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Background Rapid diagnostic tests (RDTs) are effective tools to diagnose and inform the treatment of malaria in adults and children. The recent development of a highly sensitive rapid diagnostic test (HS-RDT) for Plasmodium falciparum has prompted questions over whether it could improve the diagnosis of malaria in pregnancy and pregnancy outcomes in malaria endemic areas. Methods This landscape review collates studies addressing the clinical performance of the HS-RDT. Thirteen studies were identified comparing the HS-RDT and conventional RDT (co-RDT) to molecular methods to detect malaria in pregnancy. Using data from five completed studies, the association of epidemiological and pregnancy-related factors on the sensitivity of HS-RDT, and comparisons with co-RDT were investigated. The studies were conducted in 4 countries over a range of transmission intensities in largely asymptomatic women. Results Sensitivity of both RDTs varied widely (HS-RDT range 19.6 to 85.7%, co-RDT range 22.8 to 82.8% compared to molecular testing) yet HS-RDT detected individuals with similar parasite densities across all the studies including different geographies and transmission areas [geometric mean parasitaemia around 100 parasites per µL (p/µL)]. HS-RDTs were capable of detecting low-density parasitaemias and in one study detected around 30% of infections with parasite densities of 0–2 p/µL compared to the co-RDT in the same study which detected around 15%. Conclusion The HS-RDT has a slightly higher analytical sensitivity to detect malaria infections in pregnancy than co-RDT but this mostly translates to only fractional and not statistically significant improvement in clinical performance by gravidity, trimester, geography or transmission intensity. The analysis presented here highlights the need for larger and more studies to evaluate incremental improvements in RDTs. The HS-RDT could be used in any situation where co-RDT are currently used for P. falciparum diagnosis, if storage conditions can be adhered to.

The coronavirus disease (COVID-19) pandemic has created an urgent need for rapid, accurate, and cost-effective diagnostic tools. In this study, an economical electrochemical immunosensor for the rapid diagnosis of COVID-19 was developed and optimized based on charge transfer resistance (Rct) values obtained by electrochemical impedance spectroscopy (EIS) from the interaction between antibodies (anti-SARS-CoV-2) immobilized as a bioreceptor and the virus (SARS-CoV-2). The sensor uses modified pencil graphite electrodes (PGE) coated with poly(4-hydroxybenzoic acid), anti-SARS-CoV-2, and silver nanoparticles. The immobilization of anti-SARS-CoV-2 antibodies was optimized at a concentration of 1:250 for 30 min, followed by blocking the surface with 0.01% bovine serum albumin for 10 min. The optimal conditions for virus detection in clinical samples were a 1:10 dilution with a response time of 20 min. The immunosensor responded linearly in the range of 0.2–2.5 × 106 particles/μL. From the relationship between the obtained signal and the concentration of the analyzed sample, the limit of detection (LOD) and limit of quantification (LOQ) obtained were 1.21 × 106 and 4.04 × 106 particles/μL, respectively. The device did not cross-react with other viruses, including Influenza A and B, HIV, and Vaccinia virus. The relative standard deviation (RSD) of the six immunosensors prepared using the shared-pool sample was 3.87. Decreases of 22.3% and 12.4% were observed in the response values of the ten immunosensors stored at 25 °C and 4.0 °C, respectively. The sensor provides timely and accurate results with high sensitivity and specificity, offering a cost-effective alternative to the existing diagnostic methods.

Background Routine testing for cancer patients not presenting COVID‐19‐related symptoms and fully vaccinated for SARS‐CoV‐2 prior to cancer treatment is controversial. Methods In this retrospective study we evaluated whether antigen‐rapid‐diagnostic‐test (Ag‐RDT) monitoring for SARS‐CoV‐2 in a large cohort of consecutive asymptomatic (absence of SARS‐CoV‐2‐related symptoms such as fever, cough, sore throat or nasal congestion) and fully vaccinated cancer patients enrolled in a short period during cancer treatment has an impact on the therapeutic path of cancer patients. Results From December 27, 2021, to February 11, 2022, 2439 cancer patients were screened through Ag‐RDT for SARS‐CoV‐2 before entering the hospital for systemic treatment. Fifty‐three patients (2.17%) tested positive, of whom 7 (13.2%) subsequently developed COVID‐related symptoms, generally mild. Cancer treatment was discontinued, as a precaution, in 49 patients (92.5%) due to the test positivity. Conclusion SARS‐CoV‐2 screening in asymptomatic and fully vaccinated cancer patients during systemic treatment appeared to be not cost‐effective: the low rate of SARS‐CoV‐2 positive patients and the low percentage of overt associated infection do not seem proportional to the direct costs (nursing work for swabs, costs of materials and patient monitoring) and indirect costs (dedicated rooms, extension of waiting times for patients and oncologists in delivering therapy as well as its discontinuation in the positive ones). It can, on the other hand, be detrimental when systemic cancer treatment is suspended as a precaution. Given the small number of patients testing positive and the rapid and favorable trend of the infection, it is recommended to always consider continuing systemic oncological treatment, especially when this impacts patient survival as in the adjuvant or neoadjuvant setting. SARS‐CoV‐2 screening in asymptomatic and fully‐vaccinated cancer patients during systemic treatment appeared to be not cost‐effective.

Background & objectives: There is limited evidence regarding the accuracy of dengue rapid diagnostic kits despite their extensive use in India. We evaluated the performance of four immunochromatographic Rapid Diagnostic Test (RDTs) kits: Multisure dengue Ab/Ag rapid test (MP biomedicals; MP), Dengucheck combo (Zephyr Biomedicals; ZB), SD bioline dengue duo (Alere; SD) and Dengue day 1 test (J Mitra; JM). Methods: This is a laboratory-based diagnostic evaluation study. Rapid tests results were compared to reference non-structural (NS1) antigen or immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) results of 241 dengue-positive samples and 247 dengue-negative samples. Sensitivity and specificity of NS1 and IgM components of each RDT were calculated separately and in combination (either NS1 or IgM positive) against reference standard ELISA. Results: A total of 238, 226, 208, and 146 reference NS1 ELISA samples were tested with MP, ZB, SD, and JM tests, respectively. In comparison to the NS1 ELISA reference tests, the NS1 component of MP, ZB, SD, and JM RDTs demonstrated a sensitivity of 71.8%, 85.1%, 77.2% and 80.9% respectively and specificity of 90.1%, 92.8%, 96.1 %, and 93.6%, respectively. In comparison to the IgM ELISA reference test, the IgM component of RDTs showed a sensitivity of 40.0%, 50.3%, 47.3% and 20.0% respectively and specificity of 92.4%, 88.6%, 96.5%, and 92.2% respectively. Combining NS1 antigen and IgM antibody results led to sensitivities of 87.5%, 82.9%, 93.8% and 91.7% respectively, and specificities of 75.3%, 73.9%, 76.5%, and 80.0% respectively. Interpretation & conclusion: Though specificities were acceptable, the sensitivities of each test were markedly lower than manufacturers' claims. These results also support the added value of combined antigen-and antibody-based RDTs for the diagnosis of acute dengue.

We investigated the infectivity of 128 severe acute respiratory disease coronavirus 2-associated deaths and evaluated predictive values of standard diagnostic procedures. Maintained infectivity (20%) did not correlate with viral RNA loads but correlated well with anti-S antibody levels. Sensitivity >90% for antigen-detecting rapid diagnostic tests supports their usefulness for assessment.

Background The declining effectiveness of Intermittent Preventive Treatment in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) due to the emergence of Plasmodium falciparum resistance highlights the need for alternative malaria prevention strategies in pregnant women. A novel approach was proposed: screening with an ultra-sensitive rapid diagnostic test and treating positive with pyronaridine-artesunate (ISTp-uRDT-PA). This trial compared the impact of both strategies on maternal malaria and anaemia, abortion, intrauterine death, birth weight, preterm delivery. Methods This non-inferiority trial, conducted in Kinshasa, enrolled pregnant women in their second and third trimesters. Participants in the IPTp-SP arm (n = 124) received SP at monthly antenatal visit as per guidelines, while those in the ISTp-uRDT-PA arm (n = 126) were screened monthly with an uRDT and treated with PA if positive. Primary outcomes included asymptomatic parasitaemia (uRDT positive without fever) or symptomatic parasitaemia (uRDT positive with fever or history of fever, and parasite density by microscopy during pregnancy. Results Asymptomatic parasitaemia by uRDT during pregnancy was similar in both arms (20.8% in IPTp-SP vs 21.0% in ISTp-uRDT-PA). At delivery, asymptomatic parasitaemia was 51% higher in ISTp-uRDT-PA arm compared to IPTp-SP (cRR = 1.51 [95% CI 0.76–3.00], p = 0.24). Symptomatic parasitaemia by uRDT at delivery showed no significant difference. Malaria by microscopy at enrolment was detected in 34.4% of women. Malaria by microscopy during pregnancy was 9.6% in IPTp-SP and 10.1%. ISTp-uRDT-PA (p = 0.19), decreasing to 3.2% and 0.9%, respectively, at delivery (p = 0.24). Mean haemoglobin concentration at enrolment was 10.1 g/dl in the IPTp-SP and 9.8 g/dl in the ISTp-uRDT-PA with no significant difference in maternal anaemia at delivery (7%; cRR = 1.07 [95% CI 0.87–1.31], p = 0.52). No significant differences were found for spontaneous abortions and in utero death in both arms. The risk of a premature newborn declined by 14% in ISTp-uRDT-PA compared to the IPTp-SP arm (cRR = 0.86 [95% CI 0.29–2.85], p = 0.79) while low-birth-weight was not significantly higher (cRR = 1.74 [95% CI 0.86–3.53], p = 0.12). Conclusion ISTp-uRDT-PA was non inferior to IPTp-SP and can be considered as a future alternative for IPTp-SP in case this intervention can no longer be used due to high SP resistance. Clinical trials registration: NCT04783051.

Background Histidine Rich Protein 2 (HRP2)/pan-Lactate Dehydrogenase (pLDH) combination rapid diagnostic tests (RDTs) may address the shortcomings of RDTs that detect HRP2 alone. However, the relative contribution of the possible causes of discordant results (RDT-negative and microscopy-positive) and performance in field settings across Uganda are poorly quantified. Methods This study utilized samples from two cross-sectional surveys conducted in 32 districts at 64 sites across Uganda between November 2021 and March 2023 that enrolled 6354 febrile participants  ≥ two years of age. Discordant samples (negative by HRP2/pLDH RDT and positive by microscopy) underwent quantitative PCR (qPCR) to detect and quantify parasitaemia. Those confirmed to be positive for Plasmodium falciparum at > 1 parasites/microlitre (p/µL) were tested for pfhrp2 and pfhrp3 deletions using digital PCR. Those that were negative or had P. falciparum detected at ≤ 1 p/µL underwent Plasmodium species testing using nested PCR. The performance of the Bioline Malaria Ag P.f/Pan combination RDT was evaluated by comparison with microscopy and qPCR. Results There were 166 (8.4%) discordant samples out of 1988 microscopy positive samples. Of these, 90/166 (54.2%) were confirmed to contain P. falciparum at levels > 1 p/µL, whereas 76/166 (45.8%) were negative or had P. falciparum levels ≤ 1 p/µL. Only one P. falciparum positive sample was confirmed to have a deletion in pfhrp3 . The primary reasons for RDT-negative, microscopy-positive discordance in samples testing negative for P. falciparum by PCR were non-falciparum species (37/76, 48.7%) or false positives by microscopy (31/76, 40.8%). The sensitivity of the Bioline Malaria Ag P.f/Pan combination RDT was high (> 91%) using either microscopy or qPCR as the gold standard. However, specificity was low (56.7%) when microscopy was used as the gold standard; it improved to 64.0% when qPCR was used as the gold standard. Conclusion The Bioline Malaria Ag P.f/Pan combination RDT was found to be highly sensitive in Uganda and reliable for ruling out malaria. False negative RDT results were primarily due to low density P. falciparum infections, non-falciparum infections, or incorrect microscopy results. In contrast, false positive RDT results were common, most likely due to persistent HRP2 antigenaemia in this high transmission setting though causes of false positive RDTs were not investigated. The low specificity of HRP2-based RDTs may result in overuse of anti-malarial drugs and missed diagnoses of non-malarial febrile illnesses.

Background Rapid Diagnostic Tests (RDTs) are the primary means of malaria diagnosis in sub-Saharan Africa. Outside large health facilities, individuals performing RDTs have little or no formal laboratory training, and performing RDTs is by job aids derived from manufacturers’ instructions for use (IFU). Furthermore, in many countries, RDT products are interchanged often without associated training or notification to users of differences in characteristics not immediately obvious to non-laboratory workers. This leads to common deviations from IFUs the consequences of which have not been systematically studied. This study investigated how these errors impact RDT results. Methods Six RDT products were tested using cultured Plasmodium falciparum diluted to represent infections with a range of parasitaemia. Tests were performed according to IFU (baseline) then with deviations from the IFU including changes in buffer volume, blood volume and incubation time. Effects of the deviations on test validity and overall test result compared to baseline were captured. Also captured, were effects of deviations on test band intensity, and ease of reading result due to test window abnormalities. Results Increasing sample volume beyond the recommended 5µL impaired RDT performance, with 4 of 6 RDT products showing 83.3% (30/36) invalid results due to faulty sample migration. No invalid results were observed for the remaining two products. The shortest incubation period (5 min) led to the most deviations from baseline, whereas longer periods aligned more with baseline results. Insufficient buffer volumes caused at least one invalid outcome [10/27 (37%)] in over half the products. Conversely, exceeding buffer volumes led to reductions in the proportion of invalid results among all tests with 0 of 45 invalid results. Higher parasitaemia was associated with increased band intensity and resulted in the fewest deviations from baseline among all products. At 1,000 parasites/µL and 5 µL sample, three products achieved 100% agreement with baseline regardless of incubation time and buffer volume. Conclusion Although malaria RDTs are tolerant of some errors, in general, procedural errors adversely affect results, particularly in low parasitaemia samples. Understanding how sample and buffer volumes, alongside incorrect incubation times, influence RDT performance can be incorporated into training and continuous quality improvement.

Rapid diagnostic tests (RDTs) have revolutionized malaria diagnosis, playing a crucial role in improving timely treatment and supporting surveillance efforts, especially in resource-limited settings. However, the performance of RDTs can vary widely due to factors such as parasite genetic diversity, environmental conditions, and operational challenges. Understanding these variations is essential to ensuring accurate and reliable malaria diagnosis. This systematic review and meta-analysis critically evaluate the diagnostic performance of malaria RDTs across sub-Saharan Africa, identifying key gaps and proposing strategies for developing novel tests. By pooling data from 48 studies, the analysis quantifies the sensitivity and specificity of various RDT brands in different settings. The results reveal considerable variability, influenced by factors such as antigen persistence, cross-reactivity with other infections, and genetic polymorphism in the HRP2 gene, which can lead to false positives and negatives. The findings underscore the need for region-specific diagnostic strategies and the development of advanced diagnostic tools capable of detecting low-level parasitemia and differentiating between Plasmodium species. Emerging technologies and multi-platform approaches are recommended to enhance the accuracy and reliability of malaria diagnosis, ultimately contributing to more effective malaria control and elimination efforts in sub-Saharan Africa.

Self-testing using rapid diagnostic tests (RDTs), integrated with mobile phone-based apps, offers potential to improve health outcomes in low-resource settings, including sub-Saharan Africa. Despite its advantages, uptake remains limited because of concerns about accuracy, accessibility, and integration within existing health care systems. This study aimed to assess the acceptability of self-testing using RDTs for various health conditions, both independently and app-assisted, among community members, health care providers (HCPs), and community and public health leaders in Kenya, South Africa, and Zambia. From May 15 to August 24, 2023, we conducted an exploratory qualitative study across rural and urban areas in the 3 countries. We used key informant interviews with community leaders and public health leaders in the ministries or departments of health, in-depth interviews (IDIs) with HCPs, and IDIs and focus group discussions (FGDs) with community members. Using framework analysis, we categorized data guided by the Theoretical Framework of Acceptability to assess affective attitude, burden, ethicality, intervention coherence, opportunity costs, perceived effectiveness, and self-efficacy toward self-testing using RDTs, with and without assistance from an app, across countries and participant types. The study involved 178 participants, including 24 key informants, 41 HCPs, and 113 community members who participated in 55 IDIs and 11 FGDs across the 3 countries. Self-testing, both standalone and app-assisted, was highly acceptable to community members, HCPs, and community and public health leaders in the 3 countries for its ability to empower individuals, enhance access to health care, and improve efficiencies in health care delivery. Self-testing was aligned with values of privacy, confidentiality, and autonomy and increased reach to underresourced areas. Participants valued its potential to save time, reduce opportunity costs, and facilitate early diagnosis and treatment, while easing burdens on the health care systems. Participants perceived the benefits of self-testing to outweigh possible risks, including human error, false readings, and emotional distress from unexpected results, especially if linked by an app to real-time guidance and improved health care coordination. Apps were praised for modernity, convenience, and ability to streamline processes for users and health care systems. Foreseeable challenges included resistance from less tech-savvy individuals, ethical concerns such as misuse of self-tests, technological barriers, data security, training needs, and insufficient digital and physical infrastructure for equitable implementation. Regular education, system support, integration, and community trust were identified as critical for success. Self-testing, both alone and app-assisted, was viewed as acceptable and relevant for increasing health care accessibility and efficiency in these low-resource settings. However, to optimize its benefits, efforts must address challenges related to test accuracy, infrastructure development, data privacy, and integration into existing health care systems. Policies should further emphasize education, support, user-friendly design, and minimal costs to ensure equitable access and effective implementation across diverse populations.