to then be put in place, can make a huge difference.
WHO estimated that nearly 1 million people become infected every day with any of four curable sexually transmitted infections (STIs): chlamydia, gonorrhoea, syphilis, and trichomoniasis. Despite ...their high global incidence, STIs remain a neglected area of research. In this Commission, we have prioritised five areas that represent particular challenges in STI treatment and control. Chlamydia remains the most commonly diagnosed bacterial STI in high-income countries despite widespread testing recommendations, sensitive and specific non-invasive testing techniques, and cheap effective therapy. We discuss the challenges for chlamydia control and evidence to support a shift from the current focus on infection-based screening to improved management of diagnosed cases and of chlamydial morbidity, such as pelvic inflammatory disease. The emergence and spread of antimicrobial resistance in Neisseria gonorrhoeae is globally recognised. We review current and potential future control and treatment strategies, with a focus on novel antimicrobials. Bacterial vaginosis is the most common vaginal disorder in women, but current treatments are associated with frequent recurrence. Recurrence after treatment might relate to evidence that suggests sexual transmission is integral to the pathogenesis of bacterial vaginosis, which has substantial implications for the development of effective management approaches. STIs disproportionately affect low-income and middle-income countries. We review strategies for case management, focusing on point-of-care tests that hold considerable potential for improving STI control. Lastly, STIs in men who have sex with men have increased since the late 1990s. We discuss the contribution of new biomedical HIV prevention strategies and risk compensation. Overall, this Commission aims to enhance the understanding of some of the key challenges facing the field of STIs, and outlines new approaches to improve the clinical management of STIs and public health.
Dried blood spots (DBS) have been used as alternative specimens to plasma to increase access to HIV viral load (VL) monitoring and early infant diagnosis (EID) in remote settings. We systematically ...reviewed evidence on the performance of DBS compared to plasma for VL monitoring and EID.
Thirteen peer reviewed HIV VL publications and five HIV EID papers were included. Depending on the technology and the viral load distribution in the study population, the percentage of DBS samples that are within 0.5 log of VL in plasma ranged from 52-100%. Because the input sample volume is much smaller in a blood spot, there is a risk of false negatives with DBS. Sensitivity of DBS VL was found to be 78-100% compared to plasma at VL below 1000 copies/ml, but this increased to 100% at a threshold of 5000 copies/ml. Unlike a plasma VL test which measures only cell free HIV RNA, a DBS VL also measures proviral DNA as well as cell-associated RNA, potentially leading to false positive results when using DBS. The systematic review showed that specificity was close to 100% at DBS VL above 5000 copies/ml, and this threshold would be the most reliable for predicting true virologic failure using DBS. For early infant diagnosis, DBS has a sensitivity of 100% compared to fresh whole blood or plasma in all studies.
Although limited data are available for EID, DBS offer a highly sensitive and specific sampling strategy to make viral load monitoring and early infant diagnosis more accessible in remote settings. A standardized approach for sampling, storing, and processing DBS samples would be essential to allow successful implementation.
PROSPERO Registration #: CRD42013003621.
Objectif Rassembler les informations recentes concernant les objectifs d'élimination et ďéradication des maladies ¡nfectieuses, mais aussi clarifier la terminologie et les definitions associées aux ...différents objectifs. Méthodes Nous avons mené une recherche systématique au sein des archives institutionnelles pour l'échange d'informations (IRIS) de l'Organisation mondiale de la Santé (OMS), ainsi qu'une recherche systématique personnalisée dans Google Advanced Search, afin de trouver des documents publiés entre 2008 et 2022 portant sur les strategies d'élimination ou ďéradication de maladies ¡nfectieuses et rediges parl'OMSou par d'autres organisations sanitaires majeures. Nous avons ensuite extráit les informations relatives aux noms des maladies ¡nfectieuses, aux objectifs et délais d'élimination ou ďéradication, à la definition des objectifs, à la terminologie non standardisée, aux orientations et aux processus ďévaluation. Resultats Nous avons identifié neuf objectifs pour 27 maladies ¡nfectieuses, aliant de la lutte contre la maladie à son eradication. Selon la classification du contróle des maladies telle que définie lors de I'Atelier Dahlem en 1997, six objectifs étaient lies à la lutte contre les infections à divers degrés d'avancement, deux à ľélimination et un à l'éradication. Ces objectifs évoluaient dans un continuum de lutte contre les maladies, par exemple de la fin d'une epidémie à ľélimination de la maladie en tant que probléme ou menace pour la santé publique, en passant par sa pré-élimination. Nous avons constaté l'emploi d'une terminologie non standardisée pour certains objectifs: elimination virtuelle, elimination ďépidémies, menace sanitaire etproblemede santé publique notamment. Conclusion A mesure que nous nous rapprochons de ľéchéance de 2030 en matiere de realisation des objectifs de lutte contre les maladies, et pour que d'autres infections puissent prétendre à une elimination dans le futur, il est crucial de clarifier les definitions et les perspectives afin d'éviter toute erreur de communication et de perception chez les professionnels de la santé publique et les responsables politiques.
Visceral leishmaniasis (VL) is a systemic protozoan disease that is transmitted by phlebotomine sandflies. Poor and neglected populations in East Africa and the Indian sub-continent are particularly ...affected. Early and accurate diagnosis and treatment remain key components of VL control. In addition to improved diagnostic tests, accurate and simple tests are needed to identify treatment failures. Miltefosine, paromomycin and liposomal amphotericin B are gradually replacing pentavalent antimonials and conventional amphotericin B as the preferred treatments in some regions, but in other areas these drugs are still being evaluated in both mono- and combination therapies. New diagnostic tools and new treatment strategies will only have an impact if they are made widely available to patients.
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