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Highlights The LAMP method performs equally to international reference RT-PCR methods for detection of SARS-CoV-2 Experiments have been conducted that fulfil regulatory criteria by international bodies LAMP as an LDT does not rely on RT-PCR reagents and does not cannibalize key reagents and kits in those supply chains The test is rapid with a result in less than 30 minutes after extraction Many countries can use this LDT option internationally in one or other format and provide vital testing Potential to apply this chemistry to a point of care method exists

Background: 125 million women are pregnant each year in malaria endemic areas and are, therefore, at risk of Malaria in Pregnancy (MiP). MiP is the direct consequence of Plasmodium infection during pregnancy. The sequestration of Plasmodium falciparum parasites in the placenta adversely affects fetal development and impacts newborn birth weight. Importantly, women presenting with MiP commonly develop anaemia. In Ethiopia, the Ministry of Health recommends screening symptomatic women only at antenatal care visits with no formal intermittent preventive therapy. Since MiP can display low-level parasitaemia, current tests which include microscopy and RDT are challenged to detect these cases. Loop mediated isothermal Amplification (LAMP) technology is a highly sensitive technique for DNA detection and is field compatible. This study aims to evaluate the impact of active malaria case detection during pregnancy using LAMP technology in terms of birth outcomes. Methods: A longitudinal study was conducted in two health centres of the Kafa zone, South West Ethiopia. Both symptomatic and asymptomatic pregnant women were enrolled in the first or second trimester and allocated to either Standard of Care (SOC-microscopy and RDT) or LAMP (LAMP, microscopy and RDT). Women completed at least three visits prior to delivery, and the patient was referred for treatment if Plasmodium infection was detected by any of the testing methods. The primary outcome was to measure absolute birth weight, proportion of low birth weight, and maternal/neonatal haemoglobin in each arm. Secondary outcomes were to assess the performance of microscopy and RDT versus LAMP conducted in the field. Results: One hundred and ninety-nine women were included and assigned to either LAMP or SOC. Six were lost to follow up. In this cohort, 66.8% of women did not display any clinical symptoms and 70.9% were multi-parous. A reduced proportion of low birth weight newborns was observed in the LAMP group (0%) compared to standard of care (14%) (p <0.001). Improved neonatal haemoglobin was observed in the LAMP (13.1 g/dL) versus the SOC (12.8 g/ dL) (p = 0.024) arm. RDT and microscopy had an analytical sensitivity of 66.7% and 55.6% compared to LAMP as a reference standard.

18We have developed a reverse-transcriptase loop mediated amplification (RT-LAMP) method targeting 19 genes encoding the Spike (S) protein and RNA-dependent RNA polymerase (RdRP) of SARS-CoV-2. The 20 LAMP assay achieves comparable limit of detection as commonly used RT-PCR protocols based on 21 artificial targets, recombinant Sindbis virus, and clinical samples. Clinical validation of single-target (S 22 gene) LAMP (N=120) showed a positive percent agreement (PPA) of 41/42 (97.62%) and negative 23 percent agreement (NPA) of 77/78 (98.72%) compared to reference RT-PCR. Dual-target RT-LAMP (S and 24 RdRP gene) achieved a PPA of 44/48 (91.97%) and NPA 72/72 (100%) when including discrepant 25 samples. The assay can be performed without a formal extraction procedure, with lyophilized reagents 26 which do need cold chain, and is amenable to point-of-care application with visual detection. 27

Background Clostridioides difficile infection (CDI) is an opportunistic disease that lacks a gold standard test. Nucleic acid amplification tests (NAATs) such as real-time PCR demonstrate excellent an limit of detection (LOD) whereas antigenic methods are able to detect free toxin. Latent class analysis (LCA) provides an unbiased statistical approach to resolving true disease. Methods A cross-sectional study was conducted with suspected CDI patients (n=96). Four commercial real-time PCR tests, toxin antigen detection by enzyme immunoassay (EIA), toxigenic culture, and fecal calprotectin were performed. CDI clinical diagnosis was determined by consensus majority of three experts. LCA was performed using laboratory and clinical variables independent of any gold standard. Results Six LCA models were generated to determine CDI probability using four variables including toxin EIA, toxigenic culture, clinical diagnosis, and fecal calprotectin levels. Three defined zones as a function of real-time PCR cycle threshold (Ct) were identified using LCA: CDI likely (&gt;90% probability), equivocal (&lt;90% and &gt;10%), CDI unlikely (&lt;10%). A single model comprising toxigenic culture, clinical diagnosis, and toxin EIA showed the best fitness. The following Ct cut-offs for four commercial test platforms were obtained using this model to delineate three CDI probability zones: [GeneXpert ® : 24.00, 33.61], [Simplexa ® 28.97, 36.85], [Elite MGB ® 30.18, 37.43], and [BD Max ™ 27.60, 34.26]. Conclusion The clinical implication of applying LCA to CDI is to report Ct values assigned to probability zones based on the commercial real-time PCR platform. A broad range of equivocation suggests clinical judgement is essential to the confirmation of CDI.