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BackgroundCeftriaxone is the preferred treatment for bacteraemia caused by non-MDR (antibiotic-susceptible) Klebsiella pneumoniae. Excessive and widespread ceftriaxone use creates selection pressure for ESBLs. Cefazolin is an alternative, although there are theoretical concerns that SHV-1 β-lactamase in K. pneumoniae may inactivate cefazolin in an inoculum-dependent manner.ObjectivesIn this retrospective study, we investigated the outcomes in K. pneumoniae bacteraemia patients treated with IV cefazolin versus IV ceftriaxone as definitive therapy.MethodsA total of 917 patients infected with K. pneumoniae from 1 January to 31 December 2016 in three public acute care hospitals in Singapore were screened for study eligibility. Consecutive unique episodes of monomicrobial bacteraemia caused by cefazolin- and/or ceftriaxone-susceptible K. pneumoniae were analysed (n = 284).ResultsThere were 143 patients (50.4%) in the cefazolin group and 141 patients (49.6%) in the ceftriaxone group. Demographics, baseline illness severity and risk factors for healthcare-associated bacteraemia were comparable in the two treatment groups. The primary outcome of 28 day all-cause mortality was not significantly different between the cefazolin and ceftriaxone groups (10.5% versus 7.1%, P = 0.403). Both in the crude analysis and using a multivariable logistic regression model with inverse probability weighting based on propensity score, cefazolin treatment was not associated with increased risk of 28 day mortality (OR 1.51 with ceftriaxone as the reference group, 95% CI 0.67–3.53; adjusted OR 1.55, 95% CI 0.33–7.40).ConclusionsCefazolin may be a ceftriaxone-sparing alternative treatment for antibiotic-susceptible K. pneumoniae bacteraemia. This observation may provide sufficient clinical equipoise for a randomized controlled trial.

Purpose To investigate the prevalence and epidemiological risk factors of olfactory and/or taste disorder (OTD), in particular isolated OTD, in patients with laboratory-confirmed COVID-19 infection. Methods We conducted a retrospective and cross-sectional study. Patients with laboratory-confirmed COVID-19 infection were recruited from the National Centre for Infectious Diseases (NCID) Singapore between 24 March 2020 and 16 April 2020. The electronic health records of these patients were accessed, and demographic data and symptoms reported (respiratory, self-reported OTD and other symptoms such as headache, myalgia and lethargy) were collected. Results A total of 1065 patients with laboratory-confirmed COVID-19 were recruited. Overall, the prevalence of OTD was 12.6%. Twelve patients (1.1%) had isolated OTD. The top three symptoms associated with OTD were cough, fever and sore throat. The symptoms of runny nose and blocked nose were experienced by only 29.8 and 19.3% of patients, respectively. Multivariate analysis demonstrated that the female gender, presence of blocked nose and absence of fever were significantly associated with OTD (adjusted relative risks 1.77, 3.31, 0.42, respectively). All these factors were statistically significant. Conclusion Patients with COVID-19 infection can present with OTD, either in isolation or in combination with other general symptoms. Certain demographic profile, such as being female, and symptomatology such as the presence of blocked nose and absence of fever, were more likely to have OTD when infected by COVID-19. Further studies to elucidate the pathophysiology of OTD in these patients will be beneficial.

Current methods for dengue virus (DENV) genome amplification, amplify parts of the genome in at least 5 overlapping segments and then combine the output to characterize a full genome. This process is laborious, costly and requires at least 10 primers per serotype, thus increasing the likelihood of PCR bias. We introduce an assay to amplify near full-length dengue virus genomes as intact molecules, sequence these amplicons with third generation “nanopore” technology without fragmenting and use the sequence data to differentiate within-host viral variants with a bioinformatics tool (Nano-Q). The new assay successfully generated near full-length amplicons from DENV serotypes 1, 2 and 3 samples which were sequenced with nanopore technology. Consensus DENV sequences generated by nanopore sequencing had over 99.5% pairwise sequence similarity to Illumina generated counterparts provided the coverage was > 100 with both platforms. Maximum likelihood phylogenetic trees generated from nanopore consensus sequences were able to reproduce the exact trees made from Illumina sequencing with a conservative 99% bootstrapping threshold (after 1000 replicates and 10% burn-in). Pairwise genetic distances of within host variants identified from the Nano-Q tool were less than that of between host variants, thus enabling the phylogenetic segregation of variants from the same host.

Serologic tests to detect specific IgGs to antigens related to viral infections are urgently needed for diagnostics and therapeutics. We present a diagnostic method for serotype-specific IgG identification of dengue infection by a competitive enzyme-linked immunosorbent assay (ELISA), using high-affinity unnatural-base-containing DNA (UB-DNA) aptamers that recognize the four categorized serotypes. Using UB-DNA aptamers specific to each serotype of dengue NS1 proteins (DEN-NS1), we developed our aptamer-antibody sandwich ELISA for dengue diagnostics. Furthermore, IgGs highly specific to DEN-NS1 inhibited the serotype-specific NS1 detection, inspiring us to develop the competitive ELISA format for dengue serotype-specific IgG detection. Blood samples from Singaporean patients with primary or secondary dengue infections confirmed the highly specific IgG detection of this format, and the IgG production initially reflected the serotype of the past infection, rather than the recent infection. Using this dengue competitive ELISA format, cross-reactivity tests of 21 plasma samples from Singaporean Zika virus-infected patients revealed two distinct patterns: 8 lacked cross-reactivity, and 13 were positive with unique dengue serotype specificities, indicating previous dengue infection. This antigen-detection ELISA and antibody-detection competitive ELISA combination using the UB-DNA aptamers identifies both past and current viral infections and will facilitate specific medical care and vaccine development for infectious diseases. Agency for Science, Technology and Research (A*STAR) National Research Foundation (NRF) Published version This work was supported by the Institute of Bioengineering and Bioengineering (Biomedical Research Council, Agency for Science, Technology and Research, Singapore) and the National Research Foundation of Singapore (NRF-CRP17-2017-07).

Summary Emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern pose a challenge to the effectiveness of current vaccines. A vaccine that could prevent infection caused by known and future variants of concern as well as infection with pre-emergent sarbecoviruses (i.e., those with potential to cause disease in humans in the future) would be ideal. Here we provide data showing that potent cross-clade pan-sarbecovirus neutralizing antibodies are induced in survivors of severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) infection who have been immunized with the BNT162b2 messenger RNA (mRNA) vaccine. The antibodies are high-level and broad-spectrum, capable of neutralizing not only known variants of concern but also sarbecoviruses that have been identified in bats and pangolins and that have the potential to cause human infection. These findings show the feasibility of a pan-sarbecovirus vaccine strategy. (Funded by the Singapore National Research Foundation and National Medical Research Council.)

Plasma leakage is a major pathogenic mechanism of severe dengue, but the etiology remains unclear. The association between endothelial glycocalyx integrity and vascular permeability in older adults with dengue has not been evaluated. A prospective cohort study of adults with undifferentiated fever screened for dengue by RT-PCR or NS1 antigen testing was performed. Patients were assessed daily while symptomatic and at convalescence. Serum hyaluronic acid (HA), heparan sulfate (HS) and selected cytokines (TNF-α, IL-6, IL-10) were measured on enrollment and convalescence. Patients were diagnosed as dengue fever (DF, n = 30), dengue hemorrhagic fever (DHF, n = 20) and non-dengue (ND) febrile illness (n = 11). Acute HA and HS levels were significantly higher in all dengue patients compared to ND (p = 0.0033 and p = 0.0441 respectively), but not different between DF and DHF (p = 0.3426 and p = 0.9180 respectively). Enrolment HA inversely correlated with serum albumin, protein and platelets in all dengue and DHF (p 0.05). HA and HS in all dengue patients decreased significantly at convalescence. Serum IL-10 was significantly associated with HA in all dengue patients (p = 0.002). Serum HA and HS levels were increased in adult dengue and HA was associated with markers of disease severity. Endothelial glycocalyx damage may have a role in vascular leakage in dengue.

Summary Prior immunological exposure to dengue virus can be both protective and disease-enhancing during subsequent infections with different dengue virus serotypes. We provide here a systematic, longitudinal analysis of B cell, T cell, and antibody responses in the same patients. Antibody responses as well as T and B cell activation differentiate primary from secondary responses. Hospitalization is associated with lower frequencies of activated, terminally differentiated T cells and higher percentages of effector memory CD4 T cells. Patients with more severe disease tend to have higher percentages of plasmablasts. This does not translate into long-term antibody titers, since neutralizing titers after 6 months correlate with percentages of specific memory B cells, but not with acute plasmablast activation. Overall, our unbiased analysis reveals associations between cellular profiles and disease severity, opening opportunities to study immunopathology in dengue disease and the potential predictive value of these parameters., Graphical abstract, Highlights T cell, B cell phenotypes, and antibodies are associated with dengue disease severity CXCR3+ CD8 T cell responses are associated with memory B cell formation Treg responses are associated with plasmablast responses Memory B cell numbers correlate with long-lasting neutralizing antibody titers, Rouers et al. examine the phenotype of dengue immune responses in a longitudinal patient cohort and find associations between cellular profiles and disease severity. Immune cells that are associated with long-lasting neutralizing antibodies up to 1 year after disease onset are described.

Case identification is an ongoing issue for the COVID-19 epidemic, in particular for outpatient care where physicians must decide which patients to prioritise for further testing. This paper reports tools to classify patients based on symptom profiles based on 236 severe acute respiratory syndrome coronavirus 2 positive cases and 564 controls, accounting for the time course of illness using generalised multivariate logistic regression. Significant symptoms included abdominal pain, cough, diarrhoea, fever, headache, muscle ache, runny nose, sore throat, temperature between 37.5 and 37.9 °C and temperature above 38 °C, but their importance varied by day of illness at assessment. With a high percentile threshold for specificity at 0.95, the baseline model had reasonable sensitivity at 0.67. To further evaluate accuracy of model predictions, leave-one-out cross-validation confirmed high classification accuracy with an area under the receiver operating characteristic curve of 0.92. For the baseline model, sensitivity decreased to 0.56. External validation datasets reported similar result. Our study provides a tool to discern COVID-19 patients from controls using symptoms and day from illness onset with good predictive performance. It could be considered as a framework to complement laboratory testing in order to differentiate COVID-19 from other patients presenting with acute symptoms in outpatient care.

Case identification is an ongoing issue for the COVID-19 epidemic, in particular for outpatient care where physicians must decide which patients to prioritise for further testing. This paper reports tools to classify patients based on symptom profiles based on 236 SARS-CoV-2 positive cases and 564 controls, accounting for the time course of illness at point of assessment. Clinical differentiators of cases and controls were used to derive model-based risk scores. Significant symptoms included abdominal pain, cough, diarrhea, fever, headache, muscle ache, runny nose, sore throat, temperature between 37.5°C and 37.9°C, and temperature above 38°C, but their importance varied by day of illness at assessment. With a high percentile threshold for specificity at 0.95, the baseline model had reasonable sensitivity at 0.67. To further evaluate accuracy of model predictions, we firstly used leave-one-out cross-validation, which confirmed high classification accuracy with an area under the receiver operating characteristic curve of 0.92. For the baseline model, sensitivity decreased to 0.56. Secondly, in a separate ongoing prospective study of 237 COVID-19 and 346 primary care patients presenting with symptoms of acute respiratory infection, the baseline model had a sensitivity of 0.57 and specificity of 0.89, and in retrospective notes review of 100 COVID-19 cases diagnosed in primary care, sensitivity was 0.56. A web-app based tool has been developed for easy implementation as an adjunct to laboratory testing to differentiate COVID-19 positive cases among patients presenting in outpatient settings.

Background: The novel coronavirus disease 2019 (COVID-19) presents with non-specific clinical features. This may result in misdiagnosis or delayed diagnosis, and lead to further transmission in the community. We aimed to derive early predictors to differentiate COVID-19 from influenza and dengue.Methods: The study comprised 126 patients with COVID-19, 171 with influenza and 180 with dengue, who presented within 5 days of symptom onset. All cases were confirmed by reverse transcriptase polymerase chain reaction tests. We used logistic regression models to identify clinical characteristics and laboratory markers in classifying COVID-19 versus influenza, and COVID-19 versus dengue. The performance of the models were evaluated using receiver operating characteristic curves (ROC).Results: Shortness of breath was the strongest predictor in the models for differentiating between COVID-19 and influenza, followed by diarrhoea. Higher lymphocyte count was predictive of COVID-19 versus influenza and versus dengue. In the model for differentiating between COVID-19 and dengue, patients with cough and higher platelet count were at increased odds of COVID-19, while headache, joint pain, skin rash and vomiting/nausea were indicative of dengue. The area under the ROC was 0.92 for flu model and 0.99 for dengue model.Conclusion: Models based on clinical features and simple laboratory markers for differentiating COVID-19 from influenza and dengue, which possess good predictive performance, can serve as a useful tool for primary care physicians to determine if further investigations or referrals would be required.

To evaluate how public perceptions and trust in government communications affected the adoption of protective behaviour in Singapore during the coronavirus disease 2019 (COVID-19) pandemic.We launched our community-based cohort to assess public perceptions of infectious disease outbreaks in mid-2019. After the first case of COVID-19 was reported in Singapore on 23 January, we launched a series of seven COVID-19 surveys to both existing and regularly enrolled new participants every 2 weeks. As well as sociodemographic properties of the participants, we recorded changing responses to judge awareness of the situation, trust in various information sources and perceived risk. We used multivariable logistic regression models to evaluate associations with perceptions of risk and self-reported adopted frequencies of protective behaviour.Our cohort of 633 participants provided 2857 unique responses during the seven COVID-19 surveys. Most agreed or strongly agreed that information from official government sources (99.1%; 528/533) and Singapore-based news agencies (97.9%; 522/533) was trustworthy. Trust in government communication was significantly associated with higher perceived threat (odds ratio, OR: 2.2; 95% confidence interval, CI: 1.6-3.0), but inversely associated with perceived risk of infection (OR: 0.6; 95% CI: 0.4-0.8) or risk of death if infected (OR: 0.6; 95% CI: 0.4-0.9). Trust in government communication was also associated with a greater likelihood of adopting protective behaviour.Our findings show that trust is a vital commodity when managing an evolving outbreak. Our repeated surveys provided real-time feedback, allowing an improved understanding of the interplay between perceptions, trust and behaviour.Évaluer dans quelle mesure la perception du public et la confiance envers les communications du gouvernement ont influencé l'adoption d'un comportement de protection à Singapour durant la pandémie de maladie à coronavirus (COVID-19).Nous avons lancé notre cohorte communautaire afin d'identifier la manière dont le public percevait les épidémies de maladies infectieuses au milieu de l'année 2019. Après l'annonce du premier cas de COVID-19 à Singapour le 23 janvier, nous avons débuté une série de sept sondages sur la COVID-19 auprès de participants existants et de nouveaux inscrits à intervalles réguliers, toutes les deux semaines. Nous avons pris note des caractéristiques sociodémographiques de ces participants ainsi que de l'évolution des réponses afin de déterminer le degré de sensibilisation à la situation, la confiance vis-à-vis de diverses sources d'information et le risque perçu. Nous avons employé des modèles de régression logistique multivariée pour examiner les liens qui existent entre la perception du risque et la fréquence à laquelle les répondants déclarent avoir adopté un comportement de protection.Notre cohorte de 633 participants a fourni 2857 réponses uniques lors des sept sondages sur la COVID-19. La plupart étaient d'accord ou totalement d'accord pour dire que les informations provenant de sources gouvernementales officielles (99,1%; 528/533) et d'agences de presse établies à Singapour (97,9%; 522/533) étaient fiables. La confiance envers la communication du gouvernement était étroitement liée à l'intensité de la menace ressentie (odds ratio, OR: 2,2; intervalle de confiance de 95%, IC: 1,6–3,0), mais inversement proportionnelle au risque d'infection perçu (OR: 0,6; IC de 95%: 0,4–0,8) ou au risque de décès en cas d'infection (OR: 0,6; IC de 95%: 0,4-0,9). Cette confiance était également associée à une probabilité accrue d'adoption d'un comportement de protection.Nos résultats montrent que la confiance est un outil indispensable pour gérer la progression d'une épidémie. Les multiples études réalisées par nos soins ont livré un retour d'expérience en temps réel qui a permis de mieux comprendre les interactions entre perception, confiance et comportement.Evaluar cómo las percepciones y la confianza del público en las comunicaciones del gobierno influyeron en la adopción de un comportamiento protector en Singapur durante la pandemia de la enfermedad por coronavirus de 2019 (COVID-19).A mediados de 2019, se inició el estudio de cohorte de la población local para evaluar la percepción que tiene el público sobre los brotes epidémicos de las enfermedades infecciosas. Tras la notificación del primer caso de la COVID-19 en Singapur el 23 de enero, se iniciaron una serie de siete sondeos sobre la COVID-19, tanto a personas que ya estaban participando como a personas nuevas que se inscribían con regularidad, cada dos semanas. Además de las propiedades sociodemográficas de las personas participantes, se registraron las nuevas respuestas para juzgar el conocimiento de la situación, la confianza en las diversas fuentes de información y la percepción del riesgo. Se emplearon modelos de regresión logística multivariante para evaluar las asociaciones con las percepciones de riesgo y las frecuencias adoptadas de comportamientos protectores que facilitaron las personas participantes.La cohorte de esta investigación integrada por 633 personas aportó 2857 respuestas únicas durante los siete sondeos de la COVID-19. La mayoría estuvo de acuerdo o muy de acuerdo en que la información de las fuentes oficiales del gobierno (99,1 %; 528/533) y de las agencias de noticias con sede en Singapur (97,9 %; 522/533) era fiable. La confianza en las comunicaciones del gobierno se asoció de manera significativa con una mayor percepción de amenaza (oportunidad relativa, OR: 2,2; intervalo de confianza del 95 %, IC: 1,6-3,0), pero se asoció de manera inversa con la percepción de riesgo de infección (OR: 0,6; IC del 95 %: 0,4-0,8) o de riesgo de muerte si había contagio (OR: 0,6; IC del 95 %: 0,4-0,9). La confianza en las comunicaciones del gobierno también se asoció con una mayor probabilidad de adoptar comportamientos protectores.Los resultados indican que la confianza es un elemento vital para gestionar un brote epidémico en evolución. Los estudios que se realizaron de manera repetida aportaron información en tiempo real, lo que permitió mejorar la comprensión de la interacción entre las percepciones, la confianza y el comportamiento.الغرض تقييم مدى تأثير التصورات العامة والثقة في الاتصالات الحكومية على تبني السلوك الوقائي في سنغافورة أثناء جائحة مرض فيروس كورونا (كوفيد 19). الطريقة أطلقنا مجموعتنا المجتمعية لتقييم التصورات العامة لحالات تفشي هذا المرض المعدي في منتصف عام 2019. وبعد الإبلاغ عن الحالة الأولى للإصابة بكوفيد 19 في سنغافورة في 23 يناير/كانون ثاني، أطلقنا سلسلة من المسوح السبعة عن كوفيد 19 لكل من المشاركين الجدد الحاليين والمسجلين بانتظام كل أسبوعين. وبالإضافة إلى الخصائص الاجتماعية الديموغرافية للمشاركين، قمنا بتسجيل استجابات متغيرة للحكم على الوعي بالموقف، والثقة في مصادر المعلومات المتنوعة والمخاطر المتصورة. وقمنا باستخدام نماذج تحوّف لوجيستي متعدد المتغيرات لتقييم الارتباطات مع تصورات المخاطر وأنماط التكرار المتبعة، والتي تم الإبلاغ عنها ذاتيًا، للسلوك الوقائي. النتائج قدمت مجموعتنا المكونة من 633 مشاركًا، 2857 استجابة فريدة أثناء المسوح السبعة حول كوفيد 19. وافقت الغالبية، أو وافقت بشكل مؤكد، على أن المعلومات الواردة من المصادر الحكومية الرسمية (99.1%؛ 528/533)، وأن وكالات الأنباء في سنغافورة (97.9%؛ 522/533) كانت جديرة بالثقة. ارتبطت الثقة في الاتصالات الحكومية بشكل كبير بالتهديد الملموس بشكل أكبر (نسبة الاحتمالات: 2.2؛ فاصل الثقة 95%: 1.6 إلى 3.0) ولكنها ارتبطت بشكل عكسي مع الخطر المتصور للإصابة بالعدوى (نسبة الاحتمالات: 0.6؛ ‏بفاصل ثقة 95%: 0.4 إلى 0.8) أو خطر الوفاة في حالة الإصابة بالعدوى (نسبة الاحتمالات: 0.6؛ ‏بفاصل ثقة 95%: 0.4–0.9). كما ارتبطت الثقة في الاتصالات الحكومية باحتمالية أكبر لاتباع السلوك الوقائي. الاستنتاج توضح النتائج التي توصلنا إليها أن الثقة هي ضرورة حيوية عند إدارة حالة التفشي الجارية. قدمت المسوح المتكررة الخاصة بنا ملاحظات في الوقت الفعلي، مما سمح بتحقيق فهمًا أفضل للتفاعل بين التصورات والثقة والسلوك.旨在评估在冠状病毒病（新型冠状病毒肺炎）大流行期间，公众对政府通信的看法和信任如何影响新加坡采取保护措施。.我们发起了基于社区的群组研究，以评估公众对 2019 年年中传染病疫情的看法。1 月 23 日新加坡报告首例新型冠状病毒肺炎病例后，我们发起了一系列的（7 项）新型冠状病毒肺炎调查，每 2 周对现有的参与者和定期招募的新参与者进行一次调查。结合参与者的社会人口统计特征，我们记录了不断变化的应对方式以判断是否了解情况、信任各种信息源和感知风险。我们采用多变量逻辑回归模型评估风险感知与自我报告保护行为实施频率之间的关联。.我们的 633 名参与者在 7 项新型冠状病毒肺炎调查中提供了 2857 份独特的答案。大多数人赞同或非常赞同政府提供的官方信息（99.1%；528/533）和新加坡本地新闻机构提供的信息（97.9%；522/533）值得信赖。对政府通信的信任与较高的感知威胁显著相关（比值比，OR：2.2；95% 置信区间，CI：1.6-3.0），但与感知的感染风险（OR：0.6；95% CI：0.4–0.8）或感染后的死亡风险（OR：0.6；95% CI：0.4-0.9）成反比。对政府通信的信任也与更有可能采取保护行为相关。.我们的研究结果表明，在处理不断发展的疫情时，信任是至关重要的因素。我们反复进行的调查提供了实时反馈，让人可以更好地理解感知、信任和行为之间的相互影响。.Оценить, как общественное мнение и доверие к заявлениям правительства повлияли на принятие мер защитного поведения в Сингапуре во время пандемии коронавируса (COVID-19).В середине 2019 года из местного населения была сформирована когорта для оценки общественного мнения о вспышках инфекционных заболеваний. После того как 23 января в Сингапуре был зарегистрирован первый случай заболевания COVID-19, авторы запустили серию из семи опросов по COVID-19, проводимых каждые 2 недели, для существующих и регулярно набираемых новых участников. Помимо социально-демографических характеристик участников, авторы регистрировали изменения в ответах, чтобы оценить осведомленность о ситуации, доверие к различным источникам информации и предполагаемый риск. Авторы использовали многовариантные модели логистической регрессии для оценки ассоциаций с восприятием риска и принятой частотой применения мер защитного поведения, о которой сообщали участники.Когорта из 633 участников предоставила 2857 уникальных ответов в ходе семи опросов по COVID-19. Большинство участников согласились или полностью согласились с тем, что информация из официальных государственных источников (99,1%; 528/533) и сингапурских информационных агентств (97,9%; 522/533) заслуживает доверия. Доверие к заявлениям правительства было в значительной степени связано с более высокой предполагаемой угрозой (отношение шансов, ОШ: 2,2; 95%-й доверительный интервал, ДИ: 1,6–3,0), но обратно пропорционально связано с предполагаемым риском заражения (ОШ: 0,6; 95%-й ДИ: 0,4–0,8) или с риском смерти в случае заражения (ОШ: 0,6; 95%-й ДИ: 0,4–0,9). Доверие к заявлениям правительства также было связано с большей вероятностью принятия мер защитного поведения.Полученные результаты свидетельствуют о том, что доверие является жизненно важным ресурсом в борьбе с развивающейся вспышкой. Неоднократные опросы обеспечили обратную связь в режиме реального времени, позволяя лучше понять взаимосвязь между восприятием, доверием и поведением.

Introduction: Two billion population are at risk of dengue fever and by 2080, over six billion population will be at risk. Hepatitis is common in dengue and the liver is invariably involved in severe cases. We conducted a literature review using the PubMed database on articles covering a broad range of issues related to dengue and hepatitis.Areas covered: This article overviews available literature on changes in the definition of severe dengue, pathogenesis of liver involvement in dengue, clinical manifestations, and predictors of mortality in severe dengue with liver involvement, impact of viral hepatitis co-infections and hepatotoxic drugs, and hemophagocytic lymphohistiocytosis.Expert commentary: Hepatitis is commonly seen in dengue however the degree of elevation of transaminases did not correlate well with severity of illness in observational studies, except in the elderly. The underlying pathogenesis of liver injury is still being elucidated and further studies are required to fully understand the cellular pathways. Acute or chronic viral hepatitis does not appear to affect dengue outcomes. Commonly used medications such as paracetamol and statins may influence dengue outcomes.

Background: Monitoring of blood pressure is an important part of management of dengue illness. Large scale studies of temporal trend of blood pressure in adult dengue are lacking. In this study, we examined the differences in time trend of systolic (SBP) and diastolic blood pressure (DBP) in patients with and without severe dengue (SD), dengue hemorrhagic fever (DHF) and pre-existing hypertension, and elderly versus non-elderly patients. Methods: We studied a retrospective cohort from 2005 to 2008 of 6,070 hospitalized adult dengue patients confirmed by polymerase chain reaction or clinical criteria plus positive dengue serology. Dengue severity was defined according to World Health Organization 1997 and 2009 guidelines. We used Bayesian hierarchical Markov models to compare the daily mean SBP and DBP between different subgroups. Analysis was conducted by day of defervescence (denoted as day 0), and day of illness onset (denoted as day 1) respectively. Results: SBP decreased to a nadir during the critical phase before defervescence and was significantly lower for patients with SD or DHF, compared with patients without SD or DHF. DBP increased marginally more for patients with SD or DHF in the critical phase before defervescence. By day of defervescence, comparison of patients with and without SD showed significant difference in SBP from day -6 to day +6, except days +1, +3 and +5, and similarly in DBP except days 0, and +4 to +6. Comparison of patients with and without DHF showed significant difference in SBP from day -6 to day -1, but for DBP, significant difference was noted from day -6 to day +6, except day -2 to day 0. By day of illness, SBP differed significantly between patients with and without SD from illness days 1 to 10, and DBP from illness days 7 to 12. Between patients with and without DHF, SBP differed significantly on illness days 1, 2, 4 to 7, while DBP from days 7 to 12. On analysis by days of defervescence or by days of illness, elderly patients and those with hypertension showed consistently higher SBP and DBP throughout their hospitalization, as compared with their younger and non-hypertensive counterparts. Conclusions: In SD or DHF, SBP decreased to a nadir around the day of defervescence, and recovered to a level exceeding that in febrile phase by days 2 or 3 post-defervescence. Elderly patients and patients with pre-existing hypertension maintained higher SBP and DBP throughout the duration of dengue infection. National Medical Research Council (NMRC) National Research Foundation (NRF) Published version This work was supported by the National Research Foundation through the National Medical Research Council, Singapore [Grant Number NMRC/TCR/005/2008]. The funders had no role in study design, data collection, analysis, decision to publish or preparation of the manuscript.

Background: To demonstrate the use of a cohort for assessing knowledge, perceptions and behaviours of the Singapore population towards infectious disease outbre

Dengue is endemic in tropical countries worldwide and the four dengue virus serotypes often co-circulate. Infection with one serotype results in high titers of cross-reactive antibodies produced by plasmablasts, protecting temporarily against all serotypes, but impairing protective immunity in subsequent infections. To understand the development of these plasmablasts, we analyzed virus-specific B cell properties in patients during acute disease and at convalescence. Plasmablasts were unrelated to classical memory cells expanding in the blood during early recovery. We propose that only a small subset of memory B cells is activated as plasmablasts during repeat infection and that plasmablast responses are not representative of the memory B cell repertoire after dengue infection., Highlights • Antibody sequences and functions were analyzed in longitudinal acute and convalescent samples from dengue patients • Plasmablast antibodies were virus glycoprotein-specific whereas memory B cell-derived antibodies bound to more viral proteins • plasmablasts seem to be activated from only a small subset of memory B cells Antibody-mediated immune memory is orchestrated by various B cell types that are relevant during different phases after an infection. Antibody-secreting cells or so-called plasmablasts are generated from activated specific memory B cell a few days after re-infection. However, little in known whether the antibodies produced by these plasmablasts are relevant for protection in humans and whether the parent memory B cells are further maintained in the memory pool, possibly as affinity-matured versions of the original clones. This is important in the context of vaccination since the repertoires of individual B cell subsets could represent biomarkers to assess efficacy and long-term protection. In addition, the generation of “protective” B cell subsets could potentially be influenced by vaccine design and by the use of adjuvants. We studied the relationship of plasmablasts and memory B cells in longitudinal blood samples from dengue patients. Dengue virus (DENV) has four serotypes and pre-existing antibodies can be cross-protective or can enhance disease after a heterologous infection via Fc-gamma-receptor-mediated uptake of virus-antibody complexes. B cell memory can therefore be both beneficial and detrimental. Here we studied plasmablasts and DENV-specific memory B cells and their relationship and protective potential by assessing antibody sequences and monoclonal antibodies. We found that both populations produced largely serotype cross-neutralizing antibodies, whereas more plasmablast antibodies were neutralizing. Few plasmablast clones could be found in the memory pool, suggesting that only a subset of memory B cells is activated during acute disease and that a separate repertoire of cells is retained as longer-term memory. In this study we started to dissect the complexity of B cell immune memory to dengue infection and the finding can inform further investigations into which immune cell subsets are disease-enhancing after a heterologous infection.

Globally, dengue virus (DENV) is one of the most widespread vector-borne viruses. Dengue disease affects populations in endemic areas and, increasingly, tourists who travel to these countries, but there is currently no approved vaccine for dengue. A phase 3 efficacy trial with Sanofi-Pasteur's recombinant, live-attenuated, tetravalent dengue vaccine (CYD-TDV) conducted in South East Asia showed an overall efficacy of 56% against virologically confirmed dengue infections of any severity and any of the 4 serotypes, but the long-term protection of the vaccine has yet to be demonstrated. To address longevity of antibody titers and B cell memory, we recalled study participants from an earlier CYD immunogenicity study (Phase 2) conducted in Singapore that enrolled healthy volunteers in the year 2009. Depending on the age group, 57-84% of the participants initially generated a neutralizing antibody titer ≥ 10 to all 4 DENV serotypes 28 d after the third and final dose. We observed very low antibody titers in blood samples collected from 23 vaccinees 5 y after the first dose, particularly titers of antibodies binding to virus particles compared with those binding to recombinant E protein. The in vivo efficacy of plasma antibodies against DENV-2 challenge was also tested in a mouse model, which found that only 2 out of 23 samples were able to reduce viremia. Although the sample size is too small for general conclusions, dengue immune memory after vaccination with CYD-TDV appears relatively low.

Studies on serotype-specific features of dengue and disease severity on adults are limited. We prospectively recruited adult febrile patients without alternate diagnosis to dengue from April 2005 to December 2011. Outcomes were defined using both the World Health Organization (WHO) 1997 and 2009 criteria; Dengue hemorrhagic fever (DHF) and severe dengue (SD). Infecting serotype was identified in 469 dengue-confirmed patients comprising 22.0% dengue virus serotype 1 (DENV-1), 57.1% DENV-2, 17.1% DENV-3, and 3.8% DENV-4. Cases infected with DENV-1 were more likely to present with red eyes whereas presence of joint pain and lower platelet count was associated with DENV-2 cases. After adjusting for potential confounders, DENV-1 was associated with both DHF (adjusted Relative Risk [aRR] = 1.74) and SD (aRR = 2.1) whereas DENV-2 had a lower risk of DHF (aRR = 0.5). DENV-1 genotype 1 and DENV-2 cosmopolitan were the predominant genotypes identified. Infecting dengue serotype and possibly genotype may play an important role in disease severity among adult dengue patients in Singapore.

Clinical characteristics and outcome among dengue patients with and without human immunodeficiency virus (HIV) infection remain elusive. A total of 10 dengue virus (DENV)–HIV Chinese patients were compared with 40 Chinese dengue patients without HIV, who were matched for age, gender, type of care received, methods, and year of dengue diagnosis from 2005 to 2008. Univariate and multivariate conditional logistics regression were applied. DENV-HIV patients were significantly associated with the World Health Organization (WHO) 2009 severe dengue (conditional odds ratio [COR] = 5.72; 95% confidence interval [CI] = 1.01–32.64) but not with the WHO 1997 dengue hemorrhagic fever/dengue shock syndrome (COR = 0.40; 95% CI = 0.09–1.71). This is mainly due to severe plasma leakage and the lack of hemorrhagic manifestations. Hospitalization duration was longer for DENV-HIV patients (10.5 days; interquartile range [IQR] = 5.5–26.3 days) compared with dengue patients (5 days; IQR = 4–6 days). There were no significant differences in presentation of clinical warning signs and symptoms at admission and during hospitalization, except for rash (adjusted COR [ACOR] = 0.06; 95% CI = 0.03–0.92). DENV-HIV patients were associated with higher pulse rate (ACOR = 1.13; 95% CI = 1.02–1.25), eosinophils proportion (ACOR = 3.07; 95% CI = 1.12–8.41) and lower hematocrit level (ACOR = 0.79; 95% CI = 0.64–0.98) compared with dengue patients. Even though DENV-HIV patients may present similarly to dengue patients, they may be more likely to have severe dengue outcome. Hence, close monitoring of DENV-HIV patients is highly recommended as part of dengue clinical care and management.

Background In the aftermath of an upsurge in the number of dengue cases in 2013 and 2014, the SD BIOLINE Dengue Duo rapid diagnostic Point-of-Care Test (POCT) kit was introduced in Tan Tock Seng Hospital, Singapore in June 2013. It is known that the success of POCT usage is contingent on its implementation within the health system. We evaluated health services delivery and the Dengue Duo rapid diagnostic test kit application in Singapore from healthcare workers’ perspectives and patient experiences of dengue at surge times. Methods Focus group discussions were conducted with dengue patients, from before and after the POCT implementation period. In-depth interviews with semi-structured components with healthcare workers were carried out. A patient centred process mapping technique was used for evaluation, which mapped the patient’s journey and was mirrored from the healthcare worker’s perspective. Results Patients and healthcare workers confirmed a wide range of symptoms in adults, making it challenging to determine diagnosis. There were multiple routes to help seeking, and no ‘typical patient journey’, with patients either presenting directly to the hospital emergency department, or being referred there by a primary care provider. Patients groups diagnosed before and after POCT implementation expressed some differences between speed of diagnoses and attitudes of doctors, yet shared negative feelings about waiting times and a lack of communication and poor information delivery. However, the POCT did not in its current implementation do much to help waiting times. Healthcare workers expressed that public perceptions of dengue in recent years was a major factor in changing patient management, and that the POCT kit was helpful in improving the speed and accuracy of diagnoses. Conclusions Health service delivery for dengue patients in Singapore was overall perceived to be of an acceptable clinical standard, which was enhanced by the introduction of the POCT. However, improvements can be focused on Adapting to outbreaks by reducing and rendering Waiting experiences more comfortable; Advancing education about symptom recognition, while also Recognising better communication strategies; and Expanding follow-up care options. This is presented as the Dengue AWARE model of care delivery.

Plasma leakage is a major pathogenic mechanism of severe dengue, but the etiology remains unclear. The association between endothelial glycocalyx integrity and vascular permeability in older adults with dengue has not been evaluated. A prospective cohort study of adults with undifferentiated fever screened for dengue by RT-PCR or NS1 antigen testing was performed. Patients were assessed daily while symptomatic and at convalescence. Serum hyaluronic acid (HA), heparan sulfate (HS) and selected cytokines (TNF-α, IL-6, IL-10) were measured on enrollment and convalescence. Patients were diagnosed as dengue fever (DF, n = 30), dengue hemorrhagic fever (DHF, n = 20) and non-dengue (ND) febrile illness (n = 11). Acute HA and HS levels were significantly higher in all dengue patients compared to ND (p = 0.0033 and p = 0.0441 respectively), but not different between DF and DHF (p = 0.3426 and p = 0.9180 respectively). Enrolment HA inversely correlated with serum albumin, protein and platelets in all dengue and DHF (p

Background Dengue virus infection typically causes mild dengue fever, but, in severe cases, life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) occur. The pathophysiological hallmark of DHF and DSS is plasma leakage that leads to enhanced vascular permeability, likely due to a cytokine storm. Methods Ninety patients with dengue during 2010-2012 in Singapore were prospectively recruited and stratified according to their disease phase, primary and secondary infection status, and disease severity, measured by plasma leakage. Clinical parameters were recorded throughout the disease progression. The levels of various immune mediators were quantified using comprehensive multiplex microbead-based immunoassays for 46 immune mediators. Results Associations between clinical parameters and immune mediators were analyzed using various statistical methods. Potential immune markers, including interleukin 1 receptor antagonist, interferon γ-inducible protein 10, hepatocyte growth factor, soluble p75 tumor necrosis factor α receptor, vascular cell adhesion molecule 1, and matrix metalloproteinase 2, were significantly associated with significant plasma leakage. Secondary dengue virus infections were also shown to influence disease outcome in terms of disease severity. Conclusions This study identified several key markers for exacerbated dengue pathogenesis, notably plasma leakage. This will allow a better understanding of the molecular mechanisms of DHF and DSS in patients with dengue.

Studies on severe neutropenia in dengue are scarce, and its clinical significance is uncertain. We analyzed a cohort of 1,921 reverse transcription polymerase chain reaction-confirmed adult dengue patients admitted to the Communicable Disease Center in Singapore between 2005 and 2008. Time trend analyses for daily absolute neutrophil counts (ANCs) were done using Bayesian hierarchical and Markov models. We found that severe neutropenia, defined as ANC ≤ 0.5 × 109/L, was found in 11.8% with a median duration of 1 day. ANC nadir occurred on illness day 5. Severe neutropenia was not predictive of more severe disease and not associated with secondary bacterial infections, prolonged hospital stay, prolonged fever, or fatal outcome. We concluded that prophylactic antibiotics are not indicated in patients with severe neutropenia without indication for bacterial infection. Published version

Neurological manifestations due to Dengue virus (DENV) infection are atypical and uncommon. Genomic information of clinically characterised, neurotrophic DENV in humans is extremely limited albeit their importance in deciphering the pathogenicity is substantial. Here, we report a rare case of fatal DENV-4 infection complicated with encephalitis and multi-organ failure. The clinical presentation was unusual due to its rapid onset of encephalitis despite a very low virus titre. Full genomes of serum and CSF-derived viruses shared 99.99% similarity, indicating the virus dissemination across blood–brain barrier. Even though virus genomes did not reveal any of the neurotrophic substitutions of DENV documented so far, case isolates possessed a combination of 8 novel amino acid alterations, predominantly distributed in non-structural genes of DENV-4.

Background Thrombocytopenia is a hallmark of dengue infection, and bleeding is a dreaded complication of dengue fever. Prophylactic platelet transfusion has been used to prevent bleeding in the management of dengue fever, although the evidence for its benefit is lacking. In adult dengue patients with platelet count 50,000/mm3 and increasing length of hospitalization., Author Summary Thrombocytopenia is one of the most prominent clinical features in dengue infection. This may manifest clinically as bleeding, which carries significant morbidity and mortality. For many years, clinicians have given dengue patients platelet transfusion in a bid to increase their platelet counts to prevent hemorrhagic manifestations. However, this practice has not been proven to reduce the risk of bleeding in dengue. Conversely, transfusion of blood products may be detrimental to patients as it can carry risks of fluid overload, transmission of infectious diseases and transfusion reactions. In this study, the authors found that platelet transfusion in the absence of bleeding in adult dengue patients did not prevent bleeding. Instead, this practice is associated with a slower platelet recovery and increased length of hospitalisation. These findings may contribute to better clinical management of thrombocytopenia in dengue patients and limit the use of these precious blood products.

Dengue fever is gaining importance in Singapore with an increase in the number of cases and mortality in recent years. Although prolonged and saddleback fever have been reported in dengue fever, there are no specific studies on their significance in dengue. This study aims to examine the prevalence of prolonged and saddleback fever in dengue as well as their associations with dengue severity. A total of 2843 polymerase-chain reaction (PCR) confirmed dengue patients admitted to Tan Tock Seng Hospital from 2004 to 2008 were included in the study. Sixty-nine percent of them were male with a median age of 34 years. Prolonged fever (fever > 7 days duration) was present in 572 (20.1%) of patients. Dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS) and severe dengue (SD) were significantly more likely to occur in patients with prolonged fever. Mucosal bleeding, anorexia, diarrhea, abdominal pain, nausea or vomiting, lethargy, rash, clinical fluid accumulation, hepatomegaly, nosocomial infection, leukopenia, higher neutrophil count, higher hematocrit, higher alanine transaminase (ALT) and aspartate transaminase (AST), higher creatinine, lower protein and prolonged activated partial thromboplastin time (APTT) were significantly associated with prolonged fever but not platelet count or prothrombin time (PT). Saddleback fever was present in 165 (5.8%). Although DHF and SD were more likely to occur in patients in those with saddleback fever, DSS was not. Compared with prolonged fever, saddleback fever did not show many significant associations except for diarrhea, abdominal pain, clinical fluid accumulation, hematocrit and platelet change, and lower systolic blood pressure. This study demonstrates that prolonged fever may be associated with various warning signs and more severe forms of dengue (SD, DSS, DHF), while saddleback fever showed associations with DHF and SD but not DSS. The presence of prolonged or saddleback fever in dengue patients should therefore prompt detailed evaluation for complications of dengue, as well as early investigation to evaluate for development of nosocomial infection. Published version

Background: Clinically significant bleeding is important for subsequent optimal case management in dengue patients, but most studies have focused on dengue severity as an outcome. Our study objective was to identify differences in admission parameters between patients who developed clinically significant bleeding and those that did not. We sought to develop a model for discriminating between these patients. Methods: We conducted a retrospective study of 4,383 adults aged >18 years who were hospitalized with dengue infection at Tan Tock Seng Hospital, Singapore from 2005 to 2008. Patients were divided into those with clinically significant bleeding (n = 188), and those without (n = 4,195). Demographic, clinical, and laboratory variables on admission were compared between groups to determine factors associated with clinically significant bleeding during hospitalization. Results: On admission, female gender (p38°C (p38°C (aOR 1.81; 95% CI: 1.27–2.61), nausea/vomiting (aOR 1.39; 95% CI: 0.94–2.12), ANC (aOR 1.3; 95% CI: 1.15–1.46), ALC (aOR 0.4; 95% CI: 0.25–0.64), hematocrit percentage (aOR 0.96; 95% CI: 0.92–1.002) and platelet count (aOR 0.993; 95% CI: 0.988–0.998). At the cutoff of -3.919, the model achieved an AUC of 0.758 (sensitivity:0.87, specificity: 0.38, PPV: 0.06, NPV: 0.98). Conclusion: Clinical risk factors associated with clinically significant bleeding were identified. This model may be useful to complement clinical judgement in triaging adult dengue patients given the dynamic nature of acute dengue, particularly in pre-identifying those less likely to develop clinically significant bleeding. NMRC (Natl Medical Research Council, S’pore) Published version

Background Dengue results in a significant public health burden in endemic regions. The World Health Organization (WHO) recommended the use of warning signs (WS) to stratify patients at risk of severe dengue disease in 2009. However, WS is limited in stratifying adult dengue patients at early infection (Day 1–3 post fever), who require close monitoring in hospitals to prevent severe dengue. The aim of this study is to identify and validate prognostic models, built with differentially expressed biomarkers, that enable the early identification of those with early dengue infection that require close clinical monitoring. Methods RNA microarray and protein assays were performed to identify differentially expressed biomarkers of severity among 92 adult dengue patients recruited at early infection from years 2005–2008. This comprised 47 cases who developed WS after first presentation and required hospitalization (WS+Hosp), as well as 45 controls who did not develop WS after first presentation and did not require hospitalization (Non-WS+Non-Hosp). Independent validation was conducted with 80 adult dengue patients recruited from years 2009–2012. Prognostic models were developed based on forward stepwise and backward elimination estimation, using multiple logistic regressions. Prognostic power was estimated by the area under the receiver operating characteristic curve (AUC). Results The WS+Hosp group had significantly higher viral load (P

Introduction: Dengue fever remains a significant public health concern in Singapore. Appropriate, timely diagnosis and risk stratification for severe disease are crucial in the optimal management of this illness. In the outpatient setting, the primary care physician plays a key role in dengue diagnosis, management, and triage. We present a descriptive analysis of the variations in dengue knowledge, attitudes, and practices among primary care physicians (PCPs) in Singapore. Materials and Methods: A survey of 25 multiple-choice questions was mailed to 2000 PCPs in Singapore. Responses were analysed by physician age group (21-40, 41-60, and >61) and practice setting (government subsidised polyclinic or private practice). Results: Of the 3 questions assessing dengue knowledge, 89.9% chose 2 or 3 of the preferred responses. Half of the respondents utilised dengue diagnostic tests at least 50% of the time, and 75% used serology when doing so. Older respondents and those from private practices used diagnostic tests more often than their counterparts, and both groups favoured non-serology tests. About 85% of surveyed PCPs monitored confirmed or suspected cases daily, and one-third referred patients to a hospital always or often. Conclusions: While no major gaps in knowledge about dengue were identified in PCPs in Singapore, there were significant variations in clinical practice by physician age group and practice setting. The results of this survey provide a useful opportunity to identify strengths and areas in need of improved awareness in primary care management of dengue. Key words: Arbovirus, Guidelines, General practice, Ambulatory care

Dengue infection can affect the microcirculation by direct viral infection or activation of inflammation. We aimed to determine whether measured retinal vascular parameters were associated with acute dengue infection. Patients with acute dengue were recruited from Communicable Diseases Center, Singapore and age-gender-ethnicity matched healthy controls were selected from a population-based study. Retinal photographs were taken on recruitment and convalescence. A spectrum of quantitative retinal microvascular parameters (retinal vascular caliber, fractal dimension, tortuosity and branching angle) was measured using a semi-automated computer-based program. (Singapore I Vessel Assessment, version 3.0). We included 62 dengue patients and 127 controls. Dengue cases were more likely to have wider retinal arteriolar and venular calibers (158.3 μm vs 144.3 μm, p 4], p 4], p

Background/Purpose Bacteremia in dengue may occur with common exposure to pathogens in association with severe organ impairment or severe dengue, which may result in death. Cohort studies identifying risk factors for concurrent bacteremia among patients with dengue are rare. Methods We conducted a retrospective case–control study of adult patients with dengue who were admitted to the Department of Infectious Diseases at Tan Tock Seng Hospital, Singapore from 2004 to 2008. For each case of dengue with concurrent bacteremia (within the first 72 hours of admission), we selected four controls without bacteremia, who were matched on year of infection and dengue confirmation method. Conditional logistic regression was performed to identify risk factors for concurrent bacteremia. Results Among 9,553 patients with dengue, 29 (0.3%) had bacteremia. Eighteen of these patients (62.1%) had concurrent bacteremia. The predominant bacteria were Staphylococcus aureus , one of which was a methicillin-resistant strain. Dengue shock syndrome occurred more frequently and hospital stay was longer among cases than among controls. Three cases did not survive, whereas none of the controls died. In multivariate analysis, being critically ill at hospital presentation was independently associated with 15 times the likelihood of a patient with dengue having concurrent bacteremia. Conclusion Concurrent bacteremia in adult patients with dengue is uncommon but presents atypically and results in more deaths and longer hospital stay. Given the associated mortality, collection of blood cultures and empiric antibiotic therapy may be considered in patients who are critically ill.

Background Understanding changes in the ecology and epidemiology of dengue is important to ensure resource intensive control programmes are targeted effectively as well as to inform future dengue vaccination strategies. Methods We analyzed data from a multicentre longitudinal prospective study of fever in adults using a nested test negative case control approach to identify epidemiological risk factors for dengue disease in Singapore. From April 2005 to February 2013, adult patients presenting with fever within 72 h at selected public primary healthcare clinics and a tertiary hospital in Singapore were recruited. Acute and convalescent blood samples were collected and used to diagnose dengue using both PCR and serology methods. A dengue case was defined as having a positive RT-PCR result for DENV OR evidence of serological conversion between acute and convalescent blood samples. Similarly, controls were chosen from patients in the cohort who tested negative for dengue using the same laboratory methods. Results The host epidemiological factors which increased the likelihood of dengue disease amongst adults in Singapore were those aged between 21 and 40 years old (2 fold increase) while in contrast, Malay ethnicity was protective (OR 0.57, 95%CI 0.35 to 0.91) against dengue disease. Spatial factors which increased the odds of acquiring dengue was residing at a foreign workers dormitory or hostel (OR 3.25, 95 % CI 1.84 to 5.73) while individuals living in the North-West region of the country were less likely to get dengue (OR 0.50, 95%CI 0.29 to 0.86). Other factors such as gender, whether one primarily works indoors or outdoors, general dwelling type or floor, the type of transportation one uses to work, travel history, as well as self-reported history of mosquito bite or household dengue/fever were not useful in helping to inform a diagnosis of dengue. Conclusions We have demonstrated a test negative study design to better understand the epidemiological risk factors of adult dengue over multiple seasons. We were able to discount other previously speculated factors such as gender, whether one primarily works indoors or outdoors, dwelling floor in a building and the use of public transportation as having no effect on one’s risk of getting dengue.

Dengue, which is the most prevalent mosquito-borne viral disease afflicting human populations, causes a spectrum of clinical symptoms that include fever, muscle and joint pain, maculopapular skin rash, and hemorrhagic manifestations. Patients infected with dengue develop a broad antigen-specific T lymphocyte response, but the phenotype and functional properties of these cells are only partially understood. We show that natural infection induces dengue-specific CD8+ T lymphocytes that are highly activated and proliferating, exhibit antiviral effector functions, and express CXCR3, CCR5, and the skin-homing marker cutaneous lymphocyte-associated antigen (CLA). In the same patients, bystander human cytomegalovirus –specific CD8+ T cells are also activated during acute dengue infection but do not express the same tissue-homing phenotype. We show that CLA expression by circulating dengue-specific CD4+ and CD8+ T cells correlates with their in vivo ability to traffic to the skin during dengue infection. The juxtaposition of dengue-specific T cells with virus-permissive cell types at sites of possible dengue exposure represents a previously uncharacterized form of immune surveillance for this virus. These findings suggest that vaccination strategies may need to induce dengue-specific T cells with similar homing properties to provide durable protection against dengue viruses. ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version

Background Dengue infection can result in severe clinical manifestations requiring intensive care. Effective triage is critical for early clinical management to reduce morbidity and mortality. However, there is limited knowledge on early risk factors of intensive care unit (ICU) requirement. This study aims to identify early clinical and laboratory risk factors of ICU requirement at first presentation in hospital and 24 hours prior to ICU requirement. Method A retrospective 1:4 matched case–control study was performed with 27 dengue patients who required ICU, and 108 dengue patients who did not require ICU from year 2004–2008, matched by year of dengue presentation. Univariate and multivariate conditional logistic regression were performed. Optimal predictive models were generated with statistically significant risk factors identified using stepwise forward and backward elimination method. Results ICU dengue patients were significantly older (P=0.003) and had diabetes (P=0.031), compared with non-ICU dengue patients. There were seven deaths among ICU patients at median seven days post fever. At first presentation, the WHO 2009 classification of dengue severity was significantly associated (P

In a prospective longitudinal adult study, vascular nitric oxide bioavailability measured as reactive hyperemia index was significantly higher at enrollment in patients who developed dengue hemorrhagic fever (DHF) (n = 11), compared with the non-DHF group (n = 63) and those with other febrile illnesses (n = 25) (P = .01). After adjustment for age, fever day, and body mass index, enrollment reactive hyperemia index was associated with a 4-fold increased risk for DHF, and predicted DHF with an area under the receiver operating curve of 0.86. Increased vascular nitric oxide in dengue is associated with increased vascular permeability and impaired homeostasis and may have utility as a predictor of DHF.