Development of a new accurate lateral flow immunoassay for diagnosis of human leptospirosis.

PURPOSE: The current diagnostic methods for leptospirosis diagnosis are technically complex and expensive, with limited applicability to specialized laboratories. Furthermore, they lack diagnostic accuracy in the acute stage of the disease, which coincides with a period when antibiotics are highly effective. New simple and accurate tests are mandatory to decentralize and improve diagnosis. Here, we introduced a new lateral flow immunoassay (Lepto-LF) for human leptospirosis. METHODS: We conducted a double-blinded assay using 104 serum samples from patients with confirmed or discarded diagnosis for leptospirosis. The diagnostic performance of Lepto-LF was estimated across different ranges of days from onset of symptoms (dpo), considering the diagnostic algorithm as reference standard. Additionally, it was compared with the screening methods enzyme-linked immunosorbent assay (IgM-ELISA) and the slide agglutination test using temperature-resistant antigen (SATR). RESULTS: Lepto-LF exhibited perfect diagnostic performance with a Youden´s index J = 1 from 6 dpo in the acute phase. IgM-ELISA gave slightly lower accuracy with J = 0.91 and 95.5% of both sensitivity and specificity; while SATR showed a markedly inferior yield (J = 0.41, sensitivity = 95.5%, specificity = 45.5%). The performances remained consistent in the convalescence phase of the disease (> 10 dpo). CONCLUSION: Lepto-LF was found to be a reliable test for simple, rapid and early diagnosis of leptospirosis, resulting a promising tool for decentralizing leptospirosis diagnosis and enabling timely treatment of patients. In addition, Lepto-LF may be employed as confirmatory test, especially in remote areas and vulnerable contexts where the standard MAT is not available.

Development and evaluation of a Lateral flow immunoassay (LFIA) prototype for the detection of IgG anti-SARS-CoV-2 antibodies.

Lateral flow immunoassays (LFIA) for antibody detection represent cost-effective and user-friendly tools for serology assessment. This study evaluated a new LFIA prototype developed with a recombinant chimeric antigen from the spike/S and nucleocapsid/N proteins to detect anti-SARS-CoV-2 IgG antibodies. The evaluation of LFIA sensitivity and specificity used 811 serum samples from 349 hospitalized, SARS-CoV-2 RT-qPCR positive COVID-19 patients, collected at different time points and 193 serum samples from healthy controls. The agreement between ELISA results with the S/N chimeric antigen and LFIA results was calculated. The LFIA prototype for SARS-CoV-2 using the chimeric S/N protein demonstrated 85 % sensitivity on the first week post symptoms onset, reaching 94 % in samples collected at the fourth week of disease. The agreement between LFIA and ELISA with the same antigen was 92.7 %, 0.827 kappa Cohen value (95 % CI [0.765-0.889]). Further improvements are needed to standardize the prototype for whole blood use. The inclusion of the novel chimeric S + N antigen in the COVID-19 IgG antibody LFIA demonstrated optimal agreement with results from a comparable ELISA, highlighting the prototype's potential for accurate large-scale serologic assessments in the field in a rapid and user-friendly format.

RdJ detection tests to identify a unique MRSA clone of ST105-SCCmecII lineage and its variants disseminated in the metropolitan region of Rio de Janeiro.

Hospital bloodstream infection (BSI) caused by methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of morbidity and mortality and is frequently related to invasive procedures and medically complex patients. An important feature of MRSA is the clonal structure of its population. Specific MRSA clones may differ in their pathogenic, epidemiological, and antimicrobial resistance profiles. Whole-genome sequencing is currently the most robust and discriminatory technique for tracking hypervirulent/well-adapted MRSA clones. However, it remains an expensive and time-consuming technique that requires specialized personnel. In this work, we describe a pangenome protocol, based on binary matrix (1,0) of open reading frames (ORFs), that can be used to quickly find diagnostic, apomorphic sequence mutations that can serve as biomarkers. We use this technique to create a diagnostic screen for MRSA isolates circulating in the Rio de Janeiro metropolitan area, the RdJ clone, which is prevalent in BSI. The method described here has 100% specificity and sensitivity, eliminating the need to use genomic sequencing for clonal identification. The protocol used is relatively simple and all the steps, formulas and commands used are described in this work, such that this strategy can also be used to identify other MRSA clones and even clones from other bacterial species.

Capacidad de un ensayo rápido para diagnosticar la COVID-19 y relación con síntomas clínicos / Effectiveness of a rapid test for the diagnosis of COVID-19 and its relationship with clinical symptoms

Introducción: La detección del virus SARS-CoV-2, agente causal de la COVID-19, es determinante para disminuir la propagación de la actual pandemia. Si bien el procedimiento de elección es la determinación del ácido nucleico del virus mediante la reacción en cadena de la polimerasa, también es necesario disponer de pruebas rápidas, con alta sensibilidad y precisión. Objetivo: Analizar la validez diagnóstica de un ensayo rápido de antígeno SARS-CoV-2, utilizado para la detección de la COVID-19 en el policlínico "5 de Septiembre" del municipio Playa. Material y Métodos: Se realizó un estudio analítico de corte transversal con 590 pacientes atendidos en la consulta de infecciones respiratorias agudas, en el período de enero a agosto de 2021. La determinación de antígeno SARS-CoV-2 se realizó con un ensayo rápido y la confirmación se hizo mediante la reacción en cadena de la polimerasa. Resultados: La prueba rápida de antígeno tuvo una elevada sensibilidad (98,19 %) y especificidad (92,39 %). La concordancia de los resultados obtenidos entre ambas pruebas fue elevada (0,868). Las sintomatologías más frecuentes reportadas, fueron, cefalea (51,69 %), fiebre (39,15 %), tos (37,16 %), pérdida del gusto/olfato (34,06 %) y rinorrea (30,16 %). Conclusiones: El ensayo rápido de antígeno del SARS-CoV-2 usado para la detección de la COVID-19 demostró validez y puede ser utilizado para el diagnóstico de la enfermedad. Las sintomatologías cefalea, fiebre, tos, pérdida del gusto/olfato y rinorrea fueron las más frecuentes, reportadas en más de 30 de los casos.

Introduction: The detection of the SARS-CoV-2 virus, the causal agent of COVID-19, is decisive to reduce the spread of the current pandemic. Although the procedure of choice is the determination of the nucleic acid of the virus using the polymerase chain reaction, the availability of rapid, highly sensitive, and accurate tests is also necessary. Objective: To analyze the diagnostic validity of a SARS-CoV-2 antigen rapid diagnostic test for the detection of COVID-19 in the "5 de Septiembre" Polyclinic in Playa municipality. Material and Methods: A cross-sectional analytical study was carried out on 590 patients seen in the acute respiratory infections consulting room in the period from January to August 2021. The detection of the SARS-CoV-2 antigen was performed using a rapid test and it was confirmed by polymerase chain reaction. Results: The rapid antigen test had a high sensitivity (98.19%) and specificity (92.39%). The concordance of the results obtained from both tests was high (0.868). The most frequent reported symptoms were headache (51.69%), fever (39.15%), cough (37.16%), loss of taste/smell (34.06%), and runny nose (30.16%). Conclusions: The SARS-CoV-2 antigen rapid diagnostic test used for the detection of COVID-19 is valid and can be used in the diagnosis of the disease. Symptoms such as headache, fever, cough, loss of taste/smell, and runny nose were the most frequently reported in more than 30% of cases.

Geographical analysis of seroprevalence of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis, in clinics and dog shelters in different Mexican states.

This study aimed to determine the seroprevalence and geographical distribution of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis in dogs in Mexico, including owned dogs from veterinary clinics with regular medical care and shelter dogs. The Mexican territory was divided into eight geographical regions; 22 out of 32 states were included; 110 veterinary clinics and 53 dog shelters participated. SNAP® 4Dx Plus® (IDEXX® Laboratories) was used to detect antibodies against Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis antigens. A total of 3522 apparently healthy dogs were tested, 1648 from clinics and 1874 from shelters. The highest seroprevalence of infection/exposure was found for Ehrlichia spp. (30.9%), followed by Anaplasma spp. (14.6%), D. immitis (5.3%) and B. burgdorferi (0.1%). Significantly more positive dogs were older than 3 years. Regarding differences between facility types, there were only differences for D. immitis which was more prevalent in clinics than in shelters (OR â€‹= â€‹1.97; 95% CI: 1.45-2.69; P â€‹< â€‹0.0001). Co-infections were detected in 38.4% of the positive samples. Dogs from Mexican states located on the Atlantic and the Pacific coast were significantly more at risk for Ehrlichia spp. and Anaplasma spp. infections than dogs from interior states. Dogs in Atlantic coastal states were more at risk for Dirofilaria immitis infection.

Rapid antigen test as a tool for the identification of SARS-CoV-2 infection and its potential as a self-testing device

ABSTRACT Background: SARS-CoV-2 virus originated in Wuhan (China) in December (2019) and quickly spread worldwide. Antigen tests are rapid diagnostic tests (RDT) that produce results in 15-30 min and are an important tool for the scale-up of COVID-19 testing. COVID-19 diagnostic tests are authorized for self-testing at home in some countries, including Brazil. Widespread COVID-19 diagnostic testing is required to guide public health policies and control the speed of transmission and economic recovery. Methods: Patients with suspected COVID-19 were recruited at the Hospital da Baleia (Belo Horizonte, Brazil). The SARS-CoV-2 antigen-detecting rapid diagnostic tests were evaluated from June 2020 to June 2021 using saliva, nasal, and nasopharyngeal swab samples from 609 patients. Patient samples were simultaneously tested using a molecular assay (RT-qPCR). Sensitivity, specificity, accuracy, and positive and negative predictive values were determined using the statistical program, MedCalc, and GraphPad Prism 8.0. Results: The antigen-detecting rapid diagnostic tests displayed 98% specificity, 60% sensitivity, 96% positive predictive value, and moderate concordance with RT-qPCR. Substantial agreement was found between the two methods for patients tested < 7 days of symptom onset. Conclusions: Our findings support the use of Ag-RDT as a valuable and safe diagnostic method. Ag-RDT was also demonstrated to be an important triage tool for suspected COVID-19 patients in emergencies. Overall, Ag-RDT is an effective strategy for reducing the spread of SARS-CoV-2 and contributing to COVID-19 control.

Rendimiento diagnóstico de la prueba rápida para la detección del antígeno NS1 y anticuerpos IgM e IgG contra el virus del dengue / Diagnostic performance of the rapid test for the detection of NS1 antigen and IgM and IgG anti-antibodies against dengue virus

Objetivos. Determinar el rendimiento diagnóstico de la prueba rápida SD dengue DUO (Inyecta) para la detección de NS1, IgM e IgG en comparación con la prueba de ELISA. Materiales y métodos. Es una evaluación de prueba diagnóstica que incluyó 286 muestras de suero de pacientes con sintomatología atribuible a dengue de zonas endémicas del Perú. Las muestras se analizaron por ELISA y la prueba rápida SD dengue DUO (Inyecta) para IgM, NS1 e IgG en el Instituto de Investigación Nutricional en Lima. Resultados. La sensibilidad de la prueba rápida fue de 68% para NS1 e IgM, y 86% para IgG, mejorando este parámetro a 75% y 81% para NS1 e IgM, respectivamente, en los tres primeros días. La especificidad para los tres analitos fue mayor a 87%. La concordancia de los resultados obtenidos medidos por el coeficiente Kappa para los tres analitos fue buena y no se encontró reacción cruzada con otros arbovirus. Conclusiones. La prueba rápida SD Dengue DUO permite detectar con una adecuada sensibilidad y especificidad NS1, IgM e IgG. La sensibilidad para IgM y NS1 aumenta cuando se detecta en los tres primeros días de síntomas, por lo que se recomienda su implementación en los centros de primer nivel de atención para un diagnóstico temprano y oportuno.

Objectives . To assess the diagnostic performance of the SD dengue DUO rapid test (Inyecta) for the detection of NS1, IgM and IgG in comparison to the ELISA test. Materials and methods . This is a diagnostic test evaluation that included 286 serum samples from patients with symptomatology attributable to dengue from endemic areas of Peru. The samples were analyzed by ELISA and the SD dengue DUO rapid test (Inyecta) for IgM, NS1 and IgG at the Instituto de Investigación Nutricional in Lima. Results . The sensitivity of the rapid test was 68.0% for NS1 and IgM, and 86.0% for IgG, improving to 75.0% and 81.0% for NS1 and IgM, respectively, during the first three days. The specificity for all three analytes was greater than 87.0%. The concordance of the results, measured by the Kappa coefficient for the three analytes, was good and no cross-reaction with other arboviruses was found. Conclusions . The SD dengue DUO rapid test allows detection of NS1, IgM and IgG with adequate sensitivity and specificity. Sensitivity for IgM and NS1 increases when detected during the first three days of symptoms. Therefore, we recommend its implementation in primary care centers for early and timely diagnosis.

A SARS-CoV-2 Negative Antigen Rapid Diagnostic in RT-qPCR Positive Samples Correlates With a Low Likelihood of Infectious Viruses in the Nasopharynx.

Severe acute respiratory syndrome-related coronavirus (SARS-CoV-2) transmission occurs even among fully vaccinated individuals; thus, prompt identification of infected patients is central to control viral circulation. Antigen rapid diagnostic tests (Ag-RDTs) are highly specific, but sensitivity is variable. Discordant RT-qPCR vs. Ag-RDT results are reported, raising the question of whether negative Ag-RDT in positive RT-qPCR samples could imply the absence of infectious viruses. To study the relationship between negative Ag-RDT results with virological, molecular, and serological parameters, we selected a cross-sectional and a follow-up dataset and analyzed virus culture, subgenomic RNA quantification, and sequencing to determine infectious viruses and mutations. We demonstrated that RT-qPCR positive while SARS-CoV-2 Ag-RDT negative discordant results correlate with the absence of infectious virus in nasopharyngeal samples. A decrease in sgRNA detection together with an expected increase in detectable anti-S and anti-N IgGs was also verified in these samples. The data clearly demonstrate that a negative Ag-RDT sample is less likely to harbor infectious SARS-CoV-2 and, consequently, has a lower transmissible potential.

Diagnosis and Prevalence of Chagas Disease in an Indigenous Population of Colombia.

Chagas disease (CD) is one of the leading neglected tropical diseases. In the Americas, CD is endemic in about 21 countries, but only less than 1% of the patients have access to medical treatment. Indigenous populations are particularly affected because they live in socio-economic and climate conditions that favor CD infections. In this study, diagnostic strategies and regional prevalence of the Chagas disease were assessed. In nine villages of the indigenous tribe Wiwa, 1134 persons were tested with a Chagas-antibody-specific rapid test (RT), two different Chagas-antibody-specific ELISAs and a Chagas-specific real-time polymerase chain reaction. The overall prevalence of CD in the villages was 35.4%, with a variation from 24.9% to 52.8% for the different communities. Rapid tests and ELISAs showed the same results in all cases. The proportion of replication-active infections, defined by positive PCR results, was 8.7%. In conclusion, the assessed indigenous population in Colombia was shown to be severely affected by CD. For a serological diagnosis, one rapid test was shown to be sufficient. Replacements of ELISAs by RT would decrease costs, increase feasibility and would relevantly help detect positive patients, especially if combined with the applied real-time PCR protocol. Real-time PCR can be considered for the detection of acute cases, outbreaks, chronic cases with re-infection/activation, as well as for therapy management and control.

Development of a Rapid Gold Nanoparticle-Based Lateral Flow Immunoassay for the Detection of Dengue Virus.

Flavivirus detection in humans and mosquito reservoirs has been an important issue since it can cause a variety of illnesses and could represent a health problem in geographical zones where the vector is endemic. In this work, we designed and characterized a biosensor based on gold nanoparticles (AuNPs) and antibody 4G2 for the detection of dengue virus (DENV) in vitro, obtaining different conjugates (with different antibody concentrations). The AuNP-4G2 conjugates at concentrations of 1, 3, and 6 µg/mL presented an increase in the average hydrodynamic diameter compared to the naked AuNPs. Also, as part of the characterization, differences in the UV-Vis absorbance spectrum and electrophoretic migration were observed between the conjugated AuNPs (with BSA or antibody) and naked AuNPs. Additionally, we used this biosensor (AuNP-4G2 conjugate with 3 µg/mL antibody) in the assembly of a competitive lateral flow assay (LFA) for the development of an alternative test to detect the flavivirus envelope protein in isolated DENV samples as a future tool for dengue detection (and other flaviviruses) in the mosquito vector (Aedesaegypti) for the identification of epidemic risk regions. Functionality tests were performed using Dengue virus 2 isolated solution (TCID50/mL = 4.58 × 103) as a positive sample and PBS buffer as a negative control. The results showed that it is possible to detect Dengue virus in vitro with this gold nanoparticle-based lateral flow assay with an estimated detection limit of 5.12 × 102 PFU. We suggest that this biosensor could be used as an additional detection tool by coupling it to different point-of-care tests (POCT) for the easy detection of other flaviviruses.

Analytical Performances of the COVISTIXTM Antigen Rapid Test for SARS-CoV-2 Detection in an Unselected Population (All-Comers).

The performance and validity of the COVISTIXTM rapid antigen test for the detection of SARS-CoV-2 were evaluated in an unselected population. Additionally, we assessed the influence of the Omicron SARS-CoV-2 variant in the performance of this antigen rapid test. Swab samples were collected at two point-of-care facilities in Mexico City from individuals that were probable COVID-19 cases, as they were either symptomatic or asymptomatic persons at risk of infection due to close contact with SARS-CoV-2 positive cases. Detection of the Omicron SARS-CoV-2 variant was performed in 91 positive cases by Illumina sequencing. Specificity and sensitivity of the COVISTIXTM rapid antigen test was 96% (CI 95% 94-98) and 81% (CI 95% 76-85), respectively. The accuracy parameters were not affected in samples collected after 7 days of symptom onset, and it was possible to detect almost 65% of samples with a Ct-value between 30 and 34. The COVISTIXTM antigen rapid test is highly sensitive (93%; CI 95% 88-98) and specific (98%; CI 95% 97-99) for detecting Omicron SARS-CoV-2 variant carriers. The COVISTIXTM rapid antigen test is adequate for examining asymptomatic and symptomatic individuals, including those who have passed the peak of viral shedding, as well as carriers of the highly prevalent Omicron SARS-CoV-2 variant.

Performance of rapid test for antibodies to hepatitis C virus (anti-HCV) in hemodialysis patients and kidney transplant recipients.

Rapid tests (RT) have been widely used for screening of hepatitis C virus (HCV) in general population, but its performance in hemodialysis (HD) patients and mainly in kidney-transplant recipients (RTx) is less known. The aim of this study was to evaluate the accuracy of RT for detection of anti-HCV in HD and RTx patients. Patients were prospectively included subdivided in four groups according to the positivity for anti-HCV detected by conventional serology: (1) HD patients anti-HCV +, (2) HD patients anti-HCV -, (3) RTx patients anti-HCV +, and (4) RTx patients anti-HCV -. All patients were retested for HCV using the commercial kit Alere HCV® Bioeasy Rapid Test (Bioeasy Diagnóstica LTDA-Minas Gerais, Brazil) in capillary whole blood samples. During the period of study were included 46 HD patients anti-HCV+, 62 HD patients anti-HCV -, 53 RTx patients anti-HCV + and 56 RTx patients anti-HCV -. In patients on HD, the RT showed sensitivity (S), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy of 100%. In RTx patients, S of 96%, SP of 100%, PPV of 100% and NPV of 97% were found (accuracy of 98%). In conclusion, in patients on HD there was 100% agreement between RT and the conventional immunoassay. In the RTx group, although the agreement was not 100%, the RT performed very well when compared to conventional serology. This study demonstrates that the RT can be an alternative to conventional serology in HCV screening of patients on HD and RTx.

Evaluation of the Panbio COVID-19 Antigen Rapid Diagnostic Test in Subjects Infected with Omicron Using Different Specimens.

Community testing is a crucial tool for the early identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and transmission control. The emergence of the highly mutated Omicron variant (B.1.1.529) raised concerns about its primary site of replication, impacting sample collection and its detectability by rapid antigen tests. We tested the performance of the Panbio antigen rapid diagnostic test (Ag-RDT) using nasal and oral specimens for COVID-19 diagnosis in 192 symptomatic individuals, with quantitative reverse transcription-PCR (RT-qPCR) of nasopharyngeal samples as a control. Variant of concern (VOC) investigation was performed with the 4Plex SARS-CoV-2 screening kit. The SARS-CoV-2 positivity rate was 66.2%, with 99% of the positive samples showing an amplification profile consistent with that of the Omicron variant. Nasal Ag-RDT showed higher sensitivity (89%) than oral (12.6%) Ag-RDT. Our data showed good performance of the Ag-RDT in a pandemic scenario dominated by the Omicron VOC. Furthermore, our data also demonstrated that the Panbio COVID-19 antigen rapid diagnostic test does not provide good sensitivity with oral swabs for Omicron Ag-RDT detection. IMPORTANCE This study showed that the antigen rapid test for COVID19 worked fine using nasal swabs when it was utilized in patients infected with the Omicron variant, showing a concordance with PCR in 93% of patients tested. The nasal swab yielded more reliable results than the oral swab when an antigen rapid diagnosis test (the Panbio COVID-19 antigen rapid diagnostic test) was used in patients infected with the Omicron variant.

Diagnostic Performance of Seven Commercial COVID-19 Serology Tests Available in South America.

BACKGROUND: Although RT-qPCR remains the gold-standard for COVID-19 diagnosis, anti-SARS-CoV-2 serology-based assays have been widely used during 2020 as an alternative for individual and mass testing, and are currently used for seroprevalence studies. OBJECTIVE: To study the clinical performance of seven commercial serological tests for COVID-19 diagnosis available in South America. METHODS: We conducted a blind evaluation of five lateral-flow immunoassays (LFIA) and two enzyme-linked immunosorbent assays (ELISAs) for detecting anti-SARS-CoV-2 antibodies. RESULTS: We found no statistically significant differences among ELISA kits and LFIAs for anti-SARS-CoV-2 IgG sensitivity (values ranging from 76.4% to 83.5%) and specificity (100% for the seven serological assays). For anti-SARS-CoV-2 IgM, the five LFIAs have a significantly higher sensitivity for samples collected 15 days after the first time RT-qPCR positive test, with values ranging from 47.1% to 88.2%; moreover, the specificity varied from 85% to 100%, but the only LFIA brand with a 100% specificity had the lowest sensitivity. CONCLUSION: The diagnostic performance of the seven serological tests was acceptable for the seven brands tested for anti-SARS-CoV-2 IgG detection for seroprevalence screening purposes. On the other hand, our results show the lack of accuracy of anti-SARS-CoV-2 IgM detection in LFIAs as a tool for SARS-CoV-2 acute-phase infection diagnosis.

Visceral leishmaniasis in a recent transmission region: 27.4% infectivity rate among seronegative dogs.

American visceral leishmaniasis (VL) is a parasitic disease whose main domestic reservoir in the urban environment is dog and is considered one of the most important zoonoses in the context of public health. Serological tests are typically used for the diagnostic screening of the disease. This study aimed to analyse the performance of different methodologies used in the diagnosis of VL in dogs sampled from a recent transmission area. The sample consisted of 52 dogs separated into groups based on the absence and presence of clinical signs of VL. The following serological techniques were carried out: the DPP® rapid test (RT), the ALERE® RT and an RT and immunoenzymatic assay with a recently developed protein (rKDDR-plus). In addition, molecular techniques were carried out with conjunctival swabs, and bone marrow aspirate samples and parasitological samples were obtained directly from bone marrow aspirates. It was concluded that 27.4% of seronegative dogs were infected, but the serological tests, used as screening tests, showed unsatisfactory sensitivity results (average: 51.2%) for dogs without clinical signs. It was suggested that polymerase chain reaction with conjunctival swabbing be used as a screening test for dogs without clinical signs, as this is a non-invasive collection technique with high-sensitivity values.

Chagas Immunochromatographic Rapid Test in the Serological Diagnosis of Trypanosoma cruzi Infection in Wild and Domestic Canids.

Canis lupus familiaris (domestic dog) represents a reliable sentinel for the occurrence of a well-established transmission cycle of Trypanosoma cruzi among wild mammals in the surroundings and, consequently, where the risk of human infection exists. Serological diagnosis is the chosen method to identify T. cruzi infection in dogs that, in Brazil, rarely present positive parasitological tests. The use of recombinant chimeric parasitic antigens results in a sensitive and specific serological diagnostic test in contrast to the use of crude T. cruzi antigens. Our objective was to evaluate the Chagas/Bio-Manguinhos Lateral Flow Immunochromatographic Rapid Test (Chagas-LFRT) for the diagnosis of T. cruzi infection in domestic dogs and the potential of application of this diagnostic platform to wild canid species. Two recombinant proteins (IBMP-8.1 and IBMP-8.4) that displayed the best performance in the enzyme immunoassay (ELISA) in previous studies were tested in a platform with two diagnostic bands. A panel of 281 dog serum samples was evaluated: 133 positive for T. cruzi by serological diagnosis, including 20 samples with positive blood cultures belonging to different discrete typing units (DTUs); 129 negative samples; and 19 samples from dogs infected by other trypanosomatids: Leishmania infantum, Trypanosoma rangeli, Trypanosoma caninum and Crithidia mellificae, in addition to samples infected by Anaplasma platys, Dirofilaria immitis and Erlichia sp. that were employed to evaluate eventual cross-reactions. We also evaluated the Chagas-LFRT to detect T. cruzi infection in 9 serum samples from six wild canid species. We observed that the intensity pattern of the bands was directly proportional to the serological titer observed in IFAT. The sensitivity was 94%, the specificity was 91% according to the ROC curve, and the defined cutoff was an optical density of 4.8. The agreement obtained was considered substantial by the kappa analysis (84%). From T. cruzi positive hemoculture samples, 88.9% were positive by Chagas-LFRT. The test was efficient in recognizing infections by five of the six T. cruzi DTUs. Cross-reactions were not observed in infections by L. infantum, T. rangeli, T. caninum and D. immitis; however, they were observed in sera of dogs infected by Crithidia mellificae, Anaplasma sp. and Erlichia sp. A strong reaction was observed when serum samples from wild canids were submitted to the Protein A affinity test, confirming its applicability for these species. This test will allow rapid preventive actions in areas with high risk to the emergence of Chagas disease in a safer, reliable, low-cost and immediate manner, without the need for more complex laboratory tests.

Covid-19 rapid test by combining a Random Forest-based web system and blood tests.

The disease caused by the new type of coronavirus, Covid-19, has posed major public health challenges for many countries. With its rapid spread, since the beginning of the outbreak in December 2019, the disease transmitted by SARS-CoV-2 has already caused over 2 million deaths to date. In this work, we propose a web solution, called Heg.IA, to optimize the diagnosis of Covid-19 through the use of artificial intelligence. Our system aims to support decision-making regarding to diagnosis of Covid-19 and to the indication of hospitalization on regular ward, semi-ICU or ICU based on decision a Random Forest architecture with 90 trees. The main idea is that healthcare professionals can insert 41 hematological parameters from common blood tests and arterial gasometry into the system. Then, Heg.IA will provide a diagnostic report. The system reached good results for both Covid-19 diagnosis and to recommend hospitalization. For the first scenario we found average results of accuracy of 92.891%±0.851, kappa index of 0.858 ± 0.017, sensitivity of 0.936 ± 0.011, precision of 0.923 ± 0.011, specificity of 0.921 ± 0.012 and area under ROC of 0.984 ± 0.003. As for the indication of hospitalization, we achieved excellent performance of accuracies above 99% and more than 0.99 for the other metrics in all situations. By using a computationally simple method, based on the classical decision trees, we were able to achieve high diagnosis performance. Heg.IA system may be a way to overcome the testing unavailability in the context of Covid-19.Communicated by Ramaswamy H. Sarma.

Technical performance of a lateral flow immunoassay for detection of anti-SARS-CoV-2 IgG in the outpatient follow-up of non-severe cases and at different times after vaccination: comparison with enzyme and chemiluminescent immunoassays

ABSTRACT This study assessed the technical performance of a rapid lateral flow immunochromatographic assay (LFIA) for the detection of anti-SARS-CoV-2 IgG and compared LFIA results with chemiluminescent immunoassay (CLIA) results and an in-house enzyme immunoassay (EIA). To this end, a total of 216 whole blood or serum samples from three groups were analyzed: the first group was composed of 68 true negative cases corresponding to blood bank donors, healthy young volunteers, and eight pediatric patients diagnosed with other coronavirus infections. The serum samples from these participants were obtained and stored in a pre-COVID-19 period, thus they were not expected to have COVID-19. In the second group of true positive cases, we chose to replace natural cases of COVID-19 by 96 participants who were expected to have produced anti-SARS-CoV-2 IgG antibodies 30-60 days after the vaccine booster dose. The serum samples were collected on the same day that LFIA were tested either by EIA or CLIA. The third study group was composed of 52 participants (12 adults and 40 children) who did or did not have anti-SARS-CoV-2 IgG antibodies due to specific clinical scenarios. The 12 adults had been vaccinated more than seven months before LFIA testing, and the 40 children had non-severe COVID-19 diagnosed using RT-PCR during the acute phase of infection. They were referred for outpatient follow-up and during this period the serum samples were collected and tested by CLIA and LFIA. All tests were performed by the same healthcare operator and there was no variation of LFIA results when tests were performed on finger prick whole blood or serum samples, so that results were grouped for analysis. LFIA's sensitivity in detecting anti-SARS-CoV-2 IgG antibodies was 90%, specificity 97.6%, efficiency 93%, PPV 98.3%, NPV 86.6%, and likelihood ratio for a positive or a negative result were 37.5 and 0.01 respectively. There was a good agreement (Kappa index of 0.677) between LFIA results and serological (EIA or CLIA) results. In conclusion, LFIA analyzed in this study showed a good technical performance and agreement with reference serological assays (EIA or CLIA), therefore it can be recommended for use in the outpatient follow-up of non-severe cases of COVID-19 and to assess anti-SARS-CoV-2 IgG antibody production induced by vaccination and the antibodies decrease over time. However, LFIAs should be confirmed by using reference serological assays whenever possible.

O impacto do GeneXpert® MTB/Rif na detecção da tuberculose e seu padrão espacial em Ribeirão Preto-SP / The impact of GeneXpert® MTB/Rif in the detection of tuberculosis and its spatial pattern in Ribeirão Preto-SP

INTRODUÇÃO: Em 2010 a OMS autorizou o uso do sistema GeneXpert® MTB/RIF para a realização do Teste Rápido Molecular para TB (TRM-TB). Objetivou-se-se analisar o impacto do GeneXpert® MTB/RIF na detecção da TB e da TB multidroga-resistente e seu padrão de distribuição espacial em Ribeirão Preto-SP. MÉTODOS: Estudo ecológico realizado em Ribeirão Preto-SP. A população do estudo foi composta de casos de TB notificados no Sistema de Controle de Pacientes com Tuberculose (TBWeb) no período de 2006 a 2017. A análise descritiva dos casos foi realizada por meio de estatística descritiva dos parâmetros quantitativos através do software IBM SPS Statistics versão 25. Para classificar a tendência temporal e observar o impacto da implementação do TRM-TB, foram utilizadas as metodologias Prais-Winsten e Série Temporal Interrompida (STI) através do software StataSE versão 14 e também a modelagem ARIMA com a finalidade de obter uma previsão da taxa de TB para os próximos anos através do software RStudio. Para identificar os padrões espaciais da doença no município foram empregadas as técnicas de estimador de densidade de Kernel, G e G* e varredura (puramente espacial, variação nas tendências temporais e espaço-temporal). RESULTADOS: A tendência temporal da TB apresentou decréscimo de 18,1%/ano e de 6,9%/ano para em crianças. O Distrito Norte apresentou decréscimo de 6,67%/ano e o distrito Leste crescimento de 17,5%/ano na incidência de TB. A TB resistente, após a implementação do TRM-TB, apresentou aumento de 0,6% por ano. Na maioria dos anos analisados, a cultura é solicitada para menos da metade dos casos de TB. Foi identificado um aumento no número de solicitações de TMR e estacionariedade nas solicitações de baciloscopia. A maior parte dos casos foi diagnóstica por meio de demanda ambulatorial. Com as análises espaciais utilizadas foi observado que os casos e os aglomerados não se formam de maneira aleatória no espaço, verificando-se que a TB é distribuída desigualmente no município. CONCLUSÃO: Apesar da TB resistente não ser um problema no cenário, o estudo evidenciou um crescimento na sua incidência, o que o coloca em estado de alerta. O uso da análise espacial possibilitou a identificação das áreas prioritárias, colocando-as em evidência para ações de vigilância em saúde. Ressalta-se a importância do uso de ferramentas de análise espacial na identificação de áreas que devem ser priorizadas para o controle da TB, sendo necessária maior atenção aos indivíduos que se enquadram no perfil indicado como "de risco" para a doença

INTRODUCTION: In 2010, the WHO authorized the use of the GeneXpert® MTB/RIF system to perform the Molecular Rapid Test for TB (TRM-TB). The objective was to analyze the impact of GeneXpert® MTB/RIF in the detection of TB and multidrug-resistant TB and its spatial distribution pattern in Ribeirão Preto-SP. METHODS: Ecological study carried out in Ribeirão Preto-SP. The study population consisted of TB cases reported in the Tuberculosis Patient Control System (TBWeb) from 2006 to 2017. Descriptive analysis of cases was performed using descriptive statistics of quantitative parameters through the IBM SPS Statistics software version 25. To classify the temporal trend and observe the impact of the TRM-TB implementation, the Prais-Winsten and Interrupted Time Series (STI) methodologies were used through the StataSE software version 14 and also the ARIMA modeling in order to obtain a prediction of the TB rate for the coming years through RStudio software. To identify the spatial patterns of the disease in the city, the techniques of Kernel density estimator, G and G* and scanning (purely spatial, variation in temporal and spatio-temporal trends) were used. RESULTS: The temporal trend of TB showed a decrease of 18.1%/year and of 6.9%/year for children. The Northern District showed a decrease of 6.67%/year and the East District a growth of 17.5%/year in the incidence of TB. Resistant TB, after the implementation of the TRM-TB, increased by 0.6% per year. In most of the years analyzed, culture is requested for less than half of TB cases. An increase in the number of RMT requests and stationarity in smear microscopy requests was identified. Most cases were diagnosed through outpatient demand. With the spatial analysis used, it was observed that cases and clusters do not form randomly in space, verifying that TB is unevenly distributed in the municipality. CONCLUSION: Although resistant TB is not a problem in the scenario, the study showed an increase in its incidence, which puts it on alert. The use of spatial analysis made it possible to identify priority areas, putting them in evidence for health surveillance actions. We emphasize the importance of using spatial analysis tools to identify areas that should be prioritized for TB control, requiring greater attention to individuals who fit the profile indicated as "at risk" for the disease

O impacto do GeneXpert® MTB/Rif na detecção da tuberculose e seu padrão espacial em Ribeirão Preto-SP / The impact of GeneXpert® MTB/Rif in the detection of tuberculosis and its spatial pattern in Ribeirão Preto-SP

INTRODUÇÃO: Em 2010 a OMS autorizou o uso do sistema GeneXpert® MTB/RIF para a realização do Teste Rápido Molecular para TB (TRM-TB). Objetivou-se-se analisar o impacto do GeneXpert® MTB/RIF na detecção da TB e da TB multidroga-resistente e seu padrão de distribuição espacial em Ribeirão Preto-SP. MÉTODOS: Estudo ecológico realizado em Ribeirão Preto-SP. A população do estudo foi composta de casos de TB notificados no Sistema de Controle de Pacientes com Tuberculose (TBWeb) no período de 2006 a 2017. A análise descritiva dos casos foi realizada por meio de estatística descritiva dos parâmetros quantitativos através do software IBM SPS Statistics versão 25. Para classificar a tendência temporal e observar o impacto da implementação do TRM-TB, foram utilizadas as metodologias Prais-Winsten e Série Temporal Interrompida (STI) através do software StataSE versão 14 e também a modelagem ARIMA com a finalidade de obter uma previsão da taxa de TB para os próximos anos através do software RStudio. Para identificar os padrões espaciais da doença no município foram empregadas as técnicas de estimador de densidade de Kernel, G e G* e varredura (puramente espacial, variação nas tendências temporais e espaço-temporal). RESULTADOS: A tendência temporal da TB apresentou decréscimo de 18,1%/ano e de 6,9%/ano para em crianças. O Distrito Norte apresentou decréscimo de 6,67%/ano e o distrito Leste crescimento de 17,5%/ano na incidência de TB. A TB resistente, após a implementação do TRM-TB, apresentou aumento de 0,6% por ano. Na maioria dos anos analisados, a cultura é solicitada para menos da metade dos casos de TB. Foi identificado um aumento no número de solicitações de TMR e estacionariedade nas solicitações de baciloscopia. A maior parte dos casos foi diagnóstica por meio de demanda ambulatorial. Com as análises espaciais utilizadas foi observado que os casos e os aglomerados não se formam de maneira aleatória no espaço, verificando-se que a TB é distribuída desigualmente no município. CONCLUSÃO: Apesar da TB resistente não ser um problema no cenário, o estudo evidenciou um crescimento na sua incidência, o que o coloca em estado de alerta. O uso da análise espacial possibilitou a identificação das áreas prioritárias, colocando-as em evidência para ações de vigilância em saúde. Ressalta-se a importância do uso de ferramentas de análise espacial na identificação de áreas que devem ser priorizadas para o controle da TB, sendo necessária maior atenção aos indivíduos que se enquadram no perfil indicado como "de risco" para a doença.

INTRODUCTION: In 2010, the WHO authorized the use of the GeneXpert® MTB/RIF system to perform the Molecular Rapid Test for TB (TRM-TB). The objective was to analyze the impact of GeneXpert® MTB/RIF in the detection of TB and multidrug-resistant TB and its spatial distribution pattern in Ribeirão Preto-SP. METHODS: Ecological study carried out in Ribeirão Preto-SP. The study population consisted of TB cases reported in the Tuberculosis Patient Control System (TBWeb) from 2006 to 2017. Descriptive analysis of cases was performed using descriptive statistics of quantitative parameters through the IBM SPS Statistics software version 25. To classify the temporal trend and observe the impact of the TRM-TB implementation, the Prais-Winsten and Interrupted Time Series (STI) methodologies were used through the StataSE software version 14 and also the ARIMA modeling in order to obtain a prediction of the TB rate for the coming years through RStudio software. To identify the spatial patterns of the disease in the city, the techniques of Kernel density estimator, G and G* and scanning (purely spatial, variation in temporal and spatio-temporal trends) were used. RESULTS: The temporal trend of TB showed a decrease of 18.1%/year and of 6.9%/year for children. The Northern District showed a decrease of 6.67%/year and the East District a growth of 17.5%/year in the incidence of TB. Resistant TB, after the implementation of the TRM-TB, increased by 0.6% per year. In most of the years analyzed, culture is requested for less than half of TB cases. An increase in the number of RMT requests and stationarity in smear microscopy requests was identified. Most cases were diagnosed through outpatient demand. With the spatial analysis used, it was observed that cases and clusters do not form randomly in space, verifying that TB is unevenly distributed in the municipality. CONCLUSION: Although resistant TB is not a problem in the scenario, the study showed an increase in its incidence, which puts it on alert. The use of spatial analysis made it possible to identify priority areas, putting them in evidence for health surveillance actions. We emphasize the importance of using spatial analysis tools to identify areas that should be prioritized for TB control, requiring greater attention to individuals who fit the profile indicated as "at risk" for the disease.