Coagulation abnormalities in dengue hemorrhagic Fever: serial investigations in 167 Vietnamese children with Dengue shock syndrome

Dengue fever: Report from the task force on tropical diseases by the World Federation of Societies of Intensive and Critical Care Medicine

Dengue is an arbovirus affecting humans and spread by mosquitoes. Severe dengue follows a secondary infection with a different virus serotype. The problem is truly global as it is endemic in over 100 countries. Severe dengue can be a life-threatening because of increased vascular permeability, resulting in leakage of fluid from the intravascular compartment to the extravascular space. When major bleeding does occur, it is almost invariably combined with profound shock since this, in combination with thrombocytopenia, hypoxia, and acidosis, can lead to multiple organ failure and disseminated intravascular coagulation. Dengue hemorrhagic fever and dengue shock syndrome are among the leading causes of morbidity and mortality in patients suffering from Dengue. Commercial rapid tests and ELISA kits are freely available, ensuring early diagnosis. The basis of management of severe dengue is effective fluid replacement. Future directions in management will involve vector control and development of effective vaccination.

Spontaneous rectus sheath hematomas in dengue hemorrhagic fever: A case report

Muscle hematomas are rare complications in dengue hemorrhagic fever (DHF). We report a case of 58-year-old-female admitted with dengue fever who developed spontaneous rectus sheath hematoma complicating DHF. She presented with progressive thrombocytopenia with platelet count reaching 13000/μL at its lowest point. There was evidence of plasma leakage and persistent cough during the course of illness. During the recovery phase, she reported severe abdominal pain and developed hematoma in the right rectus sheath, which was confirmed by abdominal computed-tomography scan and serial magnetic resonance imaging. This complication during convalescent period of DHF needs to be recognized so it can be managed appropriately.

Prothrombin Time Prolongation was the Most Important Indicator of Severe Bleeding in Children with Severe Dengue Viral Infection

To determine the indicators of severe bleeding in children with severe dengue viral infection (DVI), the medical records of patients aged <15 years admitted to Songklanagarind Hospital in southern Thailand during 1989-2011 were reviewed. Severe-bleeding DVI was defined as needing blood products transfusion owing to DVI-caused bleeding. Of the 238 children with severe DVI according to the World Health Organization 2009 criteria, 44 (18.5%) had severe bleeding, of whom 28 (63.6%) died. The international normalized ratio (INR) had high correlations with both transaminase enzymes (Spearman correlation, rs = 0.67-0.69, p <0.01). Multivariate analysis found that patients who had dengue haemorrhagic fever (DHF) grade IV, platelets <20 000/mm3 and INR ≥ 1.5 had increased risk of severe bleeding with odds ratios (95% confidence intervals) of 3.4 (1.4, 8.6), 2.6 (1.1, 6.2) and 10.6 (4.0, 28.4), respectively. Blood products should be at hand in severe DHF children with high risk of severe bleeding.

Association of Endothelial Glycocalyx and Tight and Adherens Junctions With Severity of Plasma Leakage in Dengue Infection

Background.

The role of vascular endothelial (VE) components in dengue infection with plasma leakage is unknown. Therefore, we conducted a study to determine the adjusted association of the endothelial glycocalyx layer (EGL) and tight and adherens junction markers with plasma leakage.

Methods.

A prospective observational study was conducted at Cipto Mangunkusumo Hospital and Persahabatan Hospital, Jakarta, Indonesia. Adult dengue patients admitted to the hospital on the third day of fever from November 2013 through August 2015 were included in the study. Multiple regression analysis was used to determine the adjusted association of the VE biomarkers with the severity of the plasma leakage.

Results.

A total of 103 dengue-infected patients participated in the study. In the critical phase, levels of syndecan-1 (odds ratio [OR] = 1.004; 95% confidence interval [CI] = 1.001–1.007) and chondroitin sulfate (OR = 1.157; 95% CI = 1.025–1.307) had an adjusted association with plasma leakage, whereas levels of syndecan-1 (OR = 1.004; 95% CI = 1.000–1.008) and claudin-5 (OR = 1.038; 95% CI = 1.004–1.074) had an adjusted association with severe plasma leakage.

Conclusions.

In dengue-infected patients, elevated levels of syndecan-1 and chondroitin sulfate are strongly associated with plasma leakage, and elevated levels of syndecan-1 and claudin-5 are strongly associated with severe plasma leakage.

Induction of Osteopontin by Dengue Virus-3 Infection in THP-1 Cells: Inhibition of the Synthesis by Brefelamide and Its Derivative

Osteopontin (OPN) is a multifunctional matricellular protein produced by a broad range of cells including osteoclasts, macrophages, T cells, endothelial cells, and vascular smooth muscle cells. OPN modulates various physiological and pathological events such as inflammation, wound healing, and bone formation and remodeling. Dengue virus (DENV) infection causes an increase in plasma OPN levels, which is correlated with the severity of symptoms and coagulation abnormalities. DENV infection also induces OPN gene expression in human macrophages. This study investigated the inhibitory effects of brefelamide and its methyl ether derivative on DENV-3 by measuring changes in OPN levels in human THP-1 and 293T cell lines infected at different multiplicities of infection and post-infection time points. OPN mRNA expression and viral RNA were detected by reverse transcriptase quantitative real-time PCR, whereas protein level was determined by enzyme-linked immunosorbent assay. We found that viral copy number was higher in 293T than in THP-1 cells. However, THP-1 constitutively expressed higher levels of OPN mRNA and protein, which were enhanced by DENV-3 infection. Brefelamide and its derivative suppressed OPN production in DENV-3 infected THP-1 cells; the effective doses of these compounds had no effect on uninfected cells, indicating low cytotoxicity. These results suggest that brefelamide and its methyl ether derivative have therapeutic effects in preventing inflammation, coagulopathy, and fibrinolysis caused by OPN upregulation induced by DENV-3 infection.

Differentiating between dengue fever and malaria using hematological parameters in endemic areas of Thailand

Background

Dengue fever (DF) and malaria are the two major public health concerns in tropical countries such as Thailand. Early differentiation between dengue and malaria could help clinicians to identify patients who should be closely monitored for signs of dengue hemorrhagic fever or severe malaria. This study aims to build knowledge on diagnostic markers that are used to discriminate between the infections, which frequently occur in malaria-endemic areas, such as the ones in Thailand.

Methods

A retrospective study was conducted in Phop Phra Hospital, a hospital located in the Thailand-Burma border area, a malaria-endemic area, between 2013 and 2015. In brief, data on 336 patients infected with malaria were compared to data on 347 patients infected with DF.

Results

White blood cells, neutrophil, monocyte, eosinophil, neutrophil-lymphocyte ratio, and monocyte-lymphocyte ratio were significantly lower in patients with DF compared to patients with malaria (P < 0.0001). In contrast, red blood cells, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were significantly higher in patients with DF as compared to patients with malaria (P < 0.0001). A decision tree model revealed that using neutrophils, lymphocyte, MCHC, and gender was guided to discriminate between dengue and malaria infection.

Conclusion

This study concluded that several hematological parameters were different for diagnosing DF and malaria. A decision tree model revealed that using neutrophils, lymphocyte, MCHC, and gender was guided to discriminate patients with dengue and malaria infection. In addition, using these markers will thus lead to early detection, diagnosis, and prompt treatment of these tropical diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-017-0238-x) contains supplementary material, which is available to authorized users.

Magnitude of viremia, antigenemia and infection of circulating monocytes in children with mild and severe dengue

Dengue is a major public health problem in tropical regions around the world. Viral and immune host factors determine the clinical courses of the infection. We analyzed the dynamics of viremia (by real-time polymerase chain reactions), antigenemia (through detection of the viral non-structural protein [NS]-1 by enzyme-linked immunosorbent assays) and the frequency of virus-infected peripheral blood mononuclear cells (PBMCs) (by multiparametric flow cytometry) in children with primary or secondary dengue virus (DENV) infection in mild to severe cases. Additionally, we evaluated the association of these factors with clinical severity and laboratory parameters. The levels of viremia and antigenemia peaked during the early days of illness and these viral parameters were correlated (rho=0.37, P=0.003). Circulating monocytes were the most naturally infected subset within the PBMCs population, with kinetics similar to those of viremia and antigenemia. The levels of viremia and antigenemia were higher in children with primary infections than in those with secondary infections (P≤0.04). Although there were no associations between the three evaluated factors and clinical severity, the levels of plasma NS1 and the frequency of dengue virus-infected monocytes correlated with prolonged coagulation times. In short, the viremia, antigenemia and infected monocytes were detected early and were not related to clinical severity. The magnitude of antigenemia and infected circulating monocytes was associated with coagulation disorders.

Platelet activation determines the severity of thrombocytopenia in dengue infection

Thrombocytopenia is common in patients with dengue virus (DENV) infections. With a focus on understanding the possible mechanism of thrombocytopenia in DENV infections we described a direct correlation between activation and depletion of platelets in patients. Our data showed a sharp decrease in platelet counts at day 4 of fever in patients. The high DENV genome copies in platelets correlated directly with the elevated platelet activation along with increased binding of complement factor C3 and IgG on their surface at day 4. Recovery in platelet count was observed on day 10 through day 6 and 8 with simultaneous decrease in platelet activation markers. Further, our in vitro data supported the above observations describing a concentration-dependent increase in platelet activation by DENV serotype-2. The high copy number of DENV2 genome in the platelet pellet correlated directly with platelet activation, microparticle generation and clot formation. Furthermore the DENV2-activated platelets were phagocytosed in large numbers by the monocytes. The DENV2-mediated lysis and clearance of platelets were abrogated in presence of platelet activation inhibitor, prostacyclin. These observations collectively suggest that platelet activation status is an important determinant of thrombocytopenia in dengue infections. A careful strategy of inactivation of platelets may rescue them from rapid destruction during DENV infections.

Thromboelastometry analysis of thrombocytopenic dengue patients: a cross-sectional study

Background

Dengue virus infection (DVI) is a prevalent and potentially fatal viral disease associated with coagulopathy. So far, the coagulation profile of DVI patients with thrombocytopenia has not been assessed through a viscoelastic test such as rotational thromboelastometry. We aimed to describe the prevalence and characteristics of coagulation abnormalities in dengue fever outpatients with thrombocytopenia, addressed by both rotational thromboelastometry and conventional coagulation tests.

Methods

This was a cross-sectional study conducted between April 6^th and May 5^th 2015 in São Paulo, Brazil during a dengue outbreak. Thromboelastometry (ROTEM®) and the conventional coagulation tests prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), thrombin time (TT), platelet count and fibrinogen levels were performed in 53 patients with DVI and thrombocytopenia.

Results

Despite a median interquartile range (IQR) platelet count of 77 (63–88) x 10⁹/L in DVI patients, conventional coagulation tests and plasma fibrinogen levels were within the normal range. Subjects demonstrated hypocoagulability in 71.7% (38/53) in INTEM and 54.7% (29/53) in EXTEM DVI patients. FIBTEM analyses detected only 5.7% (3/53) with hypocoagulability among this population. The median (IQR) clotting time (CT), clot formation time (CFT) and maximum clot firmness (MCF) on INTEM were, respectively, 177 (160–207) sec, 144 (108–178) sec and 48 (42–52) mm. On EXTEM, median (IQR) CT, CFT and MCF were, respectively, 69 (65–78) sec, 148 (126–198) sec and 49 (44–55) mm. Median (IQR) MCF on FIBTEM was 15 (13–18) mm.

Conclusion

Thromboelastometry impairment is highly prevalent in DVI patients with thrombocytopenia, particularly in INTEM and EXTEM analyses, while standard coagulation tests are normal in this setting. Clinical implications remain to be established.

Introduction: The Complexity and Challenge of Preventing, Treating, and Managing Blood Diseases in the Developing Countries

Managing hematologic disorders in developing countries poses problems not encountered in Western societies. The clinical features of hematologic conditions may be modified by malnutrition, chronic bacterial infection, or parasitic illness. Iron deficiency is the major factor in anemia worldwide. Anemia is more common in the wet season when malaria transmission peaks. After anemia, eosinophilia is the next most common hematologic abnormality in children in the tropics. Infection with the human immunodeficiency virus can cause hematologic abnormalities. The pattern of distribution of primary disorders of the blood varies among populations and some disorders are unique to certain parts of the world.

Clinical Characteristics and Risk Factors of Dengue Shock Syndrome in Children

BACKGROUND

Dengue shock syndrome (DSS) represents one of the most severe manifestations of dengue virus infection. The objective of the present study was to analyze the clinical and laboratory characteristics, risk factors and outcome of DSS in children.

METHODS

Patients <15 years old admitted with DSS during the 2012 and 2013 outbreak of serotype 2 of dengue virus in Paraguay were included. Demographic, clinical and laboratory data of patients with/without DSS were analyzed.

RESULTS

Of 471 children hospitalized with dengue, 354 patients (75%) presented with shock at admission or developed later. The mean age of patients with DSS was 10.2 ± 4 years (no difference with patients without shock), without gender preference. Rash (50% vs. 56%), myalgias (45% vs. 40%), vomiting (66% vs. 68%) and bleeding manifestations (24% vs. 21.2%) were similar for 2 groups. Similarly, there was no difference in the frequency of DSS between primary versus secondary infection cases (76.2% vs. 71.6%, P = 0.3). Age group >5 years [odds ratio (OR) 1.6, 95% confidence interval (CI): 1-2.8, P < 0.05), presence of abdominal pain (OR 2.5, 95% CI: 1.3-4.9, P = 0.006), an activated partial thromboplastin time prolonged (OR 4; 95% CI: 1.6-10, P < 0.001) and low fibrinogen level (OR 2.5; 95% CI: 1-5.9, P = 0.02) were found significantly associated with DSS. About 12% of patients required intensive care unit admission, and 2 patients died (lethality 0.35%).

CONCLUSIONS

This study validated most of the clinical variables present in the current WHO guidelines as markers of severe disease and add additional variables that can help to predict the risk of progression to shock.

Inhibition of the Membrane Attack Complex by Dengue Virus NS1 through Interaction with Vitronectin and Terminal Complement Proteins

Dengue virus (DENV) infects millions of people worldwide and is a major public health problem. DENV nonstructural protein 1 (NS1) is a conserved glycoprotein that associates with membranes and is also secreted into the plasma in DENV-infected patients. The present study describes a novel mechanism by which NS1 inhibits the terminal complement pathway. We first identified the terminal complement regulator vitronectin (VN) as a novel DENV2 NS1 binding partner by using a yeast two-hybrid system. This interaction was further assessed by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) assay. The NS1-VN complex was also detected in plasmas from DENV-infected patients, suggesting that this interaction occurs during DENV infection. We also demonstrated that the DENV2 NS1 protein, either by itself or by interacting with VN, hinders the formation of the membrane attack complex (MAC) and C9 polymerization. Finally, we showed that DENV2, West Nile virus (WNV), and Zika virus (ZIKV) NS1 proteins produced in mammalian cells inhibited C9 polymerization. Taken together, our results points to a role for NS1 as a terminal pathway inhibitor of the complement system.

IMPORTANCE

Dengue is the most important arthropod-borne viral disease nowadays and is caused by dengue virus (DENV). The flavivirus NS1 glycoprotein has been characterized functionally as a complement evasion protein that can attenuate the activation of the classical, lectin, and alternative pathways. The present study describes a novel mechanism by which DENV NS1 inhibits the terminal complement pathway. We identified the terminal complement regulator vitronectin (VN) as a novel DENV NS1 binding partner, and the NS1-VN complex was detected in plasmas from DENV-infected patients, suggesting that this interaction occurs during DENV infection. We also demonstrated that the NS1-VN complex inhibited membrane attack complex (MAC) formation, thus interfering with the complement terminal pathway. Interestingly, NS1 itself also inhibited MAC activity, suggesting a direct role of this protein in the inhibition process. Our findings imply a role for NS1 as a terminal pathway inhibitor of the complement system.

Increased circulating procoagulant and anticoagulant factors as TF and TFPI according to severity or infecting serotypes in human dengue infection

Tissue Factor (TF) is the initiator of coagulation and Tissue Factor Inhibitor (TFPI) is the physiological inhibitor of the TF/FVIIa complex. Circulating levels of TF and TFPI were quantified in dengue patients and the relationships with disease severity and infecting serotype analysed. A significant decrease in TF and TPFI plasma levels was observed in mild DF patients compared with severe dengue. Furthermore, both factors were associated with haemorrhagic manifestations. Finally, TF levels were significantly increased in DENV-1/2 infected patients as compared with DENV-4. These findings suggest that activation of TF-pathway is an important component of DENV -related coagulation disorders.

Dengue infection

Dengue is widespread throughout the tropics and local spatial variation in dengue virus transmission is strongly influenced by rainfall, temperature, urbanization and distribution of the principal mosquito vector Aedes aegypti. Currently, endemic dengue virus transmission is reported in the Eastern Mediterranean, American, South-East Asian, Western Pacific and African regions, whereas sporadic local transmission has been reported in Europe and the United States as the result of virus introduction to areas where Ae. aegypti and Aedes albopictus, a secondary vector, occur. The global burden of the disease is not well known, but its epidemiological patterns are alarming for both human health and the global economy. Dengue has been identified as a disease of the future owing to trends toward increased urbanization, scarce water supplies and, possibly, environmental change. According to the WHO, dengue control is technically feasible with coordinated international technical and financial support for national programmes. This Primer provides a general overview on dengue, covering epidemiology, control, disease mechanisms, diagnosis, treatment and research priorities.

Dengue score: a proposed diagnostic predictor for pleural effusion and/or ascites in adults with dengue infection

Background

There are several limitations in diagnosing plasma leakage using the World Health Organization (WHO) guidelines of dengue hemorrhagic fever. We conducted a study to develop a dengue scoring system to predict pleural effusion and/or ascites using routine laboratory parameters.

Methods

A prospective observational study was carried out at Cipto Mangunkusumo Hospital and Persahabatan Hospital, Jakarta, Indonesia. Dengue-infected adults admitted on the third febrile day from March, 2010 through August, 2015 were included in the study. A multivariate analysis was conducted to determine the independent diagnostic predictors of pleural effusion and/or ascites and to convert the prediction model into a scoring system.

Results

A total of 172 dengue-infected adults were enrolled in the study. Of the 172 patients, 101 (58.7 %) developed pleural effusion and/or ascites. A multivariate analysis was conducted to determine the independent diagnostic predictors of pleural effusion and/or ascites in dengue-infected adults. The predictors were scored based on the following calculations: hemoconcentration ≥15.1 % had a score of 1 (OR, 3.11; 95 % CI, 1.41–6.88), lowest albumin concentration at critical phase ≤3.49 mg/dL had a score of 1 (OR, 4.48; 95 % CI, 1.87–10.77), lowest platelet count ≤49,500/μL had a score of 1 (OR, 3.62; 95 % CI, 1.55–8.49), and elevated ratio of AST ≥2.51 had a score of 1 (OR 2.67; 95 % CI, 1.19–5.97). At a cut off of ≥ 2, the Dengue Score predicted pleural effusion and/or ascites diagnosis with positive predictive value of 79.21 % and negative predictive value of 74.63 %. This prediction model is suitable for calibration and good discrimination.

Conclusions

We have developed a Dengue Score that could be used to identify pleural effusion and/or ascites and might be useful to stratify dengue-infected patients at risk for developing severe dengue.

Lymphocyte Apoptosis and Thrombocytopenia in Spleen during Classical Swine Fever: Role of Macrophages and Cytokines

Thirty-two Large White X Landrace pigs, 4 months old, were inoculated with the classical swine fever (CSF) or hog cholera virus strain “Alfort” in order to identify the mechanism responsible for the lymphopenia and thrombocytopenia observed in the spleen during the experimental induction of disease, by immunohistochemical and ultrastructural techniques. Results showed a progressive depletion of splenic lymphoid structures and evidence of platelet aggregation processes. Lymphoid depletion was due to lymphocyte apoptosis, which could not be ascribed to the direct action of the virus on these cells; direct virus action could play only a secondary role in the death of these cells. Absence of severe tissue and endothelial damage, together with moderate procoagulant cytokine levels in the serum, suggest that these pathologies can be ruled out as the cause of platelet aggregation and thrombocytopenia in CSF. Monocyte/macrophages were the main target cells for the CSF virus, and they exhibited phagocytic and secretory activation leading to the synthesis and release of tumor necrosis factor α, which proved to be the chief mediator, followed by IL-6, IL-1α, and C1q complement component. In view of their characteristics, TNF-α and, to a lesser extent, IL-1α and IL-6 appear to be the major cytokines involved in the pathogenesis of lymphocytopenia and thrombocytopenia; a clear spatial and temporal relationship was observed between these two phenomena.

A Proteomic Approach Identifies Candidate Early Biomarkers to Predict Severe Dengue in Children

BACKGROUND

Severe dengue with severe plasma leakage (SD-SPL) is the most frequent of dengue severe form. Plasma biomarkers for early predictive diagnosis of SD-SPL are required in the primary clinics for the prevention of dengue death.

METHODOLOGY

Among 63 confirmed dengue pediatric patients recruited, hospital based longitudinal study detected six SD-SPL and ten dengue with warning sign (DWS). To identify the specific proteins increased or decreased in the SD-SPL plasma obtained 6-48 hours before the shock compared with the DWS, the isobaric tags for relative and absolute quantification (iTRAQ) technology was performed using four patients each group. Validation was undertaken in 6 SD-SPL and 10 DWS patients.

PRINCIPAL FINDINGS

Nineteen plasma proteins exhibited significantly different relative concentrations (p<0.05), with five over-expressed and fourteen under-expressed in SD-SPL compared with DWS. The individual protein was classified to either blood coagulation, vascular regulation, cellular transport-related processes or immune response. The immunoblot quantification showed angiotensinogen and antithrombin III significantly increased in SD-SPL whole plasma of early stage compared with DWS subjects. Even using this small number of samples, antithrombin III predicted SD-SPL before shock occurrence with accuracy.

CONCLUSION

Proteins identified here may serve as candidate predictive markers to diagnose SD-SPL for timely clinical management. Since the number of subjects are small, so further studies are needed to confirm all these biomarkers.

Pathogenesis of Dengue: Dawn of a New Era

Dengue virus (DENV) infections of humans were long thought to be self-limited and of low mortality. Beginning in the 1950s, at the time when four different DENVs were discovered, a lethal variant of dengue emerged. Dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) initially observed in Southeast Asia now has spread throughout the world. Two risk factors for DHF/DSS are well-established: severe disease occurs during a second heterotypic DENV infection or during a first DENV infection in infants born to dengue-immune mothers. A large number of hypotheses have been proposed to explain severe dengue disease. As discussed, few of them attempt to explain why severe disease occurs under the two different immunological settings. New experimental evidence has demonstrated that DENV non-structural protein 1 (NS1) is toll-receptor 4 agonist that stimulates primary human myeloid cells to produce the same cytokines observed during the course of severe dengue disease. In addition, NS1 directly damages endothelial cells. These observations have been repeated and extended to an in vivo mouse model. The well-established phenomenon, antibody-dependent enhancement of DENV infection in Fc-receptor-bearing cells, should similarly enhance the production of DENV NS1 in humans, providing a unitary mechanism for severe disease in both immunological settings.

Evaluation of Prognostic Values of Tissue Plasminogen Activator and Plasminogen Activator Inhibitor-1 in Crimean-Congo Hemorrhagic Fever Patients

Background:

Crimean-Congo hemorrhagic fever (CCHF) is a widespread disease in Turkey, and was responsible for many deaths in endemic regions during the last decade. The pathogenesis of the disease is not fully understood yet.

Objectives:

In this study we aimed to determine the levels of tissue plasminogen activator (tPA) and Plasminogen activator inhibitor-1 (PAI-1) as predictors of prognosis in CCHF.

Patients and Methods:

Patients who were diagnosed by the polymerase chain reaction (PCR) and IgM positivity in the reference laboratory were included in this study. Tissue Plasminogen activator and PAI-1 levels were measured by the enzyme linked immunosorbent assay (ELISA) using a commercial kit (human t-PA ELISA and human PAL-1 ELISA; BioVendor research and diagnostic products, BioVendor-Laboratorni medicina a.s., Brno, Czech Republic).

Results:

A total of 46 patients participated in this study. The significant differences between recovering patients and the patients who died, regarding Aspartate aminotransferase (AST), Creatine Phosphokinase (CPK), Lactate Dehydrogenase (LDH), Prothrombin Time (PT), activated Partial Thromboplastin time (aPTT), and thrombocyte and fibrinogen levels, were consistent with many clinical studies in the literature. The fatal cases were found to have higher tPA and PAI-1 levels in contrast to the patients who completely recovered.

Conclusions:

We think that these findings may help the progress of understanding of CCHF pathogenesis.

Biomarkers of severe dengue disease - a review

Dengue virus infection presents a wide spectrum of manifestations including asymptomatic condition, dengue fever (DF), or severe forms, such as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) in affected individuals. The early prediction of severe dengue in patients without any warning signs who may later develop severe DHF is very important to choose appropriate intensive supportive therapy since available vaccines for immunization are yet to be approved. Severe dengue responses include T and B cell activation and apoptosis, cytokine storm, hematologic disorders and complement activation. Cytokines, complement and other unidentified factors may transiently act on the endothelium and alter normal fluid barrier function of the endothelial cells and cause plasma leakage. In this review, the host factors such as activated immune and endothelial cells and their products which can be utilized as biomarkers for severe dengue disease are discussed.

Clinico-laboratory spectrum of dengue viral infection and risk factors associated with dengue hemorrhagic fever: a retrospective study

BACKGROUND

The incidence of dengue is rising steadily in Malaysia since the first major outbreak in 1973. Despite aggressive measures taken by the relevant authorities, Malaysia is still facing worsening dengue crisis over the past few years. There is an urgent need to evaluate dengue cases for better understanding of clinic-laboratory spectrum in order to combat this disease.

METHODS

A retrospective analysis of dengue patients admitted to a tertiary care teaching hospital during the period of six years (2008 - 2013) was performed. Patient's demographics, clinical and laboratory findings were recorded via structured data collection form. Patients were categorized into dengue fever (DF) and dengue hemorrhagic fever (DHF). Appropriate statistical methods were used to compare these two groups in order to determine difference in clinico-laboratory characteristics and to identify independent risk factors of DHF.

RESULTS

A total 667 dengue patients (30.69 ± 16.13 years; Male: 56.7 %) were reviewed. Typical manifestations of dengue like fever, myalgia, arthralgia, headache, vomiting, abdominal pain and skin rash were observed in more than 40 % patients. DHF was observed in 79 (11.8 %) cases. Skin rash, dehydration, shortness of breath, pleural effusion and thick gall bladder were more significantly (P < 0.05) associated with DHF than DF. Multivariate regression analysis demonstrated presence of age > 40 years (OR: 4.1, P < 0.001), secondary infection (OR: 2.7, P = 0.042), diabetes mellitus (OR: 2.8, P = 0.041), lethargy (OR: 3.1, P = 0.005), thick gallbladder (OR: 1.7, P = 0.029) and delayed hospitalization (OR: 2.3, P = 0.037) as independent predictors of DHF. Overall mortality was 1.2 % in our study.

CONCLUSIONS

Current study demonstrated that DF and DHF present significantly different clinico-laboratory profile. Older age, secondary infection, diabetes mellitus, lethargy, thick gallbladder and delayed hospitalization significantly predict DHF. Prior knowledge of expected clinical profile and predictors of DHF/DSS development would provide information to identify individuals at higher risk and on the other hand, give sufficient time to clinicians for reducing dengue related morbidity and mortality.

Cost-utility analysis of an adjunctive recombinant activated factor VIIa for on-demand treatment of bleeding episodes in dengue haemorrhagic fever

The present study aimed to assess the cost-utility analysis of using an adjunctive recombinant activated factor VIIa (rFVIIa) in children for controlling life-threatening bleeding in dengue haemorrhagic fever (DHF)/dengue shock syndrome (DSS). We constructed a decision-tree model, comparing a standard care and the use of an additional adjuvant rFVIIa for controlling life-threatening bleeding in children with DHF/DSS. Cost and utility benefit were estimated from the societal perspective. The outcome measure was cost per quality-adjusted life years (QALYs). Overall, treatment with adjuvant rFVIIa gained QALYs, but the total cost was higher. The incremental cost-utility ratio for the introduction of adjuvant rFVIIa was $4241.27 per additional QALY. Sensitivity analyses showed the utility value assigned for calculation of QALY was the most sensitive parameter. We concluded that despite high cost, there is a role for rFVIIa in the treatment of life-threatening bleeding in patients with DHF/DSS.

Dengue in adults admitted to a referral hospital in Hanoi, Vietnam

Knowledge of adult dengue virus (DENV) infection from Hanoi, Vietnam, is limited. In 2008, we prospectively studied 143 (77 male) confirmed (nonstructural 1 antigen enzyme-linked immunosorbent assay [ELISA], DENV polymerase chain reaction, paired serology) adult dengue patients of median age 23.5 (range 16-72) years. They were admitted to the National Hospital for Tropical Diseases, Hanoi, on median illness day (D) 5 (range 1-8). By D8, 141 (98.6%) were afebrile. Platelet counts and hematocrit (median, interquartile range [IQR]) nadired and peaked on D5 and D4, respectively: 40,000/μL (10,000-109,000/μL), 43.4% (34.9-49.7%). Four (2.8%) patients had severe dengue: 1) D10 shock (N = 1) and 2) aspartate aminotransferase (AST) ≥ 1,000 IU/L (N = 3, D5 and D7). Of 143 patients, 118 (82.5%) had ≥ 1 warning sign (World Health Organization [WHO] 2009 criteria): mucosal bleeding 66/143 (46.1%), soft tissue edema 54/143 (37.7%), and ultrasound detected plasma leakage (pleural effusions/ascites) 30/129 (23.25%). 138 (96.5%) patients received intravenous (IV) fluids: 3 L (IQR: 0.5-8.5 L). Most patients had non-severe dengue with warning signs. High rates of edema and plasma leakage may be explained partly by liberal use of IV fluids. Studies are needed on optimizing fluid management in non-severe adult dengue.

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.

Thrombocytopenia in Dengue: Interrelationship between Virus and the Imbalance between Coagulation and Fibrinolysis and Inflammatory Mediators

Dengue is an infectious disease caused by dengue virus (DENV). In general, dengue is a self-limiting acute febrile illness followed by a phase of critical defervescence, in which patients may improve or progress to a severe form. Severe illness is characterized by hemodynamic disturbances, increased vascular permeability, hypovolemia, hypotension, and shock. Thrombocytopenia and platelet dysfunction are common in both cases and are related to the clinical outcome. Different mechanisms have been hypothesized to explain DENV-associated thrombocytopenia, including the suppression of bone marrow and the peripheral destruction of platelets. Studies have shown DENV-infected hematopoietic progenitors or bone marrow stromal cells. Moreover, anti-platelet antibodies would be involved in peripheral platelet destruction as platelets interact with endothelial cells, immune cells, and/or DENV. It is not yet clear whether platelets play a role in the viral spread. Here, we focus on the mechanisms of thrombocytopenia and platelet dysfunction in DENV infection. Because platelets participate in the inflammatory and immune response by promoting cytokine, chemokine, and inflammatory mediator secretion, their relevance as "immune-like effector cells" will be discussed. Finally, an implication for platelets in plasma leakage will be also regarded, as thrombocytopenia is associated with clinical outcome and higher mortality.

Time since onset of disease and individual clinical markers associate with transcriptional changes in uncomplicated dengue

BACKGROUND

Dengue virus (DENV) infection causes viral haemorrhagic fever that is characterized by extensive activation of the immune system. The aim of this study is to investigate the kinetics of the transcriptome signature changes during the course of disease and the association of genes in these signatures with clinical parameters.

METHODOLOGY/PRINCIPLE FINDINGS

Sequential whole blood samples from DENV infected patients in Jakarta were profiled using affymetrix microarrays, which were analysed using principal component analysis, limma, gene set analysis, and weighted gene co-expression network analysis. We show that time since onset of disease, but not diagnosis, has a large impact on the blood transcriptome of patients with non-severe dengue. Clinical diagnosis (according to the WHO classification) does not associate with differential gene expression. Network analysis however, indicated that the clinical markers platelet count, fibrinogen, albumin, IV fluid distributed per day and liver enzymes SGOT and SGPT strongly correlate with gene modules that are enriched for genes involved in the immune response. Overall, we see a shift in the transcriptome from immunity and inflammation to repair and recovery during the course of a DENV infection.

CONCLUSIONS/SIGNIFICANCE

Time since onset of disease associates with the shift in transcriptome signatures from immunity and inflammation to cell cycle and repair mechanisms in patients with non-severe dengue. The strong association of time with blood transcriptome changes hampers both the discovery as well as the potential application of biomarkers in dengue. However, we identified gene expression modules that associate with key clinical parameters of dengue that reflect the systemic activity of disease during the course of infection. The expression level of these gene modules may support earlier detection of disease progression as well as clinical management of dengue.

Dengue virus and antiplatelet autoantibodies synergistically induce haemorrhage through Nlrp3-inflammasome and FcγRIII

Dengue haemorrhagic fever (DHF) typically occurs during secondary infections with dengue viruses (DENVs). Although it is generally accepted that antibody-dependent enhancement is the primary reason why patients with secondary infection are at an increased risk of developing DHF, a growing body of evidence shows that other mechanisms, such as the elicitation of antiplatelet autoantibodies by DENV nonstructural protein NS1, also play crucial roles in the pathogenesis of DHF. In this study, we developed a "two-hit" model of secondary DENV infection to examine the respective roles of DENV (first hit) and antiplatelet Igs (second hit) on the induction of haemorrhage. Mice were first exposed to DENV and then exposed to antiplatelet or anti-NS1 Igs 24 hours later. The two-hit treatment induced substantial haemorrhage, coagulopathy, and cytokine surge, and additional treatment with antagonists of TNF-α, IL-1, caspase-1, and FcγRIII ameliorated such effects. In addition, knockout mice lacking the Fcγ receptor III, Toll-like receptor 3, and inflammasome components Nlrp3 and caspase-1 exhibited considerably fewer pathological alterations than did wild type controls. These findings may provide new perspectives for developing feasible approaches to treat patients with DHF.

Prognostic significance of antithrombin activity in patients with crimean-congo hemorrhagic Fever

OBJECTIVE

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral hemorrhagic fever. Disseminated intravascular coagulation (DIC) is an important complication of this disease, especially in severe and fatal cases. Antithrombin (AT) acts as an anticoagulant by inactivating thrombin, Factor IX, Factor X and Factor XI. We conducted this study to investigate the AT levels and their prognostic value in CCHF.

MATERIALS AND METHODS

Twenty-eight confirmed CCHF patients were included in this study. Diagnosis of the disease was made by CCHF IgM and/or PCR positivity. Patients were grouped based on the severity criteria described previously. The patients with platelet counts <20 000×10(6) cell/L, white blood counts >10×10(9) cell/L, prothrombin times >60 seconds, aspartate aminotransferase levels >700 IU/L or alanine aminotransferase levels >900 IU/L were accepted as severe cases. Patients whose illnesses were self-limited and who did not require blood component replacement were accepted as mild cases, and patients who improved but required blood component replacement were accepted as moderate cases. Blood samples were obtained on the day that the patient had the lowest platelet count and before any thrombocyte replacement. The antithrombin activity was measured using a chromogenic substrate test (Diagnostica Stago STA Compact) at a research laboratory.

RESULTS

Twenty-two (78.6%) of the cases were mild, 3 (10.7%) were moderate, and 3 were (10.7%) severe. The mean AT value was 101% for mild cases, 116.6 % for moderate cases, and 88% for severe cases (p>0.05). Although there were no statistically significant differences between the AT values, the mean AT activity was lower in severe CCHF cases.

CONCLUSION

The AT activity may have been decreased in severe CCHF cases. Further studies with greater numbers of patients are required to determine the level of AT activity and its correlation with disease severity and the prognosis of CCHF.

Endothelial dysfunction in dengue virus pathology

Dengue virus (DENV) is a leading cause of illness and death, mainly in the (sub)tropics, where it causes dengue fever and/or the more serious diseases dengue hemorrhagic fever and dengue shock syndrome that are associated with changes in vascular permeability. Despite extensive research, the pathogenesis of DENV is still poorly understood and, although endothelial cells represent the primary fluid barrier of the blood vessels, the extent to which these cells contribute to DENV pathology is still under debate. The primary target cells for DENV are dendritic cells and monocytes/macrophages that release various chemokines and cytokines upon infection, which can activate the endothelium and are thought to play a major role in DENV-induced vascular permeability. However, recent studies indicate that DENV also replicates in endothelial cells and that DENV-infected endothelial cells may directly contribute to viremia, immune activation, vascular permeability and immune targeting of the endothelium. Also, the viral non-structural protein-1 and antibodies directed against this secreted protein have been reported to be involved in endothelial cell dysfunction. This review provides an extensive overview of the effects of DENV infection on endothelial cell physiology and barrier function.

The revised dengue fever classification in German travelers: clinical manifestations and indicators for severe disease

BACKGROUND

The number of dengue cases imported to Germany has increased significantly in recent years. Among returning travelers, dengue is now a frequent cause of hospitalization. The aim of this study was to determine the proportion of patients with severe disease hospitalized in a European, non-endemic country applying the revised 2009 WHO classification system and to determine predictors of severe disease.

METHODS

A retrospective single-center analysis of clinical data from 56 patients, 31 (55 %) women and 25 (45 %) men, between 14 and 70 years of age treated in a tertiary care hospital between 1996 and 2010 was conducted.

RESULTS

Thirty-nine patients (69.6 %) presented with dengue fever without warning signs, 11 (19.6 %) with warning signs and 6 (10.7 %) with signs for severe dengue fever. Two patients (4 %) developed dengue shock syndrome. Non-European descent (p = 0.001), plasma protein level <6.5 mg/dl (p = 0.001), platelets <30/nl (p = 0.017) and activated partial thromboplastin time (aPTT) >44 s (p = 0.003) were associated with severe disease.

CONCLUSIONS

A significant proportion of patients hospitalized with symptomatic imported dengue fever in Germany have evidence of severe disease. Simple routine laboratory parameters such as complete blood count, plasma protein level and aPTT are helpful tools for identifying adult patients at risk for severe disease.

Hyperferritinaemia in dengue virus infected patients is associated with immune activation and coagulation disturbances

BACKGROUND

During a dengue outbreak on the Caribbean island Aruba, highly elevated levels of ferritin were detected in dengue virus infected patients. Ferritin is an acute-phase reactant and hyperferritinaemia is a hallmark of diseases caused by extensive immune activation, such as haemophagocytic lymphohistiocytosis. The aim of this study was to investigate whether hyperferritinaemia in dengue patients was associated with clinical markers of extensive immune activation and coagulation disturbances.

METHODOLOGY/PRINCIPAL FINDINGS

Levels of ferritin, standard laboratory markers, sIL-2R, IL-18 and coagulation and fibrinolytic markers were determined in samples from patients with uncomplicated dengue in Aruba. Levels of ferritin were significantly increased in dengue patients compared to patients with other febrile illnesses. Moreover, levels of ferritin associated significantly with the occurrence of viraemia. Hyperferritinaemia was also significantly associated with thrombocytopenia, elevated liver enzymes and coagulation disturbances. The results were validated in a cohort of dengue virus infected patients in Brazil. In this cohort levels of ferritin and cytokine profiles were determined. Increased levels of ferritin in dengue virus infected patients in Brazil were associated with disease severity and a pro-inflammatory cytokine profile.

CONCLUSIONS/SIGNIFICANCE

Altogether, we provide evidence that ferritin can be used as a clinical marker to discriminate between dengue and other febrile illnesses. The occurrence of hyperferritinaemia in dengue virus infected patients is indicative for highly active disease resulting in immune activation and coagulation disturbances. Therefore, we recommend that patients with hyperferritinaemia are monitored carefully.

Molecular mimicry between dengue virus and coagulation factors induces antibodies to inhibit thrombin activity and enhance fibrinolysis

Dengue virus (DENV) is the most common cause of viral hemorrhagic fever, and it may lead to life-threating dengue hemorrhagic fever and shock syndrome (DHF/DSS). Because most cases of DHF/DSS occur in patients with secondary DENV infection, anti-DENV antibodies are generally considered to play a role in the pathogenesis of DHF/DSS. Previously, we have found that antithrombin antibodies (ATAs) with both antithrombotic and profibrinolytic activities are present in the sera of dengue patients. However, the mechanism by which these autoantibodies are induced is unclear. In this study, we demonstrated that antibodies induced by DENV immunization in mice and rabbits could bind to DENV antigens as well as to human thrombin and plasminogen (Plg). The binding of anti-DENV antibodies to thrombin and Plg was inhibited by preadsorption with DENV nonstructural protein 1. In addition, affinity-purified ATAs from DENV-immunized rabbit sera could inhibit thrombin activity and enhance Plg activation both in vitro and in vivo. Taken together, our results suggest that molecular mimicry between DENV and coagulation factors can induce the production of autoantibodies with biological effects similar to those of ATAs found in dengue patients. These coagulation-factor cross-reactive anti-DENV antibodies can interfere with the balance of coagulation and fibrinolysis, which may lead to the tendency of DHF/DSS patients to bleed.

IMPORTANCE

Dengue virus (DENV) infection is the most common mosquito-borne viral disease in tropical and subtropical areas. Over 50 million DENV infection cases develop each year, and more than 2.5 billion people are at risk of dengue-induced hemorrhagic fever and shock syndrome. Currently, there is no vaccine or drug treatment for DENV. In the present study, we demonstrated that DENV immunization could induce thrombin and plasminogen (Plg) cross-reactive antibodies, which were able to inhibit thrombin activity and enhance Plg activation. These results suggest that molecular mimicry between DENV antigens, thrombin, and Plg may elicit antibodies that disturb hemostasis. The selection of appropriate candidate antigens for use in DENV vaccines should prevent these potentially dangerous autoimmune responses.

Endothelial cells in dengue hemorrhagic fever

Therapies to prevent or reverse endothelial dysfunction and vascular leak found in dengue hemorrhagic fever (DHF) have not been identified. In this review we summarize dengue viruses and the spectrum of human disease and highlight evidence of endothelial cell dysfunction in DHF based on studies in patients and mouse and tissue culture models. Evidence suggests that both virus antigen and host immune response, can cause endothelial cell dysfunction and weaken endothelial barrier integrity. We suggest possible therapeutic interventions and highlight how therapies targeting altered endothelial function might be evaluated in animal models and in patients with DHF.

Dengue human infection models supporting drug development

Dengue is a arboviral infection that represents a major global health burden. There is an unmet need for effective dengue therapeutics to reduce symptoms, duration of illness and incidence of severe complications. Here, we consider the merits of a dengue human infection model (DHIM) for drug development. A DHIM could allow experimentally controlled studies of candidate therapeutics in preselected susceptible volunteers, potentially using smaller sample sizes than trials that recruited patients with dengue in an endemic country. In addition, the DHIM would assist the conduct of intensive pharmacokinetic and basic research investigations and aid in determining optimal drug dosage. Furthermore, a DHIM could help establish proof of concept that chemoprophylaxis against dengue is feasible. The key challenge in developing the DHIM for drug development is to ensure the model reliably replicates the typical clinical and laboratory features of naturally acquired, symptomatic dengue.

Cardiovascular manifestations of the emerging dengue pandemic

Dengue is one of the most important emerging viral diseases globally. The majority of symptomatic infections result in a relatively benign disease course. However, a small proportion of patients develop severe clinical manifestations, including bleeding, organ impairment, and endothelial dysfunction with increased capillary permeability causing hypovolaemic shock that can lead to cardiovascular collapse. Evidence is increasing that dengue can also cause myocardial impairment, arrhythmias and, occasionally, fulminant myocarditis. No antiviral agents or vaccines are licensed for dengue, and treatment remains supportive with judicious fluid replacement for patients with severe disease. Defining the role of cardiac dysfunction in the haemodynamic compromise of severe dengue has potentially important management implications. In this Review, we will outline the current understanding of the cardiovascular manifestations of dengue, including myocardial and vascular involvement, and conclude with a discussion of the available therapeutic options and potential future research directions.

Regulation of cell survival and death during Flavivirus infections

Flaviviruses, ss(+) RNA viruses, include many of mankind’s most important pathogens. Their pathogenicity derives from their ability to infect many types of cells including neurons, to replicate, and eventually to kill the cells. Flaviviruses can activate tumor necrosis factor α and both intrinsic (Bax-mediated) and extrinsic pathways to apoptosis. Thus they can use many approaches for activating these pathways. Infection can lead to necrosis if viral load is extremely high or to other types of cell death if routes to apoptosis are blocked. Dengue and Japanese Encephalitis Virus can also activate autophagy. In this case the autophagy temporarily spares the infected cell, allowing a longer period of reproduction for the virus, and the autophagy further protects the cell against other stresses such as those caused by reactive oxygen species. Several of the viral proteins have been shown to induce apoptosis or autophagy on their own, independent of the presence of other viral proteins. Given the versatility of these viruses to adapt to and manipulate the metabolism, and thus to control the survival of, the infected cells, we need to understand much better how the specific viral proteins affect the pathways to apoptosis and autophagy. Only in this manner will we be able to minimize the pathology that they cause.

Elevated levels of full-length and thrombin-cleaved osteopontin during acute dengue virus infection are associated with coagulation abnormalities

INTRODUCTION

Dengue virus (DENV) is transmitted by the mosquito vector, and causes a wide range of symptoms that lead to dengue fever (DF) or life-threatening dengue hemorrhagic fever (DHF). The host and viral correlates that contribute to DF and DHF are complex and poorly understood, but appear to be linked to inflammation and impaired coagulation. Full-length osteopontin (FL-OPN), a glycoprotein, and its activated thrombin-cleaved product, trOPN, integrate multiple immunological signals through the induction of pro-inflammatory cytokines.

MATERIALS AND METHOD

To understand the role of OPN in DENV-infection, we assessed circulating levels of FL-OPN, trOPN, and several coagulation markers (D-dimer, thrombin-antithrombin complex [TAT], thrombomodulin [TM], and ferritin in blood obtained from 65 DENV infected patients in the critical and recovery phases of DF and DHF during a dengue virus epidemic in the Philippines in 2010.

RESULTS

Levels of FL-OPN, trOPN, D-dimer, TAT, and TM were significantly elevated in the critical phase in both the DF and DHF groups, as compared with healthy controls. During the recovery phase, FL-OPN levels declined while trOPN levels increased dramatically in both the DF and DHF groups. FL-OPN levels were directly correlated with D-dimer and ferritin levels, while the generation of trOPN was associated with TAT levels, platelet counts, and viral RNA load.

CONCLUSION

Our study demonstrated the marked elevation of plasma levels of FL-OPN and thrombin-cleaved OPN product, trOPN, in DENV-infection for the first time. Further studies on the biological functions of these matricellular proteins in DENV-infection would clarify its pathogenesis.

Clinical and laboratory characteristics of patients with dengue hemorrhagic fever manifestations and their transfusion profile

Background

Dengue is an infectious disease with a recurring incidence, especially in developing countries. Despite recent economic growth, success in disease control has not been achieved, and dengue has evolved from cyclic epidemic outbreaks to a lack of seasonality. The lack of scientific basis for the proper management of cases with hemorrhagic manifestations, especially regarding transfusion procedures, might contribute to the high death rate in potentially avoidable cases.

Objective

The aim of the study was to identify the clinical and laboratory manifestations in hemorrhagic dengue fever treated at the emergency services in Rio Branco, AC, Brazil, as well as to describe transfusion characteristics of patients and identify possible prognostic factors.

Methods

A retrospective descriptive study was performed to analyze the distribution of relative frequencies of clinical and laboratory variables. The study was carried out in Rio Branco with confirmed dengue fever cases. Secondary data were obtained by Acre Epidemiological Surveillance teams of cases with bleeding or platelet counts under 100.0 × 10⁹/L. The patients' clinical, laboratory and transfusion data were obtained from hospital records.

Results

A total of 90,553 dengue cases were reported of which 7,447 had serologic confirmation; 267 cases had hemorrhagic manifestations and 193 patients were located. Nearly half of the patients had anemia and the mean of the lowest platelet count of these patients was 26.4 × 10⁹/L. Platelet concentrate was transfused in 22.3% of cases with a mean of 7.5 IU/patient, fresh frozen plasma in 21.2% with a mean of 5.2 IU/patient and just 2.6% of patients received concentrated red blood cells with a mean of 3.2 IU/patient. Bleeding led to transfusions. Signs of plasma leakage and cardiopulmonary dysfunction were correlated to unfavorable outcomes.

Conclusion

The pattern of clinical and laboratory criteria observed in this investigation does not differ from the literature. Transfusions were used as part of the treatment of dengue hemorrhagic fever manifestations. Some of the clinical manifestations may be related to unfavorable outcomes.

© 2014 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. All rights reserved.

Development of clinical decision rules to predict recurrent shock in dengue

INTRODUCTION

Mortality from dengue infection is mostly due to shock. Among dengue patients with shock, approximately 30% have recurrent shock that requires a treatment change. Here, we report development of a clinical rule for use during a patient's first shock episode to predict a recurrent shock episode.

METHODS

The study was conducted in Center for Preventive Medicine in Vinh Long province and the Children's Hospital No. 2 in Ho Chi Minh City, Vietnam. We included 444 dengue patients with shock, 126 of whom had recurrent shock (28%). Univariate and multivariate analyses and a preprocessing method were used to evaluate and select 14 clinical and laboratory signs recorded at shock onset. Five variables (admission day, purpura/ecchymosis, ascites/pleural effusion, blood platelet count and pulse pressure) were finally trained and validated by a 10-fold validation strategy with 10 times of repetition, using a logistic regression model.

RESULTS

The results showed that shorter admission day (fewer days prior to admission), purpura/ecchymosis, ascites/pleural effusion, low platelet count and narrow pulse pressure were independently associated with recurrent shock. Our logistic prediction model was capable of predicting recurrent shock when compared to the null method (P < 0.05) and was not outperformed by other prediction models. Our final scoring rule provided relatively good accuracy (AUC, 0.73; sensitivity and specificity, 68%). Score points derived from the logistic prediction model revealed identical accuracy with AUCs at 0.73. Using a cutoff value greater than -154.5, our simple scoring rule showed a sensitivity of 68.3% and a specificity of 68.2%.

CONCLUSIONS

Our simple clinical rule is not to replace clinical judgment, but to help clinicians predict recurrent shock during a patient's first dengue shock episode.

Clinical characteristics of Dengue shock syndrome in Vietnamese children: a 10-year prospective study in a single hospital

BACKGROUND

Dengue shock syndrome (DSS) is a severe manifestation of dengue virus infection that particularly affects children and young adults. Despite its increasing global importance, there are no prospective studies describing the clinical characteristics, management, or outcomes of DSS.

METHODS

We describe the findings at onset of shock and the clinical evolution until discharge or death, from a comprehensive prospective dataset of 1719 Vietnamese children with laboratory-confirmed DSS managed on a single intensive care unit between 1999 and 2009.

RESULTS

The median age of patients was 10 years. Most cases had secondary immune responses, with only 6 clear primary infections, and all 4 dengue virus serotypes were represented during the 10-year study. Shock occurred commonly between days 4 and 6 of illness. Clinical signs and symptoms were generally consistent with empirical descriptions of DSS, although at presentation 153 (9%) were still febrile and almost one-third had no bleeding. Overall, 31 (2%) patients developed severe bleeding, primarily from the gastrointestinal tract, 26 of whom required blood transfusion. Only 8 patients died, although 123 of 1719 (7%) patients had unrecordable blood pressure at presentation and 417 of the remaining 1596 (26%) were hypotensive for age. The majority recovered well with standard crystalloid resuscitation or following a single colloid infusion. All cases were classified as severe dengue, while only 70% eventually fulfilled all 4 criteria for the 1997 World Health Organization classification of dengue hemorrhagic fever.

CONCLUSIONS

With prompt intervention and assiduous clinical care by experienced staff, the outcome of this potentially fatal condition can be excellent.

Hemostatic derangement in dengue hemorrhagic fever

Dengue hemorrhagic fever (DHF) is a more severe manifestation of dengue virus infection. Patients with DHF exhibit abnormal hematological indices, including high hematocrit, low white blood cells, low neutrophils, high lymphocytes, increased atypical lymphocytes, low platelets, slightly prolonged activated partial thromboplastin time, prothrombin time, and thrombin time. Abnormal platelet functions manifest as impaired platelet aggregation to ADP, and concurrent increases in plasma thromboglobulin and platelet factor 4 levels are also seen. Variable reductions in the activities of coagulation factors including prothrombin, V, VII, VIII, IX, and X may be present. The plasma level of antithrombin is typically normal, but protein C and protein S are modestly reduced. Within the fibrinolytic system, slightly increased levels of tissue-plasminogen activator accompanied by slightly increased plasminogen activator inhibitor-1 and decreased thrombin activatable fibrinolysis inhibitor have been demonstrated. These derangements are prominent in patients with DHF grades III and IV, collectively known as dengue shock syndrome. Moreover, patients with excessive depletion of intravascular volume from plasma leakage and/or massive bleeding from endothelial dysfunction, thrombocytopenia, platelet dysfunction, and coagulopathy may exhibit shock, prolonged shock and repeated shock. DIC is also commonly found in these complicated patients. However, most patients recover spontaneously with normalization of abnormal laboratory profiles during the convalescent stage or within one to two weeks after defervescence.

Reduced thrombin formation and excessive fibrinolysis are associated with bleeding complications in patients with dengue fever: a case-control study comparing dengue fever patients with and without bleeding manifestations

Background

Dengue cases have been classified according to disease severity into dengue fever (DF) and dengue hemorrhagic fever (DHF). Although DF is considered a non-severe manifestation of dengue, it has been recently demonstrated that DF represents a heterogeneous group of patients with varied clinical complications and grades of severity. Particularly, bleeding complications, commonly associated to DHF, can be detected in half of the patients with DF. Although a frequent complication, the causes of bleedings in DF have not been fully addressed. Thus, the aim of this study was to perform a comprehensive evaluation of possible pathophysiological mechanisms that could contribute to the bleeding tendency observed in patients with DF.

Methods

This is a case–control study that enrolled adults with DF without bleeding and adults with DF and bleeding complications during the defervescence period. Healthy controls were also included. Peripheral blood counts, inflammatory, fibrinolysis and endothelial cell activation markers, and thrombin generation were evaluated in patients and controls.

Results

We included 33 adults with DF without complications, 26 adults with DF and bleeding and 67 healthy controls. Bleeding episodes were mild in 15 (57.6%) and moderate in 11 (42.4%) patients, 8 (30.7%) patients had bleedings in multiple sites. Patients with DF and bleedings had lower platelet counts than DF without bleeding (median = 19,500 vs. 203,500/mm3, P < 0,0001). Levels of TNF-α, thrombomodulin and VWF were significantly increased in the two dengue groups than in healthy controls, but similar between patients with and without bleedings. Plasma levels of tPA and D-dimer were significantly increased in patients with bleedings (median tPA levels were 4.5, 5.2, 11.7 ng/ml, P < 0.0001 and median D-dimer levels were 515.5, 1028 and 1927 ng/ml, P < 0.0001). The thrombin generation test showed that patients with bleeding complications had reduced thrombin formation (total thrombin generated were 3753.4 in controls, 3367.5 in non-bleeding and 2274.5nM in bleeding patients, P < 0.002).

Conclusions

DF can manifest with spontaneous bleedings, which are associated with specific coagulation and fibrinolysis profiles that are not significantly present in DF without this complication. Particularly, thrombocytopenia, excessive fibrinolysis and reduced thrombin formation may contribute to the bleeding manifestations in DF.

The role of endothelial activation in dengue hemorrhagic fever and hantavirus pulmonary syndrome

The loss of the endothelium barrier and vascular leakage play a central role in the pathogenesis of hemorrhagic fever viruses. This can be caused either directly by the viral infection and damage of the vascular endothelium, or indirectly by a dysregulated immune response resulting in an excessive activation of the endothelium. This article briefly reviews our knowledge of the importance of the disruption of the vascular endothelial barrier in two severe disease syndromes, dengue hemorrhagic fever and hantavirus pulmonary syndrome. Both viruses cause changes in vascular permeability without damaging the endothelium. Here we focus on our understanding of the virus interaction with the endothelium, the role of the endothelium in the induced pathogenesis, and the possible mechanisms by which each virus causes vascular leakage. Understanding the dynamics between viral infection and the dysregulation of the endothelial cell barrier will help us to define potential therapeutic targets for reducing disease severity.

Re-evaluation of the pathogenic roles of nonstructural protein 1 and its antibodies during dengue virus infection

Dengue virus (DENV) infection can cause life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Vascular leakage and abnormal hemorrhage are the two major pathogenic changes found in these patients. From previous studies, it is known that both antibodies and cytokines induced in response to DENV infection are involved in the immunopathogenesis of DHF/DSS. However, the role of viral factors during DENV infection remains unclear. Nonstructural protein 1 (NS1), which is secreted in the sera of patients, is a useful diagnostic marker for acute DENV infection. Nevertheless, the roles of NS1 and its antibodies in the pathogenesis of DHF/DSS are unclear. The focus of this review is to evaluate the possible contributions of NS1 and the antibodies it induces to vascular leakage and abnormal hemorrhage during DENV infection, which may provide clues to better understanding the pathogenesis of DHF/DSS.

Dengue hepatitis sans dysfunction: experience of a single tertiary referral centre in the north Indian state of Uttarakhand

Hepatic involvement is uncommon in dengue viral infections and is traditionally thought to be associated with severe disease in terms of morbidity and mortality. This study was conducted in order to assess the liver function in patients with dengue virus infection and to analyse its effect upon patient outcome. Three hundred and twenty-seven consecutive patients with dengue virus were categorized into groups A, B, C and D on the basis of elevation of either of the hepatic transaminases (normal, <3, 3-10 and >10 times, respectively). Primary and secondary outcome measures related to morbidity and mortality were studied. Hepatitis was seen in ∼3/4 patients; an increasing grade of liver involvement was significantly associated with fewer platelets (P < 0.001). Recovery of platelets, bleeding manifestations, renal dysfunction, platelet recovery and duration of hospitalization were similar in all groups. Among the patients with manifest bleeding, the platelet count did not differ significantly but the platelet recovery was significantly slower (P = 0.044) with increasing grade. Hepatic dysfunction is self-limited without any increase in morbidity and mortality.

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.

Biomarkers of endothelial activation/dysfunction in infectious diseases

Endothelial dysfunction contributes to the pathogenesis of a variety of potentially serious infectious diseases and syndromes, including sepsis and septic shock, hemolytic-uremic syndrome, severe malaria, and dengue hemorrhagic fever. Because endothelial activation often precedes overt endothelial dysfunction, biomarkers of the activated endothelium in serum and/or plasma may be detectable before classically recognized markers of disease, and therefore, may be clinically useful as biomarkers of disease severity or prognosis in systemic infectious diseases. In this review, the current status of mediators of endothelial cell function (angiopoietins-1 and -2), components of the coagulation pathway (von Willebrand Factor, ADAMTS13, and thrombomodulin), soluble cell-surface adhesion molecules (soluble E-selectin, sICAM-1, and sVCAM-1), and regulators of vascular tone and permeability (VEGF and sFlt-1) as biomarkers in severe infectious diseases is discussed in the context of sepsis, E. coli O157:H7 infection, malaria, and dengue virus infection.

Dengue virus enhances thrombomodulin and ICAM-1 expression through the macrophage migration inhibitory factor induction of the MAPK and PI3K signaling pathways

Dengue virus (DV) infections cause mild dengue fever (DF) or severe life-threatening dengue hemorrhagic fever (DHF). The mechanisms that cause hemorrhage in DV infections remain poorly understood. Thrombomodulin (TM) is a glycoprotein expressed on the surface of vascular endothelial cells that plays an important role in the thrombin-mediated activation of protein C. Prior studies have shown that the serum levels of soluble TM (sTM) and macrophage migration inhibitory factor (MIF) are significantly increased in DHF patients compared to levels in DF patients or normal controls. In this study, we investigated how MIF and sTM concentrations are enhanced in the plasma of DHF patients and the potential effect of MIF on coagulation through its influence on two factors: thrombomodulin (TM) and intercellular adhesion molecule-1 (ICAM-1) in endothelial cells and monocytes. Recombinant human macrophage migration inhibitory factor (rMIF) was used to treat monocytic THP-1 cells and endothelial HMEC-1 cells or primary HUVEC cells. The subsequent expression of TM and ICAM-1 was assessed by immunofluorescent staining and flow cytometry analysis. Additionally, the co-incubation of THP-1 cells with various cell signaling pathway inhibitors was used to determine the pathways through which MIF mediated its effect. The data provided evidence that severe DV infections induce MIF expression, which in turn stimulates monocytes or endothelial cells to express TM and ICAM-1 via the Erk, JNK MAPK and the PI3K signaling pathways, supporting the idea that MIF may play an important role as a regulator of coagulation.