Dengue outbreak update in India: 2022.

Dengue is an emerging illness in India, where it is endemic in some areas and sometimes causes yearly epidemics. Each dengue outbreak starts with high death and morbidity, which has a significant socioeconomic impact. As of September 30, 2022, India had 63,280 dengue cases, according to information provided by the National Centre for Vector Borne Diseases Control. North India is most severely impacted by each outbreak. In Uttar Pradesh, the state with the most population in India, there have been 2060 confirmed cases of dengue and 1 mortality till September 2022 reported. Patients are being reported from semi-urban, rural, and urban areas. It is essential to properly monitor disease cases through disease surveillance in order to ensure prompt case management if dengue outbreak control is to be achieved. An efficient diagnostic approach for early diagnosis is urgently required to reduce the severity of the sickness, the length of the hospital stay, and clinical consequences.

A novel anti-NS2BNS3pro antibody-based indirect ELISA test for the diagnosis of dengue virus infections.

Dengue virus reportedly circulates as four genetically distinct serotypes for which there is no widely accepted vaccine or drug at present. Morbidity and mortality caused by this virus are alarming for the possible increased threat to human health. A suitable diagnostic test is the prerequisite for designing and developing control measures. But, the tests being employed at present possess one or the other drawback for this disease diagnosis. During the dengue virus infections, NS2B is essential for the stability and catalytic activity of the NS3 protease. N-terminal 185 amino acids of NS3 protease domain along with hydrophilic portion of NS2B (NS2BNS3pro) is being used to screen dengue inhibitors but not for diagnosis until now. In the present study, we have used purified NS2BNS3pro as an antigen to trap anti-NS2BNS3pro antibodies of the clinical samples. Antibodies were detected successfully in both Western blot analysis and enzyme-linked immunosorbent assay (ELISA) tests. In ELISA, antibodies were detected in both primary and secondary infections of all serotypes. Interestingly, 17 samples declared as other febrile infections by NS1 and IgM/IgG tests were found to be positive in present test, which were further confirmed by reverse-transcription polymerase chain reaction. In silico studies suggested the absence of conserved epitopes between NS2BNS3pro and the counterpart in JEV, Zika, and CHIKV, indicating less possibility of crossreaction, which was in turn confirmed by using synthetic peptides representing the above epitopes. Statistical analysis with 76% specificity, 87% sensitivity, and 95% concordance also supported the present test as a suitable test for large scale diagnosis of dengue virus infections.

Diagnostic accuracy and utility of three dengue diagnostic tests for the diagnosis of acute dengue infection in Malaysia.

BACKGROUND: Dengue is an emerging infectious disease that infects up to 390 million people yearly. The growing demand of dengue diagnostics especially in low-resource settings gave rise to many rapid diagnostic tests (RDT). This study evaluated the accuracy and utility of ViroTrack Dengue Acute - a new biosensors-based dengue NS1 RDT, SD Bioline Dengue Duo NS1/IgM/IgG combo - a commercially available RDT, and SD Dengue NS1 Ag enzyme-linked immunosorbent assay (ELISA), for the diagnosis of acute dengue infection. METHODS: This prospective cross-sectional study consecutively recruited 494 patients with suspected dengue from a health clinic in Malaysia. Both RDTs were performed onsite. The evaluated ELISA and reference tests were performed in a virology laboratory. The reference tests comprised of a reverse transcription-polymerase chain reaction and three ELISAs for the detection of dengue NS1 antigen, IgM and IgG antibodies, respectively. The diagnostic performance of evaluated tests was computed using STATA version 12. RESULTS: The sensitivity and specificity of ViroTrack were 62.3% (95%CI 55.6-68.7) and 95.0% (95%CI 91.7-97.3), versus 66.5% (95%CI 60.0-72.6) and 95.4% (95%CI 92.1-97.6) for SD NS1 ELISA, and 52.4% (95%CI 45.7-59.1) and 97.7% (95%CI 95.1-99.2) for NS1 component of SD Bioline, respectively. The combination of the latter with its IgM and IgG components were able to increase test sensitivity to 82.4% (95%CI 76.8-87.1) with corresponding decrease in specificity to 87.4% (95%CI 82.8-91.2). Although a positive test on any of the NS1 assays would increase the probability of dengue to above 90% in a patient, a negative result would only reduce this probability to 23.0-29.3%. In contrast, this probability of false negative diagnosis would be further reduced to 14.7% (95%CI 11.4-18.6) if SD Bioline NS1/IgM/IgG combo was negative. CONCLUSIONS: The performance of ViroTrack Dengue Acute was comparable to SD Dengue NS1 Ag ELISA. Addition of serology components to SD Bioline Dengue Duo significantly improved its sensitivity and reduced its false negative rate such that it missed the fewest dengue patients, making it a better point-of-care diagnostic tool. New RDT like ViroTrack Dengue Acute may be a potential alternative to existing RDT if its combination with serology components is proven better in future studies.

Comparison between the traditional (1997) and revised (2009) WHO classifications of dengue disease: a retrospective study of 30 670 patients.

OBJECTIVE: To compare WHO's traditional (1997) and revised (2009) guidelines for dengue classification, using a large sample of patients of all ages with varying clinical conditions from a dengue-endemic area in Brazil. METHODS: We compared 30 670 laboratory-confirmed dengue cases (1998-2012) using both WHO's dengue classification guidelines. Stereotype ordinal logistic regressions were used to analyse the association between patients' demographics and signs and symptoms related to dengue infection severity, as defined in the 1997 and 2009 guidelines. We then compared the degree of agreement in dengue classification of both guidelines. RESULTS: Dengue signs and symptoms in patients were poorly correlated to disease severity as defined by both guidelines (Cramer's V test <0.2). Hypotensive shock was the exception for both classifications, presenting dependence (Z = 56.42; P < 0.001, and Z = 55.24; P < 0.001) and high agreement (Cramers's V = 1; P < 0.001, and Cramers's V = 0.97; P < 0.001) for WHO 1997 and 2009, respectively. Last, we also found substantial agreement in disease classification between both guidelines (Kendall tau-b = 0.79; P < 0.001), although 2009 guidelines were more sensitive in the detection of severe cases. CONCLUSIONS: We hope our results will inform the debate about dengue classification guidelines, particularly concerning clinical value, study comparability, and ways in which future guidelines can support the clinical management of dengue. Our results suggest that caution should be taken when using WHO guidelines to assess dengue severity to improve clinical management of patients.

Clinical and Laboratory Diagnosis of Dengue Virus Infection.

Infection with any of the 4 dengue virus serotypes results in a diverse range of symptoms, from mild undifferentiated fever to life-threatening hemorrhagic fever and shock. Given that dengue virus infection elicits such a broad range of clinical symptoms, early and accurate laboratory diagnosis is essential for appropriate patient management. Virus detection and serological conversion have been the main targets of diagnostic assessment for many years, however cross-reactivity of antibody responses among the flaviviruses has been a confounding issue in providing a differential diagnosis. Furthermore, there is no single, definitive diagnostic biomarker that is present across the entire period of patient presentation, particularly in those experiencing a secondary dengue infection. Nevertheless, the development and commercialization of point-of-care combination tests capable of detecting markers of infection present during different stages of infection (viral nonstructural protein 1 and immunoglobulin M) has greatly simplified laboratory-based dengue diagnosis. Despite these advances, significant challenges remain in the clinical management of dengue-infected patients, especially in the absence of reliable biomarkers that provide an effective prognostic indicator of severe disease progression. This review briefly summarizes some of the complexities and issues surrounding clinical dengue diagnosis and the laboratory diagnostic options currently available.

Assessing changes in knowledge, attitude and practices on dengue diagnosis and management among primary care physicians after the largest dengue epidemic in Singapore.

BACKGROUND: Dengue results in high morbidity and mortality globally. The knowledge, attitude and practices (KAP) of dengue management, including diagnosis, among primary care physicians (PCPs) are important to reduce dengue transmission and burden. However, there is a lack of understanding on the impact of dengue epidemic on dengue management. Hence, the aim of this study is to examine the changes in KAP on dengue management among PCPs before and after the largest dengue epidemic in 2013 in Singapore. METHODS: Surveys were mailed to 2000 and 1514 PCPs registered under the Singapore Medical Council in March of year 2011 and 2014, respectively. Survey data were then collected between April and June of that year. Chi-square or Fisher's exact test was used for comparing categorical variables. A multivariate logistic regression model was implemented to determine independent factors for frequent use of dengue diagnostic tests (DDTs). All tests were conducted at 5% level of significance. Adjusted odds ratio and corresponding 95% confidence intervals were reported, where applicable. Qualitative data were descriptively coded for themes and analysis. RESULTS: Among PCPs surveyed in 2011 and 2014, 89.9% and 86% had good knowledge on dengue management respectively. The usage of DDTs had increased significantly in 2014 (N = 164;56%) as compared to 2011 (N = 107;29.5%) in both private and public clinics (p < 0.001). Dengue Duo point-of-care test (POCT) kits was independently associated with frequent use of DDTs (adjusted odds ratio = 2.15; 95% confidence interval = 1.25-3.69). There was a significant reduction in referral of dengue patients to hospital (31.4% in 2011; 13.3% in 2014; p < 0.001), and a significant increase in frequency of clinic follow-ups (18.4% in 2011; 28.5% in 2014; p = 0.003). One key theme highlighted was that dengue management can be improved with availability of POCT kit, better awareness of the disease and any revised clinical guidelines. CONCLUSION: The knowledge on dengue management remained high, while the attitude and practices, particularly on the usage of DDTs improved significantly after a large epidemic. Furthermore, PCPs had more confident in managing dengue patients in primary care settings and in educating patients on the importance of vector control and dengue warning signs to reduce dengue transmission and burden.

Increased sensitivity of NS1 ELISA by heat dissociation in acute dengue 4 cases.

BACKGROUND: Dengue is an acute febrile illness considered the major arboviral disease in terms of morbidity, mortality, economic impact and dissemination worldwide. Brazil accounts for the highest notification rate, with circulation of all four dengue serotypes. The NS1 antigen is a dengue highly conserved specific soluble glycoprotein essential for viral replication and viability that can be detected 0 to 18 days from the onset of fever (peak first 3 days). It induces a strong humoral response and is known as a complement-fixing antigen. Lower NS1 test sensitivity occurs in secondary dengue infections probably due to immune complex formation impairing antigen detection by ELISA. METHODS: We compared the sensitivity of NS1 ELISA in heat dissociated and non-dissociated samples from 156 RT-PCR confirmed acute dengue-4 cases from 362 prospectively enrolled patients. RESULTS: Secondary infections accounted for 83.3% of cases. NS1 ELISA was positive in 42.5% and indeterminate in 10.2% of dengue-4 cases. After heat dissociation, 7 negative and 16 indeterminate samples turned positive, increasing the overall test sensitivity to 57.7%. CONCLUSIONS: Although it is time consuming and requires the use of specific laboratory equipment, NS1 ELISA combined with heat dissociation could be a slightly better alternative for triage in suspected dengue cases.

Evaluation of Non-Structural Protein-1(NS1) positive patients of 2013 dengue outbreak in Khyber Pakhtunkhwa, Pakistan.

BACKGROUND & OBJECTIVE: Dengue infection is an arthropod borne disease caused by Dengue virus in humans. Dengue virus infection has more potential to produce severe form of the disease with more severe symptoms. Proper diagnosis of dengue fever is very important for its safe management. The objective of this study was to evaluate the non structural protein-1 (NS1) positive parameter for identification of dengue fever by using ELISA from 2013 dengue outbreak in Khyber Pakhtunkhwa. METHODS: It was a cross sectional study conducted among 384 patients tested for dengue admitted to different hospitals of Khyber Pakhtunkhwa April to December 2013 with symptoms related to classical dengue fever. Written informed consent was taken from 100 NS1 positive diagnosed patients, and 3 to 5 ml blood sample was collected for confirmation through ELISA testing. ELISA test for dengue IgG and IgM was performed two time in order to confirm the dengue cases. Data was entered and analyzed by using SPSS version 16. RESULT: The study performed on 100 NS1 positive samples of patients, admitted to hospitals with symptoms related to classical dengue fever, indicated that after performing the IgM and IgG capture ELISA test only 76 samples were actually found positive for dengue. The rest of the 24 samples were found negative for both IgM and IgG capture ELISAs. The study also revealed that 90.8 % patients had primary dengue infection and 35.5% patients had secondary dengue infection. Most patients were between the age of 10-20 years (26%), among them19.7% were having primary dengue infection. Among 10-20 years of age 50% female patients were false dengue patients. CONCLUSION: About 24 % NSI protein positive samples were found negative for both IgM and IgG capture ELISAs showed that NS1protein positivity does not confirm actual dengue infection.

[Clinical Update on Diagnosis, Treatment and Prevention of Dengue]. / Atualização Clínica sobre Diagnóstico, Tratamento e Prevenção da Dengue.

Dengue is a vector-borne disease that has a significant impact on global public health. The vector mosquito belongs to the genus Aedes. Two species play a key role in human transmission: Ae. aegypti, which has adapted to the urban environment of highly populated areas in tropical and subtropical countries, leading to a dramatic increase in dengue cases over the years, and Ae. albopictus, which poses a potential threat to temperate climate countries due to its ability to adapt to colder climates. The disease is widespread across the world, posing a risk to nearly half of the world's population. Although most cases are asymptomatic, dengue causes a burden on healthcare systems and mainly affects the younger population. The disease is also spreading to temperate climate countries, thus becoming a global threat. Vector control measures and vaccine development have been the main prevention strategies, as there is still no effective treatment for the disease.

A dengue é uma doença transmitida por um vetor hematófago (mosquito) que possui um impacto significativo na saúde pública mundial. O mosquito transmissor pertence ao género Aedes. São duas as espécies responsáveis pela transmissão humana: o Ae. aegypti, que se adaptou ao ambiente urbano de áreas altamente populosas de países tropicais e subtropicais, resultando num aumento dramático dos casos de dengue ao longo dos anos; e o Ae. Albopictus, que representa uma potencial ameaça para os países de clima temperado pela sua capacidade de adaptação aos climas mais frios. A doença está presente em grande parte do mundo, colocando cerca de metade da população do planeta em risco. Embora a maioria dos casos seja assintomática, a dengue causa uma sobrecarga nos sistemas de saúde e impacta principalmente os jovens. A doença também tem vindo a alastrar-se a países de clima temperado, tornando-se uma ameaça global. As medidas de controlo vetorial e o desenvolvimento de vacinas têm sido as principais estratégias de prevenção, uma vez que não existe ainda um tratamento eficaz para a doença.

Lateral flow immunoassay (LFIA) for dengue diagnosis: Recent progress and prospect.

Dengue is one of the most widespread and fatal arboviral infections in the world. Early detection of dengue virus (DENV) is essential to prevent the spread of the disease and provide an immediate response. The lateral flow immunoassay (LFIA) systems are low-cost, rapid, sensitive, targeted, and straightforward detection, which is an ideal early detection candidate for point-of-care testing (POCT) in dengue-affected areas. However, current commercial LFIA kits cannot fully satisfy the sensitivity, specificity, serotype differentiation, and multiplex detection requirements. Therefore, various strategies have been applied to optimize the LFIA for DENV detection, including label material improvement, optical enhancement and novel structure design. In this review, we comprehensively presented the snapshot of dengue, the principle of LFIA, and recent progress in the LFIA optimization for dengue diagnoses. Furthermore, this review also discusses insights into the prospect of LFIA dengue diagnostic methods, such as microfluidics, multiplex design, nucleic acid-typed probes and smartphone-assisted result analysis.

Next-generation diagnostic test for dengue virus detection using an ultrafast plasmonic colorimetric RT-PCR strategy.

The current global COVID-19 pandemic once again highlighted the urgent need for a simple, cost-effective, and sensitive diagnostic platform that can be rapidly developed for distribution and easy access in resource-limited areas. Here, we present a simple and low-cost plasmonic photothermal (PPT)-reverse transcription-colorimetric polymerase chain reaction (RTcPCR) for molecular diagnosis of dengue virus (DENV) infection. The assay can be completed within 54 min with an estimated detection limit of 1.6 copies/µL of viral nucleic acid. The analytical sensitivity and specificity of PPT-RTcPCR were comparable to that of the reference RT-qPCR assay. Moreover, the clinical performance of PPT-RTcPCR was evaluated and validated using 158 plasma samples collected from patients suspected of dengue infection. The results showed a diagnostic agreement of 97.5% compared to the reference RT-qPCR and demonstrated a clinical sensitivity and specificity of 97.0% and 100%, respectively. The simplicity and reliability of our PPT-RTcPCR strategy suggest it can provide a foundation for developing a field-deployable diagnostic assay for dengue and other infectious diseases.

Performance of VIDAS® Diagnostic Tests for the Automated Detection of Dengue Virus NS1 Antigen and of Anti-Dengue Virus IgM and IgG Antibodies: A Multicentre, International Study.

Dengue is a serious mosquito-transmitted disease caused by the dengue virus (DENV). Rapid and reliable diagnosis of DENV infection is urgently needed in dengue-endemic regions. We describe here the performance evaluation of the CE-marked VIDAS® dengue immunoassays developed for the automated detection of DENV NS1 antigen and anti-DENV IgM and IgG antibodies. A multicenter concordance study was conducted in 1296 patients from dengue-endemic regions in Asia, Latin America, and Africa. VIDAS® dengue results were compared to those of competitor enzyme-linked immunosorbent assays (ELISA). The VIDAS® dengue assays showed high precision (CV ≤ 10.7%) and limited cross-reactivity (≤15.4%) with other infections. VIDAS® DENGUE NS1 Ag showed high positive and negative percent agreement (92.8% PPA and 91.7% NPA) in acute patients within 0-5 days of symptom onset. VIDAS® Anti-DENGUE IgM and IgG showed a moderate-to-high concordance with ELISA (74.8% to 90.6%) in post-acute and recovery patients. PPA was further improved in combined VIDAS® NS1/IgM (96.4% in 0-5 days acute patients) and IgM/IgG (91.9% in post-acute patients) tests. Altogether, the VIDAS® dengue NS1, IgM, and IgG assays performed well, either alone or in combination, and should be suitable for the accurate diagnosis of DENV infection in dengue-endemic regions.

A Rapid and Easy-to-Perform Method of Nucleic-Acid Based Dengue Virus Diagnosis Using Fluorescence-Based Molecular Beacons.

Detecting dengue virus (DENV) infection in patients as early as possible makes the disease management convenient. Conventionally, DENV infection is diagnosed by ELISA-based methods, but sensitivity and specificity are major concerns. Reverse-transcription-PCR (RT-PCR)-based detection confirms the presence of DENV RNA; however, it is expensive, time-consuming, and skilled personnel are required. A fluorescence-based detection system that detects DENV RNA in patient's serum directly, without any nucleic acid amplification step, has been developed. The method uses target-specific complementary sequence in the molecular beacon, which would specifically bind to the DENV RNA. The molecular beacons are approximately 40 bases long hairpin structures, with a fluorophore-quencher system attached at the terminal ends of the stem. These probes are biotinylated in the stem region, so that they can be immobilized on the streptavidin-tagged magnetic beads. These magnetic beads, coupled with biotinylated molecular beacons, are used for the detection of the target RNA in the serum by incubating the mixture. After incubation, beads are separated and re-suspended in a buffer. The measurement of fluorescence is taken in fluorometer after 15 min incubation at 50 °C. The whole work is carried out in a single tube. This rapid method can precisely detect dengue RNA within two hours, confirming ongoing DENV replication in the patient.

Evaluation of VIDAS® Diagnostic Assay Prototypes Detecting Dengue Virus NS1 Antigen and Anti-Dengue Virus IgM and IgG Antibodies.

Dengue is a serious tropical disease caused by the mosquito-borne dengue virus (DENV). Performant, rapid, and easy-to-use assays are needed for the accurate diagnosis of acute DENV infection. We evaluated the performance of three prototype assays developed for the VIDAS® automated platform to detect dengue NS1 antigen and anti-dengue IgM and IgG antibodies. Positive and negative agreement with competitor enzyme-linked immunosorbent assays (ELISA) and rapid diagnostic tests (RDT) was evaluated in 91 Lao patients (57 adults, 34 children) with acute DENV infection. The VIDAS® NS1 assay showed the best overall agreement (95.6%) with the competitor NS1 ELISA. Both VIDAS® NS1 and NS1 ELISA assays also demonstrated high sensitivity relative to DENV RNA RT-PCR set as gold standard (85.7% and 83.9%, respectively). In contrast, NS1 RDT was less sensitive relative to DENV RNA RT-PCR (72.7%). The overall agreement of VIDAS® IgM and IgG assays with the competitor assays was moderate (72.5% for IgM ELISA, 76.9% for IgG ELISA, and 68.7% for IgM and IgG RDT). In most analyses, test agreements of the VIDAS® assays were comparable in adults and children. Altogether, the VIDAS® dengue prototypes performed very well and appear to be suitable for routine detection of dengue NS1 antigen and anti-dengue IgM/IgG antibodies.

Regional Variation in Dengue Virus Serotypes in Sri Lanka and Its Clinical and Epidemiological Relevance.

Dengue is a significant health concern in Sri Lanka, but diagnosis of the infecting dengue virus (DENV) serotype has hitherto been largely restricted to the Colombo district in the western province. Salinity tolerant Aedes vectors are present in the island's northern Jaffna peninsula, which is undergoing rapid groundwater salinization. Virus serotypes were determined by RT-qPCR in 107 and 112 patients diagnosed by NS1 antigen positivity from the Jaffna district in 2018 and 2019, respectively, and related to clinical characteristics. DENV1 and DENV2 were the most common serotypes in both years. Infections with multiple serotypes were not detected. DENV1 was significantly more prevalent in 2019 than 2018, while DENV3 was significantly more prevalent in 2018 than 2019 among the Jaffna patients. Limited genomic sequencing identified DENV1 genotype-I and DENV3 genotype-I in Jaffna patients in 2018. Dengue was more prevalent in working age persons and males among the serotyped Jaffna patients. DENV1 and DENV2 were the predominant serotypes in 2019 in the Colombo district. However, DENV1 and DENV3 were significantly more prevalent in Colombo compared with Jaffna in 2019. The differences in the prevalence of DENV1 and DENV3 between the Jaffna and Colombo districts in 2019 have implications for dengue epidemiology and vaccination. Salinity-tolerant Aedes vector strains, widespread in the Jaffna peninsula, may have contributed to differences in serotype prevalence compared with the Colombo district in 2019. Significant associations were not identified between virus serotypes and clinical characteristics among Jaffna patients.

Evaluating the validity of dengue clinical-epidemiological criteria for diagnosis in patients residing in a Brazilian endemic area.

BACKGROUND: We evaluated the validity of clinical diagnosis compared with laboratory diagnosis of dengue in a retrospective sample of patients in São José do Rio Preto, Brazil. METHODS: Our sample included 148 299 clinically (56.3%) or laboratory-diagnosed (43.7%) dengue cases. We compared the sensitivity, specificity, positive and negative predictive value (PPV and NPV) of dengue patients' demographic and clinical characteristics with laboratory-based diagnosis. We used logistic regressions to estimate the correlation between clinical and laboratory diagnosis of dengue and a full set of dengue signs and symptoms. RESULTS: We found substantial variability in sensitivity and specificity of signs and symptoms ranging from 0.8-81.1 and 21.5-99.6, respectively. Thrombocytopenia exhibited the highest PPV (92.0) and lowest NPV (42.2) and was the only symptom showing agreement with laboratory-confirmed dengue (φ = 0.38). The presence of exanthema and thrombocytopenia led to a greater likelihood of concordant clinical and laboratory diagnoses (exanthema: OR: 4.23; 95% CI: 2.09 to 8.57; thrombocytopenia: OR: 4.02; 95% CI: 1.32 to 12.27). CONCLUSIONS: We found substantial variation in sensitivity, specificity, PPV and NPV of dengue signs and symptoms. For accuracy, clinical and laboratory diagnosis of dengue should be performed concurrently. When laboratory tests are not available, we suggest focusing on the clinical manifestations most associated with dengue.

Inapparent dengue in a community living among dengue-positive Aedes mosquitoes and in a hospital in Klang Valley, Malaysia.

The public health burden of dengue is most likely under reported. Current dengue control measures only considered symptomatic dengue transmission. Hence, there is a paucity of information on the epidemiology of inapparent dengue. This study reports that many people have been unknowingly exposed to dengue infection. Almost 10% and 70% of individuals without any history of dengue infection and living in a dengue hotspot, in Selangor, Malaysia, were dengue IgM and IgG positive respectively. When dengue-positive mosquitoes were detected in the hotspot, 11 (6.3%) of the 174 individuals tested were found to have dengue viremia, of which 10 were asymptomatic. Besides, upon detection of a dengue-infected mosquito, transmission was already widespread. In a clinical setting, it appears that people living with dengue patients have been exposed to dengue, whether asymptomatic or symptomatic. They can either have circulating viral RNA and/or presence of NS1 antigen. It is also possible that they are dengue seropositive. Collectively, the results indicate that actions taken to control dengue transmission after the first report of dengue cases may be already too late. The current study also revealed challenges in diagnosing clinically inapparent dengue in hyperendemic settings. There is no one best method for diagnosing inapparent dengue. This study demonstrates empirical evidence of inapparent dengue in different settings. Early dengue surveillance in the mosquito population and active serological/virological surveillance in humans can go hand in hand. More studies are required to investigate the epidemiology, seroprevalence, diagnostics, and control of inapparent dengue. It is also crucial to educate the public, health staff and medical professionals on asymptomatic dengue and to propagate awareness, which is important for controlling transmission.

Development of clinical algorithms for the diagnosis of dengue in Colombia / Desarrollo de algoritmos clínicos para el diagnóstico del dengue en Colombia

Introduction: Due to the increase in dengue incidence and mortality, its diagnosis is relevant for endemic countries. Clinical classifications and laboratory tests have a variable performance in clinical practice with a sensitivity level between 45% and 98%, and a specificity level between 4% and 98% partly due to the variety of contexts where they are applied. Objective: To develop clinical algorithms for the diagnosis of dengue in the Colombian context. Materials and methods: A cross-sectional study was conducted based on secondary sources. We constructed clinical diagnostic algorithms of dengue based on Bayesian methods combining symptoms, signs, and blood count parameters, and then we compared them in terms of diagnostic accuracy with gold standard tests. In addition, an external validation of the algorithm with greater accuracy and sensibility was performed comparing it with the WHO-1997 and the WHO-2009 clinical classifications, the Colombian guide for 2010, and the diagnostic scale recommended by the Ministerio de Salud y Protección Social of Colombia for 2013. Results: Four algorithms were generated, two for signs and symptoms, and two that included leukocytes (≤4,500/mm3) and/or platelets (≤160,000/mm3) counts. The most accurate algorithm included blood count parameters with a sensitivity of 76.5% (95%CI: 71.9-80.5) and a specificity of 46.0% (95%CI: 37.6-54.7). In the external validation we found a sensitivity of 11.1% (95%CI: 4.9-20.7) and a specificity of 91.9% (95%CI: 87.5-93.9). The scale of the Ministerio de Salud had a sensitivity of 76.4% (95%CI: 64.9-85.6) and a specificity of 38.0% (95%CI: 32.8-43.4). Conclusion: The inclusion of blood count parameters improved the sensitivity of diagnostics algorithms based on signs and symptoms. Clinical diagnosis of dengue remains a challenge for health research.

Introducción. Dado el aumento de la incidencia y la mortalidad por dengue, su diagnóstico es relevante para los países endémicos. Las clasificaciones clínicas y las pruebas de laboratorio existentes tienen un desempeño variable en la práctica clínica, pues su sensibilidad fluctúa entre 45 y 98 %, y su especificidad, entre 4 y 98 %, lo cual se debe, en parte, a la diversidad de contextos en los que se utilizan. Objetivo. Desarrollar algoritmos clínicos para el diagnóstico del dengue en el contexto colombiano. Materiales y métodos. Se hizo un estudio transversal a partir de fuentes secundarias. Se construyeron algoritmos clínicos de diagnóstico del dengue con base en métodos bayesianos que combinaron síntomas, signos y parámetros del hemograma, y se comparó su exactitud diagnóstica con la de las pruebas de referencia. Se hizo una validación externa del algoritmo de mayor exactitud y sensibilidad, comparándolo con la clasificación clínica de la Organización Mundial de la Salud de 1997 y la del 2009, con la guía colombiana del 2010 y con la escala diagnóstica propuesta por el Ministerio de Salud y Protección Social de Colombia en el 2013. Resultados. Se generaron cuatro algoritmos, dos de signos y síntomas y dos que incluyeron el conteo de leucocitos (≤4.500/mm3) o de plaquetas (≤60.000/mm3). El algoritmo de mayor exactitud incluyó los parámetros del hemograma, con una sensibilidad de 76,5 % (IC95% 71,9-80,5) y una especificidad de 46,0 % (IC95% 37,6-54,7). En la validación externa, la sensibilidad fue de 11,1 % (IC95% 4,9-20,7) y la especificidad fue de 91,9 % (IC95% 87,5-93,9). La escala del Ministerio tuvo una sensibilidad de 76,4 % (IC95% 64,9-85,6) y una especificidad de 38,0 % (IC95% 32,8-43,4). Conclusión. La inclusión de los parámetros del hemograma mejoró la sensibilidad de los algoritmos de diagnóstico basados en los signos y los síntomas. Sin embargo, el diagnóstico clínico del dengue sigue siendo un reto para la investigación en salud.

Development of a portable and disposable NS1 based electrochemical immunosensor for early diagnosis of dengue virus.

The present study represents fabrication of nonstructural antibody (NS1) based immunosensor coupled with bovine serum albumin (BSA) modified screen printed carbon electrodes (SPCE) as transducing substrate for the early diagnosis of dengue virus. The anti-NS1 monoclonal antibody was immobilized on electro grafted BSA surface of working electrode. The electrons transfer resistance before and after NS1 attachment was monitored as a function of its concentration to perform the qualitative and quantitative analysis. The as prepared impedimetric immunosensor successfully detected the dengue virus protein with enhanced limit of detection (0.3 ng/mL) and linear range (1-200 ng/mL). The selectivity of the designed device was further elaborated with several interfering analytes and was finally demonstrated with human serum samples. The extravagant selectivity, sensitivity and easier fabrication protocol corroborate the potential applications of such immunosensor for practical diagnosis of dengue virus.

Enhanced sensing of dengue virus DNA detection using O2 plasma treated-silicon nanowire based electrical biosensor.

Dengue Virus (DENV) has become one of the most serious arthropod-borne viral diseases, causing death globally. The existing methods for DENV detection suffer from the late stage treatment due to antibodies-based detection which is feasible only after five days following the onset of the illness. Here, we demonstrated the highly effective molecular electronic based detection utilizing silicon nanowire (SiNW) integrated with standard complementary metal-oxide-semiconductor (CMOS) process as a sensing device for detecting deoxyribonucleic acid (DNA) related to DENV in an early stage diagnosis. To transform the fabricated devices as a functional sensing element, three-step procedure consist of SiNW surface modification, DNA immobilization and DNA hybridization were employed. The detection principle works by detecting the changes in current of SiNW which bridge the source and drain terminal to sense the immobilization of probe DNA and their hybridization with target DNA. The oxygen (O2) plasma was proposed as an effective strategy for increasing the binding amounts of target DNA by modified the SiNW surface. It was found that the detection limit of the optimized O2 plasma treated-SiNW device could be reduced to 1.985 × 10-14 M with a linear detection range of the sequence-specific DNA from 1.0 × 10-9 M to 1.0 × 10-13 M. In addition, the developed biosensor device was able to discriminate between complementary, single mismatch and non-complementary DNA sequences. This highly sensitive assay was then applied to the detection of reverse transcription-polymerase chain reaction (RT-PCR) product of DENV-DNA, making it as a potential method for disease diagnosis through electrical biosensor.