RESUMO

Monkeypox virus (MPXV) infection was classified as a public health emergency of international concern by the World Health Organization (WHO) in 2022, being transmitted between humans by large respiratory droplets, in contact with skin lesions, fomites, and sexually. Currently, there are no available accessible and simple-to-use diagnostic tests that accurately detect MPXV antigens for decentralized and frequent testing. Here, we report an electrochemical biosensor to detect MPXV antigens in saliva and plasma samples within 15 min using accessible materials. The electrochemical system was manufactured onto a paper substrate engraved by a CO2 laser machine, modified with gold nanostructures (AuNS) and a monoclonal antibody, enabling sensitive detection of A29 viral protein. The diagnostic test is based on the use of electrochemical impedance spectroscopy (EIS) and can be run by a miniaturized potentiostat connected to a smartphone. The impedimetric biosensing method presented excellent analytical parameters, enabling the detection of A29 glycoprotein in the concentration ranging from 1 × 10-14 to 1 × 10-7 g mL-1, with a limit of detection (LOD) of 3.0 × 10-16 g mL-1. Furthermore, it enabled the detection of MPXV antigens in the concentration ranging from 1 × 10-1 to 1 × 104 PFU mL-1, with an LOD of 7.8 × 10-3 PFU mL-1. Importantly, no cross-reactivity was observed when our device was tested in the presence of other poxvirus and nonpoxvirus strains, indicating the adequate selectivity of our nanobiosensor for MPXV detection. Collectively, the nanobiosensor presents high greenness metrics associated with the use of a reproducible and large-scale fabrication method, an accessible and sustainable paper substrate, and a low volume of sample (2.5 µL), which could facilitate frequent testing of MPXV at point-of-care (POC).

Assuntos

Monkeypox virus , Mpox , Humanos , Limite de Detecção , Proteínas Virais , Antígenos Virais

RESUMO

Laboratory-based case confirmation is an integral part of measles surveillance programmes; however, logistical constraints can delay response. Use of RDTs during initial patient contact could enhance surveillance by real-time case confirmation and accelerating public health response. Here, we evaluate performance of a novel measles IgM RDT and assess accuracy of visual interpretation using a representative collection of 125 sera from the Brazilian measles surveillance programme. RDT results were interpreted visually by a panel of six independent observers, the consensus of three observers and by relative reflectance measurements using an ESEQuant Reader. Compared to the Siemens anti-measles IgM EIA, sensitivity and specificity of the RDT were 94.9% (74/78, 87.4-98.6%) and 95.7% (45/47, 85.5-99.5%) for consensus visual results, and 93.6% (73/78, 85.7-97.9%) and 95.7% (45/47, 85.5-99.5%), for ESEQuant measurement, respectively. Observer agreement, determined by comparison between individuals and visual consensus results, and between individuals and ESEQuant measurements, achieved average kappa scores of 0.97 and 0.93 respectively. The RDT has the sensitivity and specificity required of a field-based test for measles diagnosis, and high kappa scores indicate this can be accomplished accurately by visual interpretation alone. Detailed studies are needed to establish its role within the global measles control programme.

Assuntos

Vírus do Sarampo , Sarampo , Humanos , Brasil/epidemiologia , Testes de Diagnóstico Rápido , Reprodutibilidade dos Testes , Leitura , Imunoglobulina M , Anticorpos Antivirais , Sarampo/diagnóstico , Sarampo/epidemiologia

RESUMO

INTRODUCTION: Tuberculosis (TB) is one of the most prevalent respiratory diseases in the world. In 2020 there were at least 9.9 million new infections, with 1.5 million deaths. Approximately 10% of people infected with Mycobacterium tuberculosis develop the disease during the first 2 to 5 years after infection. In South America, the diagnosis of Latent Tuberculosis Infections (LTBI) continues to be performed through the Mantoux tuberculin skin test (TST). OBJECTIVE: The objective of our study was to compare the sensitivity of a new immunofluorescence IGRA test against a widely available IGRA kit on the market. MATERIAL AND METHOD: Close contact with infectious TB patients, HIV patients, or immunocompromised for another cause were recruited. Two interferon-gamma release assay (IGRA) diagnostic kits were used and compared with TST. RESULTS: 76 patients were recruited, 93.42% were Chilean nationality, and 98.68% of the patients did not have immunosuppression. The sensitivity of the new technique was 88.89%, and the specificity was 92.50% in the study population compared to the IGRA previously used. In the subgroup older than 36 years, the sensitivity was 95.65%, and the specificity was 89.47%. CONCLUSION: IGRA techniques are a new resource in clinical laboratories to make an accurate diagnosis of LTBI in the region of the Americas. In our population, the greatest benefit of this new IGRA would be observed in people over 36 years of age, where the sensitivity of the technique was like that of the currently available test.

RESUMO

BACKGROUND: Panama is one of eight countries in Mesoamerica that aims to eliminate malaria by 2022. Malaria is concentrated in indigenous and remote regions like Guna Yala, a politically autonomous region where access to health services is limited and cases are predominately detected through intermittent active surveillance. To improve routine access to care, a joint effort was made by Guna Yala authorities and the Ministry of Health to pilot a network of community health workers (CHWs) equipped with rapid diagnostic tests and treatment. The impact of this pilot is described. METHODS: Access to care was measured using the proportion of villages targeted by the effort with active CHWs. Epidemiological impact was evaluated through standard surveillance and case management measures. Tests for differences in proportions or rates were used to compare measures prior to (October 2014-September 2016) and during the pilot (October 2016-September 2018). RESULTS: An active CHW was placed in 39 (95%) of 41 target communities. During the pilot, CHWs detected 61% of all reported cases from the region. Test positivity in the population tested by CHWs (22%) was higher than in those tested through active surveillance, both before (3.8%) and during the pilot (2.9%). From the pre-pilot to the pilot period, annual blood examination rates decreased (9.8 per 100 vs. 8.0 per 100), test positivity increased (4.2% to 8.5%, Χ2 = 126.3, p < 0.001) and reported incidence increased (4.1 cases per 1000 to 6.9 cases per 1000 [Incidence Rate Ratio = 1.83, 95% CI 1.52, 2.21]). The percent of cases tested on the day of symptom onset increased from 8 to 27% and those treated on the day of their test increased from 26 to 84%. CONCLUSIONS: The CHW network allowed for replacement of routine active surveillance with strong passive case detection leading to more targeted and timely testing and treatment. The higher test positivity among those tested by CHWs compared to active surveillance suggests that they detected cases in a high-risk population that had not previously benefited from access to diagnosis and treatment. Surveillance data acquired through this CHW network can be used to better target active case detection to populations at highest risk.

Assuntos

Agentes Comunitários de Saúde , Malária , Humanos , Administração de Caso , Malária/diagnóstico , Malária/epidemiologia , Malária/prevenção & controle , Incidência , Panamá/epidemiologia

RESUMO

Introduction: Infection by the hepatitis C virus (HCV) is an important cause of chronic liver disease, considered a public health problem worldwide with high morbidity and mortality due to limited access to diagnostic tests in developing countries. Only a small percentage know their infection status and receive timely treatment. It is critical to make diagnostic tests for HCV infection accessible and to provide timely treatment, which not only reduces the spread of infection but also stops the progression of HCV disease without symptoms. Objective: To determine the prevalence of chronic infection by HCV in patients with risk factors by using rapid tests in Cartagena, Colombia, and describe their epidemiological characteristics. Methodology: A cross-sectional descriptive observational study was carried out on asymptomatic adults with risk factors for HCV infection in the city of Cartagena between December 2017 and November 2019. A rapid immunochromatographic test was performed to detect antibodies, characterizing the population. Results: In total, 1,023 patients were identified who met the inclusion criteria, 58.5% women and 41.4% men, obtaining nine positive results, confirming chronic infection with viral load for HCV, finding seven cases of genotype 1b and two genotype 1a. Conclusion: In our study, a prevalence of hepatitis C infection of 0.9% was found in asymptomatic individuals with risk factors, which allows us to deduce that the active search for cases in risk groups constitutes a pillar for the identification of the disease, the initiation of antiviral therapy, and decreased morbidity and mortality.

RESUMO

BACKGROUND: Early and adequate antibiotic treatment is the cornerstone of improving clinical outcomes in patients with bloodstream infections (BSI). Delays in appropriate antimicrobial therapy have catastrophic consequences for patients with BSI. Microbiological characterization of multi-drug resistant pathogens (MDRP) allows clinicians to provide appropriate treatments. Current microbiologic techniques may take up to 96 h to identify causative pathogens and their resistant patterns. Therefore, there is an important need to develop rapid diagnostic strategies for MDRP. We tested a modified protocol to detect carbapenemase and extended-spectrum ß-lactamase (ESBL) producing Gram-negative bacteria (GNB) from positive blood cultures. METHODS: This is a prospective cohort study of consecutive patients with bacteremia. We developed a modified protocol using the HB&L® system to detect MDRP. The operational characteristics were analyzed for each test (HB&L-ESBL/AmpC® and HB&L-Carbapenemase® kits). The kappa coefficient, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratios (LR) with 95% confidence intervals (CI), and reduction in identification time of this novel method were calculated. RESULTS: Ninety-six patients with BSI were included in the study. A total of 161 positive blood cultures were analyzed. Escherichia coli (50%, 81/161) was the most frequently identified pathogen, followed by Klebsiella pneumoniae (15%, 24/161) and Pseudomonas aeruginosa (8%, 13/161). Thirty-three percent of isolations had usual resistance patterns. However, 34/161 (21%) of identified pathogens were producers of carbapenemases and 21/161 (13%) of extended-spectrum ß-lactamases. Concordance between our HB&L® modified protocol and the traditional method was 99% (159/161). Finally, identification times were significantly shorter using our HB&L®-modified protocol than traditional methods: median (IQR) 19 h (18, 22) vs. 61 h (60, 64), p < 0.001. CONCLUSIONS: Here, we provide novel evidence that using our HB&L®-modified protocol is an effective strategy to reduce the time to detect MDRP producers of carbapenemases or extended-spectrum ß-lactamases, with an excellent concordance rate when compared to the gold standard. Further studies are needed to confirm these findings and to determine whether this method may improve clinical outcomes.

RESUMO

We documented the outcome of an over 10-year (2011-2021) effort to diagnose acute and early HIV infections (AEHI) in an Infectious Diseases Outpatient Clinic with limited resources. Of a total of 132, 119 HIV-RNA tests were performed from 2017 to 2020, 12 cases were identified, using a simple algorithm: risk exposure of 6 weeks or less before the visit and/or symptoms compatible with acute retroviral syndrome 7-30 days after exposure and/or undetermined 3rd generation rapid diagnostic test or serology. AEHI diagnoses varied from 2.4% among asymptomatic to 25% for undetermined serology cases using this simple screening applicable to different settings.

Assuntos

Anticorpos Anti-HIV/sangue , Infecções por HIV/diagnóstico , Teste de HIV/métodos , HIV/imunologia , RNA Viral/sangue , Doença Aguda , Algoritmos , Brasil , Países em Desenvolvimento , Diagnóstico Precoce , Feminino , Humanos , Masculino , Fatores de Tempo , Carga Viral

RESUMO

Early diagnosis and treatment are fundamental to the control and elimination of malaria. In many endemic areas, routine diagnosis is primarily performed microscopically, although rapid diagnostic tests (RDTs) provide a useful point-of-care tool. Most of the commercially available RDTs detect histidine-rich protein 2 (HRP2) of Plasmodium falciparum in the blood of infected individuals. Nonetheless, parasite isolates lacking the pfhrp2 gene are relatively frequent in some endemic regions, thereby hampering the diagnosis of malaria using HRP2-based RDTs. To track the efficacy of RDTs in areas of the Brazilian Amazon, we assessed pfhrp2 deletions in 132 P. falciparum samples collected from four malaria-endemic states in Brazil. Our findings show low to moderate levels of pfhrp2 deletion in different regions of the Brazilian Amazon. Overall, during the period covered by this study (2002-2020), we found that 10% of the P. falciparum isolates were characterized by a pfhrp2 deletion. Notably, however, the presence of pfhrp2-negative isolates has not been translated into a reduction in RDT efficacy, which in part may be explained by the presence of polyclonal infections. A further important finding was the discrepancy in the proportion of pfhrp2 deletions detected using two assessed protocols (conventional PCR versus nested PCR), which reinforces the need to perform a carefully planned laboratory workflow to assess gene deletion. This is the first study to perform a comprehensive analysis of PfHRP2 sequence diversity in Brazilian isolates of P. falciparum. We identified 10 PfHRP2 sequence patterns, which were found to be exclusive of each of the assessed regions. Despite the small number of PfHRP2 sequences available from South America, we found that the PfHRP2 sequences identified in Brazil and neighboring French Guiana show similar sequence patterns. Our findings highlight the importance of continuously monitoring the occurrence and spread of parasites with pfrhp2 deletions, while also taking into account the limitations of PCR-based testing methods associated with accuracy and the complexity of infections.

Assuntos

Malária Falciparum , Plasmodium falciparum , Antígenos de Protozoários/genética , Brasil , Testes Diagnósticos de Rotina , Deleção de Genes , Histidina , Humanos , Malária Falciparum/diagnóstico , Plasmodium falciparum/genética , Proteínas de Protozoários/genética

RESUMO

BACKGROUND: COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global health threat and remains a challenge for modern medicine. Rapid and accurate diagnosis of COVID-19 is vital for proper disease and outbreak management. Our review aimed to analyze scientific articles published in the literature addressing the rapid tests available for COVID-19 diagnosis at the first year of the pandemic. METHODS: A systematic review was performed from October 22 to 27, 2020, searching data published in PubMed and Google Scholar databases, using subject headings or keywords related to point of care and rapid test diagnostic for SARS-CoV-2 and COVID-19. RESULTS: The first survey identified 403 articles, but only 23 met the defined criteria for the systematic analysis. The sensitivity and specificity parameters were assessed in 19 studies, and the data suggested that there was lower sensitivity in the period 1 to 7 days after the emergence of symptoms (∼38%) higher sensitivity at 8 to 14 days (∼90%), and the highest at 15 to 39 days (∼98%). Accuracy was reported in six studies, reporting values above 50%. Only three studies reported a possible cross-reaction. CONCLUSIONS: Our findings indicate that the rapid tests used in the first year of the pandemic were tested with a small number of samples and not adequately validated. And the studies that described them were conducted with little scientific rigor.

Assuntos

Antígenos Virais/análise , Teste para COVID-19/normas , COVID-19/diagnóstico , Reações Cruzadas , Humanos , Pandemias , Testes Imediatos/normas , Sensibilidade e Especificidade

RESUMO

BACKGROUND: Real-Time Reverse-Transcription Polymerase Chain Reaction (RT-PCR) is currently the only recommended diagnostic method for SARS-CoV-2. However, rapid immunoassays for SARS-CoV-2 antigen could significantly reduce the COVID-19 burden currently weighing on laboratories around the world. METHODS: We evaluated the performance of two rapid fluorescence immunoassays (FIAs), SOFIA SARS Antigen FIA (Quidel Corporation, San Diego, CA, USA) and STANDARD F COVID-19 Ag FIA (SD Biosensor Inc., Gyeonggi-do, Republic of Korea), which use an automated reader. The study used 64 RT-PCR characterized clinical samples (32 positive; 32 negative), which consisted of nasopharyngeal swabs in universal transport medium. RESULTS: Of the 32 positive specimens, all from patients within 5 days of symptom onset, the Quidel and SD Biosensor assays detected 30 (93.8%) and 29 (90.6%) samples, respectively. Among the 27 samples with high viral loads (Ct ≤ 25), the two tests had a sensitivity of 100%. Specificity was 96.9% for both kits. CONCLUSION: The high performance of the evaluated FIAs indicates a potential use as rapid and PCR-independent tools for COVID-19 diagnosis in early stages of infection. The excellent sensitivity to detect cases with viral loads above ~106 copies/mL (Ct values ≤ 25), the estimated threshold of contagiousness, suggests that the assays might serve to rapidly identify infective individuals.

RESUMO

BACKGROUND: In low transmission settings early diagnosis is the main strategy to reduce adverse outcomes of malaria in pregnancy; however, microscopy and rapid diagnostic tests (RDTs) are inadequate for detecting low-density infections. We studied the performance of the highly sensitive-RDT (hsRDT) and the loop mediated isothermal DNA amplification (LAMP) for the detection of P. falciparum in pregnant women. METHODS: A cross-sectional study was conducted in two malaria-endemic municipalities in Colombia. We screened pregnant women in the context of an antenatal care program in health facilities and evaluated five tests (microscopy, conventional RDT, hsRDT, LAMP and nested polymerase chain reaction-PCR) for the detection of P. falciparum in peripheral blood, using a quantitative reverse transcription PCR (qRT-PCR) as the reference standard. Diagnostic performance of hsRDT and LAMP were compared with routine testing. RESULTS: The prevalence of P. falciparum was 4.5% by qRT-PCR, half of those infections were subpatent. The sensitivity of the hsRDT (64.1%) was slightly better compared to microscopy and cRDT (59 and 53.8% respectively). LAMP had the highest sensitivity (89.7%) for detecting P. falciparum and the ability to detect very low-density infections (minimum parasite density detected 0.08 p/µL). CONCLUSIONS: There is an underestimation of Plasmodium spp. infections by tests routinely used in pregnant women attending antenatal care visits. LAMP methodology can be successfully implemented at local hospitals in malaria-endemic areas. The relevance of detecting and treating this sub-patent P. falciparum infections in pregnant women should be evaluated. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier: NCT03172221 , Date of registration: May 29, 2017.

Assuntos

Malária Falciparum/diagnóstico , Técnicas de Amplificação de Ácido Nucleico/métodos , Técnicas de Amplificação de Ácido Nucleico/normas , Plasmodium falciparum/isolamento & purificação , Complicações Parasitárias na Gravidez/diagnóstico , Adulto , Colômbia/epidemiologia , Estudos Transversais , Feminino , Humanos , Malária Falciparum/epidemiologia , Técnicas de Diagnóstico Molecular , Gravidez , Complicações Parasitárias na Gravidez/epidemiologia , Cuidado Pré-Natal , Reação em Cadeia da Polimerase em Tempo Real/métodos , Sensibilidade e Especificidade , Adulto Jovem

RESUMO

El uso de Plasma de Convaleciente de COVID-19 (PC-CoV19) como coadyuvante en el tratamiento de pacientes, tendría impacto socioeconómico importante al disminuir el periodo de estancia hospitalaria y letalidad por la enfermedad. La determinación de anticuerpos en plasma de potenciales donantes es criterio fundamental para su selección. Existe dificultad para disponer de pruebas serológicas certificadas que cuantifiquen anticuerpos específicos contra SARS-CoV-2. Las Pruebas de Diagnóstico Rápido (PDR) se convierten en herramienta útil y al alcance para la selección de pacientes recuperados, potenciales donantes de PC-CoV19. Este estudio evaluó el porcentaje de positividad de diferentes PDR en veintidós (22) muestras de pacientes con COVID-19 confirmada por RT-PCR. Las muestras se analizaron siguiendo el procedimiento descrito por cada fabricante. Se analizó el comportamiento de las PDR en pacientes sintomáticos y asintomáticos en diferentes momentos de la enfermedad. El porcentaje de positividad fue de 100% con dos de las tres pruebas utilizadas, una de las cuales discrimina IgM de IgG. Se concluye que la presencia de IgG se registra a partir de los 15 días del inicio de los síntomas y se mantiene presente a los 59 días de evolución en los pacientes sintomáticos, y que pacientes asintomáticos podrían ser considerados candidatos a donantes de PC-CoV19 pues se evidenció seroconversión para IgG. El porcentaje de positividad a IgG podría disminuir en los pacientes recuperados. Se sugiere que pacientes sintomáticos con criterio de alta médica sean considerados candidatos donantes en momento posterior a 28 días de la fecha de inicio de los síntomas. Se recomienda utilizar PDR que discriminen IgM de IgG como herramienta para la selección de donantes de PC-CoV19(AU)

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The use of COVID-19 Convales-cent Plasma (PC-CoV19) as an ad-juvant for the treatment of patients, would have a significant socioeconomic impact by reducing the leng-th of hospital stay and lethality due to the disease. The determination of antibodies in plasma from potential donors is a fundamental criterion for their selection. There is dificulty in obtaining certified serological tests that quantify specific antibodies against SARS-CoV-2. Rapid Diagnostic Tests (PDR) become a useful and accessible tool in the selection of recovered patients, potential PC-CoV19 donors. This study evaluated the positivity rate of different PDRs in twenty two (22) samples from patients with COVID-19 confirmed by RT-PCR. The samples were analyzed following the procedure described by each manufacturer. The performance of PDRs was analyzed in symptomatic and asymptomatic patients at different times of the disease. The positivity rate was 100% with two of the three tests used, one of which discriminates IgM from IgG. It is concluded that the presence of IgG is recorded 15 days after the onset of symptoms and remains present at day 59 of evolution in symptomatic patients, and that asymptomatic patients could be considered candidates for PC-CoV19 donors since IgG se-reconversion was evident. The positivity rate to IgG could decrease in the recovered patients. It is suggested that symptomatic patients with medical discharge criteria be considered donor candidates after 28 days from the date of onset of symptoms. It is recommended to use PDRs that discriminate IgM from IgG as a tool for the selection of PC-CoV19 donors

Assuntos

Humanos , Plasma , Doadores de Tecidos , Imunoglobulina G/uso terapêutico , Imunoglobulina M , Testes Sorológicos , Infecções por Coronavirus , Testes Diagnósticos de Rotina

RESUMO

BACKGROUND: Malaria diagnostics by rapid diagnostic test (RDT) relies primarily on the qualitative detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) and Plasmodium spp lactate dehydrogenase (pLDH). As novel RDTs with increased sensitivity are being developed and implemented as point of care diagnostics, highly sensitive laboratory-based assays are needed for evaluating RDT performance. Here, a quantitative suspension array technology (qSAT) was developed, validated and applied for the simultaneous detection of PfHRP2 and pLDH in a variety of biological samples (whole blood, plasma and dried blood spots) from individuals living in different endemic countries. RESULTS: The qSAT was specific for the target antigens, with analytical ranges of 6.8 to 762.8 pg/ml for PfHRP2 and 78.1 to 17076.6 pg/ml for P. falciparum LDH (Pf-LDH). The assay detected Plasmodium vivax LDH (Pv-LDH) at a lower sensitivity than Pf-LDH (analytical range of 1093.20 to 187288.5 pg/ml). Both PfHRP2 and pLDH levels determined using the qSAT showed to positively correlate with parasite densities determined by quantitative PCR (Spearman r = 0.59 and 0.75, respectively) as well as microscopy (Spearman r = 0.40 and 0.75, respectively), suggesting the assay to be a good predictor of parasite density. CONCLUSION: This immunoassay can be used as a reference test for the detection and quantification of PfHRP2 and pLDH, and could serve for external validation of RDT performance, to determine antigen persistence after parasite clearance, as well as a complementary tool to assess malaria burden in endemic settings.

Assuntos

Antígenos de Protozoários/sangue , L-Lactato Desidrogenase/sangue , Malária Falciparum/diagnóstico , Malária Vivax/diagnóstico , Proteínas de Protozoários/sangue , Adolescente , Adulto , África , Animais , Biotina , Calibragem , Criança , Estudos Transversais , Feminino , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Malária Falciparum/sangue , Malária Vivax/sangue , Camundongos , Microesferas , Parasitemia/sangue , Parasitemia/diagnóstico , Gravidez , Reação em Cadeia da Polimerase em Tempo Real , América do Sul , Espanha , Adulto Jovem

RESUMO

Accurate malaria diagnosis is foundational for control and elimination, and Haiti relies on histidine-rich protein 2 (HRP2)-based rapid diagnostic tests (RDTs) identifying Plasmodium falciparum in clinical and community settings. In 2017, 1 household and 2 easy-access group surveys tested all participants (N = 32 506) by conventional and high-sensitivity RDTs. A subset of blood samples (n = 1154) was laboratory tested for HRP2 by bead-based immunoassay and for P. falciparum 18S rDNA by photo-induced electron transfer polymerase chain reaction. Both RDT types detected low concentrations of HRP2 with sensitivity estimates between 2.6 ng/mL and 14.6 ng/mL. Compared to the predicate HRP2 laboratory assay, RDT sensitivity ranged from 86.3% to 96.0% between tests and settings, and specificity from 90.0% to 99.6%. In the household survey, the high-sensitivity RDT provided a significantly higher number of positive tests, but this represented a very small proportion (<0.2%) of all participants. These data show that a high-sensitivity RDT may have limited utility in a malaria elimination setting like Haiti.

Assuntos

Testes Diagnósticos de Rotina/métodos , Malária Falciparum/diagnóstico , Malária Falciparum/transmissão , Plasmodium falciparum/genética , Plasmodium falciparum/imunologia , Adolescente , Antígenos de Protozoários/sangue , Antígenos de Protozoários/imunologia , Criança , Pré-Escolar , DNA de Protozoário/sangue , DNA de Protozoário/genética , DNA Ribossômico/sangue , DNA Ribossômico/genética , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Haiti/epidemiologia , Humanos , Lactente , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Masculino , Reação em Cadeia da Polimerase/métodos , Proteínas de Protozoários/sangue , Proteínas de Protozoários/imunologia , Sensibilidade e Especificidade

RESUMO

BACKGROUND: There is limited data regarding the use of emergency departments (EDs) for infectious disease screening and vaccination in resource-limited regions. In these settings, EDs are often the only contact that patients have with the healthcare system, turning an ED visit into an opportune time to deliver preventative health services. METHODS: In this pilot study, patients that met inclusion criteria were prospectively tested for hepatitis B surface antigen test (HBsAg). Previously unvaccinated patients who tested negative for HBsAg were offered HBV vaccination. The study setting was a public infectious disease hospital in Cordoba, Argentina. The primary outcomes were new HBV diagnoses, as well as vaccination completion between screening modalities (Point-of-Care-Testing-POCT vs. laboratory testing) and same vs. different day vaccination. RESULTS: We screened 100 patients for HBV (75 POCT & 25 laboratory). The median age of participants was 35 years (IQR 24-52) and 55% were male. No patients tested positive for HBsAg. All patients who completed first dose vaccination were initially screened with the POCT. No patients screened with laboratory testing returned for vaccination. Patients who were scheduled for vaccination the same day were more likely to complete vaccination compared to those scheduled for another day (75% vs. 14%, p < .001). CONCLUSION: Our study supports the use of HBV POCTs in the ED in conjunction with vaccination of HBV-negative individuals. In regions with low HBV endemicity, direct vaccination without HBsAg testing may be more cost effective. We believe that this acute-care screening model is applicable to other resource-limited settings.

Assuntos

Serviço Hospitalar de Emergência , Vacinas contra Hepatite B/uso terapêutico , Hepatite B/prevenção & controle , Programas de Rastreamento/métodos , Vacinação/estatística & dados numéricos , Adulto , Argentina , Feminino , Antígenos de Superfície da Hepatite B/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Testes Imediatos , Estudos Prospectivos , Testes Sorológicos , Adulto Jovem

RESUMO

BACKGROUND: The Plasmodium falciparum parasite is the only human malaria that produces the histidine-rich protein 2 and 3 (HRP2/3) antigens. Currently, HRP2/3 are widely used in malaria rapid diagnostic tests (RDTs), but several global reports have recently emerged showing genetic deletion of one or both of these antigens in parasites. Deletion of these antigens could pose a major concern for P. falciparum diagnosis in Haiti which currently uses RDTs based solely on the detection of the HRP2/3 antigens. METHODS: From September 2012 through February 2014, dried blood spots (DBS) were collected in Haiti from 9317 febrile patients presenting to 17 health facilities in 5 departments throughout the country as part of a bed net intervention study. All DBS from RDT positive persons and a random sampling of DBS from RDT negative persons were assayed for P. falciparum DNA by nested and PET-PCR (n = 2695 total). All PCR positive samples (n = 331) and a subset of PCR negative samples (n = 95) were assayed for three malaria antigens by a multiplex bead assay: pan-Plasmodium aldolase (pAldo), pan-Plasmodium lactate dehydrogenase (pLDH), and HRP2/3. Any samples positive for P. falciparum DNA, but negative for HRP2/3 antigens were tested by nested PCR for Pfhrp2 and Pfhrp3 gene deletions. RESULTS: Of 2695 DBS tested for Plasmodium DNA, 345 (12.8%) were originally found to be positive for P. falciparum DNA; 331 of these had DBS available for antigen detection. Of these, 266 (80.4%) were positive for pAldo, 221 (66.8%) positive for pLDH, and 324 (97.9%) were positive for HRP2/3 antigens. Seven samples (2.1%) positive for P. falciparum DNA were not positive for any of the three antigens by the bead assay, and were investigated for potential Pfhrp2/3 gene deletion by PCR. These samples either successfully amplified Pfhrp2/3 genes or were at an estimated parasite density too low for sufficient DNA to perform successful genotyping. CONCLUSIONS: Malaria positive samples in multiple Haitian sites were found to contain the HRP2/3 antigens, and no evidence was found of Pfhrp2/3 deletions. Malaria RDTs based on the detection of the HRP2/3 antigens remain a reliable P. falciparum diagnostic tool as Haiti works towards malaria elimination.

Assuntos

Antígenos de Protozoários/genética , Sequência de Bases , Testes Diagnósticos de Rotina/métodos , Reação em Cadeia da Polimerase/métodos , Proteínas de Protozoários/genética , Deleção de Sequência , Adolescente , Adulto , Criança , Testes Diagnósticos de Rotina/instrumentação , Haiti , Humanos , Pessoa de Meia-Idade , Plasmodium falciparum/genética , Adulto Jovem

RESUMO

BACKGROUND: Trypanosoma cruzi, the protozoan agent of Chagas disease, is comprised of at least 6 genetic lineages (TcI-TcVI). Their geographical distribution, clinical associations and reservoir hosts are not fully elucidated, as genotyping is hampered due to the difficulty in isolating representative populations of organisms. Lineage-specific serological techniques may address these issues. METHODS: Trypanosoma cruzi lineage-specific serological assays were performed on human, canine, feline and armadillo sera from the Gran Chaco in northern Argentina, a region of ongoing transmission. Synthetic peptides representing lineage-specific epitopes of the trypomastigote small surface antigen (TSSA) were used in ELISA, and the TcII/V/VI shared epitope peptide (TSSApep-II/V/VI) was used in the Chagas Sero K-SeT rapid diagnostic test (RDT). RESULTS: Chagas Sero K-SeT RDT, using Protein G to detect human and canine IgG, was at least as sensitive as TSSApep-II/V/VI ELISA using specific secondary antibodies. For sera from humans TSSApep-II/V/VI seroprevalence by Chagas Sero K-SeT was 273/393 (69.5%), for dogs 48/73 (65.8%) and for armadillos 1/7 (14.3%); by ELISA for cats 5/19 (26.3%). The seroprevalence for humans was similar to that for Bolivian patients, amongst whom we previously observed an association of TSSApep-II/V/VI seropositivity with severity of cardiomyopathy. In humans, prevalence of TSSApep-II/V/VI recognition was associated with locality, and with increasing and decreasing age within the Qom and Creole populations, respectively. For dogs TSSApep-II/V/VI recognition was associated with being born before community-wide insecticide spraying (P = 0.05) and with Qom household (P < 0.001). CONCLUSIONS: We show here that Chagas Sero K-SeT RDT can replace ELISA for TSSApep-II/V/VI serology of humans and dogs; for humans there were statistically significant associations between a positive Chagas Sero K-SeT RDT and being resident in Area IV, and for dogs association with Qom household or with being born before the mass spraying campaign; we also show that with cats the TcII/V/VI epitope can be detected by ELISA. We assessed the lineage distribution in an unprecedented 83% of the human T. cruzi-seropositive population. These results form the basis for more detailed studies, enabling rapid in-the-field surveillance of the distribution and clustering of these lineages among humans and mammalian reservoirs of T. cruzi infection.

Assuntos

Anticorpos Antiprotozoários/sangue , Doença de Chagas/epidemiologia , Doença de Chagas/veterinária , Testes Diagnósticos de Rotina/métodos , Sorogrupo , Testes Sorológicos/métodos , Trypanosoma cruzi/classificação , Animais , Argentina/epidemiologia , Tatus , Gatos , Doença de Chagas/parasitologia , Estudos Transversais , Cães , Ensaio de Imunoadsorção Enzimática/métodos , Humanos , Estudos Soroepidemiológicos , Trypanosoma cruzi/genética , Trypanosoma cruzi/isolamento & purificação

RESUMO

BACKGROUND: Malaria is an important disease in many tropical countries. Rapid diagnostic tests (RDTs) are valuable tools for diagnosing malaria in remote areas. The majority of RDTs used for the diagnosis of Plasmodium falciparum are based on the detection of the specific histidine-rich proteins (PfHRP2 and PfHRP3). During the last decade, the threat posed by the lack of expression of these antigens and the variability of the proteins on the diagnosis of malaria has been widely discussed. The aim of this study was to evaluate the genetic diversity of pfhrp2 and pfhrp3 of P. falciparum isolates collected in three Central American countries. METHODS: DNA samples were amplified and sequenced to assess the diversity of nucleotides and amino acids. A search for known epitopes within the amino acid sequence was carried out, and the sensitivity of the sequences was evaluated according to a predictive model. A phylogenetic analysis was carried out including homologous sequences from different regions of the world. Protein structures were predicted in silico. RESULTS: Five different patterns for PfHRP2 and one pattern for PfHRP3 were identified. Isolates from Central America show a high level of genetic diversity in pfhrp2; however, the amino acid sequences seem to contain enough motifs to be detected by the RDTs currently available. CONCLUSION: It is unlikely that the variability of the pfhrp2 and pfhrp3 genes has a significant impact on the ability of the RDTs to detect the PfHRP antigens in Central America.

Assuntos

Antígenos de Protozoários/genética , Variação Genética , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Antígenos de Protozoários/química , Testes Diagnósticos de Rotina , Guatemala , Honduras , Nicarágua , Filogenia , Estrutura Terciária de Proteína , Proteínas de Protozoários/química

RESUMO

BACKGROUND: PfHRP2-based rapid diagnostic tests (RDTs), based on the recognition of the Plasmodium falciparum histidine-rich protein 2, are currently the most used tests in malaria detection. Most of the antibodies used in RDTs also detect PfHRP3. However, false-negative results were reported. Significant variation in the pfhrp2 gene could lead to the expression of a modified protein that would no longer be recognized by the antibodies used in PfHRP2-based RDTs. Additionally, parasites lacking the PfHRP2 do not express the protein and are, therefore, not identifiable. AIMS: This review aims to assess the pfhrp2 and pfhrp3 genetic variation or the prevalence of gene deletion in areas where malaria is endemic and describe its implications on RDT use. SOURCES: Publications of interest were identified using PubMed, Google Scholar and Google. CONTENT: More than 18 types of amino acid repeats were identified from the PfHRP2 sequences. Sequencing analysis revealed high-level genetic variation in the pfhrp2 and pfhrp3 genes (>90% of variation in Madagascar, Nigeria or Senegal) both within and between countries. However, genetic variation of PfHRP2 and PfHRP3 does not seem to be a major cause of false-negative results. The countries that showed the highest proportions of pfhrp2-negative parasites were Peru (20%-100%) and Guyana (41%) in South America, Ghana (36%) and Rwanda (23%) in Africa. High prevalence of pfhrp2 deletion causes a high rate of false-negatives results. IMPLICATIONS: Presence of parasites lacking the pfhrp2 gene may pose a major threat to malaria control programmes because P. falciparum-infected individuals are not diagnosed and properly treated.

Assuntos

Antígenos de Protozoários/genética , Testes Diagnósticos de Rotina/métodos , Variação Genética , Malária Falciparum/diagnóstico , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Deleção de Sequência , África , Humanos , Imunoensaio/métodos , Malária Falciparum/parasitologia , Plasmodium falciparum/isolamento & purificação , Prevalência , Sensibilidade e Especificidade , América do Sul

RESUMO

The sensitivity of rapid diagnostic tests (RDT) for Chagas disease is not great enough for their single use. The aim of this paper was to evaluate the performance of two RDTs for Chagas disease, used simultaneously. Two different RDTs (A and B) were performed in 64 and 42 serum samples that were negative and positive, respectively, by conventional serological techniques. Validity and reliability of both tests were evaluated individually and simultaneously. Sensitivity was 90.5% and 97.6%, and specificity was 100% and 93.8%, for RDT A and B, respectively. The κ statistic was 0.96. When both RDTs were used simultaneously, sensitivity was 97.4%, specificity was 100% and the discordance percentage 6.6%. The combined use of two RDTs with serum samples is an acceptable application in healthcare centres.

Assuntos

Doença de Chagas/diagnóstico , Doença de Chagas/sangue , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade