Dengue myocarditis in Singapore: two case reports

Original algorithms for the detection of cardiovascular involvement of neglected tropical diseases

INTRODUCTION

Neglected tropical diseases (NTDs) introduce considerable morbidity and mortality on a global scale, directly impacting over 1 billion individuals as well as their families and communities. Afflicted individuals may have limited access to resources and care in these regions, contributing to a high proportion of chronic, progressive, and systemic disease. The cardiovascular system is at particular risk of demise for several NTDs, yet remains largely unstudied due in part to the lack of robust data collection mechanisms in the most impacted regions.

AREAS COVERED

The present review is a part of the Neglected Tropical Diseases and other Infectious Diseases affecting the Heart (NET-Heart) Project, aiming at summarizing the current knowledge on cardiovascular implications of NTDs and providing diagnostic as well as management recommendations which can be tailored to low-resource settings. The diagnostic and management algorithms of 13 unique NTDs are presented and summarized.

EXPERT OPINION

Recognizing cardiac manifestations of NTDs can significantly alter disease trajectory and all physicians benefit from improved knowledge about NTDs. Great potential exists to advance patient care by improving data collection, communication, and international collaboration.

Myocarditis manifestations in dengue cases: A systematic review and meta-analysis

BACKGROUND

Dengue fever is a zoonotic viral infection that raises a global alarm in the tropics and subtropics, with the potentially escalating into newer geographical regions. Severe dengue may be associated with fatal complications such as myocarditis. There is a paucity of available data on the prevalence of dengue-associated myocarditis. The objective of this systematic review and meta-analysis was to estimate the global prevalence of dengue-associated myocarditis.

METHODS

A systematic search was conducted utilizing the Cochrane library, PubMed, Scopus, ProQuest, Web of Science, and Preprint servers such as arXiv, medRxiv, bioRxiv, BioRN, ChiRN, ChiRxiv, and SSRN as of November 25, 2022. All primary studies (case series, cross-sectional, retrospective, and prospective) that reported confirmed cases of dengue myocarditis were included. The I2 statistic test assessed the heterogenic characteristics and publication bias was evaluated using Doi plot and Egger regression tests.

RESULTS

A total of 12 studies conducted between 2007 and 2022 with 2795 laboratory-confirmed dengue patients were included. Of the included cases, 502 were positive for myocarditis, with a prevalence of 2.4-78%. The pooled prevalence of dengue-induced myocarditis in the studied population was 21.0% (95% CI, 9 - 38%). The prediction interval was estimated to be 0.00 - 0.81.

CONCLUSION

Myocarditis in dengue patients is a significant and understudied complication in many aspects. To prevent dengue-associated myocarditis, appropriate measures such as early detection of cases and signs, symptoms-based diagnosis via electrocardiography and echocardiography, as well as relevant vector control policies must be implemented.

Mechanism of Immune Evasion in Mosquito-Borne Diseases

In recent decades, mosquito-borne illnesses have emerged as a major health burden in many tropical regions. These diseases, such as malaria, dengue fever, chikungunya, yellow fever, Zika virus infection, Rift Valley fever, Japanese encephalitis, and West Nile virus infection, are transmitted through the bite of infected mosquitoes. These pathogens have been shown to interfere with the host's immune system through adaptive and innate immune mechanisms, as well as the human circulatory system. Crucial immune checkpoints such as antigen presentation, T cell activation, differentiation, and proinflammatory response play a vital role in the host cell's response to pathogenic infection. Furthermore, these immune evasions have the potential to stimulate the human immune system, resulting in other associated non-communicable diseases. This review aims to advance our understanding of mosquito-borne diseases and the immune evasion mechanisms by associated pathogens. Moreover, it highlights the adverse outcomes of mosquito-borne disease.

Morphological Aspects and Viremia Analysis of BALB/c Murine Model Experimentally Infected with Dengue Virus Serotype 4

Ever since its brief introduction in the Brazilian territory in 1981, dengue virus serotype 4 (DENV-4) remained absent from the national epidemiological scenario for almost 25 years. The emergence of DENV-4 in 2010 resulted in epidemics in most Brazilian states. DENV-4, however, remains one of the least studied among the four DENV serotypes. Despite being known as a mild serotype, DENV-4 is associated with severe cases and deaths and deserves to be investigated; however, the lack of suitable experimental animal models is a limiting factor for pathogenesis studies. Here, we aimed to investigate the susceptibility and potential tropism of DENV-4 for liver, lung and heart of an immunocompetent mice model, and to evaluate and investigate the resulting morphological and ultrastructural alterations upon viral infection. BALB/c mice were inoculated intravenously with non-neuroadapted doses of DENV-4 isolated from a human case. The histopathological analysis of liver revealed typical alterations of DENV, such as microsteatosis, edema and vascular congestion, while in lung, widespread areas of hemorrhage and interstitial pneumonia were observed. While milder alterations were present in heart, characterized by limited hemorrhage and discrete presence of inflammatory infiltrate, the disorganization of the structure of the intercalated disc is of particular interest. DENV-4 RNA was detected in liver, lung, heart and serum of BALB/c mice through qRT-PCR, while the NS3 viral protein was observed in all of the aforementioned organs through immunohistochemistry. These findings indicate the susceptibility of the model to the serotype and further reinforce the usefulness of BALB/c mice in studying the many alterations caused by DENV.

Cardiac evaluation in adults with dengue virus infection by serial echocardiography

Background

Dengue virus infection (DVI) is a major health problem in many parts of the world. Its manifestations range from asymptomatic infections to severe disease. Although cardiac involvement has been reported in DVI, its incidence has not yet been well established.

Methods

From July 2016 to January 2018, patients hospitalized at the Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, Thailand, with dengue virus infection confirmed by positive NS1 or positive dengue immunoglobulin M findings, participated in the study. We characterized the incidence and change in cardiac function by serial echocardiography and levels of troponin-T and creatine kinase-myocardial band (CK-MB) on the day of admission, the day of defervescence, the first day of hypotension (if any), and at 2 week follow-up.

Results

Of the 81 patients evaluated, 6 (7.41%) exhibited elevated biomarker levels. There was no difference in clinical presentation amongst dengue fever, dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS), except for the amount of bleeding. Cardiac involvement was found in 22.2% of patients: 3 (3.70%) had left ventricular systolic dysfunction, 3 (3.70%) had transient diastolic dysfunction, 6 (7.41%) had increased levels of at least one cardiac biomarker (troponin-T or CK-MB), and 6 (7.41%) had small pericardial effusion. Myocarditis was suspected in only two patients (with DHF); thus, myocarditis was uncommon in patients with dengue virus infection. Three patients developed DSS during admission and were transferred to the intensive care unit.

Conclusion

Cardiac involvement in adults with dengue infection was common, ranging from elevated cardiac biomarker to myocarditis. Abnormalities in cardiac function had resolved spontaneously by the day of follow-up, without specific treatment. We found that DHF was a significant risk factor for cardiac involvement. Echocardiography is the investigation of choice for evaluating the haemodynamic status of patients with DVI, especially in severe dengue.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06639-x.

Dengue hemorrhagic fever and cardiac involvement

Dengue viral infection (DVI) is one of the world’s most significant viral infections spreading. Most of the patients have been asymptomatic, with relatively benign clinical manifestations and outcomes. However, a small number of patients have progressed to severe dengue diseases, including hemorrhage, multi-organ impairment, and increased vascular leakage causing hypovolemic shock, which can cause cardiovascular collapse and death. Numerous lines of evidence have demonstrated that DVI could also cause cardiac dysfunction, arrhythmias, and severe myocarditis. The treatment for dengue hemorrhagic fever (DHF) patients remains symptomatic and supportive, with close monitoring of hemodynamic status. The contributory role of cardiac dysfunction in DHF patients has potentially critical implications on the management. This review will address the current knowledge of cardiac involvement in DHF patients and the management strategy to reduce the fatality outcome.

Incidence of Cardiac Manifestations in Children with Dengue Fever: A Cross-sectional Study

OBJECTIVE

The aim of our study was to explore the incidence of cardiac involvement in children with dengue infection admitted in a tertiary care hospital and to evaluate the features of cardiac involvement with the severity of dengue fever.

METHODS

This was a cross-sectional study conducted from September 2014 to August 2016. A total of 130 patients with confirmed dengue NS1 antigen or IgM antibody positivity between the ages of 1 month and 18 years were evaluated. On the third day of admission, blood samples for cardiac markers were collected, and electrocardiograms (ECG) and echocardiograms were performed for each patient.

RESULTS

Of the 130 dengue patients in the study, 60 (46.2%) were males and 70 (53.8%) were females (male to female ratio, 1:1.16). Cardiac involvement was present in 60 (46.2%) children and was more prominent in children with severe dengue (72.7%), followed by dengue with warning symptoms (53.8%) and dengue fever (28.6%). There was no significant correlation between cardiac involvement and primary/secondary dengue. Both ECG and echocardiography changes were significantly correlated with dengue severity, as opposed to cardiac markers.

CONCLUSIONS

Cardiac involvement was present in children with dengue. Evaluation with ECG, echocardiography, and cardiac markers such as creatine phosphokinase-myocardial band (CPK-MB) are required for the management of cardiac complications in children with dengue. Our study showed an association between cardiac involvement and the severity of dengue. Further studies should be framed, and follow-up of dengue patients with cardiac involvement is necessary for therapeutic management.

Spectrum of cardiac involvement in patients with dengue fever

BACKGROUND

Dengue fever (DF) is an infectious disease of viral origin common in the tropics. Studies on a large number of patients with dengue infection to assess associated cardiac involvement are rare.

METHODS

We analyzed the incidence and spectrum of cardiac abnormalities in 320 patients with dengue fever admitted to our hospital located in an endemic area for dengue infection. All patients were evaluated following the WHO guidelines. Those confirmed to have dengue infection by serology had detailed clinical evaluation, 12‑lead electrocardiography (ECG), assay for cardiac markers (troponin T, CK-MB, NT Pro BNP) and 2-D echocardiography.

RESULTS

Among the 320 patients selected for the study 112 (35%) had changes of cardiac involvement as detected by investigations. Changes in ECG were seen in all of them. Sinus bradycardia in spite of fever was the most common abnormality (n = 63;19.7%). Forty-two (13.1%) patients had left ventricular ejection fraction less than 40%. Forty-eight patients (15%) had increased serum levels of troponin-T. Serum levels of CK-MB were elevated in 34 (10.6%) and serum levels of NT-pro BNP was increased in 19 (5.9%). Fourteen patients died and all of them had abnormalities in electrocardiogram, echocardiogram and serum markers.

CONCLUSION

Our study reveals that cardiac involvement in patients with dengue infection is not uncommon. We found that ECHO or ECG abnormalities or elevated serum levels of markers of cardiac injury are predictors of risk for adverse outcome. Absence of these abnormalities has a 100% negative predictive value.

Unusual clinical manifestations of dengue disease - Real or imagined?

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

Beyond thrombocytopaenia, haemorrhage and shock: the expanded dengue syndrome

Dengue infection classically presents with fever, thrombocytopaenia, and varying degrees of plasma leakage, giving rise to shock. However, a myriad of other manifestations, involving the cardiovascular system, the nervous system, the liver, the kidneys, the gut and the haematological system have been reported in dengue. This review summarizes these varied presentations.

[Serum activity of CK and CK-MB in patients with dengue virus infection]

OBJECTIVE

To determine the serum activity of CK and CK-MB in patients with dengue infection.

METHODS

A cross section study was conducted in the State of Antioquia, Colombia. The study population consisted in 54 patients with diagnosis of dengue infection and 10 healthy controls. A blood sample was taken from all participants to confirm dengue infection and to measure the activity of CK and CK-MB.

RESULTS

The median age of dengue cases was 18 years and the median age of healthy controls was 28.5 years. Half of dengue patients (50.9 %) had elevated levels of CK-MB, in contrast with the healthy controls in which none presented increase of this enzyme. No patient presented myocarditis; however, elevated CK-MB was observed in 33.3 %, 44.4 % and 40 % of cases with bradycardia, tachycardia and hypotension respectively. In 29.6 % of the dengue patients, high level of CK was detected, in contrast to 10 % in the control group. Activity of CK elevated was observed in dengue patients with symptoms such as vomiting, hematemesis and abdominal pain, 87.5 %, 60 % and 50 %, respectively.

CONCLUSIONS

In this study, no patient with dengue infection had heart disease or myositis; however, the finding of a higher frequency of elevated level CK and CK-MB in the dengue patients compared to the control group suggests the involvement of the striated muscle and of the cardiac muscle in this group. For this reason, the monitoring of these enzymes should be considered as part of the monitoring of patients with dengue.

Characterization of the Myocarditis during the worst outbreak of dengue infection in China

Myocarditis is a common complication of severe dengue infection. However, data about prevalence and characterization of myocarditis in dengue are still lacking. In 2014, the worst outbreak of dengue in the last two decades in China occurred. In this study, we described the clinical and laboratory diagnostic features of dengue with myocarditis. Totally, 1782 diagnosed dengue patients were admitted from August to October, 2014, all of whom were subjected to electrocardiogram, ultrasound cardiogram, and cardiac enzyme test. About 201 cases of dengue patients were diagnosed with myocarditis and the prevalence of myocarditis in hospitalized dengue was 11.28%. The prevalence of myocarditis in nonsevere dengue with warning signs and severe dengue [NSD(WS+)/SD] and nonsevere dengue without warning signs [NSD(WS-)] was 46.66% and 9.72%, respectively. The NSD(WS+)/SD patients with myocarditis presented with higher incidence of cardiac symptoms, supraventricular tachycardia (14.29% vs. 0%, P < 0.001), atrial fibrillation (25.71% vs. 10.24%, P = 0.019) and heart failure compared with NSD (WS-) patients with myocarditis. About 150 cases of dengue patients without myocarditis in the same period of time in department of Cardiology were recruited as control group. The proportion of NSD(WS+)/SD in dengue patients with and without myocarditis was 17.41% and 2.53%, respectively. Dengue patients with myocarditis experienced longer hospital stay than those without myocarditis (7.17 ± 4.64 vs. 5.98 ± 2.69, P = 0.008). There was no difference between patients with and without myocarditis in the proportion of symptoms, auxiliary methods abnormality, arrhythmia, and heart failure on the discharge day. Our study demonstrates the prevalence of myocarditis in worst outbreak of dengue in China was 11.28% and the incidence of myocarditis increased with the severity of dengue. The NSD(WS+)/SD patients with myocarditis presented with higher incidence of cardiac complication compared with NSD (WS-) patients with myocarditis. The prognosis of dengue patients with and without myocarditis had no significant difference even if myocarditis patients experienced longer hospital stay.

Tackling dengue fever: Current status and challenges

According to recent statistics, 96 million apparent dengue infections were estimated worldwide in 2010. This figure is by far greater than the WHO prediction which indicates the rapid spread of this disease posing a growing threat to the economy and a major challenge to clinicians and health care services across the globe particularly in the affected areas.This article aims at bringing to light the current epidemiological and clinical status of the dengue fever. The relationship between genetic mutations, single nucleotide polymorphism (SNP) and the pathophysiology of disease progression will be put into perspective. It will also highlight the recent advances in dengue vaccine development.Thus far, a significant progress has been made in unraveling the risk factors and understanding the molecular pathogenesis associated with the disease. However, further insights in molecular features of the disease and the development of animal models will enormously help improving the therapeutic interventions and potentially contribute to finding new preventive measures for population at risk.

Sarcoidosis and the heart: A review of the literature

Sarcoidosis is a chronic multisystem disorder without any defined etiology. Cardiac sarcoidosis (CS) is detected in 2-7% of patients with sarcoidosis and more than 20% of the cases of sarcoidosis are clinically silent. Cardiac involvement in systemic sarcoidosis (SS) and isolated cardiac sarcoidosis (iCS) are associated with arrhythmia and severe heart failure (HF) and have a poor prognosis. Early diagnosis of CS and prompt initiation of corticosteroid therapy with or without other immunosuppressants is crucial. Electrocardiography, Holter monitoring, and Doppler echocardiography with speckle tracking imaging can serve as the initial steps to diagnosis of CS. Cardiac magnetic resonance (CMR) imaging and positron emission tomography (PET) are promising techniques for both diagnosis and follow-up of CS. This review discusses the main aspects of cardiac involvement in sarcoidosis.

Evaluation of Cardiac Involvement in Children with Dengue by Serial Echocardiographic Studies

Background

Infection with dengue virus results in a wide range of clinical manifestations from dengue fever (DF), a self-limited febrile illness, to dengue hemorrhagic fever (DHF) which is characterized by plasma leakage and bleeding tendency. Although cardiac involvement has been reported in dengue, the incidence and the extent of cardiac involvement are not well defined.

Methods and Principal findings

We characterized the incidence and changes in cardiac function in a prospective in-patient cohort of suspected dengue cases by serial echocardiography. Plasma leakage was detected by serial chest and abdominal ultrasonography. Daily cardiac troponin-T levels were measured. One hundred and eighty one dengue cases were enrolled. On the day of enrollment, dengue cases that already developed plasma leakage had lower cardiac index (2695 (127) vs 3188 (75) (L/min/m²), p = .003) and higher left ventricular myocardial performance index (.413 (.021) vs .328 (.026), p = .021) and systemic vascular resistance (2478 (184) vs 1820 (133) (dynes·s/cm⁵), p = .005) compared to those without plasma leakage. Early diastolic wall motion of the left ventricle was decreased in dengue cases with plasma leakage compared to those without. Decreased left ventricular wall motility was more common in dengue patients compared to non-dengue cases particularly in cases with plasma leakage. Differences in cardiac function between DF and DHF were most pronounced around the time of plasma leakage. Cardiac dysfunction was transient and did not require treatment. Transient elevated troponin-T levels were more common in DHF cases compared to DF (14.5% vs 5%, p = 0.028).

Conclusions

Transient left ventricular systolic and diastolic dysfunction was common in children hospitalized with dengue and related to severity of plasma leakage. The functional abnormality spontaneously resolved without specific treatment. Cardiac structural changes including myocarditis were uncommon.

Dengue is a viral infection with a wide range of symptoms from a self-limiting fever called dengue fever (DF) to dengue hemorrhagic fever (DHF) which is characterized by leaky blood vessels and bleeding that can lead to shock in severe cases. Abnormal heart function has been reported but the frequencies and the progression of heart involvement are not well defined. In this study children with dengue had serial evaluation of their heart function during the course of the illness. Patients with DHF had comparatively low blood volume at the time of fever resolution and had decreased blood flow into the left lower heart chamber compared to DF cases. Relaxation and contraction of the left side of the heart were also relatively decreased in DHF. These abnormalities may contribute to the clinical response and complications of fluid replacement in dengue.

Why are people with dengue dying? A scoping review of determinants for dengue mortality

BACKGROUND

Dengue is a viral disease whose clinical spectrum ranges from unapparent to severe forms and fatal outcomes. Although dengue death is 99% avoidable, every year around 20,000 deaths are estimated to occur in more than 100 countries. We consider that, along with biological factors, social determinants of health (SDHs) are related to dengue deaths as well.

METHODS

A scoping review was conducted to explore what has been written about the role of SDHs in dengue mortality. The inclusion criteria were that documents (grey or peer-reviewed) had to include information about dengue fatal cases in humans and be published between 1997 and 2013 and written in English, Spanish, Portuguese or French. The search was conducted using a set of key words related to dengue mortality in several electronic databases: PubMed, LILACS, COCHRANE, Scielo, Science Direct, WHOLIS, OpenGrey, OpenSingle and Google Scholar. Information on SDHs was categorized under individual, social and environmental, and health systems dimensions. A summative content analysis using QDA Miner was conducted to assess the frequency of information on SDHs and its contextual meaning in the reviewed literature. The role of each SDH in dengue mortality was assessed using content analysis results.

RESULTS

From a total of 971 documents retrieved, 78 met the criteria. Those documents were published in the Americas region (50.0%), Asia (38.4%), Europe (9.0%) and Africa (2.6%). The described SDHs related to dengue deaths included, in the individual dimension: age, ethnicity, education, type of infection and immunological status; and in the social dimension: poverty and care-seeking behavior. The health systems dimension included access, opportunity, and quality of care, as well as health staff knowledge. Ethnicity was considered a determinant that depends on cultural and socioeconomic conditions.

CONCLUSIONS

Along with biological factors, there are several SDHs related to dengue mortality. However, only a few of these have been systematically analyzed, suggesting the need for more studies on this subject to inform the design and implementation of sustainable interventions to decrease dengue mortality. These findings nevertheless provide a better understanding of the non-biological factors involved in dengue mortality.

Clinical implications and treatment of dengue

Dengue is a common pathogenic disease often proving fatal, more commonly affecting the tropics. Aedes mosquito is the vector for this disease, and outbreaks of dengue often cause mass damage to life. The current review is an effort to present an insight into the causes, etiology, symptoms, transmission, diagnosis, major organs affected, mitigation and line of treatment of this disease with special emphasis on drugs of natural origin. The disease has a potential to spread as an endemic, often claiming several lives and thus requires concerted efforts to work out better treatment options. Traditional medicine offers an alternative solution and could be explored as a safer treatment option. Development of a successful vaccine and immunization technique largely remains a challenge and a better antiviral approach needs to be worked out to complement the supportive therapy. No single synthetic molecule has found to be wholly effective enough to offer curative control and the line of treatment mostly utilizes a combination of fluid replacement and antipyretics-analgesics like molecules to provide symptomatic relief.

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.

Dengue: Moving from Current Standard of Care to State-of-the-Art Treatment

Treatment of dengue remains supportive in the absence of targeted antiviral therapy or approved vaccines. Responsive fluid management is key to preventing progression to shock or other severe manifestations. The dynamic natural history of dengue infection and its influence on hemodynamic homeostasis needs to be carefully considered in the planning of individualized therapy. Though largely self-limiting, the sheer burden of dengue disease on the global population will result in atypical manifestations especially in children, older adults, and comorbid patients. Management of these has not yet been systematized. The failure of recent randomized controlled trials to show utility for antiviral and immunomodulatory agents in dengue is disappointing. Vaccine candidates hold promise, but growing outbreaks require more robust, evidence-based management guidelines to inform clinicians, especially in novel epidemic situations.

Utility of warning signs in guiding admission and predicting severe disease in adult dengue

BACKGROUND

The recommendation from the 2009 World Health Organization guidelines for managing dengue suggests that patients with any warning sign can be hospitalized for observation and management. We evaluated the utility of using warning signs to guide hospital admission and predict disease progression in adults.

METHODS

We conducted a prospective cohort study from January 2010 to September 2012. Daily demographic, clinical and laboratory data were collected from adult dengue patients. Warning signs were recorded. The proportion of admitted patients using current admission criteria and warning signs was compared. The sensitivity, specificity, positive and negative predictive values of warning signs in predicting disease progression were also evaluated.

RESULTS

Four hundred and ninety-nine patients with confirmed dengue were analyzed. Using warning signs instead of the current admission criteria will lead to a 44% and 31% increase in admission for DHF II-IV and SD cases respectively. The proportion of non-severe dengue cases which were admitted also increased by 32% for non DHF II-IV and 33% for non-SD cases. Absence of any warning signs had a NPV of 91%, 100% and 100% for DHF I-IV, DHF II-IV and SD. Of those who progressed to severe illness, 16.3% had warning signs on the same day while 51.3% had warning signs the day before developing severe illness, respectively.

CONCLUSIONS

Our findings demonstrated that patients without any warning signs can be managed safely with ambulatory care to reduce hospital resource burden. No single warning sign can independently predict disease progression. The window from onset of warning sign to severe illness in most cases was within one day.

Serotype-specific host responses in rhesus macaques after primary dengue challenge

Dengue virus (DENV) is considered to be the most important arthropod-borne viral disease and causes more than 100 million human infections annually. To further characterize primary DENV infection in vivo, rhesus macaques were infected with DENV-1, DENV-2, DENV-3, or DENV-4 and clinical parameters, as well as specificity and longevity of serologic responses, were assessed. Overt clinical symptoms were not present after infection. However, abnormalities in blood biochemical parameters consistent with heart, kidney, and liver damage were observed, and changes in plasma fibrinogen, D-dimers, and protein C indicated systemic activation of the blood coagulation pathway. Significant homotypic and heterotypic serum immunoglobulins were present in all animals, and IgG persisted for at least 390 days. Serum neutralizing antibody responses were highly serotype specific by day 120. However, some heterotypic neutralizing activity was noted in infected animals. Identification of serotype-specific host responses may help elucidate mechanisms that mediate severe DENV disease after reinfection.

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.