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

Vascular dysfunction in hemorrhagic viral fevers: opportunities for organotypic modeling

The hemorrhagic fever viruses (HFVs) cause severe or fatal infections in humans. Named after their common symptom hemorrhage, these viruses induce significant vascular dysfunction by affecting endothelial cells, altering immunity, and disrupting the clotting system. Despite advances in treatments, such as cytokine blocking therapies, disease modifying treatment for this class of pathogen remains elusive. Improved understanding of the pathogenesis of these infections could provide new avenues to treatment. While animal models and traditional 2D cell cultures have contributed insight into the mechanisms by which these pathogens affect the vasculature, these models fall short in replicatingin vivohuman vascular dynamics. The emergence of microphysiological systems (MPSs) offers promising avenues for modeling these complex interactions. These MPS or 'organ-on-chip' models present opportunities to better mimic human vascular responses and thus aid in treatment development. In this review, we explore the impact of HFV on the vasculature by causing endothelial dysfunction, blood clotting irregularities, and immune dysregulation. We highlight how existing MPS have elucidated features of HFV pathogenesis as well as discuss existing knowledge gaps and the challenges in modeling these interactions using MPS. Understanding the intricate mechanisms of vascular dysfunction caused by HFV is crucial in developing therapies not only for these infections, but also for other vasculotropic conditions like sepsis.

Evaluation of clinical and laboratory characteristics of dengue viral infection and risk factors of dengue hemorrhagic fever: a multi-center retrospective analysis

BACKGROUND

Dengue Viral Infection (DVI) has become endemic in Pakistan since the first major outbreak in Karachi in 1996. Despite aggressive measures taken by relevant authorities, Pakistan has been dealing with a worsening dengue crisis for the past two decades. DHF is severe form of dengue infection which is linked with significant morbidity and mortality. Early identification of severe dengue infections can reduce the morbidity and mortality. In this context we planned current study in which we find out the different factors related with DHF as well as clinical laboratory features of DHF and compare them to DF so that patients can be best evaluated for DHF and managed accordingly at admission.

METHODS

Retrospective study conducted over a period of 6 years (2013-2018) in two tertiary care hospitals in Pakistan. Data were collected by using a pre-structured data collection form. Data were statistically analyzed to determine the clinical and laboratory characteristics of DVI and risk factors of dengue hemorrhagic fever (DHF).

RESULTS

A total 512 dengue cases (34.05 ± 15.08 years; Male 69.53%) were reviewed. Most common clinical manifestations of DVI were fever (99.60%), headache (89.1%), chills (86.5%), rigors (86.5%), myalgia (72.3%). Less common clinical manifestations were vomiting (52.5%), arthralgia (50.2%) and skin rashes (47.5%). Furthermore, nasal bleeding (44.1%), gum bleeding (32.6%), pleural effusion (13.9%) and hematuria (13.1%) were more profound clinical presentations among DHF patients. Mortality rate was 1.5% in this study. Logistic regression analysis indicated that delayed hospitalization (OR: 2.30) and diabetes mellitus (OR:2.71), shortness of breath (OR:2.21), association with risk groups i.e., living near stagnant water, travelling to endemic areas, living in endemic regions (OR:1.95), and presence of warning signs (OR:2.18) were identified as risk factors of DHF. Statistically we found that there is strong association of diabetes mellitus (DM) with DHF while the patient suffering from DM individually had higher odds (2.71) of developing DHF than patients without disease.

CONCLUSIONS

The current study demonstrated that the clinical and laboratory profiles of DF and DHF are significantly distinct. Significant predictors of DHF were advanced age, diabetes mellitus, ascites, pleural effusion, thick gallbladder and delayed hospitalization. The identification of these factors at early stage provides opportunities for the clinicians to identify high risk patients and to reduce dengue-related morbidity and mortality.

Molecular mechanisms in the pathogenesis of dengue infections

Dengue is the most rapidly emerging climate-sensitive infection, and morbidity/mortality and disease incidence are rising markedly, leading to healthcare systems being overwhelmed. There are currently no specific treatments for dengue or prognostic markers to identify those who will progress to severe disease. Owing to an increase in the burden of illness and a change in epidemiology, many patients experience severe disease. Our limited understanding of the complex mechanisms of disease pathogenesis has significantly hampered the development of safe and effective treatments, vaccines, and biomarkers. We discuss the molecular mechanisms of dengue pathogenesis, the gaps in our knowledge, and recent advances, as well as the most crucial questions to be answered to enable the development of therapeutics, biomarkers, and vaccines.

Dengue

Dengue, caused by four closely related viruses, is a growing global public health concern, with outbreaks capable of overwhelming health-care systems and disrupting economies. Dengue is endemic in more than 100 countries across tropical and subtropical regions worldwide, and the expanding range of the mosquito vector, affected in part by climate change, increases risk in new areas such as Spain, Portugal, and the southern USA, while emerging evidence points to silent epidemics in Africa. Substantial advances in our understanding of the virus, immune responses, and disease progression have been made within the past decade. Novel interventions have emerged, including partially effective vaccines and innovative mosquito control strategies, although a reliable immune correlate of protection remains a challenge for the assessment of vaccines. These developments mark the beginning of a new era in dengue prevention and control, offering promise in addressing this pressing global health issue.

APRI as a predictor of severe dengue fever

Introduction

The AST/platelet ratio index (APRI) is a well-researched indicator of liver fibrosis. Some studies have shown that APRI can be used as a predictor of severe dengue, but the data is limited. As dengue epidemics are common in our country with limited healthcare resources, we believe APRI can help emergency physicians/primary physicians in predicting the severity of dengue and plan for the appropriate use of limited healthcare resources.

Objective

1) To determine the utility of APRI as a predictor of severe dengue. 2) To determine the association of APRI with length of hospital stay and platelet requirement.

Materials and Methods

A retrospective cross-sectional study was done on patients presented to the Emergency Medicine department at Travancore Medicity Medical College with a positive Dengue NS1 antigen or IgM antibody.

Results

We found from the univariate analysis results that ALT > 74.5 IU/L has a sensitivity of 59.6 and a specificity of 76.3 (AUC: 0.696; 95% CI: 0.606-0.786), AST > 160.5 IU/L has a sensitivity of 42.3 and a specificity of 93.7 (AUC: 0.747; 95% CI: 0.665-0.829), and APRI > 3.2 has a sensitivity of 69.2 and a specificity of 84.2 (AUC: 0.806; 95% CI: 0.72-0.884) to predict severe dengue. Patients with an APRI of >3.2 required a mean hospital stay of 5.47 days (P = 0.005); 27 (81.8%) requiring platelet transfusion had an APRI of > 3.2 (P = 0.00).

Conclusion

APRI is a straightforward index that can be easily derived from AST and platelet values. APRI values of >3.2 can predict severe dengue with a sensitivity of 69.2 and a specificity of 84.2. APRI values of >3.2 are also associated with the length of hospital stay and requirement of platelet transfusion.

Dengue fever complicated with ST elevation myocardial infarction with atypical features: A case report

Dengue fever is an arboviral infection whose presentation ranges from a mild febrile illness to a multisystem complicated syndrome. We report a case of 58-year-old female presenting with fever, myalgia, arthralgia, and vomiting who was found to be infected with dengue and had electrocardiography changes revealing ST-segment elevation myocardial infarction, a rare manifestation in dengue. Dengue fever can affect the cardiovascular system leading to conduction abnormalities, hypotension, arrhythmias, myocarditis, cardiomyopathy, and occasionally myocardial infarction, which has been reported in only a few case reports prior to this. The differentiation between myocarditis and myocardial infarction is essential for which echocardiography and coronary angiography can be helpful. It is essential to keep an eye on the cardiovascular complications in a dengue patient as the presentation can be quite subtle with devastating consequences.

Severe dengue in the intensive care unit

Dengue fever is considered the most prolific vector-borne disease in the world, with its transmission rate increasing more than eight times in the last two decades. While most cases present mild to moderate symptoms, 5% of patients can develop severe disease. Although the mechanisms are yet not fully comprehended, immune-mediated activation leading to excessive cytokine expression is suggested as a cause of the two main findings in critical patients: increased vascular permeability that may shock and thrombocytopenia, and coagulopathy that can induce hemorrhage. The risk factors of severe disease include previous infection by a different serotype, specific genotypes associated with more efficient replication, certain genetic polymorphisms, and comorbidities such as diabetes, obesity, and cardiovascular disease. The World Health Organization recommends careful monitoring and prompt hospitalization of patients with warning signs or propensity for severe disease to reduce mortality. This review aims to update the diagnosis and management of patients with severe dengue in the intensive care unit.

John AL, Rathore APS. Dengue: Update on Clinically Relevant Therapeutic Strategies and Vaccines

Dengue viruses (DENV) continue to circulate worldwide, resulting in a significant burden on human health. There are four antigenically distinct serotypes of DENV, an infection of which could result in a potentially life-threatening disease. Current treatment options are limited and rely on supportive care. Although one dengue vaccine is approved for dengue-immune individuals and has modest efficacy, there is still a need for therapeutics and vaccines that can reduce dengue morbidities and lower the infection burden. There have been recent advances in the development of promising drugs for the treatment of dengue. These include direct antivirals that can reduce virus replication as well as host-targeted drugs for reducing inflammation and/or vascular pathologies. There are also new vaccine candidates that are being evaluated for their safety and efficacy in preventing dengue disease. This review highlights nuances in the current standard-of-care treatment of dengue. We also discuss emerging treatment options, therapeutic drugs, and vaccines that are currently being pursued at various stages of preclinical and clinical development.

Platelet augmentation activity of mature leaf juice of Sri Lankan wild type cultivar of Carica papaya L: Insights into potential cellular mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Carica papaya L., a common fruit crop of the family Caricaceae and its leaf juice/extract is a traditionally commended preparation against dengue and other thrombocytopenic diseases by many Asian countries.

AIM OF THE STUDY

The present study posits the potential cellular mechanisms of platelet augmentation activity of mature leaf juice of Sri Lankan wild-type Carica papaya.

MATERIALS AND METHODS

C. papaya leaf juice prepared from different cultivar types, maturity of the leaf, agro-climatic region, and preparation methods were orally administered to hydroxyurea-induced thrombocytopenic rats at 0.72 ml/100 g BW dosage to investigate the most potent platelet increasing preparation. The papaya juice doses; low dose (LD-0.18 ml/100 g BW), human equivalent dose (HED-0.36 ml/100 g BW), and high dose (HD-0.72 ml/100 g BW), were administered to thrombocytopenic rats (N = 6/group) daily for three consecutive days and post-treatment plasma levels of interleukin 6 (IL-6), thrombopoietin (TPO), and platelet-activating factor (PAF) were quantified using specific rat ELISA kits. The mature leaf juice of C. papaya induced IL-6 secretion from bone marrow cell (BMC) cultures was quantified using ELISA. The ability of papaya juice to protect the platelet membrane, from the damage caused by the lytic agent was analyzed in vitro using the lactate dehydrogenase (LDH) assay. The effect of the mature leaf juice of C. papaya on secondary hemostasis was investigated using blood coagulation and clot hydrolyzing activity.

RESULTS

The comparative analysis revealed that the platelet increasing activity of C. papaya leaf did not significantly differ among different types of cultivar, maturity of the leaf, agro-climatic regions and preparation methods (p > 0.05). Both TPO and PAF levels in thrombocytopenic rats diminished when treated with all three doses of the mature leaf juice of C. papaya (p < 0.05), yet IL-6 plasma level was unaltered (p > 0.05). Nevertheless, ex vivo treatment of the mature leaf juice of C. papaya had significantly enhanced IL-6 levels of rat BMC cultures (p < 0.05). Pre-treatment of platelets with the mature leaf juice of C. papaya at different concentrations significantly inhibited LDH leakage from platelets and may have reduced the membrane damage caused by the lytic agent (p < 0.05). Treatment of mature leaf juice of C. papaya also significantly reduced blood clotting time through the extrinsic pathway of the blood coagulation cascade (p < 0.05). Further, prolonged incubation of the plasma clot with different concentrations of the papaya leaf juice revealed dose-dependent hydrolysis of the blood clot, indicating fibrinolysis activity.

CONCLUSIONS

The current study exceeded the traditional medicinal claims, and scientifically affirmed the platelet augmentation activity of mature leaf juice of C. papaya. The mechanistic rationale tested herein explicated that the platelet augmentation activity of the papaya leaf juice can be partially attributed to the stimulation of bone marrow megakaryocytes via modulating thrombopoietic cytokines TPO and IL-6, and by inhibiting the secretion of PAF, while reducing the peripheral platelet destruction by stabilizing the platelet membrane. Further, mature leaf juice of C. papaya imparted both pro-coagulation and fibrinolysis activity of secondary hemostasis endorsing its potential against thrombocytopenia.

Dysregulation of Protein S in COVID-19

Coronavirus Disease 2019 (COVID-19) has been widely associated with increased thrombotic risk, with many different proposed mechanisms. One such mechanism is acquired deficiency of protein S (PS), a plasma protein that regulates coagulation and inflammatory processes, including complement activation and efferocytosis. Acquired PS deficiency is common in patients with severe viral infections and has been reported in multiple studies of COVID-19. This deficiency may be caused by consumption, degradation, or clearance of the protein, by decreased synthesis, or by binding of PS to other plasma proteins, which block its anticoagulant activity. Here, we review the functions of PS, the evidence of acquired PS deficiency in COVID-19 patients, the potential mechanisms of PS deficiency, and the evidence that those mechanisms may be occurring in COVID-19.

Total Plasma Protein S Is a Prothrombotic Marker in People Living With HIV

BACKGROUND

HIV-1 infection is associated with multiple procoagulant changes and increased thrombotic risk. Possible mechanisms for this risk include heigthened expression of procoagulant tissue factor (TF) on circulating monocytes, extracellular vesicles, and viral particles and/or acquired deficiency of protein S (PS), a critical cofactor for the anticoagulant protein C (PC). PS deficiency occurs in up to 76% of people living with HIV-1 (PLWH). As increased ex vivo plasma thrombin generation is a strong predictor of mortality, we investigated whether PS and plasma TF are associated with plasma thrombin generation.

METHODS

We analyzed plasma samples from 9 healthy controls, 17 PLWH on first diagnosis (naive), and 13 PLWH on antiretroviral therapy (ART). Plasma thrombin generation, total and free PS, PC, C4b-binding protein, and TF activity were measured.

RESULTS

We determined that the plasma thrombin generation assay is insensitive to PS, because of a lack of PC activation, and developed a modified PS-sensitive assay. Total plasma PS was reduced in 58% of the naive and 38% of the ART-treated PLWH samples and correlated with increased thrombin generation in the modified assay. Conversely, plasma TF was not increased in our patient population, suggesting that it does not significantly contribute to ex vivo plasma thrombin generation.

CONCLUSION

These data suggest that reduced total plasma PS contributes to the thrombotic risk associated with HIV-1 infection and can serve as a prothrombotic biomarker. In addition, our refined thrombin generation assay offers a more sensitive tool to assess the functional consequences of acquired PS deficiency in PLWH.

The Role of Platelet-Derived Extracellular Vesicles in Immune-Mediated Thrombosis

Platelet-derived extracellular vesicles (PEVs) play important roles in hemostasis and thrombosis. There are three major types of PEVs described based on their size and characteristics, but newer types may continue to emerge owing to the ongoing improvement in the methodologies and terms used to define various types of EVs. As the literature on EVs is growing, there are continuing attempts to standardize protocols for EV isolation and reach consensus in the field. This review provides information on mechanisms of PEV production, characteristics, cellular interaction, and their pathological role, especially in autoimmune and infectious diseases. We also highlight the mechanisms through which PEVs can activate parent cells in a feedback loop.

Etiology, Pathophysiology and Mortality of Shock in Children in Low (Middle) Income Countries: A Systematic Review

OBJECTIVES

Shock is a life-threatening condition in children in low- and middle-income countries (LMIC), with several controversies. This systematic review summarizes the etiology, pathophysiology and mortality of shock in children in LMIC.

METHODS

We searched for studies reporting on children with shock in LMIC in PubMed, Embase and through snowballing (up to 1 October 2019). Studies conducted in LMIC that reported on shock in children (1 month-18 years) were included. We excluded studies only containing data on neonates, cardiac surgery patients or iatrogenic causes. We presented prevalence data, pooled mortality estimates and conducted subgroup analyses per definition, region and disease. Etiology and pathophysiology data were systematically collected.

RESULTS

We identified 959 studies and included 59 studies of which six primarily studied shock. Definitions used for shock were classified into five groups. Prevalence of shock ranged from 1.5% in a pediatric hospital population to 44.3% in critically ill children. Pooled mortality estimates ranged between 3.9-33.3% for the five definition groups. Important etiologies included gastroenteritis, sepsis, malaria and severe anemia, which often coincided. The pathophysiology was poorly studied but suggests that in addition to hypovolemia, dissociative and cardiogenic shock are common in LMIC.

CONCLUSIONS

Shock is associated with high mortality in hospitalized children in LMIC. Despite the importance few studies investigated shock and as a consequence limited data on etiology and pathophysiology of shock is available. A uniform bedside definition may help boost future studies unravelling shock etiology and pathophysiology in LMIC.

Dengue and COVID-19: two sides of the same coin

BACKGROUND

Many countries in Asia and Latin America are currently facing a double burden of outbreaks due to dengue and COVID-19. Here we discuss the similarities and differences between the two infections so that lessons learnt so far from studying both infections will be helpful in further understanding their immunopathogenesis and to develop therapeutic interventions.

MAIN BODY

Although the entry routes of the SARS-CoV-2 and the dengue virus (DENV) are different, both infections result in a systemic infection, with some similar clinical presentations such as fever, headache, myalgia and gastrointestinal symptoms. However, while dengue is usually associated with a tendency to bleed, development of micro and macrothrombi is a hallmark of severe COVID-19. Apart from the initial similarities in the clinical presentation, there are further similarities between such as risk factors for development of severe illness, cytokine storms, endothelial dysfunction and multi-organ failure. Both infections are characterised by a delayed and impaired type I IFN response and a proinflammatory immune response. Furthermore, while high levels of potent neutralising antibodies are associated with protection, poorly neutralising and cross-reactive antibodies have been proposed to lead to immunopathology by different mechanisms, associated with an exaggerated plasmablast response. The virus specific T cell responses are also shown to be delayed in those who develop severe illness, while varying degrees of endothelial dysfunction leads to increased vascular permeability and coagulation abnormalities.

CONCLUSION

While there are many similarities between dengue and SARS-CoV-2 infection, there are also key differences especially in long-term disease sequelae. Therefore, it would be important to study the parallels between the immunopathogenesis of both infections for development of more effective vaccines and therapeutic interventions.

Clinical significance of differential serum-signatures for early prediction of severe dengue among Eastern Indian patients

Dengue infection can result in simple dengue fever or life-threatening severe dengue. Early identification of severe patients is needed for proper disease management. Dengue infection was screened among 168 symptomatic patients by qRT-PCR, anti-dengue IgM, and IgG ELISA. Dengue patients were categorized according to WHO classification. Viral load and dengue serotypes were determined by qRT-PCR. Levels of acute-phase-proteins (SAP, SAA2; CRP and ApoA1), endothelial (Ang2, VEGF), coagulation (fibrinogen) markers were determined by sandwich ELISA/immunoturbidimetry/western-blotting. Hepatic (ALT, AST, ALP) and other blood biochemical parameters were studied by autoanalyzer and haematology cell counter. Statistical analysis and protein-protein-interaction network were performed by GraphPad-Prism and STRINGS database, respectively. Among 87 dengue patients, significantly higher levels of Ang2, VEGF, CRP, SAA2, ApoA1, AST, ALT, and AST/ALT ratio and low level of fibrinogen were detected in severe-dengue cases compared to dengue without warning-signs, with seven of them severely altered during febrile-phase. Higher fold-change of Ang2 and VEGF as well as decreased fibrinogen were observed among patients with haemorrhagic-manifestation, clinical-fluid accumulation and thrombocytopenia. Functional network analysis predicted Ang2, VEGF, and CRP to be functionally and physically connected and SAA2 and ApoA1 to be functioning together. Correlation analyses also validated this connectivity by a strong positive correlation between Ang2, VEGF, and CRP. PCA analysis followed by hierarchical clustering heatmap analysis segregated severe-dengue patients from the rest, with VEGF, Ang2, ApoA1, AST, and ALT clearly distinguishing the severe-dengue group. Thus, serum levels of VEGF, Ang2, ApoA1, AST, and ALT might act as potential biomarkers for predicting dengue severity during the early stage.

Correlation of Dengue Warning Signs during Febrile Phase with Rotational Thromboelastometry, Cortisol and Feritin

Dengue mortality remains high despite monitoring against warning signs (WS). The associations of WS at febrile phase (FP) and hemorrhage at defervescence with the levels and kinetics of ROTEM, platelet count, cortisol, and ferritin were analyzed. Patients with confirmed dengue serology and WS in two centers were screened (n = 275) and 62 eligible patients were recruited prospectively over 9 months. “Vomiting” was the commonest WS (62.9%), with shortened clotting time (CT) INTEM (p = 0.01). “Hematocrit increase” showed significant prolonged CT INTEM, EXTEM, and FIBTEM (p < 0.05). “Platelet decrease” showed reduced platelet function and reduced clot amplitude at 10 min (A10) and maximum clot firmness (MCF) in INTEM and EXTEM (p < 0.001). The kinetics were reduced in platelet count, CT EXTEM, and cortisol (p < 0.05) but increased in CT INTEM (p = 0.03). At FP, “vomiting”, “hematocrit increase”, and “platelet decrease” demonstrated impaired CT, clot strengths A10/MCF and platelet functions. Majority (60/62, 96.7%) had non-severe outcomes, consistent with increase in cortisol kinetics. In conclusion, “vomiting”, “hematocrit increase” and “platelet decrease” at FP correlated with ROTEM. No conclusion could be made further regarding ferritin and cortisol. Larger study is required to study “hematocrit increase” with ROTEM as a potential marker for hemorrhage.

A perfect storm: acute portal vein thrombosis in a patient with severe dengue and hemorrhagic manifestations-a case report

Background

Dengue constitutes a public health problem in endemic regions. The clinical course can range from asymptomatic to severe expressions. Hemorrhagic manifestations are the most frequently reported complications; on the contrary, thrombotic complications are unusual.

Clinical case

We present the case of an adult patient who presented hemodynamic instability, severe thrombocytopenia, and positive serology for dengue, in whom acute portal vein thrombosis was documented. The possible pathophysiology of thrombocytopenia and thrombosis in dengue is discussed, as well as the dilemmas regarding the treatment of associated hemorrhagic and thrombotic manifestations.

Conclusions

The present case brings up the importance of considering the possibility of thrombotic events in patients with severe dengue. A high degree of suspicion, close assessment of hemostatic function, and quality supportive care are essential to improve outcomes. To our knowledge, this is the first report of dengue-associated portal vein thrombosis.

Coagulation abnormalities in Dengue fever infection: A systematic review and meta-analysis

BACKGROUND

Coagulation mechanisms are reported to be affected in dengue illness and evidenced by prolonged activated partial thromboplastin time (APTT) and prothrombin time (PT). The main aim of this systematic review and meta-analysis is to determine the magnitude of coagulation abnormalities among patients with dengue fever infection.

METHOD

This systematic review and meta-analysis were conducted per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The Joana Brigg's Institute (JBI) critical appraisal checklist was used for quality appraisal. STATA version 11 software was used for meta-analysis. The magnitude of coagulation abnormalities among dengue fever patients was determined by using a random-effects model. Subgroup and sensitivity analysis were performed to investigate the possible source of heterogeneity. Egger weighted regression tests were used to check the presence of publication bias among the included articles.

RESULT

Forty-two studies with a total of 12,221 dengue fever patients were eligible for meta-analysis in this study. Of which 22, 15, and 26 studies were used to determine the magnitude of prolonged APTT, PT, and thrombocytopenia, respectively. The magnitude of prolonged APTT and PT among patients with dengue fever infection were 42.91% (95% CI: 30.95, 54.87) I2 = 99.1% and 16.48% (95% CI: 10.95, 22.01) I2 = 97.0%, respectively. Besides, the magnitude of thrombocytopenia among dengue fever patients was 70.29% (95% CI: 62.69, 77.89) I2 = 99.3%. The magnitude of prolonged APTT in children and adults was 51.21% (95% CI: 24.54, 77.89) and 44.89% (95% CI: 28.32, 61.45), respectively. Similarly, the overall magnitude of prolonged PT in children and adults were 13.40% (95% CI: 6.09, 20.71) and 18.73% (95% CI: 7.49, 29.96), respectively.

CONCLUSION

The result of this study showed that there is a high magnitude of prolonged APTT and PT in dengue fever patients. Therefore, screening and early correction of coagulation abnormalities may be helpful to reduce further complications in those patients.

Insights into the Pathogenesis of Viral Haemorrhagic Fever Based on Virus Tropism and Tissue Lesions of Natural Rift Valley Fever

Rift Valley fever phlebovirus (RVFV) infects humans and a wide range of ungulates and historically has caused devastating epidemics in Africa and the Arabian Peninsula. Lesions of naturally infected cases of Rift Valley fever (RVF) have only been described in detail in sheep with a few reports concerning cattle and humans. The most frequently observed lesion in both ruminants and humans is randomly distributed necrosis, particularly in the liver. Lesions supportive of vascular endothelial injury are also present and include mild hydropericardium, hydrothorax and ascites; marked pulmonary congestion and oedema; lymph node congestion and oedema; and haemorrhages in many tissues. Although a complete understanding of RVF pathogenesis is still lacking, antigen-presenting cells in the skin are likely the early targets of the virus. Following suppression of type I IFN production and necrosis of dermal cells, RVFV spreads systemically, resulting in infection and necrosis of other cells in a variety of organs. Failure of both the innate and adaptive immune responses to control infection is exacerbated by apoptosis of lymphocytes. An excessive pro-inflammatory cytokine and chemokine response leads to microcirculatory dysfunction. Additionally, impairment of the coagulation system results in widespread haemorrhages. Fatal outcomes result from multiorgan failure, oedema in many organs (including the lungs and brain), hypotension, and circulatory shock. Here, we summarize current understanding of RVF cellular tropism as informed by lesions caused by natural infections. We specifically examine how extant knowledge informs current understanding regarding pathogenesis of the haemorrhagic fever form of RVF, identifying opportunities for future research.

Child with dengue haemorrhagic fever complicated by ileocaecal intussusception

Dengue fever is one of the most common neglected tropical diseases with an increasing trend seen in Sri Lanka and many other tropical countries. A number of unusual presentations and complications of dengue fever have been reported, and acute abdomen is one such presentation. However, intussusception as the cause of acute abdomen in a patient with dengue haemorrhagic fever has not been previously reported. The authors report a child who was diagnosed to have intussusception during the critical phase of dengue haemorrhagic fever while having a platelet count of 15×103/cumm. The child had initial point-of-care ultrasound followed by detailed ultrasound of the abdomen by the radiologist, and the diagnosis of ileocaecal intussusception was confirmed. Intussusception was relieved by saline reduction and without needing laparotomy. Early diagnosis and non-operative management prevented emergency laparotomy.

Predictors and Clinical Outcomes of Poor Platelet Recovery in Adult Dengue With Thrombocytopenia: A Multicenter, Prospective Study

BACKGROUND

Platelet transfusion is common in dengue patients with thrombocytopenia. We previously showed in a randomized clinical trial that prophylactic platelet transfusion did not reduce clinical bleeding. In this study, we aimed to characterize the predictors and clinical outcomes of poor platelet recovery in transfused and nontransfused participants.

METHODS

We analyzed patients from the Adult Dengue Platelet Study with laboratory-confirmed dengue with ≤20 000 platelets/μL and without persistent mild bleeding or any severe bleeding in a post hoc analysis. Poor platelet recovery was defined as a platelet count of ≤20 000/μL on Day 2. We recruited 372 participants from 5 acute care hospitals located in Singapore and Malaysia between 29 April 2010 and 9 December 2014. Of these, 188 were randomly assigned to the transfusion group and 184 to the control group.

RESULTS

Of 360 patients, 158 had poor platelet recovery. Age, white cell count, and day of illness at study enrollment were significant predictors of poor platelet recovery after adjustment for baseline characteristics and platelet transfusion. Patients with poor platelet recovery had longer hospitalizations but no significant difference in other clinical outcomes, regardless of transfusion. We found a significant interaction between platelet recovery and transfusion; patients with poor platelet recovery were more likely to bleed if given a prophylactic platelet transfusion (odds ratio 2.34, 95% confidence interval 1.18-4.63).

CONCLUSIONS

Dengue patients with thrombocytopenia who were older or presented earlier and with lower white cell counts were more likely to have poor platelet recovery. In patients with poor platelet recovery, platelet transfusion does not improve outcomes and may actually increase the risk of bleeding. The mechanisms of poor platelet recovery need to be determined.

CLINICAL TRIALS REGISTRATION

NCT01030211.

New Proteomic Signatures to Distinguish Between Zika and Dengue Infections

Distinguishing between Zika and dengue virus infections is critical for accurate treatment, but we still lack detailed understanding of their impact on their host. To identify new protein signatures of the two infections, we used next-generation proteomics to profile 122 serum samples from 62 Zika and dengue patients. We quantified >500 proteins and identified 13 proteins that were significantly differentially expressed (adjusted p-value < 0.05). These proteins typically function in infection and wound healing, with several also linked to pregnancy and brain function. We successfully validated expression differences with Carbonic Anhydrase 2 in both the original and an independent sample set. Three of the differentially expressed proteins, i.e., Fibrinogen Alpha, Platelet Factor 4 Variant 1, and Pro-Platelet Basic Protein, predicted Zika virus infection at a ∼70% true-positive and 6% false-positive rate. Further, we showed that intraindividual temporal changes in protein signatures can disambiguate diagnoses and serve as indicators for past infections. Taken together, we demonstrate that serum proteomics can provide new resources that serve to distinguish between different viral infections.

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Analysis of human serum samples with extreme protein abundance ranges

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Unique protein signatures for Zika and dengue virus infection

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Temporal changes in protein signatures as indicators for past infections

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Machine learning to account for confounding factors

Factors associated with progression to death in patients with Lassa fever in Nigeria: an observational study

BACKGROUND

Lassa fever is endemic in several west African countries. Case-fatality rates ranging from 21% to 69% have been reported. The pathophysiology of the disease in humans and determinants of mortality remain poorly understood. We aimed to determine host protein biomarkers capable of determining disease outcome.

METHODS

In this observational study, we analysed left-over blood samples from patients who tested positive for Lassa fever at Irrua Specialist Teaching Hospital, Nigeria, between January, 2014, and April, 2017. We measured viral load, concentrations of clinical chemistry parameters, and levels of 62 circulating proteins involved in inflammation, immune response, and haemostasis. Patients with a known outcome (survival or death) and at least 200 μL of good-quality diagnostic sample were included in logistic regression modelling to assess the correlation of parameters with Lassa fever outcome. Individuals who gave consent could further be enrolled into a longitudinal analysis to assess the association of parameters with Lassa fever outcome over time. Participants were divided into two datasets for the statistical analysis: a primary dataset (samples taken between Jan 1, 2014, and April 1, 2016), and a secondary dataset (samples taken between April 1, 2016, and April 1, 2017). Biomarkers were ranked by area under the receiver operating characteristic curve (AUC) from highest (most predictive) to lowest (least predictive).

FINDINGS

Of 554 patients who tested positive for Lassa fever during the study period, 201 (131 in the primary dataset and 70 in the secondary dataset) were included in the biomarker analysis, of whom 74 (49 in the primary dataset and 25 in the secondary dataset) had died and 127 (82 in the primary dataset and 45 in the secondary dataset) had survived. Cycle threshold values (indicating viral load) and levels of 18 host proteins at the time of admission to hospital were significantly correlated with fatal outcome. The best predictors of outcome in both datasets were plasminogen activator inhibitor-1 (PAI-1; AUC 0·878 in the primary dataset and 0·876 in the secondary dataset), soluble thrombomodulin (TM; 0·839 in the primary dataset and 0·875 in the secondary dataset), and soluble tumour necrosis factor receptor superfamily member 1A (TNF-R1; 0·807 in the primary dataset and 0·851 in the secondary dataset), all of which had higher prediction accuracy than viral load (0·774 in the primary dataset and 0·837 in the secondary dataset). Longitudinal analysis (150 patients, of whom 36 died) showed that of the biomarkers that were predictive at admission, PAI-1 levels consistently decreased to normal levels in survivors but not in those who died.

INTERPRETATION

The identification of PAI-1 and soluble TM as markers of fatal Lassa fever at admission, and of PAI-1 as a marker of fatal Lassa fever over time, suggests that dysregulated coagulation and fibrinolysis and endothelial damage have roles in the pathophysiology of Lassa fever, providing a mechanistic explanation for the association of Lassa fever with oedema and bleeding. These novel markers might aid in clinical risk stratification and disease monitoring.

FUNDING

German Research Foundation, Leibniz Association, and US National Institutes of Health.

Microvascular Fluid Exchange: Implications of the Revised Starling Model for Resuscitation of Dengue Shock Syndrome

Dengue is the most common mosquito-borne viral infection in the world. The most feared complication is a poorly understood vasculopathy that occurs in only a small minority of symptomatic individuals, especially children and young adults, but can result in potentially fatal dengue shock syndrome (DSS). Based mainly on expert opinion, WHO management guidelines for DSS recommend prompt infusion of a crystalloid fluid bolus followed by a tapering crystalloid fluid regimen, supplemented if necessary by boluses of synthetic colloid solutions. However, following publication of a number of major trials undertaken in other, primarily adult, critical care scenarios, use of both synthetic colloid solutions and of fluid boluses for volume expansion have become controversial. Synthetic colloids tend to be used for severe DSS cases in order to boost intravascular oncotic pressure, based on the classic Starling hypothesis in which opposing hydrostatic and oncotic forces determine fluid flow across the microvascular barrier. However, the revised Starling model emphasizes the critical contribution of the endothelial glycocalyx layer (EGL), indicating that it is the effective oncotic pressure gradient across the EGL not endothelial cells per se that opposes filtration. Based on several novel concepts that are integral to the revised Starling model, we review the clinical features of DSS and discuss a number of implications that are relevant for fluid management. We also highlight the need for context-specific clinical trials that address crucially important questions around the management of DSS.

Coagulation abnormalities in SARS-CoV-2 infection: overexpression tissue factor

Among the pathways and mediators that may be dysregulated in COVID-19 infection, there are proinflammatory cytokines, lymphocyte apoptosis, and the coagulation cascade. Venous and arterial thromboembolisms also are frequent in COVID-19 patients with the increased risk of some life-threatening complications such as pulmonary embolism, myocardial infarction, and ischemic stroke. In this regard, overproduction of proinflammatory cytokines such as IL-6, IL-1β, and TNF-α induce cytokine storms, increase the risk of clot formation, platelet activation, and multiorgan failure that may eventually lead to death among these patients. Surface S protein of SARS-CoV-2 binds to its target transmembrane receptor, named as angiotensin converting enzyme 2 (ACE2(, on various cells such as lymphocyte, alveolar cells, monocytes/macrophages, and platelets. Notably, the activation of the coagulation cascade occurs through tissue factor (TF)/FVIIa-initiated hemostasis. Accordingly, TF plays the major role in the activation of coagulation system during viral infection. In viral infections, the related coagulopathy multiple factors such as inflammatory cytokines and viral specific TLRs are involved, which consequently induce TF expression aberrantly. SARS-COV-2 may directly infect monocytes/ macrophages. In addition, TF expression/release from these cells may play a critical role in the development of COVID-19 coagulopathy. In this regard, the use of TF- VIIa complex inhibitor may reduce the cytokine storm and mortality among COVID-19 patients.

Elevated levels of procoagulant microvesicles in patients with dengue fever

Background: The levels of procoagulant microvesicles (MVs) and tissue factor (TF)-bearing MVs may be increased in many conditions, including dengue fever (DF). This study aimed to measure the levels of MVs and TF-bearing MVs in patients with DF and matched healthy controls. Materials & methods: Levels of MVs and TF-bearing MVs in the plasma of patients with DF and matched healthy controls were measured using functional assay. Results: The patient group had significantly elevated levels of MVs (p < 0.001) and slightly increased levels of TF-bearing MVs (p = 0.454) compared with the matched healthy controls. Conclusion: Elevated levels of MVs and TF-bearing MVs could be used as biomarkers to evaluate the hemostatic function of patients with DF.

Ovine Fetal and Placental Lesions and Cellular Tropism in Natural Rift Valley Fever Virus Infections

Infection with Rift Valley fever phlebovirus (RVFV) causes abortion storms and a wide variety of outcomes for both ewes and fetuses. Sheep fetuses and placenta specimens were examined during the 2010-2011 River Valley fever (RVF) outbreak in South Africa. A total of 72 fetuses were studied of which 58 were confirmed positive for RVF. Placenta specimens were available for 35 cases. Macroscopic lesions in fetuses were nonspecific and included marked edema and occasional hemorrhages in visceral organs. Microscopically, multifocal hepatic necrosis was present in 48 of 58 cases, and apoptotic bodies, foci of liquefactive hepatic necrosis (primary foci), and eosinophilic intranuclear inclusions in hepatocytes were useful diagnostic features. Lymphocytolysis was present in all lymphoid organs examined with the exception of thymus and Peyer's patches, and pyknosis or karyorrhexis was often present in renal glomeruli. The most significant histologic lesion in the placenta was necrosis of trophoblasts and endothelial cells in the cotyledonary and intercotyledonary chorioallantois. Immunolabeling for RVFV was most consistent in trophoblasts of the cotyledon or caruncle. Other antigen-positive cells included hepatocytes, renal tubular epithelial, juxtaglomerular and extraglomerular mesangial cells, vascular smooth muscle, endothelial and adrenocortical cells, cardiomyocytes, Purkinje fibers, and macrophages. Fetal organ samples for diagnosis must minimally include liver, kidney, and spleen. From the placenta, the minimum recommended specimens for histopathology include the cotyledonary units and caruncles from the endometrium, if available. The diagnostic investigation of abortion in endemic areas should always include routine testing for RVFV, and a diagnosis during interepidemic periods might be missed if only limited specimens are available for examination.

Assessment of aPTT-based clot waveform analysis for the detection of haemostatic changes in different types of infections

Infections cause varying degrees of haemostatic dysfunction which can be detected by clot waveform analysis (CWA), a global haemostatic marker. CWA has been shown to predict poor outcomes in severe infections with disseminated intravascular coagulopathy. The effect of less severe bacterial and viral infections on CWA has not been established. We hypothesized that different infections influence CWA distinctively. Patients admitted with bacterial infections, dengue and upper respiratory tract viral infections were recruited if they had an activated partial thromboplastin time (aPTT) measured on admission. APTT-based CWA was performed on Sysmex CS2100i automated analyser using Dade Actin FSL reagent. CWA parameters [(maximum velocity (min1), maximum acceleration (min2) and maximum deceleration (max2)] were compared against control patients. Infected patients (n = 101) had longer aPTT than controls (n = 112) (34.37 ± 7.72 s vs 27.80 ± 1.59 s, p < 0.001), with the mean (± SD) aPTT longest in dengue infection (n = 36) (37.99 ± 7.93 s), followed by bacterial infection (n = 52) (33.96 ± 7.33 s) and respiratory viral infection (n = 13) (29.98 ± 3.92 s). Compared to controls (min1; min2; max2) (5.53 ± 1.16%/s; 0.89 ± 0.19%/s²; 0.74 ± 0.16%/s²), bacterial infection has higher CWA results (6.92 ± 1.60%/s; 1.04 ± 0.28%/s²; 0.82 ± 0.24%/s², all p < 0.05); dengue infection has significantly lower CWA values (3.93 ± 1.32%/s; 0.57 ± 0.17%/s²; 0.43 ± 0.14%/s², all p < 0.001) whilst respiratory virus infection has similar results (6.19 ± 1.32%/s; 0.95 ± 0.21%/s²; 0.73 ± 0.18%/s², all p > 0.05). CWA parameters demonstrated positive correlation with C-reactive protein levels (min1: r = 0.54, min2: r = 0.44, max2: r = 0.34; all p < 0.01). Different infections affect CWA distinctively. CWA could provide information on the haemostatic milieu triggered by infection and further studies are needed to better define its application in this area.

Antiviral anticoagulation

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel envelope virus that causes coronavirus disease 2019 (COVID-19). Hallmarks of COVID-19 are a puzzling form of thrombophilia that has elevated D-dimer but only modest effects on other parameters of coagulopathy. This is combined with severe inflammation, often leading to acute respiratory distress and possible lethality. Coagulopathy and inflammation are interconnected by the transmembrane receptor, tissue factor (TF), which initiates blood clotting as a cofactor for factor VIIa (FVIIa)-mediated factor Xa (FXa) generation. TF also functions from within the nascent TF/FVIIa/FXa complex to trigger profound changes via protease-activated receptors (PARs) in many cell types, including SARS-CoV-2-trophic cells. Therefore, aberrant expression of TF may be the underlying basis of COVID-19 symptoms. Evidence suggests a correlation between infection with many virus types and development of clotting-related symptoms, ranging from heart disease to bleeding, depending on the virus. Since numerous cell types express TF and can act as sites for virus replication, a model envelope virus, herpes simplex virus type 1 (HSV1), has been used to investigate the uptake of TF into the envelope. Indeed, HSV1 and other viruses harbor surface TF antigen, which retains clotting and PAR signaling function. Strikingly, envelope TF is essential for HSV1 infection in mice, and the FXa-directed oral anticoagulant apixaban had remarkable antiviral efficacy. SARS-CoV-2 replicates in TF-bearing epithelial and endothelial cells and may stimulate and integrate host cell TF, like HSV1 and other known coagulopathic viruses. Combined with this possibility, the features of COVID-19 suggest that it is a TFopathy, and the TF/FVIIa/FXa complex is a feasible therapeutic target.

An unusual case of dengue shock syndrome complicated by ilio-femoral deep vein thrombosis; a case report

Background

Dengue fever is a hemorrhagic fever caused by flaviviruses. Hemorrhagic manifestations are well known to be associated with dengue fever, though the thrombotic events are only seldom reported. Underlying pathophysiology of thrombotic events is multifactorial and the management is challenging due to associated thrombocytopenia and bleeding tendency. We report a case of dengue shock syndrome with severe thrombocytopenia complicated by ilio-femoral deep vein thrombosis.

Case presentation

A 16 year old boy presented with dengue fever. He had dengue shock syndrome after entering the critical phase on the fifth day of the illness. With the recovery from the critical phase he developed deep vein thrombosis involving right external iliac, common femoral and superficial femoral veins. There were no provocative factors other than dengue fever itself. His platelet count was 12,000/μl at the time of diagnosis with deep vein thrombosis. Anticoagulation was started with intravenous unfractionated heparin 500 IU/hour while closely being observed for bleeding complications. 1000 IU/hour dose was commenced with the recovery of the platelet count above 50,000/μl. Thrombophilia screening was negative and he was discharged on warfarin. Venous duplex done after 6 weeks showed normal lower limb venous flow and warfarin was omitted after three months.

Conclusions

With dengue fever, complications like deep vein thrombosis can be easily missed given its rarity and that the major concern is on hemorrhagic complications. Management is challenging due to associated thrombocytopenia and hemorrhagic complications.

Severe dengue categories as research endpoints-Results from a prospective observational study in hospitalised dengue patients

Severe dengue was perceived as one clinical disease entity until the WHO 2009 classification stratified it into severe vascular leakage, severe bleeding, and severe organ dysfunction. The objectives of this study were to investigate the potential use of severe dengue categories as endpoints for intervention research. 271 patients with severe dengue among 1734 confirmed dengue patients were followed prospectively in this hospital-based observational study in Latin America and Asia. We compared the distribution of severe dengue categories according to gender and age (below/above 15y), and determined the relative frequency and the overlap of severe dengue categories in the same patients. In a next step, we extended the analysis to candidate moderate severity categories, based on recently suggested definitions which were adapted for our purposes. Severe vascular leakage occurred in 244 (90%), severe bleeding in 39 (14%), and severe organ dysfunction in 28 (10%) of 271 severe dengue patients. A higher frequency of severe leakage was seen in children or adolescents (<15y) compared to adults. More than 80% of the severe leakage cases, and 30-50% of the cases with severe bleeding or severe organ dysfunction, were defined as severe on the basis of that feature alone. In 136 out of 213 patients with severe leakage alone, neither moderate bleeding manifestation nor hepatic involvement was recorded. On the other hand, moderate leakage manifestations were detected in 4 out of 12 cases that were classified as severe based on bleeding alone. A major proportion of severe dengue patients exhibited clinical manifestations of severe vascular leakage only, which may constitute a useful endpoint for intervention research or pathophysiology studies. Severe bleeding and severe organ manifestation were recorded less frequently and exhibited a higher degree of overlap with severe leakage. Severe bleeding without leakage may be associated with individual predisposition or the presence of comorbidities. More detailed assessments are needed to explore this hypothesis. Candidate moderate disease endpoints were investigated and need to be further validated.

Case of Near Fatal Massive Intracerebral Bleed Secondary to Cerebral Venous Thrombosis in a Patient with Dengue and Refractory Thrombocytopenia

We present a case of dengue with refractory thrombocytopenia who developed cerebral venous thrombosis (CVT) with intraparenchymal hemorrhage warranting surgical decompression. Patient was concluded to have secondary immune thrombocytopenic purpura (ITP) which remained refractory to high dose steroids, IVIg therapy, but responded to thrombopoietin receptor (TPO-R) agonist, eltrombopag.

Coagulation abnormalities in dengue and dengue haemorrhagic fever patients

OBJECTIVE

The aim of this study was to assess abnormality of coagulation and anticoagulation parameters in dengue fever patients and the impact of these tests on the management of patients.

BACKGROUND

Dengue fever is endemic in Pakistan with seasonal rise in cases. Morbidities and mortalities are proportionately reported to be increasing and associated with disseminated intravascular coagulation resulting in haemorrhagic or thrombotic manifestations in patients having deranged coagulation profiles.

METHODS/MATERIALS

This observational and descriptive study was conducted on confirmed Dengue patients at the National Institute of Blood Diseases during the years 2013 to 2016. Patients of all age groups were included in this study. Results were analysed by SPSS version 23.

RESULTS

A total of 200 patients were selected with the mean age being 28.68 years (±13.28) and male predominance (147/200). The mean platelet count, haemoglobin and haematocrit at base line for bleeders and non-bleeders showed significant results, where platelet count at baseline for bleeders was 24 000, whereas for non-bleeders it was 29 000 and it showed significant correlation with bleeding (P-value .027). Platelets were transfused to 76 (38%) patients. However, none of the specialised haemostasis parameters beside the platelet count correlated with bleeding, requiring platelet transfusions.

CONCLUSION

Our study showed a significant association of platelet counts, haemoglobin and haematocrit with bleeding. It can be concluded that coagulation and anticoagulation profiles will not benefit the management of dengue patients and in countries like Pakistan, it will only add to the economic burden on the patients.

Lesions and Cellular Tropism of Natural Rift Valley Fever Virus Infection in Young Lambs

A clear distinction can be made regarding the susceptibility to and the severity of lesions in young lambs when compared to adult sheep. In particular, there are important differences in the lesions and tropism of Rift Valley fever virus (RVFV) in the liver, kidneys, and lymphoid tissues of young lambs. A total of 84 lambs (<6 weeks old), necropsied during the 2010 to 2011 Rift Valley fever (RVF) outbreak in South Africa, were examined by histopathology and immunohistochemistry (IHC). Of the 84 lambs, 71 were positive for RVFV. The most striking diagnostic feature in infected lambs was diffuse necrotizing hepatitis with multifocal liquefactive hepatic necrosis (primary foci) against a background of diffuse hepatocellular death. Lymphocytolysis was present in all lymphoid organs except for the thymus. Lesions in the kidney rarely progressed beyond hydropic change and occasional pyknosis or karyolysis in renal tubular epithelial cells. Viral antigen was diffusely present in the cytoplasm of hepatocytes, but this labeling was noticeably sparse in primary foci. Immunolabeling for RVFV in young lambs was also detected in macrophages, vascular smooth muscle cells, adrenocortical epithelial cells, renal tubular epithelial cells, renal perimacular cells, and cardiomyocytes. RVFV immunolabeling was also often present in capillaries and small blood vessels either as non-cell-associated viral antigen, as antigen in endothelial cells, or intravascular cellular debris. Specimens from the liver, spleen, kidney, and lungs were adequate to confirm a diagnosis of RVF. Characteristic lesions were present in these organs with the liver and spleen being the most consistently positive for RVFV by IHC.

Increased Mosquito Midgut Infection by Dengue Virus Recruitment of Plasmin Is Blocked by an Endogenous Kazal-type Inhibitor

Dengue symptoms include alteration of blood coagulation and fibrinolysis, causing severe hemorrhage and death. Here, we demonstrate that higher concentration of plasmin, the human fibrinolytic factor, in blood meal enhances dengue virus (DENV) infection in mosquito midgut and dissemination in mosquitoes. We also show that mosquitoes express a plasmin-selective Kazal-type inhibitor (AaTI) in the midgut to inhibit plasmin proteolysis and revert the enhanced infection. Using bio-layer interferometry, we show that DENV, plasmin, and AaTI interact to form a tripartite complex. Eventually, plasmin increases midgut internalization of dextran molecules and this is reverted by AaTI. Our study demonstrates that (1) DENV recruits plasmin to increase local proteolytic activity in the midgut, thus degrading the glycocalyx and enhancing DENV internalization and (2) AaTI can act as a transmission-blocking agent by inhibiting plasmin proteolysis. Our results indicate that dengue pathogenesis enhances DENV fitness by increasing its infectivity to mosquitoes.

Warning signs and severe dengue in end stage renal disease dialysis patients

BACKGROUND/PURPOSE

The 2009 WHO guideline established warning signs (WS) to predict severe dengue (SD). However, their positive predictive value has been found to be low in the general adult population, but they might be higher in a different population. This study investigated the association between WS and SD in end stage renal disease (ESRD) patients on maintenance dialysis in Taiwan where both diseases are prevalent.

METHODS

This study enrolled ESRD dialysis patients with dengue in 2015. Demographic, laboratory data, symptoms/signs and complication of dengue were retrospectively collected from medical records at our hospital.

RESULTS

Of 49 ESRD patients with dengue, 44 patients were receiving hemodialysis and 5 peritoneal dialysis. Older patients (>65 years old) tended to have the WS(56% vs 16.7%, P = 0.007). The rate of hospitalization, intensive care unit admission and in-hospital mortality was 79.6%, 22.5%, and 8.2%, respectively. Eighteen patients (36.7%) presented WS and eighteen patients (36.7%) developed to SD, including ten with plasma leakage, twelve with hemorrhage, and six with organ failure. Patients with WS were seven times more likely to develop SD than those without (OR: 7.06; 95%CI: 1.34-37.21). WS was associated with plasma leakage (OR: 12.36; 95% CI: 1.56-97.74) and severe hemorrhage (OR: 5.1; 95% CI: 1.03-25.18), but not organ failure.

CONCLUSIONS

Prevalence of SD is high in ESRD dialysis patients. The presence of WSs in this group was highly correlated with SD. Thus, more attention should be paid to treating ESRD patients with dengue fever if they present WSs.

The eye in dengue fever, a rarely appreciated aspect of dengue expanded syndrome: a case report

BACKGROUND

Dengue fever is a mosquito-borne illness prevalent mainly in the tropics. It is feared for causing the dengue hemorrhagic spectrum of the disease leading to significant morbidity and mortality. Its rarer manifestations are categorized as the expanded dengue syndrome, and though being recognized, they are not fully appreciated and understood. The involvement of the eye in dengue fever is one such phenomenon.

CASE PRESENTATION

A 27-year-old South-Asian woman presented on day 2 of dengue fever, without capillary leakage, for further management. Despite developing hepatitis, she had an otherwise uncomplicated progression of the illness because she did not develop capillary leakage. On day 8 of the illness, she had the lowest platelet count and developed bilateral blurred vision. Examination revealed that only gross movements were detected in the left eye, and the right eye had a visual acuity of 6/9. She was diagnosed with foveolitis in the right eye and central serous chorioretinopathy in the left eye, along with hemorrhages in both eyes. These were confirmed by funduscopy, fluorescein angiography, optical coherence tomography, and macular scans. She received systemic and intravitreal steroids and was assessed regularly. After 6 months of observation, her visual acuity was 6/6 in the right eye and 6/9 in the left eye, which remained the same thereafter.

DISCUSSION

The exact mechanism of eye involvement in dengue viral infection is poorly understood. Multiple causes have been suspected and include viral factors, immune mediation, capillary leakage, stress, and hemorrhage. Eye involvement is classically seen at the lowest platelet count and when the count begins to rise. Though symptoms are nonpathognomonic, blurring of vision is the commonest complaint, but the range of presentation is extensive and variable. Ophthalmological assessment and funduscopy are very useful in addition to advanced assessments. There is no clear consensus on management; suggestions range from conservative care to aggressive steroid therapy with immune modulation and even ophthalmological intervention. Recovery can be full or partial with a variable time scale.

CONCLUSION

The extensive spectrum of possible visual symptoms should prompt the clinician to suspect any visual complaint as potential dengue eye involvement. Guided studies and screening are needed to better understand the true incidence of eye involvement in dengue fever.

Dengue infection and advances in dengue vaccines for children

Dengue viruses are endemic in most tropical and subtropical countries where they produce disease ranging from a mild fever to a severe, potentially fatal vascular permeability syndrome. We reviewed the status of development and testing in children of three vaccines designed to protect against the four dengue viruses. The first dengue virus vaccine, Dengvaxia, now licensed in 20 endemic countries, the EU and the USA, provides protection against severe dengue in seropositive individuals but increases the risk for naive recipients to develop severe dengue and to be hospitalised. We discuss mechanisms and implications of shortcomings of the licensed vaccine and describe the structure and attributes of two other dengue virus vaccines. Based upon human dengue challenge studies, one of these vaccines promises to deliver solid, long-lasting immunity after a single dose. Because dengue virus infections are ubiquitous in residents and visitors to tropical countries, in the absence of a protective vaccine paediatricians should recognise the early signs and clinical presentation of severe dengue, understand its pathophysiology and appropriate management.

Dengue virus-elicited tryptase induces endothelial permeability and shock

Dengue virus (DENV) infection causes a characteristic pathology in humans involving dysregulation of the vascular system. In some patients with dengue hemorrhagic fever (DHF), vascular pathology can become severe, resulting in extensive microvascular permeability and plasma leakage into tissues and organs. Mast cells (MCs), which line blood vessels and regulate vascular function, are able to detect DENV in vivo and promote vascular leakage. Here, we identified that a MC-derived protease, tryptase, is consequential for promoting vascular permeability during DENV infection, through inducing breakdown of endothelial cell tight junctions. Injected tryptase alone was sufficient to induce plasma loss from the circulation and hypovolemic shock in animals. A potent tryptase inhibitor, nafamostat mesylate, blocked DENV-induced vascular leakage in vivo. Importantly, in two independent human dengue cohorts, tryptase levels correlated with the grade of DHF severity. This study defines an immune mechanism by which DENV can induce vascular pathology and shock.

A case report of dengue haemorrhagic fever complicated with psoas haematoma requiring blood transfusion

Background

Dengue fever is a common infection with increasing numbers of patients affected. Muscle haematomas are a rare complication of dengue fever. In most cases haematomas resolve spontaneously.

Case presentation

We report a case of spontaneous psoas muscle haematoma, formed during the critical phase of dengue haemorrhagic fever. A 28-year-old gentleman presented with features of severe dengue and was admitted to the Dengue High Dependency Unit. He was treated with intravenous fluid therapy and supportive measures, and gradually improved initially. However, as the critical phase ended, he suddenly developed pain in the left groin and inguinal region and physical examination was normal. Ultrasound scan revealed a left psoas haematoma. As the patient deteriorated haemodynamically blood was transfused. He recovered without further complication and was discharged home.

Conclusions

Dengue fever is a common tropical infection. Recognizing serious complications such as psoas haematoma presenting as simple complaints such as back pain and inguinal pain are important to prevent mortality.

Zika Virus Infection Induces Elevation of Tissue Factor Production and Apoptosis on Human Umbilical Vein Endothelial Cells

Zika virus (ZIKV) infection is typically characterized by a mild disease presenting with fever, maculopapular rash, headache, fatigue, myalgia, and arthralgia. A recent animal study found that ZIKV-infected pregnant Ifnar ^-/-mice developed vascular damage in the placenta and reduced amount of fetal capillaries. Moreover, ZIKV infection causes segmental thrombosis in the umbilical cord of pregnant rhesus macaques. Furthermore, several case reports suggest that ZIKV infection cause coagulation disorders. These results suggest that ZIKV could cause an alteration in the host hemostatic response, however, the mechanism has not been investigated thus far. This paper aims to determine whether ZIKV infection on HUVECs induces apoptosis and elevation of tissue factor (TF) that leads to activation of secondary hemostasis. We infected HUVECs with two ZIKV strains and performed virus titration, immunostaining, and flow cytometry to confirm and quantify infection. We measured TF concentrations with flow cytometry and performed thrombin generation test (TGT) as a functional assay to assess secondary hemostasis. Furthermore, we determined the amount of cell death using flow cytometry. We also performed enzyme-linked immunosorbent assay (ELISA) to determine interleukin (IL)-6 and IL-8 production and conducted blocking experiments to associate these cytokines with TF expression. Both ZIKV strains infected and replicated to high titers in HUVECs. We found that infection induced elevation of TF expressions. We also showed that increased TF expression led to shortened TGT time. Moreover, the data revealed that infection induced apoptosis. In addition, there was a significant increase of IL-6 and IL-8 production in infected cells. Here we provide in vitro evidence that infection of HUVECs with ZIKV induces apoptosis and elevation of TF expression that leads to activation of secondary hemostasis.

Preliminary study on the expression of endothelial cell biology related genes in the liver of dengue virus infected mice treated with Carica papaya leaf juice

Objective

The purpose of this study was to profile and identify the endothelial cell biology related genes that are affected by dengue virus infection in the liver tissue of AG129 mice, with and without Carica papaya leaf juice treatment.

Results

The dengue fever mouse model was established by intraperitoneal inoculation of dengue virus, New Guinea C strain at 2 × 10⁶ PFU. Daily oral administration of 1000 mg/kg freeze-dried C. papaya leaf juice (FCPLJ) was done starting from day 1 to day 3 post infection. The RNA was extracted from liver tissues harvested on day 4 post infection. The expression levels of 84 genes related to mouse endothelial cell biology were determined by qRT-PCR technique. Dengue virus infection upregulated 15 genes and downregulated two genes in the liver of AG129 mice. The FCPLJ treatment upregulated monocyte chemoattractant protein 1 and downregulated intercellular adhesion molecule 1, integrin beta 3 and fibronectin 1 genes during dengue virus infection. The data showed the potential effect of FCPLJ treatment on the expression profile of endothelial cell biology related genes in the liver of dengue virus infected-AG129 mice. Further proteomic studies are needed to determine the functional roles of the genes affected by FCPLJ treatment.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4242-z) contains supplementary material, which is available to authorized users.

Dengue shock syndrome complicated with acute liver failure and kidney injury, infective endocarditis, and deep vein thrombosis: a case report

Background

Dengue fever is a mosquito-borne viral disease with a very high incidence in Southeast Asia. Most patients with dengue fever recover following a self-limiting febrile illness, while a small proportion may progress to develop severe disease with complications such as acute liver failure, acute kidney injury, and multiorgan failure. Secondary bacterial infections and thrombotic events are very rare.

Case presentation

A 38-year-old previously healthy Sri Lankan woman from Colombo, Sri Lanka, presented with dengue shock syndrome leading to acute liver failure and kidney injury. She was managed with intravenously administered fluid resuscitation with close monitoring of her hemodynamic status, and hemodialysis. Her renal and liver functions and platelet count improved gradually, but the fever persisted and there was a neutrophil leukocytosis. A clinical examination and investigations to identify a focus of secondary infection revealed staphylococcal infective endocarditis. She was started on intravenously administered vancomycin, but as the response was poor the antibiotic was changed to intravenously administered linezolid, to which the response was good. She also developed right proximal femoral deep vein thrombosis, and was commenced on subcutaneous enoxaparin and warfarin. Enoxaparin was stopped after her international normalized ratio reached the desirable range, and warfarin was continued for 3 months.

Conclusions

Dengue virus is known to cause endothelial dysfunction that allows bacteria to invade tissues, defective functioning and reduction in the number of cells of the immune system, and alteration of cytokines leading to immune dysregulation, predisposing patients to develop secondary bacterial infections. Evidently, patients with dengue fever who have prolonged fever (more than 5 days) and acute kidney injury are at high risk for concurrent bacteremia. Dengue virus interferes with the components of the anti-clotting pathway, such as thrombomodulin-thrombin-protein C complex. It also activates endothelial cells and increases the expression of procoagulant factors. These factors may predispose patients with dengue viral infections to develop thrombotic complications. Therefore it is important to be aware of the possibility of serious secondary bacterial infections occurring following dengue viral infections, especially in patients with prolonged fever and acute kidney injury, and to keep in mind that thrombotic events may occur as complications of dengue viral infections.

Thromboelastographic Analysis of Hemostatic Abnormalities in Dengue Patients Admitted in a Multidisciplinary Intensive Care Unit: A Cross-sectional Study

Background

Dengue fever is an important tropical infection causing significant mortality. The pathophysiology of hematological abnormalities in dengue remains poorly studied. In this study, we analyzed the hematological abnormalities by thromboelastography (TEG).

Methods

This cross-sectional study evaluated complicated dengue patients with TEG. Thromboelastographic variables were categorized into six patterns: factor deficiency, platelet dysfunction, enzymatic hypercoagulability, combined enzymatic and platelet hypercoagulability, primary fibrinolysis, and secondary hyperfibrinolysis.

Results

Twenty-five patients were analyzed for coagulation abnormalities by TEG. Coagulation factor deficiency pattern was noted in 11 patients (44%) whereas 3 patients (12%) were found to have low fibrinogen level pattern. Low platelet function was noted in 4 (16%) patients. Enzymatic hypercoagulability and combined enzymatic and platelet hypercoagulability were noted in one patient each (4.5%). Secondary fibrinolysis was noted in 1 patient (5%) and primary fibrinolysis in 3 (15.8%) patients. Factor deficiency pattern and low fibrinogen pattern were not significantly associated with hepatitis (P > 0.05). Activated partial thromboplastin time (aPTT) was not found to be significantly associated with factor deficiency pattern (P = 0.10) and low fibrinogen pattern (P = 0.20). Platelet count was not found to be significantly associated with platelet function (P = 0.54).

Conclusion

Factor deficiency pattern was the major abnormality noted in dengue patients followed by platelet dysfunction and primary fibrinolysis. Platelet count did not show significant association with platelet function. aPTT did not show significant association with factor deficiency and low fibrinogen patterns. Factor deficiency pattern and low fibrinogen pattern did not show significant association with hepatitis.

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.