Use In Field Settings Research Articles

Development of a RPA-CRISPR/Cas12a based rapid visual detection assay for Porcine Parvovirus 7.

Porcine Parvovirus (PPV) is a significant pathogen in the pig industry, with eight genotypes, including PPV7, identified since its emergence in 2016. Co-infections with viruses such as Porcine Circovirus 2 (PCV2) and Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) pose serious risks to swine health. Thus, there is an urgent need for rapid, sensitive, and specific detection methods suitable for use in field settings or laboratories with limited resources. We developed a CRISPR/Cas12a-based assay combined with recombinase polymerase amplification (RPA) for the rapid detection of PPV7. Specific RPA primers and five CRISPR RNAs (crRNAs) were designed to target a highly conserved region within the NS1 gene of PPV7. Optimization of crRNA and single-stranded DNA (ssDNA) concentrations was performed to enhance the assay's performance. CrRNA optimization identified crRNA-05 as the optimal candidate for Cas12a-based detection of PPV7, as all synthesized crRNAs demonstrated similar performance. The optimal crRNA concentration was determined to be 200 nM, yielding consistent results across tested concentrations. For ssDNA optimization, the strongest fluorescence signal was achieved with 500 nM of the FAM-BHQ ssDNA receptor. The assay showed a minimal detection limit of 100copies/μl for PPV7, confirmed through fluorescence and lateral flow detection methods. Specificity testing indicated that only PPV7 DNA samples returned positive results, confirming the assay's accuracy. In tests of 50 lung tissue samples from diseased pigs, the RPA-Cas12a assay identified 29 positive samples (58%), surpassing the 22 positive samples (44%) detected by conventional PCR. This highlights the RPA-Cas12a method's enhanced detection capability and its potential utility in clinical surveillance and management of PPV7 in swine populations. The RPA-Cas12a assay effectively detects PPV7 in clinical samples, enhancing disease surveillance and control in pigs. Its adaptability to resource-limited settings significantly improves PPV7 management and prevention strategies, thereby supporting the overall health and development of the pig industry.

Multi-repeat sequences identification using genome mining techniques for developing highly sensitive molecular diagnostic assay for the detection of Chlamydia trachomatis.

Chlamydia trachomatis ( C. trachomatis) is a common sexually transmitted infection (STI). In 2019, the World Health Organization reported about 131 million infections. The majority of infected patients are asymptomatic with cases remaining undetected. It is likely that missed C. trachomatis infections contribute to preventable adverse health outcomes in women and children. Consequently, there is an urgent need of developing efficient diagnostic methods. In this study, genome-mining approaches to identify identical multi-repeat sequences (IMRS) distributed throughout the C. trachomatis genome were used to design a primer pair that would target regions in the genome. Genomic DNA was 10-fold serially diluted (100pg/μL to 1×10 -3pg/μL) and used as DNA template for PCR reactions. The gold standard PCR using 16S rRNA primers was also run as a comparative test, and products were resolved on agarose gel. The novel assay, C. trachomatis IMRS-PCR, had an analytical sensitivity of 4.31 pg/µL, representing better sensitivity compared with 16S rRNA PCR (9.5 fg/µL). Our experimental data demonstrate the successful development of lateral flow and isothermal assays for detecting C. trachomatis DNA with potential use in field settings. There is a potential to implement this concept in miniaturized, isothermal, microfluidic platforms, and laboratory-on-a-chip diagnostic devices for reliable point-of-care testing.

Multi-repeat sequences identification using genome mining techniques for developing highly sensitive molecular diagnostic assay for the detection of Chlamydia trachomatis

Chlamydia trachomatis (C. trachomatis) is a common sexually transmitted infection (STI). In 2019, the World Health Organization reported about 131 million infections. The majority of infected patients are asymptomatic with cases remaining undetected. It is likely that missed C. trachomatis infections contribute to preventable adverse health outcomes in women and children. Consequently, there is an urgent need of developing efficient diagnostic methods. In this study, genome-mining approaches to identify identical multi-repeat sequences (IMRS) distributed throughout the C. trachomatis genome were used to design a primer pair that would target regions in the genome. Genomic DNA was 10-fold serially diluted (100pg/mL to 1×10-3pg/mL) and used as DNA template for PCR reactions. The gold standard PCR using 16S rRNA primers was also run as a comparative test, and products were resolved on agarose gel. The novel assay, C. trachomatis IMRS-PCR, had an analytical sensitivity of 4.31 pg/µL, representing better sensitivity compared with 16S rRNA PCR (9.5 fg/µL). Our experimental data demonstrate the successful development of lateral flow and isothermal assays for detecting C. trachomatis DNA with potential use in field settings. There is a potential to implement this concept in miniaturized, isothermal, microfluidic platforms, and laboratory-on-a-chip diagnostic devices for reliable point-of-care testing.

Synopsis.

Cholangiocarcinoma (CCA) is the second most common primary liver cancer worldwide. Despite the severity of the disease and its impact on individuals, families, and communities, there remains an overall lack of awareness and interest in this disease. The information contained in the chapters of this book shows that this is indeed a significant public health and socioeconomic problem with varying levels of country-specific awareness. In Southeast Asia liver fluke, O. viverrini related CCA is endemic with the highest incidence worldwide in northeast Thailand, yet it is treatable and preventable. The chapters highlight significant advances in our knowledge of the biology and epidemiology of the O. viverrini species complex, intermediate hosts, systematics, population genetics, and the complexity of the three-host life cycle. A comprehensive conceptual framework has been developed to assist in understanding the complexity of molecular mechanisms of CCA carcinogenesis and cancer development which can result in improvement of targeted CCA therapy. There have been many advances in understanding the pathology of CCA in the biliary tract, including advances in prognosis and molecular pathogenesis. The development of different modalities and their advantages for diagnosis have increased diagnostic accuracy, providing reliable information allowing appropriate treatment and management programs to be selected for each patient. Particularly exciting is the recent development of a urine antigen assay which has revolutionized the diagnostic approach of opisthorchiasis due to its simplicity, the non-invasive nature of sample collection, and its ease of use in field settings. Significant in-roads and advances have been made in the surgical and systemic treatment of CCA patients. Additionally, a sophisticated data collection and analysis system, the Isan Cohort, has been developed and established for the treatment and control of CCA. Importantly, a greater understanding has been made of the social, community, religious, and anthropological issues initiating and sustaining the eating behavior of raw, partially cooked, and/or fermented fresh water fish. Specially designed education programs/curricula, based on currently available multidisciplinary hard data targeting school children, have been introduced since the inception of the Cholangiocarcinoma Screening and Care Program (CASCAP) and the subsequent strategic Fluke Free Thailand Model. The education program is being expanded to other provinces in Thailand and in the near future to other Southeast Asian countries, initially to Lao PDR, where the Fluke Free Lao PDR program has already been implemented. Despite advances that have been made in many disciplines focused on O. viverrini related CCA, raising awareness of CCA at all levels, particularly across endemic regions, is still needed, as is raising the awareness of CCA globally. As parasites and parasite related diseases have no borders, it is critical that an effective common strategic plan is instigated and established between all countries where liver fluke, O. viverrini related CCA is a significant public health problem, thereby increasing the quality of life and life expectancy of millions of people who suffer from this insidious disease.

Atoms for Nutrition: IAEA’s Contribution to Tackling Malnutrition

Nuclear techniques, including stable isotope techniques, provide great potential for understanding nutrition and human health with better accuracy and precision compared with other routine techniques. The International Atomic Energy Agency (IAEA) has been at the forefront for more than 25 y to offer guidance and support on the use of nuclear techniques. This article demonstrates how the IAEA has enabled its Member States to contribute to good health and well-being in their countries and to assess progress toward achieving global nutrition and health targets to combat malnutrition in all its forms. Support is provided in several ways including research, capacity building, education, and training as well as the provision of guidance materials. The nuclear techniques help to objectively measure nutritional and health-related outcomes such as body composition, energy expenditure, nutrient uptake, and body stores and assess breastfeeding practices as well as environmental interactions. These techniques are continuously improved to make nutritional assessments more affordable and less invasive with wide use in field settings. New research areas are emerging to assess diet quality with changing food systems and to explore stable isotope-assisted metabolomics to address key questions on nutrient metabolism. Through a deeper understanding of mechanisms, nuclear techniques can contribute to eradicating malnutrition worldwide.

Evaluation of the CL Detect Rapid Test in Ethiopian patients suspected for Cutaneous Leishmaniasis

BackgroundCutaneous leishmaniasis (CL) is common in Ethiopia, mainly affecting impoverished populations in rural areas with poor access to health care. CL is routinely diagnosed using skin slit smear microscopy, which requires skilled staff and appropriately equipped laboratories. We evaluated the CL Detect Rapid Test (InBios, Washington, USA), which is supplied with a dental broach sampling device, as a diagnostic alternative which could be used in field settings.Methodology/Principal findingsWe evaluated the diagnostic accuracy of the CL Detect Rapid Test on skin slit and dental broach samples from suspected CL patients at the Leishmaniasis Research and Treatment Center in Gondar, Ethiopia. A combined reference test of microscopy and PCR on the skin slit sample was used, which was considered positive if one of the two tests was positive. We recruited 165 patients consecutively, of which 128 (77.6%) were confirmed as CL. All microscopy-positive results (n = 71) were also PCR-positive, and 57 patients were only positive for PCR. Sensitivity of the CL Detect Rapid Test on the skin slit was 31.3% (95% confidence interval (CI) 23.9–39.7), which was significantly higher (p = 0.010) than for the dental broach (22.7%, 95% CI 16.3–30.6). Sensitivity for both methods was significantly lower than for the routinely used microscopy, which had a sensitivity of 55.5% (IQR 46.8–63.8) compared to PCR as a reference.Conclusions/SignificanceThe diagnostic accuracy of the CL Detect Rapid Test was low for skin slit and dental broach samples. Therefore, we do not recommend its use neither in hospital nor field settings.Trial registrationThis study is registered at ClinicalTrials.gov as NCT03837431.

Antigen-Based Point of Care Testing (POCT) for Diagnosing SARS-CoV-2: Assessing Performance.

Currently, the most accurate way to diagnose an active SARS-CoV-2 (COVID-19) infection is through detection of viral RNA using reverse transcription polymerase chain reaction (RT-PCR) test. While RT-PCR tests are the most sensitive for identifying infection, there are significant limitations, such as global access to sufficient test kits, turnaround times (TAT) from specimen collection to test result is often greater than 24h and the need for skilled operators in accredited laboratories requiring specialized equipment. A rapid test performed at the point of care (POC) could provide a result within an approximate time of 30min post specimen collection, be performed by a health care worker and comprise a simple workflow, improving both turnaround time and potentially decreasing costs (e.g., transport, cold-chain, skilled laboratory staff, complex equipment). Determining the performance of SARS-CoV-2 RT-PCR tests is, however, easier to assess than antigen-based POCT, as residual clinical specimens (swabs in universal transport media [UTM]) are readily available in laboratory environments, and do not require patient informed consent. Evaluating the performance of POCT requires informed-consent driven studies, with patients required to provide a standard of care specimen as well as study evaluation specimens, which is often not acceptable as nasopharyngeal swabbing can be invasive, clinical field trials are costly and time consuming. Many institutions and regulatory bodies also require preliminary data prior to use in field settings. Therefore, we have developed a method to determine the performance of antigen based POCT that can be used by implementers in national healthcare programs, regulators and rapid test developers. The method investigates both quantitative and qualitative parameters, with the latter providing insights into the capability for implementation and national program uptake.

Relationships Between WUT (Body Weight, Urine Color, and Thirst Level) Criteria and Urine Indices of Hydration Status.

A Venn diagram consisting of percentage body mass loss, urine color, and thirst perception (weight, urine, thirst [WUT]) has been suggested as a practical method to assess hydration status. However, no study to date has examined relationships between WUT and urine hydration indices. Thus, the purpose of this study was to investigate relationships between urine specific gravity, urine osmolality, and the WUT criteria. Urine specific gravity and urine osmolality indicate hypohydration when the WUT criteria demonstrate hypohydration (≥2 markers). Laboratory cohort study. Level 3. A total of 22 women (mean ± SD; age, 20 ± 1 years; mass, 65.4 ± 12.6 kg) and 21 men (age, 21 ± 1 years; body mass, 78.7 ± 14.6 kg) participated in this study. First morning body mass, urine color, urine specific gravity, urine osmolality, and thirst level were collected for 10 consecutive days in a free-living situation. Body mass loss >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels were counted and categorized into either 3, 2, 1, or 0 WUT markers that indicated dehydration. One-way analysis of variance with Tukey pairwise comparisons was used to assess the differences in urine specific gravity and urine osmolality between the different number of WUT markers. Urine specific gravity in 3 WUT markers (mean ± SD [effect size], 1.021 ± 0.007 [0.57]; P = 0.025) and 2 WUT markers (1.019 ± 0.010 [0.31]; P = 0.026) was significantly higher than 1 WUT marker (1.016 ± 0.009). Urine mosmolality in 2 WUT markers (705 ± 253 mOsmol [0.43]; P = 0.018) was significantly higher than 1 WUT (597 ± 253 mOsmol). Meeting at 3 WUT resulted in specificity of 0.956 and at 0 WUT resulted in sensitivity of 0.937 for urine osmolality>700mOsm. These results suggest that when 3 WUT markers are met, urine specific gravity and urine osmolality indicated hypohydration and 0 WUT represents a high likelihood of euhydration. 1 and 2 WUT values are indeterminate of hydration status. The WUT criterion is a useful tool to use in field settings to assess hydration status when first morning urine sample was used. Athletes, coaches, sports scientists, and medical professionals can use WUT criteria to monitor dehydration with reduced cost and time.

A modified physiological strain index for workplace-based assessment of heat strain experienced by agricultural workers.

As global temperatures rise, increasing numbers of individuals will work in hot environments. Interventions to protect their health are critical, as are reliable methods to measure the physiological strain experienced from heat exposure. The physiological strain index (PSI) is a measure of heat strain that relies on heart rate and core temperature but is challenging to calculate in a real-world occupational setting. We modified the PSI for use in field settings where resting temperature and heart rate are not available and used the modified physiological strain index (mPSI) to describe risk factors for high heat strain (mPSI ≥ 7) experienced by agricultural workers in Florida during the summers of 2015 through 2017. mPSI was calculated for 221 workers, yielding 465 days of data. A higher heat index (β = 0.185; 95% CI: 0.064, 0.307) and higher levels of physical activity at work (0.033; 95% CI: 0.017, 0.050) were associated with a higher maximum mPSI. More years worked in US agriculture (-0.041; 95% CI: -0.061, -0.020) were protective against a higher maximum mPSI. Out of 23 workdays that a participant experienced a maximum mPSI ≥ 7, 22 were also classified as strained by at least one other measure of high heat strain (core temperature [Tc] >38.5°C, sustained heart rate>(180 - age), and mean heart rate > 115 bpm). This study provides critical information on risk factors for elevated heat strain for agricultural workers and suggests a practical approach for using PSI in field-based settings.

Feasibility Study of Hydration Monitoring Using Microwaves–Part 2: Measurements of Athletes

Hydration is a key consideration for athletes, where even mild levels of dehydration may negatively impact performance. Existing methods of assessment are either inaccurate or impractical for use in field settings, motivating the search for new approaches. Extremity microwave measurement is a promising method for ongoing hydration monitoring, owing to the inherent differences in dielectric properties with varying tissue water content. This paper reports on a feasibility study of in vivo hydration assessment using microwave measurements in athletes undergoing acute water loss during exercise. We developed and then tested a system for performing reliable microwave property estimation at the forearm. This system was used to measure hydration status in varsity wrestlers before and after a training session. A relationship between estimated permittivity and body weight change due to water loss was found, showing promise for the use of microwaves to assess hydration status. No significant relationship with attenuation was found. A novel method of assessing changes in hydration status is described, which may be of practical use for athletes in guiding fluid replacement during and after exercise.

A Direct from Blood/Plasma Reverse Transcription-Polymerase Chain Reaction for Dengue Virus Detection in Point-of-Care Settings.

Infection with dengue virus (DENV) is widespread across tropical regions and can result in severe disease. Early diagnosis is important both for patient management and to differentiate infections that present with similar symptoms, such as malaria, chikungunya, and Zika. Rapid diagnostic tests that are used presently for point-of-care detection of DENV antigens lack the sensitivity of molecular diagnostics that detect viral RNA. However, no molecular diagnostic test for DENV is available for use in field settings. In this study, we developed and validated a reverse transcription-polymerase chain reaction (RT-PCR) for the detection of DENV adapted for use in field settings. Reverse transcription-polymerase chain reaction was performed directly from plasma samples without RNA extraction. The assay detected all four serotypes of DENV spiked into blood or plasma. Our RT-PCR does not cross-react with pathogens that cause symptoms that overlap with dengue infection. The test performed equally well in a conventional laboratory qPCR instrument and a small, low-cost portable instrument that can be used in a field setting. The lower limit of detection for the assay was 1 × 104 genome copy equivalents/mL in blood. Finally, we validated our test using 126 archived patient samples. The sensitivity of our RT-PCR was 76.7% (95% CI: 65.8-87.9%) on the conventional instrument, and 78.3% (95% CI: 65.8-87.9%) on the field instrument, when compared with the RealStar Dengue RT-PCR Kit 2.0. The molecular test described here is user-friendly, low-cost, and can be used in regions with limited laboratory capabilities.

Laboratory Validation of Hexoskin Biometric Shirt at Rest, Submaximal Exercise, and Maximal Exercise While Riding a Stationary Bicycle.

Evaluate Hexoskin performance on a stationary bike against "gold standard" laboratory equipment and develop adjustment models for future use in field settings. Compared respiratory rate (RR), tidal volume (VT), minute ventilation (VE), and heart rate (HR) measured by the Hexoskin shirt to simultaneous spirometry and full 12-lead electrocardiogram during a laboratory based incremental exercise test on a stationary bicycle. Data from 17 participants demonstrated Hexoskin VT and VE had the best agreement in the submaximal exercise level (discrepancies less than or equal to 5.3%) with larger discrepancies observed at rest (less than or equal to 15.3%) and at maximal exercise level (less than or equal to 11.7%). The discrepancies for HR and RR were lower at all levels (less than 10%). Adjusting for sex and body weight allowed for a single VE algorithm across the entire range of effort (r = 0.89). These discrepancies are acceptable for field use in comparison to the ranges typical of bicycle commuting.

Probing rate estimation methods for multiphase flow through surface chokes

Choke is an essential device that controls flow rates at either subsurface or surface. Many models and correlations have appeared over decades handling multiphase flow through surface chokes. But, direct comparison of their relative performance has been a few, if any. This study evaluates several models and correlations to explore their relative performances. As expected, models anchored in thermodynamic principles outperformed others. Improvements in modeling followed the initial findings.We studied several models to explore their relative merits and ease of use in field settings. Seven different data sets gathered from laboratory and field settings, involving about 1000 independent data points, constituted the essence of this study. The study found the importance of PVT data in any flow through choke calculations. Specifically, we found that changes in density and heat capacity of fluids with pressure and temperature should be part of any rigorous effort for computation of flow rates.To ensure reliability and consistency in solutions, a model based on thermodynamic considerations deserve preference for generalized applications because it can handle pressure and temperature-dependent fluid properties. In this context, the recognition of choke-discharge coefficient's dependence on flow rate and Reynolds number constitutes an important element in ensuring the reliable outcome of results.

Avirulent Bacillus anthracis Strain with Molecular Assay Targets as Surrogate for Irradiation-Inactivated Virulent Spores.

The revelation in May 2015 of the shipment of γ irradiation–inactivated wild-type Bacillus anthracis spore preparations containing a small number of live spores raised concern about the safety and security of these materials. The finding also raised doubts about the validity of the protocols and procedures used to prepare them. Such inactivated reference materials were used as positive controls in assays to detect suspected B. anthracis in samples because live agent cannot be shipped for use in field settings, in improvement of currently deployed detection methods or development of new methods, or for quality assurance and training activities. Hence, risk-mitigated B. anthracis strains are needed to fulfill these requirements. We constructed a genetically inactivated or attenuated strain containing relevant molecular assay targets and tested to compare assay performance using this strain to the historical data obtained using irradiation-inactivated virulent spores.

Development and application of a rapid Mycobacterium tuberculosis detection technique using polymerase spiral reaction

Mycobacterium tuberculosis is an age-old bacterium that is difficult to eliminate. A simple and rapid diagnostic method is of great importance to prevent the spread of M. tuberculosis. Here, we developed a low-cost rapid M. tuberculosis nucleic acid detection technique, named GenePop, which enabled the storage and transport of M. tuberculosis diagnostic reagent at ambient temperatures, without the need for professional operations or expensive instrumentation. Using a vitrification method, we vitrified heat-unstable components onto the cap of a reaction tube, and placed heat-stable components at the bottom of the reaction tube by sealing them with paraffin wax. The all-in-one detection tube, when used together with our other invention—a multi-functional sample treatment tube pre-filled with a nucleic acid-releasing agent—only required three simple steps to yield results. A comparative analysis with a commercial qPCR kit for M. tuberculosis indicated that our new technique had a concordance rate of 91.6%, showing no cross-reactivity with 11 other bacteria. The complete operation time was only 65 min. It is suitable for use in field settings or by personnel in grass-root units, and is applicable in household activities, hence can be used in developing countries.

Anthropometric multicompartmental model to predict body composition In Brazilian girls

BackgroundAnthropometric models remain appropriate alternatives to estimate body composition of peripubertal populations. However, these traditional models do not consider other body components that undergo major changes during peripubertal growth spurt, with restrictions to a multicompartimental approach as a quantitative growth. DXA has great potential to determine pediatric body composition in more than one component (3-C), but has limited use in field settings. Thus, the aim of this study was to propose and validate an anthropometric model for simultaneous estimation of lean soft tissue (LST), bone mineral content (BMC) and fat mass (FM) in healthy girls, from a multivariate approach of densitometric technique, as the criterion method.MethodsA sample of 84 Brazilian girls (7-17 years) was defined by chronological age and maturity offset. Whole total and regional DXA body scan were performed and, the components were defined (LST, BMC and FM) and considered as dependent variables. Twenty-one anthropometric measures were recorded as independent variables. From a multivariate regression, an anthropometric multicompartmental model was obtained.ResultsIt was possible to predict DXA body components with only four predictive measurements: body weight (BW); supra-iliac skinfold (SiSk); horizontal abdominal skinfold (HaSk) and contracted arm circumference (CaCi) with high coefficients of determination and low estimation errors (LST = 0.6662657 BW - 0. 2157279 SiSk - 0.2069373 HaSk + 0.3411678 CaCi - 1.8504187; BMC = 0.0222185 BW - 0.1001097 SiSk - 0.0064539 HaSk - 0.0084785 CaCi + 0.3733974 and FM = 0.3645630 BW + 0.1000325 SiSk - 0.2888978 HaSk - 0.4752146 CaCi + 2.8461916). The cross-validation was confirmed through the sum of squares of residuals (PRESS) method, presenting accurate coefficients (Q2PRESS from 0.81 to 0.93) and reduced error reliability (SPRESS from 0.01 to 0.30).ConclusionsWhen sophisticated instruments are not available, this model provides valid estimates of multicompartmental body composition of girls in healthy Brazilian pediatric populations.

A no film slot blot for the detection of developing P. falciparum oocysts in mosquitoes.

Non-microscopy-based assays for sensitive and rapid detection of Plasmodium infection in mosquitoes are needed to allow rapid and high throughput measurement of transmission intensity and malaria control program effectiveness. Here, we report on a modified enhanced chemiluminescence-based slot blot assay for detection of Plasmodium falciparum (Pf) circumsporozite protein (PfCSP) expressed on parasite oocysts developing inside the mosquito midgut. This modified assay has several novel features that include eliminating the need for exposure to autoradiography (AR) film, as well as utilizing a novel high affinity anti-CSP antibody, and optimizing assay procedures resulting in significant reduction in the time required to perform the assay. The chemiluminescent signal for the detection of PfCSP in mosquito samples was captured digitally utilizing the C-Digit blot scanner that, allowed the detection of 0.01 pg of recombinant P. falciparum CSP and as few as 0.02 P. falciparum oocysts in a little over two hours. The earlier ECL-SB detected rCSP and oocysts and took approximately 5 h to perform. Whole mosquito lysates from both high and low prevalence—infected mosquito populations were prepared and evaluated for PfCSP detection on the ECL-SB by both AR film and digital data capture and analysis. There was a 100% agreement between the AR film and the C-Digit scanner methods for PfCSP detection in randomly sampled mosquitoes. This novel “No Film” Slot Blot assay obviates the need for AR film exposure and development and significantly reduces the assay time enabling widespread use in field settings.

Lateral flow-based antibody testing for Chlamydia trachomatis

We describe here a lateral flow-based assay (LFA) for the detection of antibodies against immunodominant antigen Pgp3 from Chlamydia trachomatis, the causative agent of urogenital chlamydia infection and ocular trachoma. Optimal signal detection was achieved when the gold-conjugate and test line contained Pgp3, creating a dual sandwich capture assay. The LFA yielded positive signals with serum and whole blood but not with eluted dried blood spots. For serum, the agreement of the LFA with the non-reference multiplex assay was 96%, the specificity using nonendemic pediatric sera was 100%, and the inter-rater agreement was κ=0.961. For whole blood, the agreement of LFA with multiplex was 81.5%, the specificity was 100%, and the inter-rater agreement was κ=0.940. The LFA was tested in a field environment and yielded similar results to those from laboratory-based testing. These data show the successful development of a lateral flow assay for detection of antibodies against Pgp3 with reliable use in field settings, which would make antibody-based testing for trachoma surveillance highly practical, especially after cessation of trachoma elimination programs.

Comparative Validation of Five Quantitative Rapid Test Kits for the Analysis of Salt Iodine Content: Laboratory Performance, User- and Field-Friendliness.

BackgroundIodine deficiency has important health and development consequences and the introduction of iodized salt as national programs has been a great public health success in the past decades. To render national salt iodization programs sustainable and ensure adequate iodization levels, simple methods to quantitatively assess whether salt is adequately iodized are required. Several methods claim to be simple and reliable, and are available on the market or are in development.ObjectiveThis work has validated the currently available quantitative rapid test kits (quantRTK) in a comparative manner for both their laboratory performance and ease of use in field settings.MethodsLaboratory performance parameters (linearity, detection and quantification limit, intra- and inter-assay imprecision) were conducted on 5 quantRTK. We assessed inter-operator imprecision using salt of different quality along with the comparison of 59 salt samples from across the globe; measurements were made both in a laboratory and a field setting by technicians and non-technicians. Results from the quantRTK were compared against iodometric titration for validity. An ‘ease-of-use’ rating system was developed to identify the most suitable quantRTK for a given task.ResultsMost of the devices showed acceptable laboratory performance, but for some of the devices, use by non-technicians revealed poorer performance when working in a routine manner. Of the quantRTK tested, the iCheck® and I-Reader® showed most consistent performance and ease of use, and a newly developed paper-based method (saltPAD) holds promise if further developed.ConclusionsUser- and field-friendly devices are now available and the most appropriate quantRTK can be selected depending on the number of samples and the budget available.

Comparison of Visceral Adiposity and Obesity Parameters in Caucasian and Hispanic Adults

Abdominal adiposity can be classified generally as total, subcutaneous, and visceral. The distribution of these fat depots is important, as visceral adiposity is a better indicator of adverse health risks than subcutaneous adiposity. Yet the bulkiness and high costs associated with current detection devices limit their use in field settings. This study determined central obesity parameters via a three‐dimensional stereovision body imaging (SBI), an inexpensive, portable method of fat assessment. 121 Caucasian and Hispanic adults were measured for anthropometrics, abdominal adiposity volumes by magnetic resonance imaging; and body circumferences and central obesity by SBI. The Hispanic women had the highest amount of total abdominal and subcutaneous adiposity. Conversely, Caucasian men had the lowest depots of total abdominal and subcutaneous adiposity, but greater visceral adiposity. Central obesity depth (Caucasian r=0.83 and Hispanic r=0.78 women; Caucasian r=0.76 and Hispanic r=0.52 men) and the ratio of central obesity depth and width (Caucasian r=0.81 and Hispanic r=0.75 women; Caucasian r=0.88 and Hispanic r=0.65 men) were the most reliable parameters that exhibited a significantly positive association with visceral adiposity. These results suggest that SBI is an effective means to evaluate central adiposity in clinical settings in diverse populations. NIH 3R21DK081206–02S1.