Fatal dengue hemorrhagic fever in adults during a dengue epidemic in Singapore

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.

Association Between Leucopenia, Transaminitis, Nonstructural Protein One Antigen (Ns1Ag) Level, and Thrombocytopenia in Adult Dengue Patients in a Tertiary Care Hospital: A Cross-Sectional Study

BACKGROUND

The dengue virus is present throughout the tropics. Thrombocytopenia is one of the severe manifestations of the dengue virus. We studied the association of thrombocytopenia with serum transaminase level, leucopenia, and nonstructural protein one antigen (Ns1Ag) level.

METHODS

Data were taken retrospectively from hospital records after obtaining ethical committee approval. In the study, we included 102 patients with acute febrile illness with clinical features suggestive of dengue fever (dengue Ns1Ag positive, dengue IgM positive, or both). We excluded patients with thrombocytopenia due to other causes. Patients' demographic, clinical, and laboratory parameters were collected. We also noted episodes of bleeding or the need for a platelet transfusion. We did a statistical analysis to find out the correlation between age, sex, leucopenia, transaminitis, Ns1Ag level, and thrombocytopenia and its severity.

RESULTS

Multiple regression analysis was used to find thrombocytopenia predictors among aspartate transaminase (AST), alanine transaminase (ALT), Ns1Ag level, and leucopenia. AST and ALT correlated inversely with thrombocytopenia, with p-values of 0.012 and 0.027, respectively. Ns1Ag and leucopenia were not associated with thrombocytopenia, with p-values of 0.802 and 0.532, respectively (p-values significant at 0.01<= p<=0.05).

CONCLUSION

Serum AST and ALT levels correlate with thrombocytopenia in dengue fever.

Aspergillus coinfection in critically Ill patients with severe dengue

In 2014-2015, a significant outbreak of dengue fever occurred in southern Taiwan, with a subsequent decline in dengue incidence. Despite this, there is emerging concern about virus-associated aspergillosis, yet limited research has explored coinfections involving dengue and aspergillosis. We conducted a retrospective study at a single center in Southern Taiwan, specifically focusing on dengue patients admitted to the intensive care unit during the period between July and November 2015. Among the 142 dengue patients studied, only 8.06 % (10/142) underwent serum galactomannan testing, with a single patient undergoing bronchoalveolar lavage (BAL) galactomannan assay. Out of those tested, 20 % (2/10) returned positive serum galactomannan results. Herein, we present two consecutive cases of coinfection involving dengue and pulmonary aspergillosis in immunocompetent patients.

Clinical profiles and predictors of survival in severe dengue cases

Introduction

Dengue is endemic in tropical countries. Severe dengue has a high risk of morbidity and mortality. We aimed to identify factors associated with dengue survival among our intensive care unit (ICU) patients.

Methods

A retrospective study was conducted among dengue cases admitted to the ICU of Hospital Sultan Abdul Halim, Kedah, Malaysia from 2016 to 2019.

Results

Out of 1,852 dengue cases admitted to the hospital, 7.2% of patients required ICU admission. Survival rate was 88.6% among severe dengue cases. The majority of severe dengue patients were obese, while other notable comorbidities included hypertension and diabetes mellitus. Also, 73% of patients presented in the critical phase, at a median of Day 4 of illness. All patients admitted to the ICU had a history of fever. The predominant warning signs were lethargy, fluid accumulation and haemoconcentration with rapid platelet reduction. Among nonsurvivors, 69.2% had fulminant hepatitis, 53.8% had massive bleeding or disseminated intravascular coagulation, 38.5% had haemophagocytic lymphohistiocytosis and 30.8% had myocarditis. The predominant serotypes were DENV-3 and DENV-1. The least number of cases was seen in 2017, when all serotypes were equally presented. Multiple logistic regression showed that Sequential Organ Failure Assessment (SOFA) score, peak international normalised ratio, peak partial thromboplastin time and aspartate aminotransferase on admission were independent risk factors for survival. This model had an area under the curve of 0.98, giving an overall 98.2% accuracy.

Conclusions

Specific warning signs and blood investigations in dengue patients may aid in early decision for ICU admission. Monitoring of SOFA scores plus coagulation and liver enzyme profiles could improve dengue survival rates.

Spontaneous retroperitoneal haematoma in severe dengue: A case report

Dengue is endemic in over 100 countries worldwide, predominantly in the subtropical and tropical regions and the incidence has been increasing globally. Patients with severe dengue may develop massive bleeding, disseminated intravascular coagulopathy and multi-organ failure. Bleeding may occur in various body cavities and muscles; however, bleeding in the retroperitoneal space is uncommon. We report a case of a 37-year-old gentleman who presented with a 4-day history of fever associated with chills and rigours. On Day 6 of illness, he complained of left lumbar and left iliac fossa pain which was aggravated by movement. A computed tomography angiography scan of the abdomen showed the presence of a retroperitoneal haematoma, left iliopsoas and quadratus lumbarum intramuscular haematoma with active bleeding and left abdominal wall muscles haematoma. His condition gradually improved after multiple blood transfusions and he gained full recovery. Spontaneous retroperitoneal haematoma is an uncommon complication of severe dengue infection. Early diagnosis based on high index of clinical suspicion using appropriate imaging will aid in prompt management of these cases and may prevent deaths.

Angiotensin II and dengue

Dengue is a disease caused by a flavivirus that is transmitted principally by the bite of an Aedes aegypti mosquito and represents a major public-health problem. Many studies have been carried out to identify soluble factors that are involved in the pathogenesis of this infection. Cytokines, soluble factors, and oxidative stress have been reported to be involved in the development of severe disease. Angiotensin II (Ang II) is a hormone with the ability to induce the production of cytokines and soluble factors related to the inflammatory processes and coagulation disorders observed in dengue. However, a direct involvement of Ang II in this disease has not been demonstrated. This review primarily summarizes the pathophysiology of dengue, the role of Ang II in various diseases, and reports that are highly suggestive of the involvement of this hormone in dengue.

Blocking NS3-NS4B interaction inhibits dengue virus in non-human primates

Dengue is a major health threat and the number of symptomatic infections caused by the four dengue serotypes is estimated to be 96 million1 with annually around 10,000 deaths2. However, no antiviral drugs are available for the treatment or prophylaxis of dengue. We recently described the interaction between non-structural proteins NS3 and NS4B as a promising target for the development of pan-serotype dengue virus (DENV) inhibitors3. Here we present JNJ-1802-a highly potent DENV inhibitor that blocks the NS3-NS4B interaction within the viral replication complex. JNJ-1802 exerts picomolar to low nanomolar in vitro antiviral activity, a high barrier to resistance and potent in vivo efficacy in mice against infection with any of the four DENV serotypes. Finally, we demonstrate that the small-molecule inhibitor JNJ-1802 is highly effective against viral infection with DENV-1 or DENV-2 in non-human primates. JNJ-1802 has successfully completed a phase I first-in-human clinical study in healthy volunteers and was found to be safe and well tolerated4. These findings support the further clinical development of JNJ-1802, a first-in-class antiviral agent against dengue, which is now progressing in clinical studies for the prevention and treatment of dengue.

Acute Pancreatitis Secondary to Dengue Fever: An Uncommon Presentation of a Common Endemic Illness

Dengue viral infection is considered endemic in Ecuador. It is more frequent during winter, caused by an RNA virus in the Flavivirus group. Its presentation can range from an asymptomatic state to hemorrhagic fever with shock signs. Acute pancreatitis could be a rare form of acute abdomen presentation associated with dengue virus infection. This case illustrates a 26-year-old man who presents to the hospital with cramp-like pain in the epigastrium and radiation to the right upper quadrant, accompanied by nausea and vomiting. He also endorsed additional symptoms such as throbbing-like headache, myoarthralgias, and fever of 40.4°C (104.72°F). Laboratory tests revealed elevated hematocrit, thrombocytopenia, elevated pancreatic enzymes, transaminitis, elevated alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT). Ultrasonography of the abdomen revealed hepatic steatosis, free fluid in the abdominal cavity, and small bilateral pleural effusions. Additional testing revealed IgM and IgG antibodies positivity to dengue virus. The patient was treated conservatively with intravenous (IV) fluid hydration and bowel rest. Acute pancreatitis should be considered when a patient presents with a suspected acute abdomen in the emergency department, and a detailed medical history is necessary to make a correct approach to the differential diagnosis.

Self-medication dilemma in dengue fever

This paper focuses on the trends of self-medication practices in treating symptoms that may lead to fatal complications in dengue. As dengue is a viral infection with increasing incidence, decision regarding its treatment is mostly affected by public health believes and practices to self-treat the condition by different home remedies, over-the-counter (OTC) drugs or using outdated prescription drugs that proved beneficial in the past experience. Poverty, lack of education, and poor access to health facilities pave the way for making such decisions. Future complications can be averted by raising awareness, counseling the patients and dispensing of pharmaceuticals with strict monitoring.

Risk Factors for Mortality in Patients with Dengue: A Systematic Review and Meta-Analysis

OBJECTIVE

To investigate risk factors for mortality in dengue.

METHODS

Systematic review and meta-analysis searching MEDLINE, Embase, SciELO, LILACS Bireme, and OpenGrey to identify eligible observational studies of patients with dengue, of both genders, aged 14 years or older, that analyzed risk factors associated with mortality and reported adjusted risk measures with their respective confidence intervals (CIs). We estimated the pooled weighted mean difference and 95% CIs with a DerSimonian and Laird random-effects model. Methodological quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

Of 1,170 citations reviewed, 18 papers, with a total of 25,851 patients, were included in the systematic review and 12 in the meta-analysis. Severe hepatitis (OR 29.222, 95% CI: 3.876-220.314), dengue shock syndrome (OR 23.575, 95% CI 3.664-151.702), altered mental status (OR 3.76, 95% CI 1.67-8.42), diabetes mellitus (OR 3.698, 95% CI 1.196-11.433), and higher pulse rate (OR 1.039, 95% CI 1.011-1.067) are associated with mortality in patients with dengue. All studies included were classified as having a high quality.

CONCLUSIONS

Proper identification and management of these risk factors should be considered to improve patient outcomes and reduce the hidden burden of this neglected tropical disease. Future well-designed studies are needed to investigate the association of other clinical, radiological, and laboratorial findings with mortality in dengue, as well as to develop prognostic models based on the risk factors found in our study.

Is fractional-order chaos theory the new tool to model chaotic pandemics as Covid-19?

The deadly outbreak of the second wave of Covid-19, especially in worst hit lower-middle-income countries like India, and the drastic rise of another growing epidemic of Mucormycosis, call for an efficient mathematical tool to model pandemics, analyse their course of outbreak and help in adopting quicker control strategies to converge to an infection-free equilibrium. This review paper on prominent pandemics reveals that their dispersion is chaotic in nature having long-range memory effects and features which the existing integer-order models fail to capture. This paper thus puts forward the use of fractional-order (FO) chaos theory that has memory capacity and hereditary properties, as a potential tool to model the pandemics with more accuracy and closeness to their real physical dynamics. We investigate eight FO models of Bombay plague, Cancer and Covid-19 pandemics through phase portraits, time series, Lyapunov exponents and bifurcation analysis. FO controllers (FOCs) on the concepts of fuzzy logic, adaptive sliding mode and active backstepping control are designed to stabilise chaos. Also, FOCs based on adaptive sliding mode and active backstepping synchronisation are designed to synchronise a chaotic epidemic with a non-chaotic one, to mitigate the unpredictability due to chaos during transmission. It is found that severity and complexity of the models increase as the memory fades, indicating that FO can be used as a crucial parameter to analyse the progression of a pandemic. To sum it up, this paper will help researchers to have an overview of using fractional calculus in modelling pandemics more precisely and also to approximate, choose, stabilise and synchronise the chaos control parameter that will eliminate the extreme sensitivity and irregularity of the models.

Searching for plant-derived antivirals against dengue virus and Zika virus

Background

The worldwide epidemics of diseases as dengue and Zika have triggered an intense effort to repurpose drugs and search for novel antivirals to treat patients as no approved drugs for these diseases are currently available. Our aim was to screen plant-derived extracts to identify and isolate compounds with antiviral properties against dengue virus (DENV) and Zika virus (ZIKV).

Methods

Seven thousand plant extracts were screened in vitro for their antiviral properties against DENV-2 and ZIKV by their viral cytopathic effect reduction followed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, previously validated for this purpose. Selected extracts were submitted to bioactivity-guided fractionation using high- and ultrahigh-pressure liquid chromatography. In parallel, high-resolution mass spectrometric data (MSn) were collected from each fraction, allowing compounds into the active fractions to be tracked in subsequent fractionation procedures. The virucidal activity of extracts and compounds was assessed by using the plaque reduction assay. EC₅₀ and CC₅₀ were determined by dose response experiments, and the ratio (EC₅₀/CC₅₀) was used as a selectivity index (SI) to measure the antiviral vs. cytotoxic activity. Purified compounds were used in nuclear magnetic resonance spectroscopy to identify their chemical structures. Two compounds were associated in different proportions and submitted to bioassays against both viruses to investigate possible synergy. In silico prediction of the pharmacokinetic and toxicity (ADMET) properties of the antiviral compounds were calculated using the pkCSM platform.

Results

We detected antiviral activity against DENV-2 and ZIKV in 21 extracts obtained from 15 plant species. Hippeastrum (Amaryllidaceae) was the most represented genus, affording seven active extracts. Bioactivity-guided fractionation of several extracts led to the purification of lycorine, pretazettine, narciclasine, and narciclasine-4-O-β-D-xylopyranoside (NXP). Another 16 compounds were identified in active fractions. Association of lycorine and pretazettine did not improve their antiviral activity against DENV-2 and neither to ZIKV. ADMET prediction suggested that these four compounds may have a good metabolism and no mutagenic toxicity. Predicted oral absorption, distribution, and excretion parameters of lycorine and pretazettine indicate them as candidates to be tested in animal models.

Conclusions

Our results showed that plant extracts, especially those from the Hippeastrum genus, can be a valuable source of antiviral compounds against ZIKV and DENV-2. The majority of compounds identified have never been previously described for their activity against ZIKV and other viruses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01751-z.

Using amino acids co-occurrence matrices and explainability model to investigate patterns in dengue virus proteins

Background

Dengue is a common vector-borne disease in tropical countries caused by the Dengue virus. This virus may trigger a disease with several symptoms like fever, headache, nausea, vomiting, and muscle pain. Indeed, dengue illness may also present more severe and life-threatening conditions like hemorrhagic fever and dengue shock syndrome. The causes that lead hosts to develop severe infections are multifactorial and not fully understood. However, it is hypothesized that different viral genome signatures may partially contribute to the disease outcome. Therefore, it is plausible to suggest that deeper DENV genetic information analysis may bring new clues about genetic markers linked to severe illness.

Method

Pattern recognition in very long protein sequences is a challenge. To overcome this difficulty, we map protein chains onto matrix data structures that reveal patterns and allow us to classify dengue proteins associated with severe illness outcomes in human hosts. Our analysis uses co-occurrence of amino acids to build the matrices and Random Forests to classify them. We then interpret the classification model using SHAP Values to identify which amino acid co-occurrences increase the likelihood of severe outcomes.

Results

We trained ten binary classifiers, one for each dengue virus protein sequence. We assessed the classifier performance through five metrics: PR-AUC, ROC-AUC, F1-score, Precision and Recall. The highest score on all metrics corresponds to the protein E with a 95% confidence interval. We also compared the means of the classification metrics using the Tukey HSD statistical test. In four of five metrics, protein E was statistically different from proteins M, NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5, showing that E markers has a greater chance to be associated with severe dengue. Furthermore, the amino acid co-occurrence matrix highlight pairs of amino acids within Domain 1 of E protein that may be associated with the classification result.

Conclusion

We show the co-occurrence patterns of amino acids present in the protein sequences that most correlate with severe dengue. This evidence, used by the classification model and verified by statistical tests, mainly associates the E protein with the severe outcome of dengue in human hosts. In addition, we present information suggesting that patterns associated with such severe cases can be found mostly in Domain 1, inside protein E. Altogether, our results may aid in developing new treatments and being the target of debate on new theories regarding the infection caused by dengue in human hosts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-022-04597-y.

Short-term, medium-term, and long-term risks of nonvariceal upper gastrointestinal bleeding after dengue virus infection

Dengue patients have an increased risk of acute gastrointestinal (GI) bleeding. However, whether dengue virus (DENV) infection can cause an increased long-term risk of GI bleeding remains unknown, especially among elderly individuals who commonly take antithrombotic drugs. A retrospective population-based cohort study was conducted by analyzing the National Health Insurance Research Databases. Laboratory-confirmed dengue patients from 2002 to 2012 and four matched nondengue controls were identified. Multivariate Cox proportional hazard regression was used to evaluate the acute (<30 days), medium-term (31–365 days), and long-term (>365 days) risks of nonvariceal upper GI bleeding after DENV infection. Stratified analyses by age group (≤50, 51–64, ≥65 years old) were also performed. In total, 13267 confirmed dengue patients and 53068 nondengue matched controls were included. After adjusting for sex, age, area of residence, comorbidities, and medications, dengue patients had a significantly increased risk of nonvariceal upper GI bleeding within 30 days of disease onset (adjusted HR 55.40; 95% CI: 32.17–95.42). However, DENV infection was not associated with increased medium-term and long-term risks of upper GI bleeding overall or in each age group. Even dengue patients who developed acute GI bleeding did not have increased medium-term (adjusted HR; 0.55, 95% CI 0.05–6.18) and long-term risks of upper GI bleeding (adjusted HR; 1.78, 95% CI 0.89–3.55). DENV infection was associated with a significantly increased risk of nonvariceal upper GI bleeding within 30 days but not thereafter. Recovered dengue patients with acute GI bleeding can resume antithrombotic treatments to minimize the risk of thrombosis.

Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Dengue patients can have low platelet counts and might have acute gastrointestinal bleeding (tarry stool, bloody stool or bloody vomiting). Most dengue patients will fully recover and return to their previous health levels. Previous studies have indicated that some dengue patients have persistent low platelet counts and high inflammatory responses. The medium-term and long-term upper gastrointestinal bleeding risks remain unknown. Our study suggested that dengue was significantly associated with an increased risk of nonvariceal upper GI bleeding within 30 days after infection but was not associated with increased medium-term (31–365 days) and long-term risks (>365 days) of upper GI bleeding. Therefore, the risk of acute gastroenterology bleeding returned to baseline levels after 30 days. Recovered dengue patients with acute GI bleeding can resume antiplatelet, antithrombotic, and oral anticoagulation (OAC) treatments.

Development of a Dengue Virus Serotype-Specific Non-Structural Protein 1 Capture Immunochromatography Method

Four serotypes of dengue virus (DENV), type 1 to 4 (DENV-1 to DENV-4), exhibit approximately 25–40% of the difference in the encoded amino acid residues of viral proteins. Reverse transcription of RNA extracted from specimens followed by PCR amplification is the current standard method of DENV serotype determination. However, since this method is time-consuming, rapid detection systems are desirable. We established several mouse monoclonal antibodies directed against DENV non-structural protein 1 and integrated them into rapid DENV detection systems. We successfully developed serotype-specific immunochromatography systems for all four DENV serotypes. Each system can detect 10⁴ copies/mL in 15 min using laboratory and clinical isolates of DENV. No cross-reaction between DENV serotypes was observed in these DENV isolates. We also confirmed that there was no cross-reaction with chikungunya, Japanese encephalitis, Sindbis, and Zika viruses. Evaluation of these systems using serum from DENV-infected individuals indicated a serotype specificity of almost 100%. These assay systems could accelerate both DENV infection diagnosis and epidemiologic studies in DENV-endemic areas.

Aedes-AI: Neural network models of mosquito abundance

We present artificial neural networks as a feasible replacement for a mechanistic model of mosquito abundance. We develop a feed-forward neural network, a long short-term memory recurrent neural network, and a gated recurrent unit network. We evaluate the networks in their ability to replicate the spatiotemporal features of mosquito populations predicted by the mechanistic model, and discuss how augmenting the training data with time series that emphasize specific dynamical behaviors affects model performance. We conclude with an outlook on how such equation-free models may facilitate vector control or the estimation of disease risk at arbitrary spatial scales.

Aedes aegypti mosquitoes affect millions of people each year through infectious diseases such as chikungunya, dengue, and Zika. Because local vector levels need to be sufficiently high for associated outbreaks to occur, the ability to estimate mosquito abundance is a central component of assessing disease risk. The mosquito landscape model (MoLS) is a mechanistic model that estimates Aedes aegypti abundance from local weather time series, and is able to reproduce trends observed in surveillance data. However, scaling this up to a large number of locations is resource intensive, requiring a high-performance computing system. In this article, we develop artificial neural network models that are significantly faster than MoLS and can produce abundance estimates directly from local weather data. This approach reduces the computational time associated with estimating local mosquito levels, thereby allowing for a corresponding increase in the spatiotemporal resolution of these predictions. We compare network design choices, including architecture and training data, in their ability to accurately reproduce MoLS estimates and analyze model performance in locations across the contiguous United States.

Risk factors for hospitalization and mortality due to dengue fever in a Mexican population: a retrospective cohort study

OBJECTIVES

Identify risk factors associated with increased hospital admission and mortality due to dengue fever (DF), and estimate the risk magnitude associated with each individual variable.

METHODS

Records of patients diagnosed with dengue were obtained from the Mexican National Epidemiological Surveillance System. Descriptive statistics were performed in all variables. Demographic characteristics and comorbidities were compared between patients based on type of care and mortality. Multivariable analysis was done with a logistic regression model, using two different outcomes: hospitalization and mortality.

RESULTS

A total of 24,495 patients were included in the analysis, with a DF case fatality rate of 0.58%. Patients younger than 10 and older than 60, were found to have a greater risk of both hospitalization and mortality due to DF. Comorbidities associated with a higher risk for hospital admission include cirrhosis, CKD, immunosuppression, diabetes, and hypertension. For mortality, CKD, diabetes, and hypertension were identified as risk factors, along with pregnancy.

CONCLUSION

Identification of risk factors associated with increased hospitalization and mortality due to DF can help categorize patients that require close monitoring and inpatient care. Early identification of warning signs and patients at increased risk is key to avoiding delay of supportive care.

Fatal outcomes of imported dengue fever in adult travelers from non-endemic areas are associated with primary infections

BACKGROUND

The case-fatality rate of dengue in travelers is low. Secondary dengue virus (DENV) infections are considered a risk factor for fatal outcome in endemic populations; however, the impact of secondary infections on mortality in travelers has not been studied systematically. We performed a descriptive analysis of case reports of dengue fatalities in travelers.

METHODS

We searched Medline for clinical case reports, using the free terms and MeSH headings: 'Dengue' OR 'Severe Dengue' AND 'Travel-Related Illness' OR 'travel' AND 'Mortality' OR 'Fatal Outcome'. We analyzed case reports of fatal dengue in returning travelers published from 1995 to 2020, with the objective to detail risk factors for dengue mortality in this population. We verified the authors' classifications of primary or secondary dengue infections; infections were considered as primary by absence of anti-DENV immunoglobulin (Ig)G or by IgM-to-IgG ratios greater than or equal to 1.8 in the first 7 days post symptom onset.

RESULTS

We identified nine detailed reports of dengue with fatal outcome among travelers from non-endemic countries. Eight fatalities were female. The median age was 32 years (range 21-63). Out of nine fatal cases, seven travelers had a primary DENV infection, one had a secondary infection and, in one, these data were not reported. The infecting DENV serotypes were DENV-1 (n = 2), DENV-2 (n = 2) and DENV-3 (n = 3); DENV-1 or 2 (n = 1) and in one case, the serotype could not be determined.

CONCLUSIONS

Dengue-related deaths in travelers are rare. Most dengue cases in travelers are primary infections. Contrary to prevailing conceptions, we found that fatal outcomes of dengue in travelers from non-endemic countries were reported mainly with primary DENV infections. We alert health care providers that primary DENV infections are not always harmless and that in adult travelers from non-endemic countries, primary infections may contribute more to dengue-related mortality than secondary infections.

Dengue and the Lectin Pathway of the Complement System

Dengue is a mosquito-borne viral disease causing significant health and economic burdens globally. The dengue virus (DENV) comprises four serotypes (DENV1-4). Usually, the primary infection is asymptomatic or causes mild dengue fever (DF), while secondary infections with a different serotype increase the risk of severe dengue disease (dengue hemorrhagic fever, DHF). Complement system activation induces inflammation and tissue injury, contributing to disease pathogenesis. However, in asymptomatic or primary infections, protective immunity largely results from the complement system’s lectin pathway (LP), which is activated through foreign glycan recognition. Differences in N-glycans displayed on the DENV envelope membrane influence the lectin pattern recognition receptor (PRR) binding efficiency. The important PRR, mannan binding lectin (MBL), mediates DENV neutralization through (1) a complement activation-independent mechanism via direct MBL glycan recognition, thereby inhibiting DENV attachment to host target cells, or (2) a complement activation-dependent mechanism following the attachment of complement opsonins C3b and C4b to virion surfaces. The serum concentrations of lectin PRRs and their polymorphisms influence these LP activities. Conversely, to escape the LP attack and enhance the infectivity, DENV utilizes the secreted form of nonstructural protein 1 (sNS1) to counteract the MBL effects, thereby increasing viral survival and dissemination.

Low socio-economic status associated with increased risk of dengue haemorrhagic fever in Taiwanese patients with dengue fever: a population-based cohort study

BACKGROUND

Evidence indicates that socio-economic status (SES) may affect health outcomes in patients with chronic diseases. However, little is known about the impact of SES on the prognosis of acute dengue. This nationwide cohort study determined the risk of dengue haemorrhagic fever (DHF) in Taiwanese dengue fever patients from 2000 to 2014.

METHODS

From 1 January 2000, we identified adult dengue cases reported in the Taiwan Centers for Disease Control Notifiable Diseases Surveillance System Database. Dengue cases were defined as positive virus isolation, nucleic acid amplification tests or serological tests. Associations between SES and incident DHF were estimated using a Cox proportional hazards model.

RESULTS

Of 27 750 dengue patients, 985 (3.5%) had incident DHF during the follow-up period, including 442 (4.8%) and 543 (2.9%) with low and high SES, respectively. After adjusting for age, sex, history of dengue fever and comorbidities, low SES was significantly associated with an increased risk of incident DHF (adjusted hazard ratio [AHR] 1.61 [95% confidence interval {CI} 1.42 to 1.83]). Rural-dwelling dengue patients had a higher likelihood of DHF complication than their urban counterparts (AHR 2.18 [95% CI 1.90 to 2.51]).

CONCLUSIONS

This study suggests low SES is an independent risk factor for DHF. Future dengue control programs should particularly target dengue patients with low SES for improved outcomes.

Social, health system and clinical determinants of fever mortality during an outbreak of dengue fever in Kerala, India

Background and Objectives:

The morbidity and mortality spectrum of the south Indian state of Kerala is dominated by chronic non-communicable diseases, yet febrile illnesses because of neglected tropical diseases and emerging viral infections are often reported. As fever deaths are mostly avoidable, understanding the determinants of mortality is essential for implementing preventive measures.

Methods:

A case-control study was done during an ongoing dengue outbreak in Thiruvananthapuram district, Kerala during 2017–18. Cases included all fever deaths from the line list of Integrated Disease Surveillance Program (IDSP). Data were obtained from hospital case records and by interviewing patients or care givers. The theoretical model for determinants of mortality was constructed at three levels namely sociodemographic factors, access to health care and health seeking behavior, and clinical determinants.

Results:

This study confirmed association of mortality with age above 40 years (P = 0.010, OR = 3.48), being heavy built (P = 0.029, OR = 13.25), clinical symptoms of breathlessness (P < 0.001, OR = 24.89), restlessness (P < 0.001, OR = 97.26), clinical signs of drowsiness (P = 0.024, OR = 7.97), hypotension (P < 0.001, OR = 42.22), complications such as ARDS (P = 0.047, OR = 171.56), and myocarditis (P = 0.012, OR = 16.59). A low occupation status of semiskilled work or less (P = 0.012, OR = 0.30), choosing a nearby hospital for treatment (P = 0.018, OR = 0.48) and shortening the time gap between onset of symptom and final diagnosis (P = 0.044, OR = 0.72) was found to be protective.

Conclusion:

Along with biological and clinical factors, distal determinants like social factors, health seeking behavior, and health system factors are associated with fever mortality.

Causes of death among dengue patients causes of death among hospitalized adults with dengue fever in Tainan, 2015: Emphasis on cardiac events and bacterial infections

INTRODUCTION

The 2015 dengue outbreak in southern Taiwan caused substantial mortality. We analyzed the causes of death among these patients.

MATERIALS AND METHODS

This retrospective study was conducted at a medical center in Tainan from August 2015 to December 2015. Dengue was diagnosed based on the detection of serum dengue NS1 antigen, IgM, or viral RNA in the blood. Causes of death were retrieved from chart reviews by three clinicians.

RESULTS

There were 4488 cases of dengue in the study hospital, with an in-hospital fatality rate of 1.3% (60 cases). The mean age of the 60 fatal cases was 73 years, among whom 90% were aged ≥65 years. Twenty-eight (46.7%) patients died of severe dengue, and 29 (48.3%) deaths were possibly related to dengue. Of the latter, 24 (40%) died of secondary infections. Thirteen cardiac arrest events, including out-of-hospital (5 events) and in-hospital (8) cardiac arrests in the emergency department, occurred during the dengue epidemic. Seven (53.8%) patients did not receive medical aid before the event. Of the 40 deaths that occurred within one week after hospitalization, 60% died of severe dengue. In contrast, 50% of 20 deaths that occurred one week after hospitalization were related to hospital-acquired infections, mainly pneumonia.

CONCLUSION

Of 60 fatal cases, with a predominance of elderly patients, deaths were related to severe dengue within the first week after admission and secondary infections thereafter. The absence of medical care before cardiac arrest events highlights the importance of health education for warning signs of dengue.

Controlling Wolbachia Transmission and Invasion Dynamics among Aedes Aegypti Population via Impulsive Control Strategy

This work is devoted to analyzing an impulsive control synthesis to maintain the self-sustainability of Wolbachia among Aedes Aegypti mosquitoes. The present paper provides a fractional order Wolbachia invasive model. Through fixed point theory, this work derives the existence and uniqueness results for the proposed model. Also, we performed a global Mittag-Leffler stability analysis via Linear Matrix Inequality theory and Lyapunov theory. As a result of this controller synthesis, the sustainability of Wolbachia is preserved and non-Wolbachia mosquitoes are eradicated. Finally, a numerical simulation is established for the published data to analyze the nature of the proposed Wolbachia invasive model.

The Role of Temperature in Shaping Mosquito-Borne Viruses Transmission

Mosquito-borne diseases having the greatest impact on human health are typically prevalent in the tropical belt of the world. However, these diseases are conquering temperate regions, raising the question of the role of temperature on their dynamics and expansion. Temperature is one of the most significant abiotic factors affecting, in many ways, insect vectors and the pathogens they transmit. Here, we debate the veracity of this claim by synthesizing current knowledge on the effects of temperature on arboviruses and their vectors, as well as the outcome of their interactions.

Risk Factors Associated with Fatal Dengue Hemorrhagic Fever in Adults: A Case Control Study

Background

Dengue is endemic in most parts of the tropics with a significant mortality of 1-5%. Although individual case reports and case series have been published, large-scale case controls studies are few. The objective of this study was to find clinical and laboratory predictors of mortality in dengue.

Methods

Hospital case record based case control study was performed.

Results

Twenty fatalities with 80 controls were analyzed. Clinical parameters of postural dizziness (OR 3.2; 95% CI 1.1-8.9), bleeding (OR 31.9; 95% CI 6.08-167.34), presence of plasma leakage (OR 64.6; 95% CI 7.45-560.5), abdominal tenderness (OR 2.24; 95% CI 0.79-6.38), and signs of cardiorespiratory instability at admission increased the risk of dying from dengue. Altered consciousness was exclusively seen in 20% of cases. Laboratory parameters of elevated CRP (OR 1.652; 95% CI 1.28-2.14), AST, or ALT > 500 IU/L (OR 52.5; 95% CI 12.52-220.1) and acute kidney injury (AKI) (OR 103.5; 95% CI 13.26-807.78) during hospital stay increased the odds of dying. Need for assisted ventilation and multiorgan dysfunction (MOD) were exclusively seen in the cases. Multivariate logistic regression revealed bleeding at admission, AKI, and elevated hepatic transaminase >500 IU/L to be independent predictors of mortality.

Conclusions

This case control study revealed that mortality from dengue could be predicted using clinical parameters at admission and low cost routine laboratory investigations.

Daily Dengue Severity Score to Assess Severe Manifestations

BACKGROUND

The study aimed to develop dengue severity score to assess severe manifestations among hospitalized patients with dengue infection.

METHOD

Children and adolescents with serologically confirmed dengue infection admitted at Ramathibodi Hospital from 2004 to 2018 and treated by an expert multidisciplinary team were recruited. Medical records were retrospectively reviewed and 14 items, related to clinical parameters and managements during hospitalization, were obtained daily as dengue severity score.

RESULTS

A total of 191 patients with a mean age of 10.7 years from 2004 to 2013 were recruited. They were classified as dengue fever (35), dengue hemorrhagic fever (DHF) I (53), II (50), III (37) and IV (16). The analysis of 593 daily records revealed the range of daily severity score among patients with DHF grades III (10-20) and IV (31-47) were significantly higher than those of other groups (dengue fever, 5-13; DHF I, 2-10; DHF II, 6-11) with P-values of 0.0001. Using a validity test, a total daily score of ≥12 was an assessment tool for dengue shock syndrome with sensitivity, 86% and specificity, 84%. An additional 51 hospitalized patients with DHF grades II, III and IV with similar ages from 2014 to 2018 were recruited. The number of patients with severe manifestations, having daily score of ≥12, was significantly higher than those without severe manifestations starting from Day -3 to Day +1 of illness.

CONCLUSIONS

Daily dengue severity score of ≥12 was an accurate assessment tool for severe manifestations.

Identification of Immune Responses to Japanese Encephalitis Virus Specific T Cell Epitopes

Background: Due to the similarity between the dengue (DENV) and the Japanese encephalitis virus (JEV) there is potential for immune cross-reaction. We sought to identify T cell epitopes that are specific to JEV and do not cross react with DENV. Methodology: 20mer peptides were synthesized from regions which showed >90% conservation. Using IFNγ cultured ELISpot assays, we investigated JEV-specific T cell responses in DENV^- and JEV^- non-immune individuals (DENV^-JEV^- = 21), JEV seronegative and had not received the JE vaccine, but who were DENV seropositive (DENV⁺JEV^- = 22), JEV⁺(seropositive for JEV and had received the JE vaccine), but seronegative for DENV (DENV^-JEV⁺ = 23). We further assessed the responses to these peptides by undertaking ex vivo IFNγ assays and flow cytometry. Results: None of DENV^-JEV^- individuals responded to any of the 20 JEV-specific peptides. High frequency of responses was seen to 6/20 peptides by individuals who were JEV⁺ but DENV^-, where over 75% of the individuals responded to at least one peptide. P34 was the most immunogenic peptide, recognized by 20/23 (86.9%) individuals who were DENV^-JEV⁺, followed by peptide 3 and peptide 7 recognized by 19/23 (82.6%). Peptide 34 from the NS2a region, showed <25% homology with any flaviviruses, and <20% homology with any DENV serotype. Peptide 20 and 32, which were also from the non-structural protein regions, showed <25% homology with DENV. Ex vivo responses to these peptides were less frequent, with only 40% of individuals responding to peptide 34 and 16-28% to other peptides, probably as 5/6 peptides were recognized by CD4+ T cells. Discussion: We identified six highly conserved, T cell epitopes which are highly specific for JEV, in the Sri Lankan population. Since both JEV and DENV co-circulate in the same regions and since both JE and dengue vaccines are likely to be co-administered in the same geographical regions in future, these JEV-specific T cell epitopes would be useful to study JEV-specific T cell responses, in order to further understand how DENV and JEV-specific cellular immune responses influence each other.

Dengue and malaria infections in pregnancy : Maternal, fetal and neonatal outcomes at a tertiary care hospital

Background

Malaria and dengue cause major morbidity in developing nations and are more severe in pregnancy. Maternal, fetal, and neonatal outcomes in pregnant patients infected with dengue or malaria were studied.

Methods

The medical records of pregnant women admitted with either dengue or malaria infections from 2011–2015 to this hospital were reviewed. Clinical outcomes and laboratory tests were examined.

Results

Of 85 women, 56%, 21%, and 22% had contracted dengue, malaria, and multiple infections, respectively. Pregnant women who had contracted dengue fever alone were more likely to present to the hospital at an earlier gestational age (24 weeks, p = 0.03). Women with multiple infections, were more likely to deliver earlier (30 weeks, p < 0.01). Women with malaria were more likely to have low birth weight deliveries (mean birth weight 2394 g, p = 0.03). The incidence of in-hospital deaths among the cohort was 7%.

Conclusion

It is imperative to develop guidelines to screen for and diagnose dengue and malaria in pregnancy.

Electronic supplementary material

The online version of this article (10.1007/s00508-019-01606-8) contains supplementary material, which is available to authorized users.

Altered monocyte response to the dengue virus in those with varying severity of past dengue infection

OBJECTIVE

We sought to investigate the differences in monocyte immune responses to the dengue virus (DENV) in those who previously had either severe disease (past SD) or non-severe dengue (past NSD) following a secondary dengue infection.

METHOD

Monocytes from healthy individuals who had either past SD (n = 6) or past NSD (n = 6) were infected at MOI one with all four DENV serotypes following incubation with autologous serum. 36-hours post infection, levels of inflammatory cytokines and viral loads were measured in the supernatant and expression of genes involved in viral sensing and interferon signaling was determined.

RESULTS

Monocytes of individuals with past SD produced significantly higher viral loads (p = 0.0426 and cytokines (IL-10 p = 0.008, IL-1β p = 0.008 and IL-6 p = 0.0411) when infected with DENV serotypes they were not immune to, compared to those who has past NSD. Monocytes of individuals with past SD also produced significantly higher viral loads (p = 0.022) and cytokines (IL-10 p < 0.0001, IL-1β < 0.0001 and IL-6 p < 0.0001) when infected with DENV serotypes they were previously exposed to, despite the monocytes being infected in the presence of autologous serum. A significant upregulation of NLRP3 (p = 0.005), RIG-I (0.0004) and IFNB-1 (0.01) genes were observed in those who had past SD compared to past NSD when infected with non-immune DENV serotypes.

CONCLUSION

Monocytes from those with past SD appear to show marked differences in viral loads, viral sensing and production of inflammatory mediators in response to the DENV, when compared to those who experienced past NSD, suggesting that initial innate immune responses may influence the disease outcome.

Clinical Indicators of Fatal Dengue in Two Endemic Areas of Colombia: A Hospital-Based Case-Control Study

According to the World Health Organization, 98% of fatal dengue cases can be prevented; however, endemic countries such as Colombia have recorded higher case fatality rates during recent epidemics. We aimed to identify the predictors of mortality that allow risk stratification and timely intervention in patients with dengue. We conducted a hospital-based, case-control (1:2) study in two endemic areas of Colombia (2009-2015). Fatal cases were defined as having either 1) positive serological test (IgM or NS1), 2) positive virological test (RT-PCR or viral isolation), or 3) autopsy findings compatible with death from dengue. Controls (matched by state and year) were hospitalized nonfatal patients and had a positive serological or virological dengue test. Exposure data were extracted from medical records by trained staff. We used conditional logistic regression (adjusting for age, gender, disease's duration, and health-care provider) in the context of multiple imputation to estimate exposure to case-control associations. We evaluated 110 cases and 217 controls (mean age: 35.0 versus 18.9; disease's duration pre-admission: 4.9 versus 5.0 days). In multivariable analysis, retro-ocular pain (odds ratios [OR] = 0.23), nausea (OR = 0.29), and diarrhea (OR = 0.19) were less prevalent among fatal than nonfatal cases, whereas increased age (OR = 2.46 per 10 years), respiratory distress (OR = 16.3), impaired consciousness (OR = 15.9), jaundice (OR = 32.2), and increased heart rate (OR = 2.01 per 10 beats per minute) increased the likelihood of death (AUC: 0.97, 95% confidence interval: 0.96, 0.99). These results provide evidence that features of severe dengue are associated with higher mortality, which strengthens the recommendations related to triaging patients in dengue-endemic areas.

Clinical Profile and Outcome of Dengue Fever in Multidisciplinary Intensive Care Unit of a Tertiary Level Hospital in India

Background

India is one of the seven identified countries in South-East Asia region regularly reporting dengue fever (DF)/dengue hemorrhagic fever (DHF) outbreaks. Even though the dengue prodrome and evolution of illness are most often similar in many patients, progress and outcome may differ significantly depending on the severity of illness as well as treatment instituted. We studied the clinical manifestations, outcome and factors predicting mortality of serology confirmed dengue fever cases admitted in Multidisciplinary Intensive Care Unit (MICU) of a high acuity healthcare facility in India.

Methodology

All patients with serology proven dengue fever admitted to MICU between 1st July 2015 and1st December 2015 were included in the study. Clinical presentation, laboratory findings, severity of illness scores and outcome were recorded.

Results

Majority of the patients (58.4%) belonged to 21–40 year age group. Hepatic (96.8%) followed by hematological (79.2%) involvement were the most common findings. CNS involvement observed among 27%. Survival to hospital discharge was 78.9%. Respiratory and gastrointestinal system involvement was associated with increased mortality. Acute respiratory distress syndrome (ARDS), acute kidney injury (AKI) and shock were the clinical syndromes associated with mortality. Serum lactate, aspartate transaminase (AST) and alanine transaminase (ALT) were significantly elevated among non survivors. Significant difference in sequential organ failure assessment (SOFA) and acute physiology and chronic health evaluation (APACHE) scores was also observed among survivors and non survivors.

Conclusion

Organ system involvement and higher disease severity scores are strong predictors of mortality. High index of suspicion for atypical manifestations of dengue is warranted.

How to cite this article

Padyana M, Karanth S, Vaidya S, Gopaldas JA. Clinical Profile and Outcome of Dengue Fever in Multidisciplinary Intensive Care Unit of a Tertiary Level Hospital in India. Indian J Crit Care Med 2019;23(6):270–273.

Dengue fever in Dar es Salaam, Tanzania: clinical features and outcome in populations of black and non-black racial category

BACKGROUND

Although the incidence of dengue across Africa is high, severe dengue is reported infrequently. We describe the clinical features and the outcome of dengue according to raceduring an outbreak in Dar es Salaam, Tanzania that occurred in both native and expatriate populations.

METHODS

Adults with confirmed dengue (NS1 and/or IgM on rapid diagnostic test and/or PCR positive) were included between December 2013 and July 2014 in outpatient clinics. Seven-day outcome was assessed by a visit or a call. Association between black race and clinical presentation, including warning signs, was assessed by logistic regression adjusted for age, malaria coinfection, secondary dengue and duration of symptoms at inclusion. The independent association between demographic and comorbidities characteristics of the patients and severe dengue was evaluated by multivariate logistic regression that included potential confounders.

RESULTS

After exclusion of 3 patients of mixed race, 431 patients with dengue (serotype 2, genotype Cosmopolitan) were included: 241 of black and 190 of non-black race. Black patients were younger (median age 30 versus 41 years; p < 0.001) and attended care after a slightly longer duration of symptoms (median of 2.9 versus 2.7 days; p = 0.01). Malaria coinfection was not significantly different between black (5%) and non-black (1.6%) patients (p = 0.06). The same proportion of patients in both group had secondary dengue (13 and 14%; p = 0.78). Among warning signs, only mucosal bleed was associated with race, black race being protective (adjusted OR 0.44; 95% CI 0.21-0.92). Overall, 20 patients (4.7%) presented with severe dengue. Non-black race (adjusted OR 3.9; 95% CI 1.3-12) and previously known diabetes (adjusted OR 43; 95% CI 5.2-361) were independently associated with severe dengue.

CONCLUSIONS

Although all patients were infected with the same dengue virus genotype, black race was independently protective against a severe course of dengue, suggesting the presence of protective genetic or environmental host factors among people of African ancestry. The milder clinical presentation of dengue in black patients might partly explain why dengue outbreaks are under-reported in Africa and often mistaken for malaria. These results highlight the need to introduce point-of-care tests, beside the one for malaria, to detect outbreaks and orientate diagnosis.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT01947075 , retrospectively registered on the 13 of September 2014.

Mathematics of dengue transmission dynamics: Roles of vector vertical transmission and temperature fluctuations

A new deterministic model is designed and used to gain insight into the effect of seasonal variations in temperature and vector vertical transmission on the transmission dynamics of dengue disease. The model, which incorporates (among many other features) the dynamics of the immature dengue-competent mosquitoes, vertical transmission in the vector population, density-dependent larval mortality and temperature effects, is rigorously analysed and simulated using data relevant to the disease dynamics in Chiang Mai province of Thailand. The non-trivial disease-free equilibrium of the model is shown to be globally-asymptotically stable when the associated basic reproduction number of the model is less than unity. Numerical simulations of the model, using data relevant to the disease dynamics in the Chiang Mai province of Thailand, show that vertical transmission in the vector population has only marginal impact on the disease dynamics, and that the effect of vertical transmission is temperature-dependent (in particular, the effect of vertical transmission on the disease dynamics increases for values of the mean monthly temperature in the range[ 16 - 28 ] ∘ C, and decreases with increasing mean monthly temperature thereafter). It is further shown that dengue burden (as measured in terms of disease incidence) is maximized when the mean monthly temperature is in the range[ 26 - 28 ] ∘ C (and dengue burden decreases for mean monthly temperature values above28 ∘ C). Thus, this study suggests that anti-dengue control efforts should be intensified during the period when this temperature range is recorded in the Chiang Mai province (this occurs between June and August).

Prognostic Factors in Adult Patients with Dengue: Developing Risk Scoring Models and Emphasizing Factors Associated with Death ≤7 Days after Illness Onset and ≤3 Days after Presentation

Dengue is a mosquito-borne viral disease that is a threat to global health. However, information relating to mortality ≤7 days after dengue onset and ≤3 days after presentation is limited. We retrospectively analyzed 1086 adults with dengue during a 12-year period. Three scoring models were established: model-1 (death ≤3 days after presentation), model-2 (death ≤7 days after illness onset), and model-3 (overall fatality). In total, 39 patients with fatal dengue were identified, of which 17 and 14 patients died ≤7 days after illness onset and ≤3 days after presentation, respectively. In model-1 (range: 0‒4 points), gastrointestinal bleeding ≤72 h after presentation, thrombocytopenia (<50 × 10⁸ cells/L) at presentation, and acute kidney injury after hospitalization, using a cutoff level of 2 points, exhibited good discrimination (area under the receiver curve (AUC): 0.975) between survivors and non-survivors. In model-2, the significant predictors were gastrointestinal bleeding ≤72 h after presentation, and hemoconcentration and leukocytosis after hospitalization. Model-2 (range: 0⁻4 points) showed an AUC of 0.974, with a cutoff value of 2 points. The independent factors in model-2 were the predictors of overall mortality (model-3), which include thrombocytopenia (<50 × 10⁸ cells/L) at presentation. Using a cutoff value of 2 points, model-3 (range: 0⁻7 points) revealed an excellent discrimination between survivors and non-survivors (AUC: 0.963).

A simple mathematical model to describe antibody-dependent enhancement in heterologous secondary infection in dengue

We develop a mathematical model to describe the role of antibody-dependent enhancement (ADE) in heterologous secondary infections, assuming that antibodies specific to primary dengue virus (DENV) infection are being produced by immunological memory. The model has a virus-free equilibrium (VFE) and a unique virus-presence equilibrium (VPE). VFE is asymptotically stable when VPE is unstable; and unstable, otherwise. Additionally, there is an asymptotic attractor (not a fixed point) due to the fact that the model assumes unbounded increase in memory cells. In the analysis of the model, ADE must be accounted in the initial stage of infection (a window of time of few days), period of time elapsed from the heterologous infection until the immune system mounting an effective response against the secondary infection. We apply the results yielded by model to evaluate ADE phenomonon in heterologous DENV infection. We also associate the possible occurrence of severe dengue with huge viremia mediated by ADE phenomenon.

30 years of dengue fatal cases in Brazil: a laboratorial-based investigation of 1047 cases

BACKGROUND

Dengue viruses (DENV) have emerged and reemerged in Brazil in the past 30 years causing explosive epidemics. The disease may range from clinically asymptomatic infections to severe and fatal outcomes. We aimed to describe the epidemiological, clinical and laboratorial aspects of the dengue fatal cases received by a Regional Reference Laboratory, Brazil in 30 years.

METHODS

A total of 1047 suspected fatal dengue cases were received from 1986 to 2015 and analyzed in the Laboratory of Flavivirus, FIOCRUZ. Suspected cases were submitted to viral detection, serological and molecular methods for cases confirmation. Influence of gender, age, serotype and type of infection (primary/secondary) on death outcome, as well the interactions between serotype and age or infection and age and type of infection were also studied.

RESULTS

A total of 359 cases (34.2%) were confirmed and DENV-1 (11.1%), DENV-2 (43.9%), DENV-3 (32.8%) and DENV-4 (13.7%) were detected. Overall, fatal cases occurred more often in primary infections (59.3%, p = 0.001). However, in 2008, fatal cases were mainly associated to secondary infections (p = 0.003). In 2008 and 2011, deaths were more frequent on children and those infected by DENV-2 presented a higher risk for fatal outcome. Moreover, children with secondary infections had a 4-fold higher risk for death.

CONCLUSIONS

Dengue is a multifactorial disease and, factors such as viral strain/serotype, occurrence of secondary infections and co-morbidities may lead to a severe outcome. However, the high dengue incidence and transmission during epidemics, such as those observed in Brazil may overwhelm and collapse the public health services, potentially impacting on increased disease severity and mortality.

Comorbidities increase in-hospital mortality in dengue patients in Brazil

Dengue remains an unmet public health burden. We determined risk factors for dengue in-hospital mortality in Brazil. Of 326,380 hospitalised dengue cases in 9-45-year-old individuals, there were 971 deaths. Risk of dying was 11-times higher in the presence of underlying common comorbidities (renal, infectious, pulmonary disease and diabetes), similar to the risk of dying from severe dengue and much higher with the combination. Ensuring access to integrated dengue preventative measures in individuals aged ≥ 9 years including those with comorbidities may help achieve the WHO objective of 50% reduction in mortality and 25% reduction in morbidity due to dengue by 2020.

Rapid antigen tests for dengue virus serotypes and Zika virus in patient serum

The recent Zika virus (ZIKV) outbreak demonstrates that cost-effective clinical diagnostics are urgently needed to detect and distinguish viral infections to improve patient care. Unlike dengue virus (DENV), ZIKV infections during pregnancy correlate with severe birth defects, including microcephaly and neurological disorders. Because ZIKV and DENV are related flaviviruses, their homologous proteins and nucleic acids can cause cross-reactions and false-positive results in molecular, antigenic, and serologic diagnostics. We report the characterization of monoclonal antibody pairs that have been translated into rapid immunochromatography tests to specifically detect the viral nonstructural 1 (NS1) protein antigen and distinguish the four DENV serotypes (DENV1-4) and ZIKV without cross-reaction. To complement visual test analysis and remove user subjectivity in reading test results, we used image processing and data analysis for data capture and test result quantification. Using a 30-μl serum sample, the sensitivity and specificity values of the DENV1-4 tests and the pan-DENV test, which detects all four dengue serotypes, ranged from 0.76 to 1.00. Sensitivity/specificity for the ZIKV rapid test was 0.81/0.86, respectively, using a 150-μl serum input. Serum ZIKV NS1 protein concentrations were about 10-fold lower than corresponding DENV NS1 concentrations in infected patients; moreover, ZIKV NS1 protein was not detected in polymerase chain reaction-positive patient urine samples. Our rapid immunochromatography approach and reagents have immediate application in differential clinical diagnosis of acute ZIKV and DENV cases, and the platform can be applied toward developing rapid antigen diagnostics for emerging viruses.

Critical care for dengue in adult patients: an overview of current knowledge and future challenges

PURPOSE OF REVIEW

This review aims to update and summarize the current knowledge about clinical features, management, and risk factors of adult dengue patients requiring intensive care with consequently higher risk of mortality.

RECENT FINDINGS

Increasingly, there are more adult dengue patients who require intensive care. This may be due to a shift in epidemiology of dengue infection from mainly a pediatric disease toward adult disease. In addition, multiorgan dysfunction was observed to be a key risk factor for ICU admission and mortality. This may be due to older adults having preexisting comorbidities that potentially predispose to have multiple severe organ impairment. Interventions remain largely supportive but also require more evidence-based trials and treatment protocols.

SUMMARY

These findings highlight the common clinical manifestations of adult dengue patients and the challenges of clinical management in ICU. Risk factors for prediction of adult dengue patients who require ICU are available, but they lack validation and consistent study design for meta-analysis in future. Early recognition of these risk factors, with close monitoring and prompt clinical management, remains critical to reduce mortality.

Characteristics and predictors for gastrointestinal hemorrhage among adult patients with dengue virus infection: Emphasizing the impact of existing comorbid disease(s)

BACKGROUND

Gastrointestinal (GI) bleeding is a leading cause of death in dengue. This study aims to identify predictors for GI bleeding in adult dengue patients, emphasizing the impact of existing comorbid disease(s).

METHODS

Of 1300 adults with dengue virus infection, 175 (mean age, 56.5±13.7 years) patients with GI bleeding and 1,125 (mean age, 49.2±15.6 years) without GI bleeding (controls) were retrospectively analyzed.

RESULTS

Among 175 patients with GI bleeding, dengue hemorrhagic fever was found in 119 (68%) patients; the median duration from onset dengue illness to GI bleeding was 5 days. Gastric ulcer, erythematous gastritis, duodenal ulcer, erosive gastritis, and hemorrhagic gastritis were found in 52.3%, 33.3%, 28.6%, 28.6%, and 14.3% of 42 patients with GI bleeding who had undergone endoscopic examination, respectively. Overall, nine of the 175 patients with GI bleeding died, giving an in-hospital mortality rate of 5.1%. Multivariate analysis showed age ≥60 years (cases vs. controls: 48% vs. 28.3%) (odds ratio [OR]: 1.663, 95% confidence interval [CI]: 1.128-2.453), end stage renal disease with additional comorbidities (cases vs. controls: 1.7% vs. 0.2%) (OR: 9.405, 95% CI: 1.4-63.198), previous stroke with additional comorbidities (cases vs. controls: 7.4% vs. 0.6%) (OR: 9.772, 95% CI: 3.302-28.918), gum bleeding (cases vs. controls: 27.4% vs. 11.5%) (OR: 1.732, 95% CI: 1.1-2.727), petechiae (cases vs. controls: 56.6% vs. 29.1%) (OR: 2.109, 95% CI: 1.411-3.153), and platelet count <50×109 cells/L (cases vs. controls: 53.1% vs. 25.8%) (OR: 3.419, 95% CI: 2.103-5.558) were independent predictors of GI bleeding in patients with dengue virus infection.

CONCLUSIONS

Our study is the first to disclose that end stage renal disease and previous stroke, with additional comorbidities, were strongly significant associated with the risk of GI bleeding in patients with dengue virus infection. Identification of these risk factors can be incorporated into the patient assessment and management protocol of dengue virus infection to reduce its mortality.

Symptoms associated with adverse dengue fever prognoses at the time of reporting in the 2015 dengue outbreak in Taiwan

BACKGROUND

Tainan experienced the most severe dengue epidemic in Taiwan in 2015. This study investigates the association between the signs and symptoms at the time of reporting with the adverse dengue prognoses.

METHODS

A descriptive study was conducted using secondary data from the Dengue Disease Reporting System in Tainan, Taiwan, between January 1 and December 31, 2015. A multivariate stepwise logistic regression was used to identify the risk factors for the adverse prognoses: ICU admissions and mortality.

RESULTS

There were 22,777 laboratory-confirmed reported cases (mean age 45.6 ± 21.2 years), of which 3.7% were admitted to intensive care units (ICU), and 0.8% were fatal. The most common symptoms were fever (92.8%), myalgia (26.6%), and headache (22.4%). The prevalence of respiratory distress, altered consciousness, shock, bleeding, and thrombocytopenia increased with age. The multivariate analysis indicated that being in 65-89 years old age group [Adjusted Odds Ratio (aOR):4.95], or the 90 years old and above age group (aOR: 9.06), and presenting with shock (aOR: 8.90) and respiratory distress (aOR: 5.31) were significantly associated with the risk of ICU admission. While old age (aOR: 1.11), respiratory distress (aOR: 9.66), altered consciousness (aOR: 7.06), and thrombocytopenia (aOR: 2.55) were significantly associated with the risk of mortality.

CONCLUSIONS

Dengue patients older than 65 and those with severe and non-specific signs and symptoms at the time of reporting were at a higher risk of ICU admission and mortality. First-line healthcare providers need to be aware of the varied presentations between the different age groups to allow early diagnosis and in-time management, which would prevent ICU admissions and fatalities in dengue patients.

Clinical Audit of Dengue Related Deaths in 2011-Mayo Hospital Lahore Pakistan

Background and Objective:

Dengue infection has evolved into an epidemic during last few years in Pakistan and has been associated with poor outcomes. Literature with respect to mortality risk factors in Dengue infection is not sufficient. This compelled us to conduct this study to find out major contributory factors to death in patients with dengue viral infection at one of Asia’s ancient hospital setting with an aim to recognize complications at earliest and improve case management in future.

Methods:

A retrospective observational study of 95 adult dengue deaths was performed at Mayo Hospital Lahore from July 1st 2011 to 31st December 2011 during a major dengue epidemic. Patients who tested positive by dengue IgM in the presence of acute fever fulfilling the World Health Organization criteria for Dengue Fever, Dengue Hemorrhagic Fever or Dengue Shock Syndrome and died within same setting, were included. Data regarding demographic profile, clinical and laboratory parameters along with treatment details were obtained and analysed. All records examined were anonymized.

Results:

Median age was 36 years (range13-80 years) among 95 deaths due to Dengue. Male gender comprised 60 (63.1%). Co-morbidities existed in 74 (77.9%) with hypertension in 21 (22.1%) diabetes in 11 (11.58%), liver disease in 9 (9.47%) and ischemic heart disease in 8(8.4%) cases. Patients presented at second day of fever for admission (range 1-8 days) and death occurred at a median of 4 days (range 30 minutes to 23 days). Hospital stay was for less than a week for seventy nine (83.2%) patients and 16 (16.8%) were admitted for more than 7 days. Critical care was required in 67(71%). Severe hepatitis occurred in 41 (43.1%), acute renal impairment occurred in 32 (33.7%) and disseminated intravascular coagulation in 16 (16.8%). Deaths were due to prolonged shock 49 (51.5%) fluid overload 46 (48.4%) and massive bleeding 18(19%) leading to organ failure.

Conclusion:

Decompensated shock complicated by either massive plasma leakage, frank bleeding, multi organ failure or deranged clotting profile results in enhanced mortality in Dengue infection. Co-morbidities especially Diabetes are poor prognostic factors in predicting Dengue mortality.

An economic evaluation of vector control in the age of a dengue vaccine

INTRODUCTION

Dengue is a rapidly emerging vector-borne Neglected Tropical Disease, with a 30-fold increase in the number of cases reported since 1960. The economic cost of the illness is measured in the billions of dollars annually. Environmental change and unplanned urbanization are conspiring to raise the health and economic cost even further beyond the reach of health systems and households. The health-sector response has depended in large part on control of the Aedes aegypti and Ae. albopictus (mosquito) vectors. The cost-effectiveness of the first-ever dengue vaccine remains to be evaluated in the field. In this paper, we examine how it might affect the cost-effectiveness of sustained vector control.

METHODS

We employ a dynamic Markov model of the effects of vector control on dengue in both vectors and humans over a 15-year period, in six countries: Brazil, Columbia, Malaysia, Mexico, the Philippines, and Thailand. We evaluate the cost (direct medical costs and control programme costs) and cost-effectiveness of sustained vector control, outbreak response and/or medical case management, in the presence of a (hypothetical) highly targeted and low cost immunization strategy using a (non-hypothetical) medium-efficacy vaccine.

RESULTS

Sustained vector control using existing technologies would cost little more than outbreak response, given the associated costs of medical case management. If sustained use of existing or upcoming technologies (of similar price) reduce vector populations by 70-90%, the cost per disability-adjusted life year averted is 2013 US$ 679-1331 (best estimates) relative to no intervention. Sustained vector control could be highly cost-effective even with less effective technologies (50-70% reduction in vector populations) and in the presence of a highly targeted and low cost immunization strategy using a medium-efficacy vaccine.

DISCUSSION

Economic evaluation of the first-ever dengue vaccine is ongoing. However, even under very optimistic assumptions about a highly targeted and low cost immunization strategy, our results suggest that sustained vector control will continue to play an important role in mitigating the impact of environmental change and urbanization on human health. If additional benefits for the control of other Aedes borne diseases, such as Chikungunya, yellow fever and Zika fever are taken into account, the investment case is even stronger. High-burden endemic countries should proceed to map populations to be covered by sustained vector control.

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

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

Dengue in the elderly: a review

INTRODUCTION

Changing dengue epidemiological trends have resulted in a shift in the disease burden to the adult population. Older adults suffer from poorer outcomes as compared to their younger counterparts, making clinical management of this sub-population particularly challenging. Areas covered: We present a review of the current literature on the changing epidemiology of dengue in the elderly, the atypical features of the clinical disease in this population with emphasis on severe disease presentations and challenges in the current management strategies. Expert commentary: Dengue in the elderly is an increasingly important yet greatly understudied area. There is an urgent need to refine the current diagnostic criteria to improve diagnosis, classification of disease severity and identify individuals in this population who are likely to progress to severe disease. Management strategies in this population would have to be adjusted to account for the increased number of co-morbidities. The role of the available dengue vaccines in this group is uncertain, and more studies into their safety and efficacy are critically needed.

Determinants of mortality and prolonged hospital stay among dengue patients attending tertiary care hospital: a cross-sectional retrospective analysis

OBJECTIVES

Dengue imposes substantial economic, societal and personal burden in terms of hospital stay, morbidity and mortality. Early identification of dengue cases with high propensity of increased hospital stay and death could be of value in isolating patients in need of early interventions. The current study was aimed to determine the significant factors associated with dengue-related prolonged hospitalisation and death.

DESIGN

Cross-sectional retrospective study.

SETTING

Tertiary care teaching hospital.

PARTICIPANTS

Patients with confirmed dengue diagnosis were stratified into two categories on the basis of prolonged hospitalisation (≤3 days and >3 days) and mortality (fatal cases and non-fatal cases). Clinico-laboratory characteristics between these categories were compared by using appropriate statistical methods.

RESULTS

Of 667 patients enrolled, 328 (49.2%) had prolonged hospitalisation. The mean hospital stay was 4.88±2.74 days. Multivariate analysis showed that dengue haemorrhagic fever (OR 2.3), elevated alkaline phosphatase (ALP) (OR 2.3), prolonged prothrombin time (PT) (OR 1.7), activated partial thromboplastin time (aPTT) (OR 1.9) and multiple-organ dysfunctions (OR 2.1) were independently associated with prolonged hospitalisation. Overall case fatality rate was 1.1%. Factors associated with dengue mortality were age >40 years (p=0.004), secondary infection (p=0.040), comorbidities (p<0.05), acute kidney injury (p<0.001), prolonged PT (p=0.022), multiple-organ dysfunctions (p<0.001), haematocrit >20% (p=0.001), rhabdomyolosis (p<0.001) and respiratory failure (p=0.007). Approximately half of the fatal cases in our study had prolonged hospital stay of greater than three days.

CONCLUSIONS

The results underscore the high proportion of dengue patients with prolonged hospital stay. Early identification of factors relating to prolonged hospitalisation and death will have obvious advantages in terms of appropriate decisions about treatment and management in high dependency units.