Major Histocompatibility Complex Class I Chain-Related A and B (MICA and MICB) Gene, Allele, and Haplotype Associations With Dengue Infections in Ethnic Thais.

BACKGROUND: Major histocompatibility complex class I chain-related (MIC) A and B (MICA and MICB) are polymorphic stress molecules recognized by natural killer cells. This study was performed to analyze MIC gene profiles in hospitalized Thai children with acute dengue illness. METHODS: MIC allele profiles were determined in a discovery cohort of patients with dengue fever or dengue hemorrhagic fever (DHF) (n = 166) and controls (n = 149). A replication cohort of patients with dengue (n = 222) was used to confirm specific MICB associations with disease. RESULTS: MICA*045 and MICB*004 associated with susceptibility to DHF in secondary dengue virus (DENV) infections (odds ratio [OR], 3.22; [95% confidence interval (CI), 1.18-8.84] and 1.99 [1.07-2.13], respectively), and MICB*002 with protection from DHF in secondary DENV infections (OR, 0.41; 95% CI, .21-.68). The protective effect of MICB*002 against secondary DHF was confirmed in the replication cohort (OR, 0.43; 95% CI, .22-.82) and was stronger when MICB*002 is present in individuals also carrying HLA-B*18, B*40, and B*44 alleles which form the B44 supertype of functionally related alleles (0.29, 95% CI, .14-.60). CONCLUSIONS: Given that MICB*002 is a low expresser of soluble proteins, these data indicate that surface expression of MICB*002 with B44 supertype alleles on DENV-infected cells confer a protective advantage in controlling DENV infection using natural killer cells.

Activation of Peripheral T Follicular Helper Cells During Acute Dengue Virus Infection.

Background: Follicular helper T cells (TFH) are specialized CD4 T cells required for B-cell help and antibody production. Methods: Given the postulated role of immune activation in dengue disease, we measured the expansion and activation of TFH in the circulation (peripheral TFH [pTFH]) collected from Thai children with laboratory-confirmed acute dengue virus (DENV) infection. Results: We found significant expansion and activation of pTFH subsets during acute infection with the highest frequencies of activated pTFH (PD1hi pTFH and PD1+CD38+ pTFH) detected during the critical phase of illness. Numbers of activated pTFH were higher in patients with secondary compared with primary infections and in patients with more severe disease. We also found a positive correlation between the frequencies of activated pTFH and the frequencies of plasmablasts. Conclusions: To our knowledge, this is the first ex vivo analysis of pTFH activation during acute DENV infection. Overall, our study supports the model that pTFH contribute to disease evolution during the critical stage of illness.

Case Management of Dengue: Lessons Learned.

The global burden of dengue and its geographic distribution have increased over the past several decades. The introduction of dengue in new areas has often been accompanied by high case-fatality rates. Drawing on the experience in managing dengue cases at the Queen Sirikit National Institute of Child Health in Bangkok, Thailand, this article provides the authors' perspectives on key clinical lessons to improve dengue-related outcomes. Parallels between this clinical experience and outcomes reported in randomized controlled trials, results of efforts to disseminate practice recommendations, and suggestions for areas for further research are also discussed.

Dengue Virus (DENV) Neutralizing Antibody Kinetics in Children After Symptomatic Primary and Postprimary DENV Infection.

The immune response to dengue virus (DENV) infection is complex and not fully understood. Using longitudinal data from 181 children with dengue in Thailand who were followed for up to 3 years, we describe neutralizing antibody kinetics following symptomatic DENV infection. We observed that antibody titers varied by serotype, homotypic vs heterotypic responses, and primary versus postprimary infections. The rates of change in antibody titers over time varied between primary and postprimary responses. For primary infections, titers increased from convalescence to 6 months. By comparing homotypic and heterotypic antibody titers, we saw an increase in type specificity from convalescence to 6 months for primary DENV3 infections but not primary DENV1 infections. In postprimary cases, there was a decrease in titers from convalescence up until 6 months after infection. Beginning 1 year after both primary and postprimary infections, there was evidence of increasing antibody titers, with greater increases in children with lower titers, suggesting that antibody titers were boosted due to infection and that higher levels of neutralizing antibody may be more likely to confer a sterilizing immune response. These findings may help to model virus transmission dynamics and provide baseline data to support the development of vaccines and therapeutics.

HLA Class I Supertype Associations With Clinical Outcome of Secondary Dengue Virus Infections in Ethnic Thais.

BACKGROUND: Human leukocyte antigen (HLA) supertypes are groups of functionally related alleles that present structurally similar antigens to the immune system. OBJECTIVES: To analyze HLA class I supertype associations with clinical outcome in hospitalized Thai children with acute dengue illness. METHODS: Seven hundred sixty-two patients and population-matched controls recruited predominantly in Bangkok were HLA-A and -B typed. HLA supertype frequencies were compared and tested for significant dengue disease associations using logistic regression analyses. Multivariable models were built by conducting forward stepwise selection procedures. RESULTS: In the final logistic regression model, the HLA-B44 supertype was protective against dengue hemorrhagic fever (DHF) in secondary infections (odds ratio [OR] = 0.46, 95% confidence interval [CI], .30-.72), while the HLA-A02 supertype (OR = 1.92, 95% CI, 1.30-2.83) and the HLA-A01/03 supertype (OR = 3.01, 95% CI, 1.01-8.92) were associated with susceptibility to secondary dengue fever. The B07 supertype was associated with susceptibility to secondary DHF in the univariate analysis (OR = 1.60, 95% CI, 1.05-2.46), whereas that was not retained in the final model. CONCLUSIONS: As the HLA-B44 supertype is predicted to target conserved epitopes in dengue, our results suggest that B44 supertype-restricted immune responses to highly conserved regions of the dengue proteome may protect against secondary DHF.

Sequential dengue virus infections detected in active and passive surveillance programs in Thailand, 1994-2010.

BACKGROUND: The effect of prior dengue virus (DENV) exposure on subsequent heterologous infection can be beneficial or detrimental depending on many factors including timing of infection. We sought to evaluate this effect by examining a large database of DENV infections captured by both active and passive surveillance encompassing a wide clinical spectrum of disease. METHODS: We evaluated datasets from 17 years of hospital-based passive surveillance and nine years of cohort studies, including clinical and subclinical DENV infections, to assess the outcomes of sequential heterologous infections. Chi square or Fisher's exact test was used to compare proportions of infection outcomes such as disease severity; ANOVA was used for continuous variables. Multivariate logistic regression was used to assess risk factors for infection outcomes. RESULTS: Of 38,740 DENV infections, two or more infections were detected in 502 individuals; 14 had three infections. The mean ages at the time of the first and second detected infections were 7.6 ± 3.0 and 11.2 ± 3.0 years. The shortest time between sequential infections was 66 days. A longer time interval between sequential infections was associated with dengue hemorrhagic fever (DHF) in the second detected infection (OR 1.3, 95% CI 1.2-1.4). All possible sequential serotype pairs were observed among 201 subjects with DHF at the second detected infection, except DENV-4 followed by DENV-3. Among DENV infections detected in cohort subjects by active study surveillance and subsequent non-study hospital-based passive surveillance, hospitalization at the first detected infection increased the likelihood of hospitalization at the second detected infection. CONCLUSIONS: Increasing time between sequential DENV infections was associated with greater severity of the second detected infection, supporting the role of heterotypic immunity in both protection and enhancement. Hospitalization was positively associated between the first and second detected infections, suggesting a possible predisposition in some individuals to more severe dengue disease.

Revealing the microscale spatial signature of dengue transmission and immunity in an urban population.

It is well-known that the distribution of immunity in a population dictates the future incidence of infectious disease, but this process is generally understood at individual or macroscales. For example, herd immunity to multiple pathogens has been observed at national and city levels. However, the effects of population immunity have not previously been shown at scales smaller than the city (e.g., neighborhoods). In particular, no study has shown long-term effects of population immunity at scales consistent with the spatial scale of person-to-person transmission. Here, we use the location of dengue patients' homes in Bangkok with the serotype of the infecting pathogen to investigate the spatiotemporal distribution of disease risk at small spatial scales over a 5-y period. We find evidence for localized transmission at distances of under 1 km. We also observe patterns of spatiotemporal dependence consistent with the expected impacts of homotypic immunity, heterotypic immunity, and immune enhancement of disease at these distances. Our observations indicate that immunological memory of dengue serotypes occurs at the neighborhood level in this large urban setting. These methods have broad applications to studying the spatiotemporal structure of disease risk where pathogen serotype or genetic information is known.

Distinct activation phenotype of a highly conserved novel HLA-B57-restricted epitope during dengue virus infection.

Variation in the sequence of T-cell epitopes between dengue virus (DENV) serotypes is believed to alter memory T-cell responses during second heterologous infections. We identified a highly conserved, novel, HLA-B57-restricted epitope on the DENV NS1 protein. We predicted higher frequencies of B57-NS1(26-34) -specific CD8(+) T cells in peripheral blood mononuclear cells from individuals undergoing secondary rather than primary DENV infection. However, high tetramer-positive T-cell frequencies during acute infection were seen in only one of nine subjects with secondary infection. B57-NS1(26-34) -specific and other DENV epitope-specific CD8(+) T cells, as well as total CD8(+) T cells, expressed an activated phenotype (CD69(+) and/or CD38(+)) during acute infection. In contrast, expression of CD71 was largely limited to DENV epitope-specific CD8(+) T cells. In vitro stimulation of cell lines indicated that CD71 expression was differentially sensitive to stimulation by homologous and heterologous variant peptides. CD71 may represent a useful marker of antigen-specific T-cell activation.

Preliminary evaluation of near infrared spectroscopy as a method to detect plasma leakage in children with dengue hemorrhagic fever.

BACKGROUND: Dengue viral infections are prevalent in the tropical and sub-tropical regions of the world, resulting in substantial morbidity and mortality. Clinical manifestations range from a self-limited fever to a potential life-threatening plasma leakage syndrome (dengue hemorrhagic fever). The objective of this study was to assess the utility of near infrared spectroscopy (NIRS) measurements of muscle oxygen saturation (SmO2) as a possible continuous measure to detect plasma leakage in children with dengue. METHODS: Children ages 6 months to 15 years of age admitted with suspected dengue were enrolled from the dengue ward at Queen Sirikit National Institute for Child Health. Children were monitored daily until discharge. NIRS data were collected continuously using a prototype CareGuide Oximeter 1100 with sensors placed on the deltoid or thigh. Daily ultrasound of the chest and a right lateral decubitus chest x-ray the day after defervescence were performed to detect and quantitate plasma leakage in the pleural cavity. RESULTS: NIRS data were obtained from 19 children with laboratory-confirmed dengue. Average minimum SmO2 decreased for all subjects prior to defervescence. Average minimum SmO2 subsequently increased in children with no ultrasound evidence of pleural effusion but remained low in children with pleural effusion following defervescence. Average minimum SmO2 was inversely correlated with pleural space fluid volume. ROC analysis revealed a cut-off value for SmO2 which yielded high specificity and sensitivity. CONCLUSIONS: SmO2 measured using NIRS may be a useful guide for real-time and non-invasive identification of plasma leakage in children with dengue. Further investigation of the utility of NIRS measurements for prediction and management of severe dengue syndromes is warranted.

Serum lactate and lactate dehydrogenase as parameters for the prediction of dengue severity.

BACKGROUND: Lactate and lactate dehydrogenase (LDH) have been found to be elevated in cardiopulmonary failure, sepsis, shock and hepatic injury. Severe dengue hemorrhagic fever (DHF) patients also develop shock and experience a certain degree of hepatic injury, implicating that serum lactate and LDH may be elevated in Dengue shock syndrome (DSS). OBJECTIVE: To determine serum lactate and LDH levels in dengue patients to see whether they can be used as predictors of severe dengue cases. MATERIAL AND METHOD: A cross sectional study was conducted on suspected dengue patients admitted to the dengue ward, Queen Sirikit National Institute of Child Health (QSNICH), between May 2011 and February 2012. Laboratory tests were used to confirm dengue cases in the enrolled patients. Blood for serum lactate was drawn in patients every day after enrollment. Blood for LDH and liver function test (LFT) were drawn 3 times: enrollment day, day of leakage, and discharge day. Lactate and LDH levels are compared among dengue and non-dengue patients. Dengue fever (DF), DHF and DSS patients were classified according to the WHO 1997 dengue classification. RESULTS: 253 patients were enrolled, comprising of 120 DF, 75 DH, 30 DSS, and 28 non-dengue patients. The majority of dengue patients had liver impairment, demonstrated by elevated aspartate aminotransferase (AST) (94.9%) and alanine aminotransferase (ALT) levels (68.6%) while non-dengue patients have minimal elevation. Serum lactate levels were not elevated in the early stages in dengue patients, but were elevated in non-dengue patients. The mean serum lactate levels in DSS patients increased towards the end of febrile phase and reached maximum values on Day 0 (2.2 U/L). On the other hand, serum lactate levels were found to be decreasing in the non-dengue group. The mean serum lactate levels on Day 0 was found to be different in DSS patients (2.26 U/L) compared to DF 1.63 U/L), DHF (1.79 U/L) and non-dengue patients (1.68 U/L) (p < 0.05). Mean serum LDH levels were elevated in the early stages of the disease in all groups of patients, but with different levels. Mean serum LDH levels was 709.2 in DF, 1,873 in DHF, 654.5 in DSS, and 434 IU in non-dengue patients. The mean LDH levels in dengue patients were > 500 IU, while it was < 500 IU in non-dengue patients. The increasing mean levels of LDH towards the end of febrile phase were only seen in DHF and DSS patients, but not in DF and non-dengue patients. The mean levels of LDH on Day 0 in DHF, DSS, DF and non-dengue patients are 1,060.7, 1,180.7, 787.2, and 423.8 IU, respectively. CONCLUSION: Serum lactate and LDH was found to be elevated in DHF and/or DSS patients. Lactate may be used as a predictor of DSS if the level is > 2 U/L on Day 0. LDH can be used to differentiate patients with or without dengue in the early febrile phase, if the level is > 500 IU. If the level of LDH is increased to approximately 1, 000 IU on Day 0, it may be a predictor of severe dengue infection or DHF and DSS with plasma leakage.

Intra-genotypic variation of predominant genotype II strains of dengue type-3 virus isolated during different epidemics in Thailand from 1973 to 2001.

The prevalence of all four dengue virus (DENV) serotypes has increased dramatically in recent years in many tropical and sub-tropical countries accompanied by an increase in genetic diversity within each serotype. This expansion in genetic diversity is expected to give rise to viruses with altered antigenicity, virulence, and transmissibility. We previously demonstrated the co-circulation of multiple DENV genotypes in Thailand and identified a predominant genotype for each serotype. In this study, we performed a comparative analysis of the complete genomic sequences of 28 DENV-3 predominant genotype II strains previously collected during different DENV-3 epidemics in Thailand from 1973 to 2001 with the goal to define mutations that might correlate with virulence, transmission frequency, and epidemiological impact. The results revealed (1) 37 amino acid and six nucleotide substitutions adopted and fixed in the virus genome after their initial substitutions over nearly 30-year-sampling period, (2) the presence of more amino acid and nucleotide substitutions in recent virus isolates compared with earlier isolates, (3) six amino acid substitutions in capsid (C), pre-membrane (prM), envelope (E), and nonstructural (NS) proteins NS4B and NS5, which appeared to be associated with periods of high DENV-3 epidemic activity, (4) the highest degree of conservation in C, NS2B and the 5'-untranslated region (UTR), and (5) the highest percentage of amino acid substitutions in NS2A protein.

Secondary dengue serotype 1 infection causing dengue shock syndrome with rhombencephalitis and bleeding associated with refractory thrombocytopenia: A case report.

Background: Dengue has a wide spectrum of manifestations, from an asymptomatic condition to dengue shock syndrome. Extensive plasma leakage, severe bleeding, or both, could lead to dengue shock syndrome, a common cause of death in dengue-infected patients. Thrombocytopenia is a common laboratory finding in dengue, which correlates with the disease severity and rapidly resolves during the recovery phase. Therefore, refractory thrombocytopenia is rare in patients with dengue. Rhombencephalitis is an inflammatory disease affecting the hindbrain, rarely associated with dengue. We report the second case of dengue-associated rhombencephalitis, wherein the patient developed dengue shock syndrome and severe bleeding associated with refractory thrombocytopenia. Case report: A 47-year-old Thai female with secondary dengue serotype 1 infection developed dengue shock syndrome with rhombencephalitis, manifested as altered sensorium and status epilepticus in the critical phase. Cerebrospinal fluid analysis showed pleocytosis with predominantly mononuclear cells and high protein levels. Magnetic resonance imaging of the brain showed multifocal brain signal abnormalities involving the medulla oblongata, pons, midbrain, bilateral hippocampi, thalami, posterior limb of internal capsules, external capsules, and deep hemispheric white matter. The patient had partial neurological recovery following rhombencephalitis for one month. During the recovery phase, severe bleeding with refractory thrombocytopenia and acute kidney injury were observed. Methylprednisolone with eltrombopag was administered, which resulted in an increased the platelet count, cessation of bleeding and recovery of kidney function within 4 days. Conclusions: Dengue is a potential cause of rhombencephalitis. Dengue-associated rhombencephalitis develops during the critical phase, with only partial neurological recovery. However, severe bleeding and refractory thrombocytopenia were also observed during the recovery phase. Methylprednisolone with a thrombopoietin receptor agonist could be an effective treatment for increasing platelet count and stopping bleeding in dengue.

B-cell responses during primary and secondary dengue virus infections in humans.

Low-avidity serotype-cross-reactive antibodies are hypothesized to play a key role in triggering severe disease in patients with secondary dengue virus (DENV) infection. However, there is little systematic information about the frequency, avidity, and cross-reactivity of DENV-specific B cells in individuals experiencing primary instead of secondary infection. We compared DENV-specific B-cell responses in a cohort of Thai children with primary or secondary DENV infection. B cells specific for DENV precursor membrane protein, envelope (E) protein, and nonstructural protein 1 were detectable in immune peripheral blood mononuclear cells with the highest frequencies of DENV E-specific B cells detected in patients experiencing primary DENV-1 infections. DENV E-specific B cells were highly serotype-specific after primary DENV infections, whereas most E-specific B cells in patients with secondary infection were serotype-cross-reactive and secreted antibodies with higher avidity to heterologous DENV serotypes. Our data suggest that the minor populations of serotype-cross-reactive B cells generated by primary DENV infection are preferentially expanded during secondary DENV infection.

Dengue--how best to classify it.

Dengue has emerged as a major public health problem worldwide. Dengue virus infection causes a wide range of clinical manifestations. Since the 1970s, clinical dengue has been classified according to the World Health Organization guideline as dengue fever and dengue hemorrhagic fever. The classification has been criticized with regard to its usefulness and its applicability. In 2009, the World Health Organization issued a new guideline that classifies clinical dengue as dengue and severe dengue. The 2009 classification differs significantly from the previous classification in both conceptual and practical levels. The impacts of the new classification on clinical practice, dengue research, and public health policy are discussed.

Memory CD8+ T cells from naturally acquired primary dengue virus infection are highly cross-reactive.

Cross-reactive memory T cells induced by primary infection with one of the four serotypes of dengue virus (DENV) are hypothesized to have an immunopathological function in secondary heterologous DENV infection. To define the T-cell response to heterologous serotypes, we isolated HLA-A(*)1101-restricted epitope-specific CD8(+) T-cell lines from primary DENV-immune donors. Cell lines exhibited marked cross-reactivity toward peptide variants representing the four DENV serotypes in tetramer binding and functional assays. Many clones responded similarly to homologous and heterologous serotypes with striking cross-reactivity between the DENV-1 and DENV-3 epitope variants. In vitro-stimulated T-cell lines consistently revealed a hierarchical induction of MIP-1ß>degranulation>tumor necrosis factor α (TNFα)>interferon-γ (IFNγ), which depended on the concentration of agonistic peptide. Phosphoflow assays showed peptide dose-dependent phosphorylation of ERK1/2, which correlated with cytolysis, degranulation, and induction of TNFα and IFNγ, but not MIP-1ß production. This is the first study to show significant DENV serotype-cross-reactivity of CD8(+) T cells after naturally acquired primary infection. We also show qualitatively different T-cell receptor signaling after stimulation with homologous and heterologous peptides. Our data support a model whereby the order of sequential DENV infections influences the immune response to secondary heterologous DENV infection, contributing to varying disease outcomes.

Dengue classification: current WHO vs. the newly suggested classification for better clinical application?

INTRODUCTION: There has been confusion regarding the clinical classification of dengue. The current WHO classification used since the 70s classifies dengue into dengue fever (DF), dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS). In 2009, a new classification of dengue proposed by WHO Tropical Disease Research (TDR) was published in the WHO TDR 2009 dengue guidelines. This new classification classifies dengue into dengue (D), dengue with warning signs (DW) and severe dengue (SD). OBJECTIVE: To compare the effectiveness in clinical management between the current WHO classification and the newly suggested classification (TDR) and to assess the 4 criteria of the DHF case definition of the current WHO classification for possible modification. MATERIAL AND METHOD: A prospective study of suspected dengue patients admitted to the Dengue Unit, Queen Sirikit National Institute of Child Health between June-August 2009 was done. All cases were managed according to the Thai National Dengue Guidelines 2008. The final diagnoses were based on the current WHO Classification together with dengue laboratory confirmation. TDR classification was applied later by the author, using the data from the present study case report forms of each patient. Statistical analysis comparing clinical and laboratory data between each group of patients was done by using SPSS version 14. RESULTS: Total 274 confirmed dengue patients and 24 non-dengue febrile illnesses (ND) were used for analysis. There were 180 DF (65.7%), 53 DHF grade I (19.3%), 19 DHF grade II (6.9%), 19 DHF grade II (6.9%) and 3 DHF grade IV (1.1%) as classified by the current WHO classification while the suggested TDR classified 85 (31%), 160 (58.4%) and 29 (1.1%) as D, DW and SD respectively. At least one of the warning signs were found in 50, 53.3, 83, 88.2, 100 and 100% of ND, DF, DHF grade I, DHF grade II, DHF grade III and DHF grade IV patients. Vomiting and abdominal pain were the 2 most common warning signs found in both ND and dengue patients. Intensive monitoring and careful medical and i.v. fluid management were needed for 94 DHF patients compared to 189 DW and SD patients by the new TDR classification. There were 8 DSS patients who had AST > 1,000U and one patient presented with encephalopathy. These 8 patients cannot be classified properly in the current WHO classification. One non-dengue patient who presented with gastrointestinal bleeding was classified as SD. Bleeding and/or positive tourniquet test was found in and 69.7% of DHF patients. Plasma leakage detected using hemoconcentration, chest x-ray (CXR) and ultrasonography. Hemoconcentration could detect plasma leakage in 44.7% and CXR added up evidence of plasma leakage to 86.3%. Ultrasonography was the most sensitive technique to add evidence of plasma leakage up to 100%. Platelet < or = 100,000 cells/mm3 was found in 93.5% of DHF patients. CONCLUSION: Current WHO classification is recommended for continuing use because the newly suggested TDR classification creates about 2 times the workload to health care personnel. In addition, the TDR classification needs dengue confirmatory tests. More than 90% of DHF defined by WHO case definition are dengue confirmed. However, current WHO classification needs to be modified for more simple and friendly use. The suggested modification is to address plasma leakage as the major criteria. Tourniquet test positive or bleeding symptoms can be considered as minor criteria. Unusual dengue is proposed to be added to the current WHO classification to cover those patients who do not fit with the current WHO classification.

Dengue shock syndrome at the emergency room of Queen Sirikit National Institute of Child Health, Bangkok, Thailand.

BACKGROUND: Dengue virus infection is an important mosquito-borne disease with the reported 40,000-100,000 cases per year in Thailand. Shock is one of the common presentations at the emergency room (ER) and dengue shock syndrome (DSS) is among the common causes of shock. Proper and timely management of DSS determines the outcomes and prognosis of DSS patients. OBJECTIVE: To find the prevalence of DSS at the ER and evaluate the medical management and risk factors associated with the outcome of DSS patients. MATERIAL AND METHOD: A retrospective study on patients who presented with shock, including DSS patients at the ER of Queen Sirikit National Institute of Child Health (QSNICH), Bangkok, Thailand, from 1st January 2008 to 31st December 2009 was done. The prevalence of patients who presented with shock at the ER was retrieved from the Statistical and Information Technology Departments. Out-patient cards and In-patient charts of DSS patients were reviewed. Clinical and laboratory data were compared between recovered and death cases. Statistical analysis was done by using SPSS version 14.0. RESULTS: There were 109 shock patients seen at the ER during the present study period with 59 DSS (54.1%), 30 septic shock (27.5%), 13 hypovolemic shock (11.9%), 1 cardiogenic shock (0.9%) and 6 other non-specific shock (5.5%). DSS cases were found all year round with the peak prevalence from June to August which is the rainy season. Twenty-six of DSS (44.1%) were referred cases and 5 of them died, case fatality rate was 8.8%. All death cases had prolonged shock, massive bleeding and liver failure at presentation while these findings were found in 2 (4.4%), 16 (35.6%) and 10 (22.2%) cases of recovered cases. Encephalopathy, renal failure and respiratory failure were found in 80, 60 and 60% of the death cases while in recovered cases they were found in 11.1, 4.4 and 2.2%. Acidosis was found higher in the death group (60%) than in recovered group (8.9%). Other common presenting findings in death and recovered groups were bleeding (35.6 vs 100.0%), fluid over load (31.1 vs. 80%), hyponatremia (40% for both groups) and hypocalcemia (83.3 vs. 80%). Among the 45 recovered cases; 3 cases were misdiagnosed and another 8 cases (17.8%) received no i.v. fluid at the ER. Cross matching was done in 32 cases (64%) and blood was transfused in 16 cases (50% of the cross matching). CONCLUSION: DSS is the most common shock found at the ER especially during June to August. ER physicians should be alert for making the correct diagnosis of DSS with proper intravenous fluid resuscitation and correction of the common complications/laboratory abnormalities, i.e. acidosis, hyponatremia, hypocalcemia and cross matching for massive bleeding. A referred case with liver failure together with renal and respiratory failure was likely associated with mortality while fluid overload and significant bleeding do not if they are managed properly. Early signs of shock should be detected in walk in cases to prevent later shock after admission.

Dengue hemorrhagic fever grade III with diabetic ketoacidosis: a case report.

A 16-year-old, previously healthy Thai girl presented with DHF grade III. Fifteen hours after the first episode of shock, she had received an excessive amount of crystalloid isotonic solution and 20 ml per kilograms of Dextran-40 however she still had persistently rapid pulse rate and high hematocrit but also had polyuria with more than 4 ml/kg/hr of urine output. She was re-evaluated. Clinical signs showed severe dehydration with some ascites without signs of pleural effusion. Blood gas revealed increased anion gap metabolic acidosis. The cause of polyuria and metabolic acidosis was identified with hyperglycemia, ketouria and glucosuria. Afterwards she was diagnosed and treated as DHF grade III and DKA. Besides insulin administration, fluid resuscitation was very crucial. Intravenous fluid rehydration was needed while the unnecessary extra-volume could cause massive plasma leakage and later on fluid overload. Volume replacement was adjusted to degree of dehydration when signs of volume overload were monitored closely. She was out of DKA at 14 hours after the start of insulin and the intravenous fluid was stopped at 27 hours (36 hours after the first episode of shock). The final diagnosis was DHF grade III, diabetes mellitus with DKA and hepatitis.

Mechanisms of immune evasion induced by a complex of dengue virus and preexisting enhancing antibodies.

We have found that dengue virus (DENV) not only uses preexisting enhancing antibodies to promote its entry into Fc receptor-bearing cells but also exploits enhancing antibodies for intracellular immune evasion through 2 mechanisms. In the first mechanism, entry of DENV-antibody complexes into human monocytic cells activates negative regulators, dihydroxyacetone kinase and autophagy-related 5-autophagy-related 12, which then disrupt the retinoic acide incucible gene I and melanoma differentiation associated gene 5 signaling cascade and disable type 1 interferon production, leading to suppression of interferon-mediated antiviral responses. In the second mechanism, the immune evasion was found to be mediated by the suppressive cytokine interleukin 10 (IL-10). High levels of IL-10 activated expression of suppressor of cytokine signaling 3 gene, which subsequently inactivated the Janus kinase-signal transducer and activator of transcription pathway. Inhibition of IL-10 production by small interfering RNA down-regulated suppressor of cytokine signaling 3 gene expression, restored inducible nitric oxide synthase gene expression, and suppressed DENV replication. Importantly, we were able to demonstrate that these 2 loops of suppression occurred in patients with severe secondary dengue infection (dengue hemorrhagic fever) but not in patients with mild secondary dengue infection (dengue fever).

Predictors of plasma leakage among dengue patients in Thailand: A plasma-leak score analysis.

Delayed plasma leakage recognition could lead to improper fluid administration resulting in dengue shock syndrome, subsequently, multi-organ failure, and death. This prospective observational study was conducted in Bangkok, Thailand, between March 2018 and February 2020 to determine predictors of plasma leakage and develop a plasma leakage predictive score among dengue patients aged ≥15 years. Of 667 confirmed dengue patients, 318 (47.7%) developed plasma leakage, and 349 (52.3%) had no plasma leakage. Multivariate analysis showed three independent factors associated with plasma leakage, including body mass index ≥25.0 kg/m2 (odds ratio [OR] = 1.784; 95% confidence interval [CI] = 1.040-3.057; P = 0.035), platelet count <100,000/mm3 on fever days 3 to 4 (OR = 2.151; 95% CI = 1.269-3.647; P = 0.004), and aspartate aminotransferase or alanine aminotransferase ≥100 U/l on fever days 3 to 4 (OR = 2.189; 95% CI = 1.231-3.891; P = 0.008). Because these three parameters had evidence of equality, each independent factor was weighted to give a score of 1 with a total plasma-leak score of 3. Higher scores were associated with increased plasma leakage occurrence, with ORs of 2.017 (95% CI = 1.052-3.869; P = 0.035) for score 1, 6.158 (95% CI = 2.914-13.015; P <0.001) for score 2, and 6.300 (95% CI = 2.419-16.407; P <0.001) for score 3. The area under the receiver operating characteristics curves for predicting plasma leakage was good (0.677 [95% CI = 0.616-0.739]). Patients with a plasma-leak score ≥1 had high sensitivity (88.8%), and those with a plasma-leak score of 3 had high specificity (93.4%) for plasma leakage occurrence. This simple and easily accessible clinical score might help physicians provide early and timely appropriate clinical dengue management in endemic areas.