Maternal Immunity and Vaccination Influence Disease Severity in Progeny in a Novel Mast Cell-Deficient Mouse Model of Severe Dengue.

Sub-neutralizing concentrations of antibodies in dengue infected patients is a major risk factor for the development of dengue hemorrhagic fever and dengue shock syndrome. Here, we describe a mouse model with a deficiency in mast cells (MCs) in addition to a deficiency in Type-I and II IFN receptors for studying dengue virus (DENV) infection. We used this model to understand the influence of MCs in a maternal antibody-dependent model of severe dengue, where offspring born to DENV-immune mothers are challenged with a heterologous DENV serotype. Mice lacking both MCs and IFN receptors were found susceptible to primary DENV infection and showed morbidity and mortality. When these mice were immunized, pups born to DENV-immune mothers were found to be protected for a longer duration from a heterologous DENV challenge. In the absence of MCs and type-I interferon signaling, IFN-γ was found to protect pups born to naïve mothers but had the opposite effect on pups born to DENV-immune mothers. Our results highlight the complex interactions between MCs and IFN-signaling in influencing the role of maternal antibodies in DENV-induced disease severity.

Dengue Virus Infection and Associated Risk Factors in Africa: A Systematic Review and Meta-Analysis.

Dengue contributes a significant burden on global public health and economies. In Africa, the burden of dengue virus (DENV) infection is not well described. This review was undertaken to determine the prevalence of dengue and associated risk factors. A literature search was done on PubMed/MEDLINE, Scopus, Embase, and Google Scholar databases to identify articles published between 1960 and 2020. Meta-analysis was performed using a random-effect model at a 95% confidence interval, followed by subgroup meta-analysis to determine the overall prevalence. Between 1960 and 2020, 45 outbreaks were identified, of which 17 and 16 occurred in East and West Africa, respectively. Dengue virus serotype 1 (DENV-1) and DENV-2 were the dominant serotypes contributing to 60% of the epidemics. Of 2211 cases reported between 2009 and 2020; 1954 (88.4%) were reported during outbreaks. Overall, the prevalence of dengue was 29% (95% CI: 20-39%) and 3% (95% CI: 1-5%) during the outbreak and non-outbreak periods, respectively. Old age (6/21 studies), lack of mosquito control (6/21), urban residence (4/21), climate change (3/21), and recent history of travel (3/21) were the leading risk factors. This review reports a high burden of dengue and increased risk of severe disease in Africa. Our findings provide useful information for clinical practice and health policy decisions to implement effective interventions.

Exposure to Dengue Envelope Protein Domain III Induces Nlrp3 Inflammasome-Dependent Endothelial Dysfunction and Hemorrhage in Mice.

Typically occurring during secondary dengue virus (DENV) infections, dengue hemorrhagic fever (DHF) causes abnormal immune responses, as well as endothelial vascular dysfunction, for which the responsible viral factor remains unclear. During peak viremia, the plasma levels of virion-associated envelope protein domain III (EIII) increases to a point at which cell death is sufficiently induced in megakaryocytes in vitro. Thus, EIII may constitute a virulence factor for endothelial damage. In this study, we examined endothelial cell death induced by treatment with DENV and EIII in vitro. Notably, pyroptosis, the major type of endothelial cell death observed, was attenuated through treatment with Nlrp3 inflammasome inhibitors. EIII injection effectively induced endothelial abnormalities, and sequential injection of EIII and DENV-NS1 autoantibodies induced further vascular damage, liver dysfunction, thrombocytopenia, and hemorrhage, which are typical manifestations in DHF. Under the same treatments, pathophysiological changes in the Nlrp3 inflammasome-deficient mice were notably reduced compared with those in the wild-type mice. These results suggest that the Nlrp3 inflammasome constitutes a potential therapeutic target for treating DENV-induced hemorrhage in DHF.

Eficacia y seguridad de la vacuna contra el dengue / Efficacy and safety of dengue vaccine

El dengue es un problema creciente para la salud pública mundial. En Argentina, los casos se han ido incrementado en los últimos años. La vacuna Dengvaxia (CYD-TDV) fue aprobada por la Agencia Nacional de Medicamentos, Alimentos y Tecnología (ANMAT) en 2017, y actualmente está indicada para personas entre los 9 y 45 años de edad que residan enzonas endémicas. A partir de la consulta de una paciente sobre la posibilidad de vacunarse contra el dengue, la autora se plantea la pertinencia de su indicación, teniendo en cuenta la eficacia y seguridad de la vacuna. Luego de una búsqueda rápida se encontró evidencia que señala que la vacuna contra el dengue CYD-TDV mostró poca eficacia en comparación con otras vacunas disponibles en el mercado, siendo más segura y eficaz en personas que ya han sido infectadas anteriormente por el virus del dengue (sujetos seropositivos). En cambio, se observó un aumento del riesgo de dengue grave en los infectados por vez primera tras la vacunación (sujetos seronegativos). Se concluye que la estrategia recomendada consiste en vacunar únicamente a las personas que hayan tenido infección por dengue con anterioridad, consistiendo en una buena práctica la toma de decisiones compartidas con cada paciente. (AU)

Dengue is a growing problem for global public health. In Argentina, cases have been increasing in recent years. The Dengvaxia vaccine (CYD-TDV) was approved by the National Agency for Medicines, Food and Technology in 2017, and it is currently indicated for people between 9 and 45 years of age who reside in endemic areas. Based on the consultation of a patient about the possibility of being vaccinated against dengue, the author considers the relevance of its indication, taking into account the efficacy and safety of the vaccine. After a quick search, evidence was found that indicates that the CYD-TDV dengue vaccine showed little efficacy compared to other vaccines available on the market, being safer and more effective in people who have already been previously infected by the dengue virus (seropositive subjects). In contrast, an increased risk of severe dengue was observed in those infected for the first time after vaccination (seronegative subjects). It is concluded that the recommended strategy consists of vaccinating only people who have had dengue infection before, making shared decisions with each patient a good practice. (AU)

Mast cell mediators in relation to dengue severity: A systematic review and meta-analysis.

BACKGROUND: Degranulation of mast cells (MCs) releases several mediators such as vascular endothelial growth factor (VEGF), chymase, tryptase, histamine, and cytokines, which all have important roles in the severity of dengue infection. We aimed to investigate the role of MCs in severity of dengue. METHODS: We searched for relevant studies in 10 databases on 15 August 2016. Meta-analysis (MA) was conducted by R version 3.5.0. RESULTS: We included 24 studies. in vivo and in vitro studies showed higher MC products released from infected mice/cells with dengue virus. In addition, when administering MC stabilizers or antihistaminic drugs, there was a decrease in vascular/capillary permeability. In human and at early stages, studies revealed an insignificant difference in VEGF levels in dengue fever (DF) versus dengue hemorrhagic fever (DHF) (standardized mean difference [SMD] 0.145; 95% confidence interval [CI], -0.348-0.638). Meanwhile, at acute stages and compared with healthy controls, high heterogeneity with an inconclusive difference in VEGF levels were noted in DF and DHF. However, pooled serum and plasma levels of VEGF were increased significantly in dengue shock syndrome (DSS) versus healthy controls (SMD 0.65; 95% CI, 0.3-0.95). There were also significantly higher chymase levels in DHF patients compared with DF during the acute phase (MD -6.531; 95% CI, -12.2 to -0.9). CONCLUSION: VEGF and chymase levels are mediators in dengue pathogenesis. However, limited data were available to support their role in severe dengue cases. Further studies are needed to evaluate the function of other mediators in dengue severity.

Dengue infection during pregnancy in Burkina Faso: a cross-sectional study.

BACKGROUND: Dengue fever is prevalent in the world; in recent years, several outbreaks occurred in West Africa. It affects pregnant women. We aimed to assess the consequences of dengue fever on pregnant women and their fetuses during dengue epidemic in Burkina Faso. METHODS: We conducted a cross-sectional study from November 1, 2015 to January 31, 2017 in 15 public and private health facilities in Ouagadougou, using secondary data. Immunochromatographic rapid test Duo detecting specific antibodies, immunoglobin M/G and /or dengue non structural antigen1 virus was used to diagnose dengue cases. RESULTS: Out of 399 (48%) women registered during the study period, 25 (6%) were pregnant. The average age of pregnant women was 30 years, with 18 and 45 years as extremes. The main symptoms were fever (92%) and headache (92%). Nine patients (36%) had severe dengue characterized by bleeding (16%), neurological symptoms (16%) and acute respiratory distress (8%). Eight (32%) of the 25 women had early miscarriage and 8 (32%) women gave birth to viable fetuses. Among those with viable babies, 5 (20%) presented post-partum hemorrhage and 3 (12%) presented early delivery. The main fetal complications included 3 cases of acute fetal distress (12%). One case of maternal death (4%) and 4 cases of neonatal mortality (44.5%) were notified. CONCLUSION: Dengue fever occurring during pregnancy increases maternal and neonatal mortality. Its severe complications require specific monitoring of pregnant women until delivery.

Risk prediction for severe disease and better diagnostic accuracy in early dengue infection; the Colombo dengue study.

BACKGROUND: A major challenge in dengue management in resource limited settings is the confirmation of diagnosis. Clinical features of dengue often overlap with other infections and molecular diagnostic tools are not readily accessible to clinicians at hospitals. In addition, the prediction of plasma leakage in dengue is also difficult. Hematocrit level and ultrasound scans (combined with clinical parameters) are helpful to detect plasma leakage once it has happened, not before. METHODS: Colombo Dengue Study (CDS) is a prospective cohort study of clinically suspected adult dengue patients recruited from the National hospital of Sri Lanka (within the first 3 days of fever) that aimed to a) identify clinical and basic laboratory test parameters to differentiate dengue from non-dengue fever, b) evaluate the comparative efficacy of loop-mediated isothermal amplification (LAMP) for dengue diagnosis (vs. NS1 antigen test and RT-qPCR) and c) identify early associations that are predictive of plasma leakage or severe dengue. The basic laboratory tests considered here included hematological parameters, serum biochemistry and inflammatory markers. RESULTS: Only 70% of clinically suspected patients were confirmed as having dengue by either the NS1 antigen test or RT-qPCR. On a Bayesian latent class model which assumes no "gold standard", LAMP performed equally or better than RT-qPCR and NS1 antigen test respectively. When confirmed dengue patients were compared with others, the earlier group had significantly lower lymphocyte counts and higher aspartate aminotransferase levels (AST) within the first 3 days of fever. Confirmed dengue patients with plasma leakage had a lower mean age and a higher median baseline AST level compared to those without plasma leakage (p < 0.05). CONCLUSION: Clinical suspicion overestimates the true number of dengue patients. RT-LAMP is a potentially useful low-cost diagnostic tool for dengue diagnosis. Confirmed dengue patients had significantly higher AST levels and lower lymphocyte counts in early disease compared to others. In confirmed dengue patients, younger age and a higher AST level in early infection were associated with subsequent plasma leakage.

Unusual clinical manifestations of dengue disease - Real or imagined?

The disease caused by each of the four serotypes of dengue virus (DENV) have plagued humans since last century. Symptoms of dengue virus (DENV) infection range from asymptomatic to dengue fever (DF) to severe dengue disease (SDD). One third of the world's population lives in regions with active urban DENV transmission, and thousands of serologically naïve travelers visit these areas annually, making a significant portion of the human population at risk of being infected. Even though lifelong immunity to the homotypic serotype is achieved after a primary DENV infection. Heterotypic DENV infections may be exacerbated by a pre-existing immune memory to the primary infection and can result in an increased probability of severe disease. Not only, age, comorbidities and presence of antibodies transferred passively from dengue-immune mother to infants are considered risk factors to dengue severe forms. Plasma leakage and multiple organ impairment are well documented in the literature, affecting liver, lung, brain, muscle, and kidney. However, unusual manifestation, severe or not, have been reported and may require medical attention. This review will summarize and discuss the increasing reports of unusual manifestations in the clinical course of dengue infection.

Dengue fever in renal allograft recipients: Clinical course and outcome.

BACKGROUND: There are annual outbreaks of dengue infection in tropical and subtropical countries. This retrospective study aimed to assess the clinical manifestation of dengue and outcome in renal transplant recipients. METHODS: Renal transplant recipients diagnosed with dengue in the nephrology department during the outbreak from August 2015 to December 2015 were included in the study. RESULTS: Twenty patients developed dengue presenting during the outbreak. Mean age was 31.9 ± 8.8 years and all were males. Two patients had severe dengue (dengue hemorrhagic fever, dengue shock syndrome). Clinical presentation included febrile illness (95%), myalgia (65%), headache (30%), retro-orbital pain (10%), and mucocutaneous bleeding manifestations (10%). Three (15%) had third space fluid accumulation and 2 (10%) had hypotension. Ninety percent patients had thrombocytopenia, with 4 requiring platelet transfusion. Leucopenia (WBC < 4000/mm3 ) developed in 50% patients. About 60% had transient transaminitis. One patient with severed dengue expired and 1 recovered with IV immunoglobulin therapy. About 40% patients had rise in serum creatinine, with complete recovery in all patients. CONCLUSION: Clinical manifestations of dengue infection in renal transplant recipients were similar to that in general population. However, leucopenia necessitating temporary withdrawal of immunosuppression was common. Renal dysfunction was frequent but completely reversible.

Microparticles as prognostic biomarkers in dengue virus infection.

Promising biomarkers which may help predict the risk of developing severe dengue virus infection (DVI) are lacking and will be helpful. Thus the main aim of this study was to analyze the role of cell-derived microparticles (MP) in DVI. Sixty patients with DVI i.e. 18: dengue with warning signs (DWS); 1: DSS and 41: dengue without warning signs (DWOS); along with 15 controls (other febrile illness) were included in the study. The following MPs were assessed: annexinV, platelet (CD41a), red blood cell (RBC) (CD235a) and activated endothelial (CD62e) MPs. Patients with profound thrombocytopenia without bleeding had statistically elevated platelet MP (PMP) levels when compared to patients with profound thrombocytopenia with bleeding (p < .001). RBC MPs were found to be significantly elevated in the 2nd phase in patient with DWS which was seen earliest on day 4 of infection with a cut off of ≥2200 MPs/µl when compared to patients with DWOS (p < .0001). PMPs may prove to be a promising novel biomarker which helps discriminate patients in need of prophylactic platelet transfusion from those who do not. RBC MPs, on the other hand could be potential biomarkers capable of identifying potentially severe patients who require immediate care. Thus, MPs seem to be a promising important biomarker in many aspects of DVI.

[Probabilistic spatial-temporal prediction of total and severe epidemic of dengue in Colombia]. / Predicción espacio-temporal probabilista de la epidemia de dengue total y grave en Colombia.

OBJECTIVE: To establish a new predictive methodology to determine the proportion of severe dengue with respect to the annual total of dengue infections per department based on the probability theory. MATERIALS AND METHODS: Based on annual data on the number of infected persons by department in the period 2005-2010, the proportion of cases of severe dengue was calculated with respect to the total for each year. Probability spaces were constructed to evaluate these events in the ranges 0.5 and 0.3. Sets of ranges were determined and probability, mean square deviation and the difference between them were estimated. A prediction of the range of infected people for 2011 was made using the arithmetic average of the values of the last two years. RESULTS: The range in which the proportion of the number of people infected with severe dengue is included with respect to the total amount in each department was correctly predicted, with an effectiveness of 93.3% for the 0.5 range and 86.7% for the 0.3 range. CONCLUSION: A mathematical spatial-temporal self-organization was found in the proportion of severe dengue with respect to the total, which allows establishing useful predictions for decision-making in public health.

OBJETIVO: Establecer una nueva metodología predictiva de la proporción de dengue grave respecto al total anual de infectados de dengue por departamento con base en la teoría de la probabilidad. MÉTODOS: Con base en los datos anuales de número de infectados por departamentos en el periodo 2005 -2010, se calculó la proporción entre casos de dengue grave respecto al total para cada año, y se construyeron espacios de probabilidad que evalúan estos eventos en rangos de 0,5 y 0,3. Se determinaron conjuntos de rangos y se calculó probabilidad, desviación media cuadrática y la diferencia entre ellas. Se realizó una predicción del rango de infectados para el 2011 con el promedio aritmético de los valores de los últimos dos años. RESULTADOS: Se predijo correctamente el rango en el que se encuentra incluida la proporción de número de infectados de dengue grave sobre el total en cada departamento con una efectividad del 93,3% para el rango de 0,5 y de 86,7% para el de 0,3. CONCLUSIÓN: Se evidenció una autoorganización matemática espacio temporal en la proporción de dengue grave respecto al total que permite establecer predicciones de utilidad para la toma de decisiones de salud pública.

A retrospective cohort study to predict severe dengue in Honduran patients.

BACKGROUND: An important challenge in the identification of dengue is how to predict which patients will go on to experience severe illness, which is typically characterized by fever, thrombocytopenia, haemorrhagic manifestations, and plasma leakage. Accurate prediction could result in the appropriate hospital triage of high risk patients. The objective of this study was to identify clinical factors observed within the first 24 h of hospital admission that could predict subsequent severe dengue. METHODS: We conducted a retrospective cohort study of 320 patients with febrile illness who had confirmation of dengue within one week of admission, using data from the 2009-2010 Honduras Epidemiological Survey for Dengue. The outcome measure was plasma leakage defined using hemoconcentration ≥15% as determined by serial hematocrit testing. We conducted univariable analysis and multivariable logistic regression analysis to construct a predictive model for severe dengue. RESULTS: Thirty-four (10.6%) of patients in the 320 patient cohort had hemoconcentration ≥15%. In the final multivariable logistic regression model the presence of ascites, OR 7.29, 95% CI 1.85 to 28.7, and a platelet count <50,000 platelets/mm3 at admission, OR 3.02, 95% CI 1.42 to 6.42, were significantly associated with plasma leakage, while the presence of petechiae, OR 0.24 95% CI 0.080 to 0.73, and headache, OR 0.38, 95% CI 0.15 to 0.95, were negatively associated with leakage. Using an estimated probability of 7% as a threshold for a person being considered a severe case correctly predicted 26 of the 34 severe cases (sensitivity 76.4%) and 201 of the 286 non-severe cases (specificity of 70.3%) for a percentage correctly classified of 70.9%. CONCLUSION: We identified signs and symptoms that can correctly identify a majority of patients who eventually develop severe dengue in Honduras. It will be important to further refine our models and validate them in other populations.

Genetic variants of MICB and PLCE1 and associations with the laboratory features of dengue.

BACKGROUND: A previous genome-wide association study identified 2 susceptibility loci for severe dengue at MICB rs3132468 and PLCE1 rs3740360 and further work showed these mutations to be also associated with less severe clinical presentations. The aim of this study was to determine if these specific loci were associated with laboratory features of dengue that correlate with clinical severity with the aim of elucidating the functional basis of these genetic variants. METHODS: This was a case-only analysis of laboratory-confirmed dengue patients obtained from 2 prospective cohort studies and 1 randomised clinical trial in Vietnam (Trial registration: ISRCTN ISRCTN03147572. Registered 24th July 2012). 2742 dengue cases were successfully genotyped at MICB rs3132468 and PLCE1 rs3740360. Laboratory variables were compared between genotypes and stratified by DENV serotype. RESULTS: The analysis showed no association between MICB and PLCE1 genotype and early viraemia level, platelet nadir, white cell count nadir, or maximum haematocrit in both overall analysis and in analysis stratified by serotype. DISCUSSION: The lack of an association between genotype and viremia level may reflect the sampling procedures within the included studies. The study findings mean that the functional basis of these mutations remains unclear. TRIAL REGISTRATION: ISRCTN ISRCTN03147572 . Registered 24th July 2012.

A Prognostic Model for Development of Profound Shock among Children Presenting with Dengue Shock Syndrome.

PURPOSE: To identify risk factors and develop a prediction model for the development of profound and recurrent shock amongst children presenting with dengue shock syndrome (DSS). METHODS: We analyzed data from a prospective cohort of children with DSS recruited at the Paediatric Intensive Care Unit of the Hospital for Tropical Disease in Ho Chi Minh City, Vietnam. The primary endpoint was "profound DSS", defined as ≥2 recurrent shock episodes (for subjects presenting in compensated shock), or ≥1 recurrent shock episodes (for subjects presenting initially with decompensated/hypotensive shock), and/or requirement for inotropic support. Recurrent shock was evaluated as a secondary endpoint. Risk factors were pre-defined clinical and laboratory variables collected at the time of presentation with shock. Prognostic model development was based on logistic regression and compared to several alternative approaches. RESULTS: The analysis population included 1207 children of whom 222 (18%) progressed to "profound DSS" and 433 (36%) had recurrent shock. Independent risk factors for both endpoints included younger age, earlier presentation, higher pulse rate, higher temperature, higher haematocrit and, for females, worse hemodynamic status at presentation. The final prognostic model for "profound DSS" showed acceptable discrimination (AUC=0.69 for internal validation) and calibration and is presented as a simple score-chart. CONCLUSIONS: Several risk factors for development of profound or recurrent shock among children presenting with DSS were identified. The score-chart derived from the prognostic models should improve triage and management of children presenting with DSS in dengue-endemic areas.

Arterial hypertension and skin allergy are risk factors for progression from dengue to dengue hemorrhagic fever: a case control study.

BACKGROUND: Currently, knowledge does not allow early prediction of which cases of dengue fever (DF) will progress to dengue hemorrhagic fever (DHF), to allow early intervention to prevent progression or to limit severity. The objective of this study is to investigate the hypothesis that some specific comorbidities increase the likelihood of a DF case progressing to DHF. METHODS: A concurrent case-control study, conducted during dengue epidemics, from 2009 to 2012. Cases were patients with dengue fever that progressed to DHF, and controls were patients of dengue fever who did not progress to DHF. Logistic regression was used to estimate the association between DHF and comorbidities. RESULTS: There were 490 cases of DHF and 1,316 controls. Among adults, progression to DHF was associated with self-reported hypertension (OR = 1.6; 95% CI 1.1-2.1) and skin allergy (OR = 1.8; 95% CI 1.1-3.2) with DHF after adjusting for ethnicity and socio-economic variables. There was no statistically significant association between any chronic disease and progression to DHF in those younger than 15 years. CONCLUSIONS: Physicians attending patients with dengue fever should keep those with hypertension or skin allergies in health units to monitor progression for early intervention. This would reduce mortality by dengue.

An evaluation of the World Health Organization's 1997 and 2009 dengue classifications in hospitalized dengue patients in Malaysia.

INTRODUCTION: The latest revised version of the World Health Organization's dengue classification was released in 2009. A handful of studies have taken initiatives to evaluate the old and revised guidelines to determine early signs and symptoms of severe dengue. This retrospective study aimed to compare the classification of dengue using both the 1997 and 2009 guidelines in a selected cohort of dengue patients from Peninsular Malaysia between 2008 and 2012. METHODOLOGY: Adult dengue patients were recruited from tertiary hospitals in two different states, Selangor and Kelantan, in Peninsular Malaysia. Their clinical manifestations were assessed. RESULTS: A total of 281 confirmed dengue patients were enrolled; the mean duration of illness at admission was five days. Of these, 88.6%, 10.7%, and 0.7% were classified according to the 1997 guidelines as having dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS), respectively. When the WHO 2009 guidelines were applied, 17.1%, 78.3%, and 4.6% were classified as dengue without warning signs, dengue with warning signs, and severe dengue, respectively. CONCLUSIONS: Our data suggests that the revised WHO 2009 guidelines stratify a much larger proportion of patients into a category that requires a higher level of medical and nursing care.

Antibodies against thrombin in dengue patients contain both anti-thrombotic and pro-fibrinolytic activities.

Dengue virus (DENV) infection may result in severe life-threatening Dengue haemorrhagic fever (DHF). The mechanisms causing haemorrhage in those with DHF are unclear. In this study, we demonstrated that antibodies against human thrombin were increased in the sera of Dengue patients but not in that of patients infected with other viruses. To further characterise the properties of these antibodies, affinity-purified anti-thrombin antibodies (ATAs) were collected from Dengue patient sera by thrombin and protein A/L affinity columns. Most of the ATAs belonged to the IgG class and recognized DENV nonstructural protein 1 (NS1). In addition, we found that dengue patient ATAs also cross-reacted with human plasminogen (Plg). Functional studies in vitro indicated that Dengue patient ATAs could inhibit thrombin activity and enhance Plg activation. Taken together, these results suggest that DENV NS1-induced thrombin and Plg cross-reactive antibodies may contribute to the development of haemorrhage in patients with DHF by interfering with coagulation and fibrinolysis.