Dengue haemorrhagic fever in children in the 1996 Delhi epidemic

Age, gender, and infectious status-wise assessments of hematological parameters among patients with dengue infection

Background

The aim of this study was to examine the impact of different stages of dengue infection on immune cell counts among dengue patients and to compare them with cases of non-dengue febrile illness.

Methods

The recruited patients were divided into two groups: the first group served as a control (n = 55), representing non-dengue febrile illness, and the second group was identified as dengue febrile illness (n = 149), which was further divided into three groups based on infection stage. Blood samples were collected from the selected patients and subjected to blood cell component analysis. To find IgG and IgM as well as the dengue virus non-structural antigen-1 (NS1), an immunochromatographic test (ICT) kit was utilized. Additionally, a hematological analyzer was used to determine complete blood cell counts (CBC). Data was thoroughly analyzed using Graph Pad Prism 6 software. The differences in means of different groups were calculated by applying the student's t-test.

Results

The findings revealed the presence of severe leucopenia and thrombocytopenia at stages 1 and 2, accompanied by lymphopenia at stage 1. Group comparisons indicated that only teenagers exhibited a significantly lower white blood cell count compared to older individuals, while no significant differences were observed in lymphocytes, platelets, and monocytes across all age groups. Comparing different age groups of normal individuals to dengue-infected patients, the results unveiled that leucopenia was most severe in adults, followed by teenagers and children, with no significant difference in the elderly. Furthermore, adults showed the greatest degree of thrombocytopenia, followed by teens and kids, with the elderly showing the greatest degree of thrombocytopenia. Adults and teens showed extreme neutrophilia, whereas young children and the elderly showed no discernible abnormalities. Elderly patients experienced a marked decrease in monocyte count, a phenomenon not observed in other age groups.

Conclusion

In conclusion both, leucopenia & thrombocytopenia, are most severe in stages 1 and 2, whereas neutrophilia & lymphopenia are predominantly severe in stage 1. These results imply that the consequences associated with dengue infection are more severe in the early stages and tend to ameliorate as the patient progresses toward recovery.

Is the rise in childhood obesity rates leading to an increase in hospitalizations due to dengue?

BACKGROUND

Obesity and diabetes are known risk factors for severe dengue. Therefore, we sought to investigate the association of obesity with increased risk of hospitalization, as there is limited information.

METHODS AND FINDINGS

Children aged 10 to 18 years (n = 4782), were recruited from 9 districts in Sri Lanka using a stratified multi-stage cluster sampling method. Details of previous admissions to hospital due to dengue and anthropometric measurements were recorded and seropositivity rates for dengue were assessed. The body mass index (BMI) centile in children aged 10 to 18, was derived by plotting the values on the WHO BMI-for-age growth charts, to acquire the percentile ranking.

RESULTS

Although the dengue seropositivity rates were similar in children of the different BMI centiles, 12/66 (18.2%) seropositive children with a BMI centile >97th, had been hospitalized for dengue, compared to 103/1086 (9.48%) of children with a BMI centile of <97th. The logistic regression model suggested that BMI centiles 50th to 85th (OR = 1.06, 95% CI, 1.00 to 1.11, p = 0.048) and BMI centile of >97th (OR 2.33, 95% CI, 1.47 to 3.67, p = 0.0003) was significantly associated with hospitalization when compared to children in other BMI categories.

CONCLUSIONS

Obesity appears to be associated with an increased risk of hospitalization in dengue, which should be further investigated in longitudinal prospective studies. With the increase in obesity in many countries, it would be important to create awareness regarding obesity and risk of severe disease and hospitalization in dengue.

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.

Dengue virus serotype did not contribute to clinical severity or mortality in Taiwan's largest dengue outbreak in 2015

BACKGROUND

Dengue virus serotype 2 (DENV-2) was the major serotype in the 2015 dengue outbreak in Taiwan, while DENV-1 and DENV-3 were dominant between 2005 and 2014. We aimed to investigate whether DENV-2 contributed to disease severity and mortality in the outbreak in Kaohsiung city, Taiwan.

METHODS

We collected serum samples from dengue patients to detect the presence of DENV and determine the serotypes by using quantitative reverse transcription-polymerase chain reaction. Our cohorts comprised 105 DENV-1-infected cases and 1,550 DENV-2-infected cases. Demographic data, DENV serotype, and comorbidities were covariates for univariate and multivariate analyses to explore the association with severity and mortality.

RESULTS

The results suggested that DENV-1 persisted and circulated, while DENV-2 was dominant during the dengue outbreak that occurred between September and December 2015. However, DENV-2 did not directly contribute to either severity or mortality. Aged patients and patients with diabetes mellitus (DM) or moderate to severe chronic kidney disease (CKD) had a higher risk of developing severe dengue. The mortality of dengue patients was related to a higher Charlson comorbidity index score and severe dengue. Among DENV-2-infected patients and older patients, preexisting anti-dengue IgG, DM, and moderate to severe CKD were associated with severe dengue. Moreover, female sex and severe dengue were associated with a significantly higher risk of death.

CONCLUSIONS

Our findings highlight the importance of timely serological testing in elderly patients to identify potential secondary infections and focus on the meticulous management of elderly patients with DM or moderate to severe CKD to reduce dengue-related death.

A Historical Review of Military Medical Strategies for Fighting Infectious Diseases: From Battlefields to Global Health

The environmental conditions generated by war and characterized by poverty, undernutrition, stress, difficult access to safe water and food as well as lack of environmental and personal hygiene favor the spread of many infectious diseases. Epidemic typhus, plague, malaria, cholera, typhoid fever, hepatitis, tetanus, and smallpox have nearly constantly accompanied wars, frequently deeply conditioning the outcome of battles/wars more than weapons and military strategy. At the end of the nineteenth century, with the birth of bacteriology, military medical researchers in Germany, the United Kingdom, and France were active in discovering the etiological agents of some diseases and in developing preventive vaccines. Emil von Behring, Ronald Ross and Charles Laveran, who were or served as military physicians, won the first, the second, and the seventh Nobel Prize for Physiology or Medicine for discovering passive anti-diphtheria/tetanus immunotherapy and for identifying mosquito Anopheline as a malaria vector and plasmodium as its etiological agent, respectively. Meanwhile, Major Walter Reed in the United States of America discovered the mosquito vector of yellow fever, thus paving the way for its prevention by vector control. In this work, the military relevance of some vaccine-preventable and non-vaccine-preventable infectious diseases, as well as of biological weapons, and the military contributions to their control will be described. Currently, the civil-military medical collaboration is getting closer and becoming interdependent, from research and development for the prevention of infectious diseases to disasters and emergencies management, as recently demonstrated in Ebola and Zika outbreaks and the COVID-19 pandemic, even with the high biocontainment aeromedical evacuation, in a sort of global health diplomacy.

Larvicidal Activity of Elytraria acaulis against Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae)

Background

Mosquitoes are blood sucking arthropods and serve as vectors of many diseases causing serious health problems to human beings. Culex quinquefasciatus and Aedes aegypti were responsible for Filariasis and Dengue. Synthetic pesticides were effective against mosquitoes as well as main sources of environmental pollution and most of them are immunosuppressant. Botanicals were widely used as insecticides, growth disruptors, repellents, etc. The aim of this research was to determine larvicidal properties of powdered leaf, Elytraria acaulis against late third or early fourth in-star larvae of Cx. quinquefasciatus and Ae. aegypti.

Methods

Larvae of Cx. quinquefasciatus and Ae. aegypti were tested at various concentrations of 100, 120, 140, 160, 180 and 200mg/100ml and mortality was recorded after 24h. The LC₅₀ values of the E. acaulis leaf powder were calculated by Probit analysis.

Results

The plant powder exhibited strong larvicidal activity against Cx. quinquefasciatus with LC₅₀ value of 116.07mg/100ml against Ae. aegypti 124.25mg/100ml respectively. The result indicated that the plant powder of E. acaulis showed potential larvicidal activity against Cx. quinquefasciatus and Ae. aegypti.

Conclusion

The overall findings of the present investigation suggested that the E. acaulis highly effective against Cx. quinquefasciatus and Ae. aegypti larvae. Elytraria acaulis may be used as an alternative to synthetic chemical pesticides for control of vectors to reduce vector borne diseases and did not harm to total environment.

Seropositivity and history of hospitalisation for dengue in relation to anthropometric indices among Colombian children and adults

The role of anthropometric status on dengue is uncertain. We investigated the relations between anthropometric characteristics (height, body mass index and waist circumference (WC)) and two dengue outcomes, seropositivity and hospitalisation, in a cross-sectional study of 2038 children (aged 2–15 years) and 408 adults (aged 18–72 years) from Bucaramanga, Colombia. Anthropometric variables were standardised by age and sex in children. Seropositivity was determined through immunoglobulin G antibodies; past hospitalisation for dengue was self-reported. We modelled the prevalence of each outcome by levels of anthropometric exposures using generalised estimating equations with restricted cubic splines. In children, dengue seropositivity was 60.8%; 9.9% of seropositive children reported prior hospitalisation for dengue. WC was positively associated with seropositivity in girls (90th vs. 10th percentile adjusted prevalence ratio (APR) = 1.19; 95% confidence interval (CI) 1.03–1.36). Among adults, dengue seropositivity was 95.1%; 8.1% of seropositive adults reported past hospitalisation. Height was inversely associated with seropositivity (APR = 0.90; 95% CI 0.83–0.99) and with hospitalisation history (APR = 0.19; 95% CI 0.04–0.79). WC was inversely associated with seropositivity (APR = 0.89; 95% CI 0.81–0.98). We conclude that anthropometry correlates with a history of dengue, but could not determine causation. Prospective studies are warranted to enhance causal inference on these questions.

Skin Viral Infections: Host Antiviral Innate Immunity and Viral Immune Evasion

The skin is an active immune organ that functions as the first and largest site of defense to the outside environment. Serving as the primary interface between host and pathogen, the skin’s early immune responses to viral invaders often determine the course and severity of infection. We review the current literature pertaining to the mechanisms of cutaneous viral invasion for classical skin-tropic, oncogenic, and vector-borne skin viruses. We discuss the skin’s evolved mechanisms for innate immune viral defense against these invading pathogens, as well as unique strategies utilized by the viruses to escape immune detection. We additionally explore the roles that demographic and environmental factors, such as age, biological sex, and the cutaneous microbiome, play in altering the host immune response to viral threats.

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

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

Dengue infection in India: A systematic review and meta-analysis

INTRODUCTION

Dengue is the most extensively spread mosquito-borne disease; endemic in more than 100 countries. Information about dengue disease burden, its prevalence, incidence and geographic distribution is critical in planning appropriate control measures against dengue fever. We conducted a systematic review and meta-analysis of dengue fever in India.

METHODS

We searched for studies published until 2017 reporting the incidence, the prevalence or case fatality of dengue in India. Our primary outcomes were (a) prevalence of laboratory confirmed dengue infection among clinically suspected patients, (b) seroprevalence in the general population and (c) case fatality ratio among laboratory confirmed dengue patients. We used binomial-normal mixed effects regression model to estimate the pooled proportion of dengue infections. Forest plots were used to display pooled estimates. The metafor package of R software was used to conduct meta-analysis.

RESULTS

Of the 2285 identified articles on dengue, we included 233 in the analysis wherein 180 reported prevalence of laboratory confirmed dengue infection, seven reported seroprevalence as evidenced by IgG or neutralizing antibodies against dengue and 77 reported case fatality. The overall estimate of the prevalence of laboratory confirmed dengue infection among clinically suspected patients was 38.3% (95% CI: 34.8%-41.8%). The pooled estimate of dengue seroprevalence in the general population and CFR among laboratory confirmed patients was 56.9% (95% CI: 37.5-74.4) and 2.6% (95% CI: 2-3.4) respectively. There was significant heterogeneity in reported outcomes (p-values<0.001).

CONCLUSIONS

Identified gaps in the understanding of dengue epidemiology in India emphasize the need to initiate community-based cohort studies representing different geographic regions to generate reliable estimates of age-specific incidence of dengue and studies to generate dengue seroprevalence data in the country.

Dengue fever. Clinical features of 567 consecutive patients admitted to a tertiary care center in Saudi Arabia

OBJECTIVES

To delineate the clinical features and outcomes of dengue infection and to guide clinician of early diagnosis and identification of risks factors for dengue hemorrhagic fever. Methods: This study is a retrospective cross-sectional. Clinical records of 567 patients with a confirmed diagnosis of dengue infection, admitted to a single hospital in Jeddah, Saudi Arabia, between January 2010 and  June 2014 were reviewed.  Results: Dengue infection was most common in adult males. Sixty-eight percent of infections were in Saudi nationals. In addition to the diagnostic clinical features, leucopenia and thrombocytopenia were typical of dengue infection. Approximately 4.1% of adult patients and 7.1% of pediatric patients developed dengue hemorrhagic fever (DHF). Abdominal pain and vomiting were more common in patients developing DHF. Mean platelet count was lower in adult, but not pediatric patients developing DHF. Peak alanine aminotransferase (ALT) was higher in adult and pediatric patients developing DHF. Three patients died, 2 of them developed DHF. Ninety-eight percent of adult patients and 92% of pediatric patients made a full recovery. Conclusions:   Dengue infection is common in Jeddah.  Abdominal pain and vomiting, thrombocytopenia, and elevated ALT are typical of severe infection, which is more likely to be associated with significant morbidity and mortality.

Validity of International Classification of Diseases (ICD) coding for dengue infections in hospital discharge records in Malaysia

Background

Hospitalization due to dengue illness is an important measure of dengue morbidity. However, limited studies are based on administrative database because the validity of the diagnosis codes is unknown. We validated the International Classification of Diseases, 10th revision (ICD) diagnosis coding for dengue infections in the Malaysian Ministry of Health’s (MOH) hospital discharge database.

Methods

This validation study involves retrospective review of available hospital discharge records and hand-search medical records for years 2010 and 2013. We randomly selected 3219 hospital discharge records coded with dengue and non-dengue infections as their discharge diagnoses from the national hospital discharge database. We then randomly sampled 216 and 144 records for patients with and without codes for dengue respectively, in keeping with their relative frequency in the MOH database, for chart review. The ICD codes for dengue were validated against lab–based diagnostic standard (NS1 or IgM).

Results

The ICD-10-CM codes for dengue had a sensitivity of 94%, modest specificity of 83%, positive predictive value of 87% and negative predictive value 92%. These results were stable between 2010 and 2013. However, its specificity decreased substantially when patients manifested with bleeding or low platelet count.

Conclusion

The diagnostic performance of the ICD codes for dengue in the MOH’s hospital discharge database is adequate for use in health services research on dengue.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-3104-z) contains supplementary material, which is available to authorized users.

Clinical and Hematological Profile of Patients with Dengue Fever at a Tertiary Care Hospital - An Observational Study

Background

Dengue is a major health issue with seasonal rise in dengue fever cases imposing an additional burden on hospitals, necessitating bolstering of services in the emergency department, laboratory with creation of additional dengue fever wards.

Objectives

To study the clinical and hematological profile of dengue fever cases presenting to a hospital.

Methods

Patients with fever and other signs of dengue with either positive NS1 antigen test or IgM or IgG antibody were included. Age, gender, clinical presentation, platelet count and hematocrit were noted and patients classified as dengue fever without warning signs (DF) or with warning signs (DFWS), and severe dengue (SD) with severe plasma leakage, severe bleeding or severe organ involvement. Duration of hospitalization, bleeding manifestations, requirement for platelet component support and mortality were recorded.

Results

There were 443 adults and 57 children between 6 months to 77 year age. NS1 was positive in 115 patients (23%). Fever (99.8%) and severe body ache (97.4%) were the commonest presentation. DF was seen in 429 (85.8 %), DFWS in 55 (11%), SD with severe bleeding in 10 (2%) and SD with severe plasma leakage in 6 cases (1.2%). Outpatient department (OPD) treatment was needed in 412 (82%) and hospitalization in 88 (18%). Intravenous fluid resuscitation was needed in 16 (3.2%) patients. Thrombocytopenia was seen in 335 (67%) patients at presentation. Platelet transfusion was needed in 46 (9.2%). Packed red blood cell (PRBC) transfusion was given in 3 patients with DFWS and 10 of SD with severe bleeding. Death occurred in 3 patients of SD with severe plasma leak and 2 patients with SD and severe bleeding.

Conclusions

Majority of DF cases can be managed on OPD basis. SD with severe bleeding or with severe plasma leakage carries high mortality. Hospitals can analyze annual data for resource allocation for capacity expansion.

Low sensitivity of the tourniquet test for differential diagnosis of dengue: an analysis of 28,000 trials in patients

Background

The aim of this study was to evaluate the utility of the tourniquet test (TT) for dengue diagnosing. To our knowledge, no previous study with such a large sample, of this duration, with as many laboratory methods referenced, or relating the results of the TT to the 2009 WHO classification of severity has been conducted thus far.

Methods

In this study, we analyzed the records of 119,589 suspected dengue cases in a Brazilian city, with 30,670 confirmed cases. The Cohen’s Kappa test was applied to evaluate the degree of agreement between the tests, and the sensitivity and specificity was calculated for the TT.

Results

Twenty-eight thousand six hundred thirty-five TT were performed. No association between the outcome of the TT and greater severity of infection, according to the 2009 guideline, was observed (P = 0.28); furthermore, relevant agreement with the final diagnosis (κ = 0.01; 95 % CI = 0.00 to 0.02) or individually with the IgM enzyme-linked immunoassay was not observed (κ = 0.05; 95 % CI = 0.04 to 0.06), and was even lower with PCR (κ = 0.27; 95 % CI = 0.06 to 0.49). Most importance of the TT was shown in relation to specificity (88.9 %; 95 % CI = 0.88 to 0.89) and negative predictive value (70.3 %; CI 95 % = 0.70 to 0.71).

Conclusions

TT was more effective in detecting cases that were truly negative than positive. These results suggest that the TT should not be used as diagnosis of dengue.

A study on gender-related differences in laboratory characteristics of dengue fever

Studies have reported significant gender-related differences in serological tests for detection of NS1 antigen and IgM antibody used for diagnosing dengue fever. However, no such study has been undertaken in India though dengue fever is endemic in this country. Therefore, this study was planned to study the association of serological findings with gender in 700 patients suspected to be suffering from dengue fever in the Indian setting. Haematological parameters of seropositive patients were also studied. Seropositivity and haemorrhagic findings were significantly associated with the female gender. Positive NS1 antigen and IgM antibody results were significantly associated with females and males, respectively.

Dengue infection

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

Tourniquet Test for Dengue Diagnosis: Systematic Review and Meta-analysis of Diagnostic Test Accuracy

BACKGROUND

Dengue fever is a ubiquitous arboviral infection in tropical and sub-tropical regions, whose incidence has increased over recent decades. In the absence of a rapid point of care test, the clinical diagnosis of dengue is complex. The World Health Organisation has outlined diagnostic criteria for making the diagnosis of dengue infection, which includes the use of the tourniquet test (TT).

PURPOSE

To assess the quality of the evidence supporting the use of the TT and perform a diagnostic accuracy meta-analysis comparing the TT to antibody response measured by ELISA.

DATA SOURCES

A comprehensive literature search was conducted in the following databases to April, 2016: MEDLINE (PubMed), EMBASE, Cochrane Central Register of Controlled Trials, BIOSIS, Web of Science, SCOPUS.

STUDY SELECTION

Studies comparing the diagnostic accuracy of the tourniquet test with ELISA for the diagnosis of dengue were included.

DATA EXTRACTION

Two independent authors extracted data using a standardized form.

DATA SYNTHESIS

A total of 16 studies with 28,739 participants were included in the meta-analysis. Pooled sensitivity for dengue diagnosis by TT was 58% (95% Confidence Interval (CI), 43%-71%) and the specificity was 71% (95% CI, 60%-80%). In the subgroup analysis sensitivity for non-severe dengue diagnosis was 55% (95% CI, 52%-59%) and the specificity was 63% (95% CI, 60%-66%), whilst sensitivity for dengue hemorrhagic fever diagnosis was 62% (95% CI, 53%-71%) and the specificity was 60% (95% CI, 48%-70%). Receiver-operator characteristics demonstrated a test accuracy (AUC) of 0.70 (95% CI, 0.66-0.74).

CONCLUSION

The tourniquet test is widely used in resource poor settings despite currently available evidence demonstrating only a marginal benefit in making a diagnosis of dengue infection alone.

REGISTRATION

The protocol for this systematic review was registered at

PROSPERO

CRD42015020323.

Association between nutritional status and dengue infection: a systematic review and meta-analysis

Background

Dengue infection has various clinical manifestations, often with unpredictable clinical evolutions and outcomes. Several factors including nutritional status have been studied to find the relationship with dengue severity. However, the nutritional status had conflicting effects on the complication of dengue in some previous studies. Therefore, we conducted a systematic review and performed a meta-analysis to analyze the association between nutritional status and the outcome of dengue infection.

Methods

Eleven electronic databases and manual searching of reference lists were used to identify the relevant studies published before August 2013. At least two authors worked independently in every step to select eligible studies and extract data. Dengue severity in the included studies must be classified into three categories: dengue fever (DF), dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS).

Results

Thirteen articles that met the inclusion criteria came to final analysis. A meta-analysis using fixed- or random-effects models was conducted to calculate pooled odds ratios (OR) with corresponding 95 % confidence intervals. It has shown that there was no statistically significant association between DHF group and DSS group in malnutritional and overweight/obesity patients with OR: 1.17 (95 % CI: 0.99–1.39), 1.31 (0.91–1.88), respectively. A significantly inverse relation between DF and DHF groups of malnutritional patients was revealed (OR = 0.71, 95 % CI: 0.56–0.90). Our meta-analysis also indicated a statistically significant negative correlation between malnourished children with dengue virus infection and healthy children (OR = 0.46, 95 % CI: 0.3–0.70). When analyzing patients with normal nutrition status, we found out that there was a significantly negative relationship between DHF and DSS groups (0.87; 95 % CI: 0.77–0.99). Other comparisons of DSS with DF/DHF groups, DSS/DHF with DF groups, and DHF with DF groups in normal nutritional patients showed no significant correlation. However, the findings should be interpreted cautiously because all significant associations were lost after removing of the largest study.

Conclusions

Results from previous studies failed to show any solid consistency regarding the association between the nutritional status and dengue infection. Consequently, the effects of nutritional status on dengue disease outcome has been controversial. Further studies are recommended to clarify the impact of nutritional status on dengue infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1498-y) contains supplementary material, which is available to authorized users.

Dengue in children: a systematic review of clinical and laboratory factors associated with severity

Dengue is a potentially life-threatening illness, and children are at higher risk of severity. This review aimed to systematize the identified clinical and laboratory parameters associated with severe dengue in children, as monitoring these signs and fluid-replacement therapy are actually the cornerstones of dengue treatment. Of the 527 studies initially reviewed, 21 were selected as follows: three cohort studies, three case-control studies, 14 cross-sectional studies and one not defined. Eighteen studies were carried out in Asia and three in the Americas. Hepatomegaly, lethargy, abdominal pain, bleeding, hemoconcentration and thrombocytopenia, all referenced as warning signs in the WHO 2009 Guidelines, were the clinical and laboratory parameters independently associated with severity in more than one study. The recognition of these known warning signs associated to severe dengue disease underlines the usefulness of the WHO 2009 classification.

The emergence of dengue in Bangladesh: epidemiology, challenges and future disease risk

Dengue occurred sporadically in Bangladesh from 1964 until a large epidemic in 2000 established the virus. We trace dengue from the time it was first identified in Bangladesh and identify factors favourable to future dengue haemorrhagic fever epidemics. The epidemic in 2000 was likely due to introduction of a dengue virus strain from a nearby endemic country, probably Thailand. Cessation of dichlorodiphenyltrichloroethane (DDT) spraying, climatic, socio-demographic, and lifestyle factors also contributed to epidemic transmission. The largest number of cases was notified in 2002 and since then reported outbreaks have generally declined, although with increased notifications in alternate years. The apparent decline might be partially due to public awareness with consequent reduction in mosquito breeding and increased prevalence of immunity. However, passive hospital-based surveillance has changed with mandatory serological confirmation now required for case reporting. Further, a large number of cases remain undetected because only patients with severe dengue require hospitalisation. Thus, the reduction in notification numbers may be an artefact of the surveillance system. Indeed, population-based serological survey indicates that dengue transmission continues to be common. In the future, the absence of active interventions, unplanned urbanisation, environmental deterioration, increasing population mobility, and economic factors will heighten dengue risk. Projected increases in temperature and rainfall may exacerbate this.

Approaches to refining estimates of global burden and economics of dengue

Dengue presents a formidable and growing global economic and disease burden, with around half the world's population estimated to be at risk of infection. There is wide variation and substantial uncertainty in current estimates of dengue disease burden and, consequently, on economic burden estimates. Dengue disease varies across time, geography and persons affected. Variations in the transmission of four different viruses and interactions among vector density and host's immune status, age, pre-existing medical conditions, all contribute to the disease's complexity. This systematic review aims to identify and examine estimates of dengue disease burden and costs, discuss major sources of uncertainty, and suggest next steps to improve estimates. Economic analysis of dengue is mainly concerned with costs of illness, particularly in estimating total episodes of symptomatic dengue. However, national dengue disease reporting systems show a great diversity in design and implementation, hindering accurate global estimates of dengue episodes and country comparisons. A combination of immediate, short-, and long-term strategies could substantially improve estimates of disease and, consequently, of economic burden of dengue. Suggestions for immediate implementation include refining analysis of currently available data to adjust reported episodes and expanding data collection in empirical studies, such as documenting the number of ambulatory visits before and after hospitalization and including breakdowns by age. Short-term recommendations include merging multiple data sources, such as cohort and surveillance data to evaluate the accuracy of reporting rates (by health sector, treatment, severity, etc.), and using covariates to extrapolate dengue incidence to locations with no or limited reporting. Long-term efforts aim at strengthening capacity to document dengue transmission using serological methods to systematically analyze and relate to epidemiologic data. As promising tools for diagnosis, vaccination, vector control, and treatment are being developed, these recommended steps should improve objective, systematic measures of dengue burden to strengthen health policy decisions.

The changing incidence of dengue haemorrhagic fever in Indonesia: a 45-year registry-based analysis

Background

Increases in human population size, dengue vector-density and human mobility cause rapid spread of dengue virus in Indonesia. We investigated the changes in dengue haemorrhagic fever (DHF) incidence in Indonesia over a 45-year period and determined age-specific trends in annual DHF incidence.

Methods

Using an on-going nationwide dengue surveillance program starting in 1968, we evaluated all DHF cases and related deaths longitudinally up to 2013. Population demographics were used to calculate annual incidence and case fatality ratios (CFRs). Age-specific data on DHF available from 1993 onwards were used to assess trends in DHF age-distribution. Time-dependency of DHF incidence and CFRs was assessed using the Cochrane-Armitage trend test.

Results

The annual DHF incidence increased from 0.05/100,000 in 1968 to ~ 35-40/100,000 in 2013, with superimposed epidemics demonstrating a similar increasing trend with the highest epidemic occurring in 2010 (85.70/100,000; p < 0.01). The CFR declined from 41% in 1968 to 0.73% in 2013 (p < 0.01). Mean age of DHF cases increased during the observation period. Highest incidence of DHF was observed among children aged 5 to 14 years up to 1998, but declined thereafter (p < 0.01). In those aged 15 years or over, DHF incidence increased (p < 0.01) and surpassed that of 5 to 14 year olds from 1999 onwards.

Conclusions

Incidence of DHF over the past 45 years in Indonesia increased rapidly with peak incidence shifting from young children to older age groups. The shifting age pattern should have consequences for targeted surveillance and prevention.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-412) contains supplementary material, which is available to authorized users.

Dengue infection in children and adolescents: clinical profile in a reference hospital in northeast Brazil

INTRODUCTION

This study aimed to describe the clinical spectrum of dengue in children and adolescents from a hyperendemic region who were admitted for hospitalization.

METHODS

A retrospective study was conducted on patients diagnosed with dengue infection upon admission to a reference center in Fortaleza, Brazil.

RESULTS

Of the 84 patients included, 42 underwent confirmatory testing. The main symptoms were fever, abdominal pain and vomiting. The median level of serum aspartate aminotransferase was 143.5±128mg/dL.

CONCLUSIONS

A peculiar clinical profile was evident among children and adolescents with dengue infection in a reference center in northeast Brazil, including gastrointestinal symptoms and liver involvement.

Comparative performance of the probable case definitions of dengue by WHO (2009) and the WHO-SEAR expert group (2011)

BACKGROUND

The primary objective of this study was to find the performance of the 2009 probable case definition of dengue and compare it with the definition given by the WHO-SEAR expert group in 2011.

METHODS

A cross-sectional study was conducted in Thiruvananthapuram district of Kerala, which is hyperendemic for dengue. A consecutive series of 851 participants defined by the selection criteria were recruited from the primary, secondary, and tertiary health care settings. Sensitivity, specificity, predictive values, and likelihood ratios of the clinical case definitions were calculated using reverse transcriptase-polymerized chain reaction (RT-PCR) as gold standard in case of fever less than or equal to 5 days and serology (IgM positivity) for fever >5 days. Diagnostic odds ratio (DOR) was also calculated as a single indicator of performance of the case definition.

RESULTS

The 2009 World Health Organization (WHO) case definition had a sensitivity of 76·4% (69·6-82·1) and negative predictive value of 87·5%. The 2011 WHO-SEAR expert group case definition had a higher sensitivity of 87·9% (82·2-91·9) but lower negative predictive value of 86·6%. The three independent criteria which were significantly associated with dengue were thrombocytopenia less than 150,000 (OR 2·80), leukopenia (OR 2·28), and absence of backache (OR 2·68). The performance of 2009 case definition was better (DOR 2·4) than the 2011 WHO-SEAR expert group case definition. This was further enhanced when thrombocytopenia was specified as platelet count less than 150,000 (DOR2·7). When 'no backahe' was added as an additional criteria, the performance of both definitions improved.

CONCLUSIONS

The 2009 WHO case definition has better discriminatory power than the 2011 WHO-SEAR expert group case definition. The performance of 2009 WHO case definition is enhanced by specifying thrombocytopenia as platelet count less than 150,000. The inclusion of 'no backache' further improves the discriminatory power. This may be more useful in primary care settings, to rule out dengue.

Unusual and rare manifestations of dengue during a dengue outbreak in a tertiary care hospital in South India

Dengue is the most rapidly spreading mosquito-borne viral disease in the world, and as a larger proportion of the population is being affected, more unusual manifestations are being reported. Very few studies have documented unusual manifestations of dengue in South India. This prospective study was undertaken from July 2011 to June 2013 to document rare manifestations of dengue fever in 175 hospitalized patients. The clinical diagnosis was confirmed by the detection of NS1Ag, dengue IgM, or IgG by ELISA and/or a RT-PCR and CDC real-time PCR for dengue virus (DENV) RNA. The daily profiles of the hematological and biochemical investigations were followed and recorded. Unusual and rare manifestations of dengue were documented for 115 patients (66 %). Hepatitis was observed in 70 % of the cases. Pleural effusion was seen in 11 %, acute renal failure in 10 %, neurological complications such as encephalitis in 7.4 %, myocarditis in 9 %, and bleeding gastric ulcers in 3.4 % of the cases. DENV serotype 2 was more prevalent in patients with unusual manifestations of dengue in our study. The WHO classification system does not include unusual and rare manifestations; hence, it is essential to be aware of these manifestations and closely monitor them for better clinical management and outcome of patients.

Factors associated with dengue shock syndrome: a systematic review and meta-analysis

BACKGROUND

The pathogenesis of dengue shock syndrome (DSS, grade 3 and 4) is not yet completely understood. Several factors are reportedly associated with DSS, a more severe form of dengue infection that reportedly causes 50 times higher mortality compared to that of dengue patients without DSS. However, the results from these reports remain inconclusive. To better understand the epidemiology, clinical manifestation, and pathogenesis of DSS for development of new therapy, we systematically reviewed and performed a meta-analysis of relevant studies that reported factors in both DSS and dengue hemorrhagic fever (DHF, grade 1 and 2) patients.

METHODS AND FINDINGS

PubMed, EMBASE, Scopus, Google Scholar, Dengue Bulletin, Cochrane Library, Virtual Health Library, and a manual search of reference lists of articles published before September 2010 were used to retrieve relevant studies. A meta-analysis using fixed- or random-effects models was used to calculate pooled odds ratios (OR) or event rate with corresponding 95% confidence intervals. Assessment of heterogeneity and publication bias, meta-regression analysis, subgroup analysis, sensitivity analysis, and analysis of factor-specific relationships were further performed. There were 198 studies constituting 203 data sets that met our eligibility criteria. Our meta-regression analysis showed a sustained reduction of DSS/dengue hemorrhagic fever (DHF) ratio over a period of 40 years in Southeast Asia, especially in Thailand. The meta-analysis revealed that age, female sex, neurological signs, nausea/vomiting, abdominal pain, gastrointestinal bleeding, hemoconcentration, ascites, pleural effusion, hypoalbuminemia, hypoproteinemia, hepatomegaly, levels of alanine transaminase and aspartate transaminase, thrombocytopenia, prothrombin time, activated partial thromboplastin time, fibrinogen level, primary/secondary infection, and dengue virus serotype-2 were significantly associated with DSS when pooling all original relevant studies.

CONCLUSIONS

The results improve our knowledge of the pathogenesis of DSS by identifying the association between the epidemiology, clinical signs, and biomarkers involved in DSS.

Performance of the tourniquet test for diagnosing dengue in Peru

The tourniquet test (TT) is a physical examination maneuver often performed on patients suspected of having dengue. It has been incorporated into dengue diagnostic guidelines and is used in clinical studies. However, little is known about TT performance characteristics in different patient types or epidemiologic conditions. In the dengue-endemic city of Iquitos, Peru, we performed TTs and dengue laboratory assays on 13,548 persons with febrile disease, recruited through either active (n = 1,095) or passive (n = 12,453) surveillance. The sensitivity was 52% and 56%, the specificity was 58% and 68%, the positive predictive value was 45% and 55%, and the negative predictive value was 64% and 69% for persons enrolled in active and passive surveillance, respectively. We demonstrated that the TT was more sensitive identifying dengue disease in women and those of younger age and that sensitivity increased the later a person came to a medical clinic for care.

A review of dengue fever: a resurging tropical disease

Dengue is a resurging mosquito-borne disease that is often contracted in U.S. travelers to Latin America, Asia, and the Caribbean. The clinical symptoms range from a simple febrile illness to hemorrhagic fever or shock. The clinical course has a wide range of outcomes, and adequate supportive care can reduce mortality rates dramatically. Repeated exposures to the virus can lead to a more complicated clinical course.

Fifty years of dengue in India

Dengue is the most important mosquito-borne, human viral disease in many tropical and sub-tropical areas. In India the disease has been essentially described in the form of case series. We reviewed the epidemiology of dengue in India to improve understanding of its evolution in the last 50 years and support the development of effective local prevention and control measures. Early outbreak reports showed a classic epidemic pattern of transmission with sporadic outbreaks, with low to moderate numbers of cases, usually localized to urban centres and neighbouring regions, but occasionally spreading and causing larger epidemics. Trends in recent decades include: larger and more frequent outbreaks; geographic expansion of endemic transmission; spread of the disease from urban to peri-urban and rural areas; an increasing proportion of severe cases and deaths; and progression to hyperendemicity, particularly in large urban areas. The global picture of dengue in India is currently that of a largely endemic country. Understanding demographic differences in infection rates and severity of dengue has important implications for the planning and implementation of effective public health prevention and control measures and targeting of future vaccination campaigns.

Evaluation of the traditional and revised WHO classifications of Dengue disease severity

Dengue is a major public health problem worldwide and continues to increase in incidence. Dengue virus (DENV) infection leads to a range of outcomes, including subclinical infection, undifferentiated febrile illness, Dengue Fever (DF), life-threatening syndromes with fluid loss and hypotensive shock, or other severe manifestations such as bleeding and organ failure. The long-standing World Health Organization (WHO) dengue classification and management scheme was recently revised, replacing DF, Dengue Hemorrhagic Fever (DHF), and Dengue Shock Syndrome (DSS) with Dengue without Warning Signs, Dengue with Warning Signs (abdominal pain, persistent vomiting, fluid accumulation, mucosal bleeding, lethargy, liver enlargement, increasing hematocrit with decreasing platelets) and Severe Dengue (SD; dengue with severe plasma leakage, severe bleeding, or organ failure). We evaluated the traditional and revised classification schemes against clinical intervention levels to determine how each captures disease severity using data from five years (2005–2010) of a hospital-based study of pediatric dengue in Managua, Nicaragua. Laboratory-confirmed dengue cases (n = 544) were categorized using both classification schemes and by level of care (I–III). Category I was out-patient care, Category II was in-patient care that did not meet criteria for Category III, which included ICU admission, ventilation, administration of inotropic drugs, or organ failure. Sensitivity and specificity to capture Category III care for DHF/DSS were 39.0% and 75.5%, respectively; sensitivity and specificity for SD were 92.1% and 78.5%, respectively. In this data set, DENV-2 was found to be significantly associated with DHF/DSS; however, this association was not observed with the revised classification. Among dengue-confirmed cases, the revised WHO classification for severe dengue appears to have higher sensitivity and specificity to identify cases in need of heightened care, although it is no longer as specific for a particular pathogenic entity as was the traditional schema.

Dengue is a mosquito-transmitted viral disease that is a major public health problem worldwide. Dengue virus (DENV) infection leads to Dengue Fever (DF) and a spectrum of life-threatening syndromes with fluid loss and hypotensive shock or other severe manifestations. Recently, the traditional World Health Organization (WHO) dengue classification scheme (classic DF, Dengue Hemorrhagic Fever (DHF), and Dengue Shock Syndrome (DSS)) was replaced with Dengue without Warning Signs, Dengue with Warning Signs and Severe Dengue (SD). Using data from 544 laboratory-confirmed dengue cases recruited over five years of a hospital-based study of pediatric dengue in Managua, Nicaragua, we evaluated the traditional and revised classification schemes against clinical intervention levels (I–III) to determine how each captures disease severity. The sensitivity and specificity to capture Category III care for DHF/DSS were 39.0% and 75.5%, respectively, and for SD were 92.1% and 78.5%, respectively. Interestingly, DENV-2 was significantly associated with DHF/DSS; however, this association was not observed with the revised classification. This study indicates that among dengue-confirmed cases, the revised WHO classification appears to have higher sensitivity and specificity for identifying cases in need of heightened care, although it is no longer as specific for a particular pathogenic entity as was the traditional schema.

The pathogenesis of dengue

Dengue is an important cause of childhood and adult morbidity in Asian and Latin American countries and its geographic footprint is growing. The clinical manifestations of dengue are the expression of a constellation of host and viral factors, some acquired, others intrinsic to the individual. The virulence of the virus plus the flavivirus infection history, age, gender and genotype of the host all appear to help shape the severity of infection. Similarly, the characteristics of the innate and acquired host immune response subsequent to infection are also likely determinants of outcome. This review summarises recent developments in the understanding of dengue pathogenesis and their relevance to dengue vaccine development.

The laboratorial diagnosis of dengue: applications and implications

The diagnosis of infection by the dengue virus relies, in most cases, on the clinical judgment of the patient, since only a few major centers have clinical laboratories that offer diagnostic tests to confirm the clinical impressions of an infection. At present, routine laboratory diagnosis is done by different kinds of testing. Among them are the methods of serological research, virus isolation, detection of viral antigens, and detection of viral genomes. The continued development of diagnostic tests, which are cheap, sensitive, specific, easy to perform, and capable of giving early diagnosis of the dengue virus infection is still a need. There are also other obstacles that are not specifically related to the technological development of diagnostic methods. For instance, infrastructure of the laboratories, the training of personnel, and the capacity of research of these laboratories are still limited in many parts of Brazil and the world, where dengue is endemic. Clinical laboratories, especially the ones that serve regions with a high incidence of dengue, should be aware of all the diagnostic methods available for routine these days, and choose the one that best suit their working conditions and populations served, in order to save lives.

Dengue shock

Shock syndrome is a dangerous complication of dengue infection and is associated with high mortality. Severe dengue occurs as a result of secondary infection with a different virus serotype. Increased vascular permeability, together with myocardial dysfunction and dehydration, contribute to the development of shock, with resultant multiorgan failure. The onset of shock in dengue can be dramatic, and its progression relentless. The pathogenesis of shock in dengue is complex. It is known that endothelial dysfunction induced by cytokines and chemical mediators occurs. Diagnosis is largely clinical and is supported by serology and identification of viral material in blood. No specific methods are available to predict outcome and progression. Careful fluid management and supportive therapy is the mainstay of management. Corticosteroids and intravenous immunoglobulins are of no proven benefit. No specific therapy has been shown to be effective in improving survival.

Multicentre prospective study on dengue classification in four South-east Asian and three Latin American countries

OBJECTIVE

To evaluate the existing WHO dengue classification across all age groups and a wide geographical range and to develop a revised evidence-based classification that would better reflect clinical severity.

METHODS

We followed suspected dengue cases daily in seven countries across South-east Asia and Latin America and then categorised them into one of three intervention groups describing disease severity according to the overall level of medical and nursing support required. Using a pre-defined analysis plan, we explored the clinical and laboratory profiles characteristic of these intervention categories and presented the most promising options for a revised classification scheme to an independent group of WHO dengue experts for consideration. Potential warning signs were also evaluated by comparing contemporaneous data of patients who progressed to severe disease with the data of those who did not.

RESULTS

A total of 2259 patients were recruited during 2006-2007 and 230 (13%) of the 1734 laboratory-confirmed patients required major intervention. Applying the existing WHO system, 47/210 (22%) of patients with shock did not fulfil all the criteria for dengue haemorrhagic fever. However, no three-tier revision adequately described the different severity groups either. Inclusion of readily discernible complications (shock/severe vascular leakage and/or severe bleeding and/or severe organ dysfunction) was necessary to devise a system that identified patients requiring major intervention with sufficient sensitivity and specificity to be practically useful. Only a small number of subjects (5%) progressed to severe disease while under observation; several warning signs were identified, but much larger studies are necessary to fully characterize features associated with disease progression.

CONCLUSIONS

Based on these results, a revised classification system comprised of two entities, 'Dengue' and 'Severe Dengue', was proposed and has now been incorporated into the new WHO guidelines.

Epidemiological factors associated with dengue shock syndrome and mortality in hospitalized dengue patients in Ho Chi Minh City, Vietnam

Understanding trends in dengue disease burden and risk factors for severe disease can inform health service allocation, clinical management, and planning for vaccines and therapeutics. Dengue admissions at three tertiary hospitals in Ho Chi Minh City, Vietnam, increased between 1996 and 2009, peaking at 22,860 in 2008. Children aged 6–10 years had highest risk of dengue shock syndrome (DSS); however, mortality was highest in younger children and decreased with increasing age (odds ratio [OR] = 0.52, 95% confidence interval [CI] = 0.36–0.75 in 6- to 10- year-old children and OR = 0.27, 95% CI = 0.16–0.44 in 11- to 15-year-old children compared with 1- to 5-year-old children). Males were overrepresented among dengue cases; however, girls had higher risk of DSS (OR = 1.19, 95% CI = 1.14–1.24) and death (OR = 1.57, 95% CI = 1.14–2.17). Young children with dengue had greatest risk of death and should be targeted in dengue vaccine and drug trials. The increased risk of severe outcomes in girls warrants further attention in studies of pathogenesis, health-seeking behavior, and clinical care.

Dengue hemorrhagic fever and shock syndromes

OBJECTIVES

To provide a comprehensive review of dengue, with an emphasis on clinical syndromes, classification, diagnosis, and management, and to outline relevant aspects of epidemiology, immunopathogenesis, and prevention strategies. Dengue, a leading cause of childhood mortality in Asia and South America, is the most rapidly spreading and important arboviral disease in the world and has a geographic distribution of > 100 countries.

DATA SOURCE

Boolean searches were carried out by using PubMed from 1975 to March 2009 and the Cochrane Database of Systematic Reviews from 1993 to March 2009 to identify potentially relevant articles by key search terms such as: "dengue"; "dengue fever"; "dengue hemorrhagic fever"; "dengue shock syndrome"; "severe dengue" and "immunopathogenesis," pathogenesis," "classification," "complications," and "management." In addition, authoritative seminal and up-to-date reviews by experts were used.

STUDY SELECTION

Original research and up-to-date reviews and authoritative reviews consensus statements relevant to diagnosis and therapy were selected.

DATA EXTRACTION AND SYNTHESIS

We considered the most relevant articles that would be important and of interest to the critical care practitioner as well as authoritative consensus statements from the World Health Organization and the Centers for Disease Control and Prevention. Dengue viral infections are caused by one of four single-stranded ribonucleic acid viruses of the family Flaviviridae and are transmitted by their mosquito vector, Aedes aegypti. The clinical syndromes caused by dengue viral infections occur along a continuum; most cases are asymptomatic and few present with severe forms characterized by shock. Management is predominantly supportive and includes methods to judiciously resolve shock and control bleeding while at the same time preventing fluid overload.

CONCLUSIONS

Dengue is no longer confined to the tropics and is a global disease. Treatment is supportive. Outcomes can be optimized by early recognition and cautious titrated fluid replacement, especially in resource-limited environments.

Clinico-epidemiological profile of children hospitalized with dengue

OBJECTIVE

To study the clinico-epidemiological profile of children hospitalized with dengue illness.

METHODS

Prospective study of children hospitalized with the diagnosis of dengue illness during from September through November 2006 at a tertiary care centre in Jaipur.

RESULTS

A total of 948 children including 671 (70.8%) boys and 277 (29.2%) girls were diagnosed to have dengue illness during the outbreak. Two third of children were from urban areas while 6-12 years was the most commonly affected age group (45.8%). 58.3% cases had dengue fever (DF) while 41.7% had DHF (dengue hemorrhagic fever). Dengue fever with bleed (DFB) accounted for 32% of cases. Common constitutional symptoms were vomiting (35.2%), pain abdomen (22.1%) and myalgia (10.1%). Bleeding manifestations were observed in 44.5% of cases.. Positive tourniquet test was the most common manifestation which was seen in 300 cases (31.6%) while in 9.2% cases bleeding was the only manifestation. Epistaxis (25%) was the most common spontaneous bleeding manifestation. Thrombocytopenia was documented in 84% of total cases and bleeding occurred more often in patients with severe thrombocytopenia. Ten children expired with a case fatality rate of 1.1%.

CONCLUSIONS

Children between 6 and 12 yrs were most affected by dengue with larger number of cases from urban areas. DFB cases accounted for almost one third cases of dengue. Epistaxis was the most common spontaneous bleeding manifestation. Bleeding occurs more often in patients with severe thrombocytopenia.

Association between nutritional status and severity of dengue infection in children in El Salvador

Clinical observations and some studies suggest that dengue virus infection is more severe among children with better nutritional status. We examined the nutritional status of children in El Salvador and its relationship between this and the severity of dengue infection. Z-scores for weight-for-age, height-for-age, and body mass index (BMI)-for-age of children with dengue fever (66), dengue hemorrhagic fever (62), and healthy controls (74) were compared. There were no differences in weight-for-age or BMI-for-age Z-scores between the three groups. Children with dengue fever had a greater height-for-age than healthy controls but no significant differences in rates of stunting. There was no difference in height between children with dengue fever and dengue hemorrhagic fever. Excess nutrition does not appear to be a risk factor for severe forms of dengue infection in El Salvador, nor does malnutrition appear to be predictive of good outcomes.

Dengue viral infections

Dengue viral infections are one of the most important mosquito-borne diseases in the world. Presently dengue is endemic in 112 countries in the world. It has been estimated that almost 100 million cases of dengue fever and half a million cases of dengue hemorrhagic fever (DHF) occur worldwide. An increasing proportion of DHF is in children less than 15 years of age, especially in South East and South Asia. The unique structure of the dengue virus and the pathophysiologic responses of the host, different serotypes, and favorable conditions for vector breeding have led to the virulence and spread of the infections. The manifestations of dengue infections are protean from being asymptomatic to undifferentiated fever, severe dengue infections, and unusual complications. Early recognition and prompt initiation of appropriate supportive treatment are often delayed resulting in unnecessarily high morbidity and mortality. Attempts are underway for the development of a vaccine for preventing the burden of this neglected disease. This review outlines the epidemiology, clinical features, pathophysiologic mechanisms, management, and control of dengue infections.

Oxidative stress in severe dengue viral infection: association of thrombocytopenia with lipid peroxidation

Oxidative stress in viral infections has been suggested. The study was carried out to assess the oxidative stress in the different clinical spectrums of dengue infection and to evaluate if thrombocytopenia is associated with lipid and protein oxidative injury. Twenty-seven dengue fever (DF), 32 dengue hemorrhagic fever (DHF) and 21 dengue shock syndrome (DSS) cases were studied at 3, 5 and 7 days of illness. Sixty-three healthy subjects were selected as controls. Serum protein carbonyls (PCOs), malendialdehyde (MDA) and total antioxidant status (TAS) were estimated in blood. Dengue infected individuals had significantly high levels of PCOs and MDA on the three days tested in comparison to controls. In DF cases, no significant changes in the levels of MDA and PCOs were found in course of time. However, among DHF and DSS, significant increase in MDA levels was found in the fifth and seventh day samples in comparison to their respective third day sample (P < 0.05). Using one way ANOVA, high PCOs levels were found in DSS in comparison to DF and DHF cases on all the three days tested (P < 0.001). TAS levels were found to be low among DSS on days 5 and 7 and day 7 in DHF when compared with DF cases. Correlation analysis between MDA and hematocrit revealed a significant positive association between them in DHF and DSS on day 5 (DHF r = 0.372; p = 0.024 and DSS r = 0.535; p = 0.0-01) and day 7 (DHF r = 0.412; p = 0.003 and DSS r = 0.765; p < 0.0001). There was an important negative correlation between platelet count and plasma lipid peroxidation levels among DHF and DSS on all three days tested [day 3 (DHF r = -0.392; p = 0.012 and DSS r = -0.453; p = 0.004), day 5 (DHF r = -0.592; p < 0.001 and DSS r = -0.581; p < 0.001) and day 7 (DHF r = -0.418; p = 0.001 and DSS r = -0.515; p = 0.002)]. This study concludes that an increase in oxidative stress was found in dengue viral infection. The level of oxidative stress was maximal in DSS followed by DHF and its severity was minimal in DF. The thrombocytopenia of dengue infection was associated with the extent of lipid peroxidation. Future studies might be carried out to find the role of oxidative damage in the ethiopathogenesis of thrombocytopenia and vascular leakage in dengue infection.

Cellular and molecular basis of antibody-dependent enhancement in human dengue pathogenesis

Dengue fever is gaining increased attention as a major global health problem. It occurs annually in 50–100 million people in more than 100 countries, and places half a million people at risk of life-threatening diseases: dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS). The pathogenic mechanisms causing DHF/DSS are not clearly understood. This article reviews cellular and molecular mechanisms that might be responsible for the initiation of the pathogenic processes, including hypotheses for DHF/DSS, dengue-permissive target cells, putative dengue receptors, neutralizing and enhancing antibodies to dengue virus, mechanisms of vascular plasma leakage, innate immune response in dengue infection and antibody-dependent enhancement of dengue infection. While reviewing the literature, the article also gives the author’s opinion on perceived areas of importance for future research in human dengue pathogenesis.

Polymorphisms of the TAP 1 and 2 gene may influence clinical outcome of primary dengue viral infection

Antigen peptides are actively transported across the endoplasmic reticulum by the transporters associated with antigen presentation (TAP). TAP genes polymorphism could influence the selection process that determines which antigen peptides play a role in the pathogenesis of dengue infection. The aim of this study was to investigate the association of TAP genes polymorphism in diverse pathogenesis of dengue infection. This study included 197 dengue-infected patients who were further categorized into 64, 23 and 11 primary dengue fever (DF), dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS) cases, respectively and 26, 52, and 21 secondary DF, DHF and DSS cases, respectively as per WHO grading system. TAP1 and 2 gene polymorphisms were performed by the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). Analysis of TAP1 gene polymorphism demonstrated decreased frequency of Ile/Ile genotype at TAP1(333) in primary DHF cases (39.1%) when compared with primary DF (64.1%, P < 0.034, OR = 0.611). The genotype frequency of Val/Val at TAP2(379) locus was significantly decreased among primary DHF (43.5%) in comparison to primary DF (71.9%, P = 0.015, OR = 0.605). Significant low proportion of primary DSS were found to have TAP1(637) Asp/Asp genotypes (54.5%) when compared with primary DF (70.3%, P = 0.043). Asp/Asp genotype at TAP1(637) was found to reduce the risk by 0.643 times for primary DSS. There was no significant difference in the genotypes studied between primary and secondary infection and also within secondary dengue infection in all three clinical groups. This report on TAP gene polymorphisms in dengue suggested that among the primary-infected individuals, homozygous patterns for Ile at TAP1(333) Val at TAP2(379) loci and Asp at TAP1(637) were found to be a protective factor against development of DHF and DSS, respectively.

Clinical and biochemical profile of dengue haemorrhagic fever in children in Delhi

The clinical and biochemical profile of dengue haemorrhagic fever (DHF) varies from epidemic to epidemic. We studied children hospitalized with DHF from September 2003 to December 2003. All were diagnosed, managed and monitored according to a standard protocol. Of the 34 who fulfilled the World Health Organization criteria of DHF, 22 (64.6%) were male. All patients presented with fever and hepatomegaly. Examination also revealed splenomegaly in 11 (32.4%), ascites in 6 (17.6%) and pleural effusion in 3 (8.8%). Common bleeding manifestations were positive tourniquet test in 22 (64.7%) and epistaxis in eight (23.5%). Most children had a platelet count of between 20,000/mm(3) and 50,000/mm(3) (56%). Bleeding manifestations were not related to platelet count (P > 0.05). Serum glutamic pyruvic transaminase (SGPT) >40 IU/L was seen in 22 (64.6%) patients, alkaline phosphate (ALP) >400 IU/L in 12 (35.3%) and serum bilirubin >1 mg% in 3 (8.8%). IgM dengue serology was positive in 68.5% cases. There was no significant difference in liver function tests with age or sex (P > 0.05). Clinical features of DHF varied from the previous epidemic. Hepatic dysfunction with increased levels of serum enzymes was common in DHF.

Fulminant liver failure secondary to haemorrhagic dengue in an international traveller

Dengue infections are caused by a single-stranded RNA virus, which has four serotypes (DEN 1-4); mosquitoes of the genus Aedes serve as vectors of transmission. Risk factors for dengue infection are related to both the host and virus. Age, gender, immune status, and genetic background of the host all contribute to the severity of dengue infection. Recently, international travel to endemic areas has also been identified as a major risk factor for both primary and secondary dengue infection. Dengue remains a diagnostic challenge, given its protean nature, ranging from mild febrile illness to profound shock. The most severe manifestation of dengue infection is dengue shock syndrome, which has an estimated mortality rate close to 50%. Dengue shock syndrome typically presents with increased anion gap metabolic acidosis, disseminated intravascular coagulation, severe hypotension, and jaundice. Liver involvement appears to occur more frequently when infections involve DEN-3 and DEN-4 serotypes. While hepatocellular damage has been reported previously in dengue infection, acute liver failure is an extremely rare occurrence in adults. We report a patient with dengue shock syndrome who presented with acute liver failure and hepatic encephalopathy after recent travel to an endemic area.

Dengue disease severity in Indonesian children: an evaluation of the World Health Organization classification system

Background

Dengue disease severity is usually classified using criteria set up by the World Health Organization (WHO). We aimed to assess the diagnostic accuracy of the WHO classification system and modifications to this system, and evaluated their potential practical usefulness.

Methods

Patients, admitted consecutively to the hospital with severe dengue, were classified using the WHO classification system and modifications to this system. Treating physicians were asked to classify patients immediately after discharge. We calculated the sensitivity of the various classification systems for the detection of shock and the agreement between the various classification systems and the treating physician's classification.

Results

Of 152 patients with confirmed dengue, sixty-six (43%) had evidence of circulatory failure. The WHO classification system had a sensitivity of 86% (95%CI 76–94) for the detection of patients with shock. All modifications to the WHO classification system had a higher sensitivity than the WHO classification system (sensitivity ranging from 88% to 99%). The WHO classification system was in only modest agreement with the intuitive classification by treating physicians whereas several modified classification systems were in good agreement.

Conclusion

The use of the WHO classification system to classify dengue disease severity is to be questioned, because it is not accurate in correctly classifying dengue disease severity and it lacks sufficient agreement with clinical practice.