Ultrasound measurement of gallbladder wall thickening as a diagnostic test and prognostic indicator for severe dengue in pediatric patients

Evaluation of remote radiologist-interpreted point-of-care ultrasound for suspected dengue patients in a primary health care facility in Colombia

BACKGROUND

Early identification of plasma leakage may guide treatment decisions in dengue patients. This study evaluated the value of point-of-care ultrasound (POCUS) to detect plasma leakage and predict hospitalization or referral to a higher level of care in suspected dengue patients under routine conditions at a primary care facility in Colombia.

METHODS

We conducted a cohort study between April 2019 and March 2020 in a primary care hospital in Cali, Colombia. We prospectively included and followed 178 patients who were at least 2 years old with fever of less than 10 days and clinician-suspected dengue. A trained general practitioner performed a standardized POCUS protocol. Images were quality-rated and overread by an expert radiologist, and her results and those of the general practitioner were compared using the Kappa index. Logistic regression was used to identify factors associated with plasma leakage at enrollment and explore its prognostic value regarding hospital admission or referral to a higher level of care.

RESULTS

Half (49.6%) POCUS images were of suitable quality to be interpreted. The proportion of plasma leakage reported by the radiologist was 85.1% (95% CI: 78.6-90.2%) and 47.2% by the study physician (Kappa = 0.25, 95% CI: 0.15-0.35). The most frequent ultrasound findings were ascites (hepatorenal 87.2%, splenorenal 64%, or pelvic 21.8%) and gallbladder wall thickening (10.5%). Plasma leakage was higher in subjects with thrombocytopenia (aOR = 4, 95% CI: 1.3-12.1) and lower in patients 30-59 years old (aOR = 0.1, 95% CI: 0.0-0.4) than in those 18 years old or younger. POCUS evidence of plasma leakage (aOR = 8.2, 95% CI: 2.2-29.9), thrombocytopenia (aOR = 6.3, 95% CI: 2.4-16.0) and pulse pressure (aOR = 1.1, 95% CI: 1.07-1.2) were associated with hospital admission or referral to a higher level of care.

CONCLUSIONS

Ultrasound is useful to detect plasma leakage in primary care and, challenges remain to guarantee high-quality images and diagnostic accuracy, for which a standardized dengue POCUS protocol and training program is needed.

Long-Segment Epidural Hemorrhage of the Cervical and Dorsal Spine: A Case Report of a Rare Complication of Dengue Virus Disease

Dengue hemorrhagic fever is a severe form of dengue virus disease, characterized by minor to major bleeding, thrombocytopenia, and plasma leakage. Common hemorrhagic manifestations include epistaxis, gum bleeding, gastrointestinal bleeding, hypermenorrhea, and hematuria. Intracranial hemorrhage is one of the most fatal manifestations of central nervous system involvement by dengue disease which is a part of the expanded dengue syndrome. Here we present a case of A 37-year-old male patient who presented with complaints of intermittent high-grade fever and generalized weakness four days prior to consultation. Laboratory investigations revealed mild thrombocytopenia and positive dengue serology. Magnetic resonance imaging of the brain and spine revealed mild diffuse subarachnoid hemorrhage in bilateral parieto-occipital lobes with long segment cervical and dorsal spinal epidural hemorrhage.

Incidental Findings of Gallbladder and Bile Ducts-Management Strategies: General Aspects, Gallbladder Polyps and Gallbladder Wall Thickening-A World Federation of Ultrasound in Medicine and Biology (WFUMB) Position Paper

The World Federation of Ultrasound in Medicine and Biology (WFUMB) is addressing the issue of incidental findings with a series of position papers to give advice on characterization and management. The biliary system (gallbladder and biliary tree) is the third most frequent site for incidental findings. This first part of the position paper on incidental findings of the biliary system is related to general aspects, gallbladder polyps and other incidental findings of the gallbladder wall. Available evidence on prevalence, diagnostic work-up, malignancy risk, follow-up and treatment is summarized with a special focus on ultrasound techniques. Multiparametric ultrasound features of gallbladder polyps and other incidentally detected gallbladder wall pathologies are described, and their inclusion in assessment of malignancy risk and decision- making on further management is suggested.

Early diagnostic markers in predicting the severity of dengue disease

The aim of the present study was to determine whether the serum ferritin, the biomarker of an acute phase reactant and the gall bladder wall edema, an early indicator of capillary leakage can predict the severity of dengue fever. This study included 131 patients, who were between the age group of 18–80 years. The patients presented to our department with an acute illness, within the first four days of high temperature. The statistical analysis of this study was performed by using the Chi-square and independent Student’s t tests. The diagnostic markers are considered statistically significant, if the serum ferritin level is higher than 500 ng/ml and the gall bladder wall thickness is more than 3 mm. The present study observed that, 39 patients (89%) who had severe dengue (n = 44) revealed a significant gall bladder wall thickening, and this correlation was significant statistically (p < 0.000). It was also observed that, the ferritin levels have a highly significant positive correlation with the severity of dengue. The severe dengue patients had a mean ferritin level of 9125.34 μg/l, whereas the non-severe group had 4271 μg/l. This comparison was also statistically significant, as the p value was 0.003. We report that the serum ferritin levels have a highly significant positive correlation with the severity of dengue. The gall bladder wall edema during the third and fourth day of the illness was also associated with severe dengue. However, diffuse gall bladder wall thickening and high serum ferritin levels are also reported in various other conditions and their exact cause have to be determined by the correlation of associated clinical findings and imaging features.

The association of ultrasound assessment of gallbladder wall thickness with dengue fever severity

Objectives

To evaluate the association between ultrasound assessment of gallbladder wall thickness (GBWT) among severe dengue patients and dengue patients with warning signs to their clinical outcomes.

Methods

A prospective, cross-sectional study involving adult dengue patients presented to our emergency department between March until September 2018. The patients were classified based on WHO classification. A gallbladder wall scan was performed on all patients.

Results

A total of 44 patients were enrolled into the study; majority of the patients with GBWT had severe dengue, significantly more than the dengue patients with warning signs (90.5% sensitivity; 69.6% specificity). The sensitivity of GBWT in determining admission to critical care areas or general ward was 100% with a specificity of 62.1%. Our analysis showed that the two variables significant in determining the severity of dengue were age (p = 0.045) and GBWT (p < 0.001). Both factors together gave 81.0% sensitivity and 78.3% specificity in predicting patients for severe dengue. The receiver operator characteristic curve revealed that using variable GBWT status can discriminate 87.1% (95%CI 66.3, 93.7%) of having severe dengue or dengue with warning signs.

Conclusion

The finding of GBWT when consolidated with other clinical parameters may assist clinicians to perform risk stratification in the emergency department and become another adjunct to the assessment of severe dengue.

Unusual clinical manifestations of dengue disease - Real or imagined?

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

Clinical relevance of gallbladder wall thickening for dengue severity: A cross-sectional study

Dengue fever is the most important arthropod-borne viral infection worldwide. Secondary prevention to reduce mortality through improved clinical case management has substantially lowered the mortality rate for severe dengue during the past two decades. Gallbladder wall thickening (GBWT) is a nonspecific finding often associated with more severe cases of dengue infection. This study had the aim to describe the ultrasonographic findings in hospitalized patients with dengue infection from Manaus (in the Western Brazilian Amazon) and to correlate the GBWT with dengue severity, symptoms and laboratorial analysis. Patients from 13-84 years admitted to the emergency department at the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD) were enrolled in this study. Patients' selection occurred during the most recent and huge dengue outbreak within the first semester of 2011. All enrolled subjects were systematically tested in order to rule out other possible etiologies for gallbladder inflammation. Abdominal ultrasound was performed by a single physician through bedside portable equipment and all other clinical and laboratorial information were retrieved from patients' electronic files. 54 subjects were considered for analysis, with confirmed dengue infection by NS1 and/or RT-PCR positivity. From all enrolled patients, 50 (42.4%) presented GBWT. GBWT was significantly and independently related to: age under 31 years, pregnancy, presence of bleeding, presence of any cavitary effusion, DHF classification and severe dengue classifications. During dengue outbreaks, the GBWT identification through a non-invasive and bedside procedure is a confident marker for prompt recognition of potential severe cases.

Ultrasound Assessment of Hepatobiliary and Splenic Changes in Patients With Dengue and Warning Signs During the Acute and Recovery Phases

OBJECTIVES

To evaluate whether abdominal ultrasound (US) with a gallbladder (GB) contractility study or motor function test can be used as a diagnostic tool in patients with dengue and warning signs in acute and recovery phases.

METHODS

Fifty-one individuals in the acute phase of dengue presenting with warning signs (dengue group) and 49 healthy individuals without a history of dengue or hepatobiliary disease (control group) were studied with abdominal US and a GB contractility study.

RESULTS

Statistical differences in US measurements of the liver (right lobe, P = .012; left lobe, P = .001) and spleen (P = .008) dimensions, GB wall thickness (P < .001), and the GB emptying fraction (P < .001) were observed in dengue during the acute phase compared with the control group. After 60 days, abdominal US of the dengue group showed a statistical difference in liver (right lobe, P < .001; left lobe, P = .078) and spleen (P < .001) dimensions, GB wall thickness, and the GB emptying fraction (P < .001) compared with the results obtained during the acute phase. Furthermore, a statistical difference in the spleen volume and GB emptying fraction (P < .001) was observed when comparing dengue after clinical recovery and the control group. Abdominal pain in patients with dengue was positively associated with hepatomegaly (P = .031), splenomegaly (P = .008), increased GB wall thickness (P = .016), and a reduced GB emptying fraction (P = .038) during the acute phase and with splenomegaly (P = .001) and a reduced GB emptying fraction (P = .003) after clinical recovery.

CONCLUSIONS

Abdominal US with a GB motor function test can be used as a diagnostic tool in patients with dengue during acute and recovery phases.

The Clinical and Serological Profile of Pediatric Dengue

OBJECTIVE

To classify suspected dengue into dengue, dengue with warning signs and severe dengue, based on clinical features as per the revised WHO guidelines with special emphasis on serology.

METHODS

It was a prospective cross-sectional study for five years from 2011-2016 in a tertiary care medical college hospital in Bangalore. All cases of fever of three to five days duration with symptoms like dengue were enrolled for the study. They were categorized into three groups as per the Revised WHO 2012 criteria. Laboratory parameters, serology, ultrasound abdomen and X-ray were done in almost all patients. Data was analysed by SPSS software, version 16, and different groups were compared with Chi square test.

RESULTS

Five hundred sixty eight children were diagnosed to have dengue fever; 4.2% of the sample belonged to infancy. Majority were in the age group of 5-10 y (42.6%). Fever and flushing were present in majority of the children. Gastrointestinal bleed was more commonly seen in the severe dengue group. Dengue nonstructural protein antigen (NS1Ag) was positive in 78%, immunoglobulin M (IgM) in 15.8% and immunoglobulin G (IgG) in 14.6%. Children with IgG had more complications, though not statistically significant. Mortality was reported in 1.2%. Dengue serology helped to confirm the diagnosis, however did not help in patient management.

CONCLUSIONS

There is a considerable overlap in the symptomatology of dengue with warning signs and severe dengue. More studies are required on the severity and type of response to treatment in infants and obese adoloscents with severe dengue.

Ultrasound is Not Useful as a Screening Tool for Dengue Fever

Background

Dengue fever is a tropical disease that is transmitted by female Aedes Aegypti mosquitos. Early diagnosis is necessary to reduce the mortality and morbidity associated with the disease. A combination of clinical, laboratory, and sonography findings can be potentially helpful in making an early diagnosis of dengue fever. There is paucity of literature on the use of ultrasound for dengue fever screening; hence, the primary objective of the study was to evaluate the utility of ultrasound as a screening tool in dengue fever.

Material/Methods

A total of 160 patients of suspected dengue fever were included in the study. They underwent ultrasound examinations in order to search for thickening of the gallbladder wall, pleural effusion, and ascites. On the basis of ultrasound findings, 65 cases were positive and 95 cases were negative for dengue fever. Serological tests were also used for diagnosing dengue fever, 93 cases were seropositive and 67 cases were seronegative. The ultrasonically diagnosed cases were compared with serologically diagnosed cases, and appropriate descriptive statistical analyses were applied.

Results

The ultrasound findings included gall bladder wall thickening in 66 patients (41.2%). The sensitivity, specificity, and positive predictive value of ultrasound in diagnosing dengue fever were 58%, 84%, and 83%, respectively. The negative predictive value and accuracy were 59% and 68.8%, respectively.

Conclusions

The present study suggests that increased gall bladder wall thickness, pleural effusion, ascites, hepatomegaly, and splenomegaly are highly suggestive of dengue fever in clinically suspected cases. However, ultrasound should not be used as a screening tool, as negative ultrasound findings cannot rule out dengue fever due to the low sensitivity of this examination.

Patterns of Gall Bladder Wall Thickening in Dengue Fever: A Mirror of the Severity of Disease

BACKGROUND

Dengue fever is a major public health problem with an increased incidence in recent years. Gall bladder wall thickening has been reported as one of the most common findings in dengue fever. There is a paucity of literature regarding the various patterns of gall bladder wall thickening in dengue fever and their significance in predicting the severity of disease.

METHODOLOGY AND SIGNIFICANT FINDINGS

Out of 93 seropositive patients included in the study, 54 patients with dengue fever had gall bladder wall thickening. 4 patterns of gall bladder wall thickening are demonstrated in this study. A uniform echogenic pattern in 20 patients, striated or tram track pattern in 11 patients, an asymmetric pattern in 2 patients and a honeycombing pattern in 21 patients. The range of patterns of wall thickening included normal wall thickening or uniform echogenic wall thickening in DF without warning signs, a striated or tram track pattern, and a honeycomb pattern in severe DF. Serial ultrasound done on consecutive alternate days revealed a change in the pattern of gall bladder wall thickening according to the severity of disease.

CONCLUSION

The present study revealed 4 distinct patterns of gall bladder wall thickening. The uniform echogenic pattern was found to be more prevalent in dengue fever without warning signs, while the honeycomb pattern was found to be more prevalent in severe dengue fever. A change in the pattern of gall bladder wall thickening on subsequent serial ultrasound can predict the severity of the disease.

[Autochthonous dengue]

Dengue is the arboviral disease that has massively spread in intertropical regions these past few years. The rise in imported cases of dengue and the rapid spread of the Aedes vector mosquitoes in continental France since 2004 explain the occurrence of indigenous dengue cases among the nonimmune population and points to an epidemic risk. Severe dengue cases are rare, but lethality is highest among children under 5 years of age. Like pediatricians in tropical regions, we must learn how dengue presents in metropolitan France and how it can be managed, and pay special attention to severe and potentially fatal forms. The epidemiological, pathophysiological, clinical, diagnostic, and therapeutic characteristics of dengue are presented herein.

Clinical Profile of Atypical Manifestations of Dengue Fever

OBJECTIVES

To study the clinical profile and outcome of the atypical manifestations of dengue fever in children.

METHODS

All children (0-12 y of age) diagnosed and confirmed as dengue fever at a tertiary care hospital at Puducherry, between the 1st of August 2012 and January 31st 2015 were reviewed retrospectively from hospital case records as per the revised World Health Organization (WHO) guidelines 2011 for dengue fever. The diagnosis was confirmed by NS1 antigen-based ELISA test or dengue serology for IgM and IgG antibodies and the data was analyzed using SPSS 16.0 statistical software.

RESULTS

Out of 254 children admitted with dengue fever, non-severe dengue and severe dengue were seen in 62.6 % and 37.4 % respectively. Atypical manifestations were seen in 106 cases (41.7 %). Mean age of presentation was 6.9(3.3) y. M: F ratio was 1.2:1. The common manifestations of severe dengue infection were shock (37.4 %), bleeding (20.1 %) and multi-organ dysfunction (2.4 %). The most common atypical manifestations of dengue fever were lymphadenopathy (41.7 %), splenomegaly (21.2 %), biphasic fever (18.1 %), hepatitis (11.4 %), febrile diarrhea (6.3 %), refractory shock (2.4 %) and impaired consciousness (1.9 %). The other atypical manifestations present were portal hypertension, acalculous cholecystitis, appendicitis, acute respiratory distress syndrome (ARDS), myocarditis, pericardial effusion, paroxysmal supraventricular tachycardia (PSVT), myositis, acute kidney injury (AKI), hemophagocytic syndrome and disseminated intravascular coagulopathy (DIC). Platelet count did not always correlate well with the severity of bleeding. There were six deaths (2.4 %) and out of them four presented with impaired consciousness (66.6 %). The common causes for poor outcome were multiorgan failure, encephalopathy and refractory shock.

CONCLUSIONS

The atypical manifestations of dengue fever are no more a rare entity. Clinicians should have a high index of suspicion and vigilance for atypical manifestations of dengue fever as lack of timely detection and management could be fatal. Impaired consciousness was the most ominous atypical manifestation of severe dengue infection.

Is Ultrasound a Useful Tool to Predict Severe Dengue Infection?

OBJECTIVES

To study the role of ultrasound in children with dengue fever and determine its role in predicting the severity of the disease.

METHODS

This was a retrospective hospital based study conducted from 1(st) August 2012 to January 31(st) 2015 at a tertiary care hospital in Puducherry.

RESULTS

Two hundred and fifty four children were admitted with dengue fever and among them non-severe dengue and severe dengue were seen in 62.6 % and 37.4 % respectively. Mean age of presentation was 7.0 (3.3) years. M: F ratio was 1.2:1 Ultrasound was performed on all children with dengue fever during the critical period of illness as an early sign of plasma leakage and at the time of discharge. The diagnosis was confirmed by NS1 antigen and dengue serology. Ultrasonography showed positive findings in 156 cases (61.4 %) during the critical period of illness. Ultrasound findings were analyzed using logistic regression among severe and non-severe dengue and P value of <0.05 was taken as significant. The common ultrasound findings that were significantly associated with severe dengue infection on univariate analysis were gall bladder wall thickening, ascites, pleural effusion, pericardial effusion, pericholecystic fluid, hepatomegaly, splenomegaly and mesenteric adenopathy. On multivariate analysis, gall bladder thickening and hepatomegaly were significantly associated with severe dengue infection. Gall bladder wall thickening (GBWT) with honeycombing pattern was the most specific finding in severe dengue infection in the study and significantly associated with severe thrombocytopenia (Platelet count <50,000/mm(3)). The clinical improvement coincided with resolving of the ultrasound findings at the time of discharge.

CONCLUSIONS

Ultrasound can be used as an early predictor as well as an important prognostic sign for severe dengue infection especially during an epidemic.

Vascular leakage in dengue--clinical spectrum and influence of parenteral fluid therapy

OBJECTIVE

Clinical management of dengue relies on careful monitoring of fluid balance combined with judicious intravenous (IV) fluid therapy. However, in patients with significant vascular leakage, IV fluids may aggravate serosal fluid accumulation and result in respiratory distress.

METHODS

Trained physicians followed suspected dengue cases prospectively at seven hospitals across Asia and Latin America, using a comprehensive case report form that included daily clinical assessment and detailed documentation of parenteral fluid therapy. Applying Cox regression, we evaluated risk factors for the development of shock or respiratory distress with fluid accumulation.

RESULTS

Most confirmed dengue patients (1524/1734, 88%) never experienced dengue shock syndrome (DSS). Among those with DSS, 176/210 (84%) had fluid accumulation, and in the majority (83%), this was detectable clinically. Among all cases with clinically detectable fluid accumulation, 179/447 (40%) were diagnosed with shock or respiratory distress. The risk for respiratory distress with fluid accumulation increased significantly as the infused volume over the preceding 24 h increased (hazard ratio 1.18 per 10 ml/kg increase; P < 0.001). Longer duration of IV therapy, use of a fluid bolus in the preceding 24 h, female gender and poor nutrition also constituted independent risk factors.

CONCLUSIONS

Shock and respiratory distress are relatively rare manifestations of dengue, but some evidence of fluid accumulation is seen in around 50% of cases. IV fluids play a crucial role in management, but they must be administered with caution. Clinically and/or radiologically detectable fluid accumulations have potential as intermediate severity endpoints for therapeutic intervention trials and/or pathogenesis studies.

Application of Ultrasonography in the Diagnosis of Infectious Diseases in Resource-Limited Settings

Ultrasound (US) has vast potential in the field of infectious diseases, especially so in resource-limited settings. Recent technological advances have increased availability and access to ultrasound in low-resource settings, where the burden of infectious diseases is greatest. This paper collates the evidence for the utilization of ultrasound and evaluates its effectiveness in the diagnosis and management of a range of infectious diseases. This paper explores the role of ultrasound in population-based screening for specific diseases as well as highlights its benefits for individual patient management. We describe the common diagnostic signs seen on US for common and neglected parasitic, bacterial, and viral diseases. We proceed to document the emerging field of chest US which is proving to be a superior imaging modality for the diagnosis of specific pulmonary conditions. We conclude by discussing the efforts needed to formalize and rigorously evaluate the role of ultrasound in infectious diseases.

Risk factors for shock in children with dengue fever

OBJECTIVES

To evaluate and analyze the clinical and laboratory parameters that were predictive of the development of shock in children with dengue fever.

SUBJECTS AND METHODS

Retrospective study carried out from August 2012 to July 2014 at a tertiary care hospital in Puducherry.

RESULTS

Two hundred and fifty-four children were admitted with dengue fever and among them dengue fever without shock was present in 159 children (62.5%) and dengue fever with shock was present in 95 cases (37.4%). Various clinical and laboratory parameters were analyzed using univariate and multivariate logistic regression between the two groups and a P value of <0.05 was taken as significant. The most common risk factors for shock on univariate analysis were headache, retro-orbital pain, palmar erythema, joint pain, facial flush, splenomegaly, lymphadenopathy, bleeding, giddiness, persistent vomiting, pleural effusion, ascites, hematocrit >20% with concomitant platelet count <50,000/mm(3) on admission, deranged liver function tests, and gallbladder wall edema. On multivariate analysis, it was seen that in age >6 years, hepatomegaly, pain in the abdomen, and oliguria were the most common risk factors associated with shock in children with dengue fever. There were six deaths (2.4%) and out of them four presented with impaired consciousness (66.6%) at the time of admission.

CONCLUSION

Age >6 years, hepatomegaly, abdomen pain, and oliguria were the most common risk factors for shock in children with dengue fever. Impaired consciousness at admission was the most ominous sign for mortality in dengue fever. Hence, these features should be identified early, monitored closely, and managed timely.

Infectious Chikungunya Virus in the Saliva of Mice, Monkeys and Humans

Chikungunya virus (CHIKV) is a reemerging, ordinarily mosquito-transmitted, alphavirus that occasionally produces hemorrhagic manifestations, such as nose bleed and bleeding gums, in human patients. Interferon response factor 3 and 7 deficient (IRF3/7^-/-) mice, which are deficient for interferon α/β responses, reliably develop hemorrhagic manifestations after CHIKV infection. Here we show that infectious virus was present in the oral cavity of CHIKV infected IRF3/7^-/- mice, likely due to hemorrhagic lesions in the olfactory epithelium that allow egress of infected blood into the nasal, and subsequently, oral cavities. In addition, IRF3/7^-/- mice were more susceptible to infection with CHIKV via intranasal and oral routes, with IRF3/7^-/- mice also able to transmit virus mouse-to-mouse without an arthropod vector. Cynomolgus macaques often show bleeding gums after CHIKV infection, and analysis of saliva from several infected monkeys also revealed the presence of viral RNA and infectious virus. Furthermore, saliva samples collected from several acute CHIKV patients with hemorrhagic manifestations were found to contain viral RNA and infectious virus. Oral fluids can therefore be infectious during acute CHIKV infections, likely due to hemorrhagic manifestations in the oral/nasal cavities.

Clinical profile of dengue among children according to revised WHO classification: analysis of a 2012 outbreak from Southern India

OBJECTIVE

To study the clinical profile of dengue fever and its outcome in children with application of revised WHO classification and to identify risk factors for severe dengue.

METHODS

This study was a prospective observational study of children diagnosed with dengue from July 2012 through February 2013 at a tertiary care hospital in Bangalore, Karnataka (South India).

RESULTS

Eighty one children including 55(67.9 %) boys and 26(32.1 %) girls were diagnosed with dengue. Mean age of presentation was 8 y. Vomiting (60.5 %), pain abdomen (32 %), headache (30.9 %), myalgia (23.5 %) and bleeding manifestations (16 %) were the common presenting complaints. Facial puffiness (63 %), hepatomegaly (51.9 %), ascites (48.1 %), pleural effusion (39.5 %) and petechiae (14.8 %) were noted during examination. Dengue NS1 antigen, IgM, IgG were positive in 66.7 %, 29.6 % and 18.5 % of cases respectively. Investigations showed hemoconcentration in 72.8 %, leucopenia (34.5 %), thrombocytopenia (82.7 %), abnormal liver function test (LFT) (33.3 %). USG abdomen was suggestive of dengue in 66.7 % and gall bladder edema was noted in 53.1 %. Two patients died out of the total 81 patients with mortality rate of 2.5 %. Number of cases classified as Dengue without warning signs (D), Dengue with warning signs (DW) and Severe Dengue (SD) were 48.1 %, 27.2 % and 24.7 % respectively.

CONCLUSIONS

Children between 5 and 15 y were most affected by dengue fever. Pain abdomen and vomiting were most common presenting symptoms. Ascites, plerural effusion, hepatomegaly, gall bladder wall thickening and abnormal LFT were found significantly high in severe dengue cases.

Dengue

Dengue viruses have spread rapidly within countries and across regions in the past few decades, resulting in an increased frequency of epidemics and severe dengue disease, hyperendemicity of multiple dengue virus serotypes in many tropical countries, and autochthonous transmission in Europe and the USA. Today, dengue is regarded as the most prevalent and rapidly spreading mosquito-borne viral disease of human beings. Importantly, the past decade has also seen an upsurge in research on dengue virology, pathogenesis, and immunology and in development of antivirals, vaccines, and new vector-control strategies that can positively impact dengue control and prevention.

The revised dengue fever classification in German travelers: clinical manifestations and indicators for severe disease

BACKGROUND

The number of dengue cases imported to Germany has increased significantly in recent years. Among returning travelers, dengue is now a frequent cause of hospitalization. The aim of this study was to determine the proportion of patients with severe disease hospitalized in a European, non-endemic country applying the revised 2009 WHO classification system and to determine predictors of severe disease.

METHODS

A retrospective single-center analysis of clinical data from 56 patients, 31 (55 %) women and 25 (45 %) men, between 14 and 70 years of age treated in a tertiary care hospital between 1996 and 2010 was conducted.

RESULTS

Thirty-nine patients (69.6 %) presented with dengue fever without warning signs, 11 (19.6 %) with warning signs and 6 (10.7 %) with signs for severe dengue fever. Two patients (4 %) developed dengue shock syndrome. Non-European descent (p = 0.001), plasma protein level <6.5 mg/dl (p = 0.001), platelets <30/nl (p = 0.017) and activated partial thromboplastin time (aPTT) >44 s (p = 0.003) were associated with severe disease.

CONCLUSIONS

A significant proportion of patients hospitalized with symptomatic imported dengue fever in Germany have evidence of severe disease. Simple routine laboratory parameters such as complete blood count, plasma protein level and aPTT are helpful tools for identifying adult patients at risk for severe disease.

Predicting outcome from dengue

Dengue is emerging as one of the most abundant vector-borne disease globally. Although the majority of infections are asymptomatic or result in only a brief systemic viral illness, a small proportion of patients develop potentially fatal complications. These severe manifestations, including a unique plasma leakage syndrome, a coagulopathy sometimes accompanied by bleeding, and organ impairment, occur relatively late in the disease course, presenting a window of opportunity to identify the group of patients likely to progress to these complications. However, as yet, differentiating this group from the thousands of milder cases seen each day during outbreaks remains challenging, and simple and inexpensive strategies are urgently needed in order to improve case management and to facilitate appropriate use of limited resources. This review will cover the current understanding of the risk factors associated with poor outcome in dengue. We focus particularly on the clinical features of the disease and on conventional investigations that are usually accessible in mid-level healthcare facilities in endemic areas, and then discuss a variety of viral, immunological and vascular biomarkers that have the potential to improve risk prediction. We conclude with a description of several novel methods of assessing vascular function and intravascular volume status non-invasively.

Endothelial cells in dengue hemorrhagic fever

Therapies to prevent or reverse endothelial dysfunction and vascular leak found in dengue hemorrhagic fever (DHF) have not been identified. In this review we summarize dengue viruses and the spectrum of human disease and highlight evidence of endothelial cell dysfunction in DHF based on studies in patients and mouse and tissue culture models. Evidence suggests that both virus antigen and host immune response, can cause endothelial cell dysfunction and weaken endothelial barrier integrity. We suggest possible therapeutic interventions and highlight how therapies targeting altered endothelial function might be evaluated in animal models and in patients with DHF.

Cardiovascular manifestations of the emerging dengue pandemic

Dengue is one of the most important emerging viral diseases globally. The majority of symptomatic infections result in a relatively benign disease course. However, a small proportion of patients develop severe clinical manifestations, including bleeding, organ impairment, and endothelial dysfunction with increased capillary permeability causing hypovolaemic shock that can lead to cardiovascular collapse. Evidence is increasing that dengue can also cause myocardial impairment, arrhythmias and, occasionally, fulminant myocarditis. No antiviral agents or vaccines are licensed for dengue, and treatment remains supportive with judicious fluid replacement for patients with severe disease. Defining the role of cardiac dysfunction in the haemodynamic compromise of severe dengue has potentially important management implications. In this Review, we will outline the current understanding of the cardiovascular manifestations of dengue, including myocardial and vascular involvement, and conclude with a discussion of the available therapeutic options and potential future research directions.

Evaluation of the diagnostic utility of the traditional and revised WHO dengue case definitions

Dengue, a mosquito-borne viral illness, is a major public health problem worldwide, and its incidence continues to increase. In 2009, the World Health Organization published guidelines that included a revision of the dengue case definition. Compared to the traditional definition, the revised case definition relies more on signs than on symptoms, making it more applicable to young children. We evaluated the diagnostic utility of both case definitions in two studies of pediatric dengue in Managua, Nicaragua. In a community-based cohort study, we included data from 3,407 suspected dengue cases, of which 476 were laboratory-confirmed. In the second study, we collected information from 1,160 participants recruited at the national pediatric reference hospital (723 laboratory-confirmed). In the cohort study, the traditional definition had 89.3% sensitivity and 43.1% specificity, while the revised definition yielded similar sensitivity (86.6%) and higher specificity (55.2%, p<0.001). In the hospital study, the traditional case definition yielded 96.7% sensitivity and 22.0% specificity, whereas the revised case definition had higher sensitivity (99.3%, p<0.001) but lower specificity (8.5%, p<0.001). We then evaluated the performance of two diagnostic models based on the signs/symptoms included in each definition by analyzing the effect of increasing numbers of signs/symptoms on the sensitivity and specificity of case capture. Receiver operating characteristic analysis showed a slightly better performance for the revised model in both studies. Interestingly, despite containing less symptoms that cannot be readily expressed by children aged less than 4 years, the revised definition did not perform better in this age group. Overall, our results indicate that both case definitions have similar capacity to diagnose dengue. Owing to their high sensitivity and low specificity, they should be primarily used for screening purposes. However, in a primary care setting, neither of the case definitions performed well as a screening test in younger children.

Dengue, a mosquito-borne viral infectious disease, is a major health problem worldwide. Its incidence has dramatically increased in the last 3 decades, particularly in the Americas. The traditional World Health Organization dengue case definition was in use for over 30 years, but in 2009 a revised dengue case definition, containing fewer symptoms and more signs, was published. In this study, we evaluate the diagnostic utility of both case definitions in children in Managua, Nicaragua. We used clinical data from suspected dengue cases enrolled at two different sites: a health center and the national pediatric reference hospital. Laboratory tests were performed to determine dengue virus infection status. At both sites, the case definitions showed high sensitivity (≥85%) and low specificity (8–55%). In children under 4 years old, who cannot express some of the symptoms included in the definitions, both case definitions showed reduced sensitivity and increased specificity. This reduction was particularly important in the health center, where sensitivity dropped below 50%. In conclusion, both case definitions should be primarily used for screening and not for diagnosis, and caution must be exercised when applying the definitions to younger children. This is the first published evaluation of the revised dengue case definition in pediatric populations.

Ultrasonography as a tool in predicting the severity of dengue fever in children--a useful aid in a developing country

BACKGROUND

Dengue fever accounts for significant mortality in developing countries. Dengue fever serology takes a week at least to be reported positive, thus necessitating the need for other markers of diagnosis and prognosis.

OBJECTIVE

The purpose of this study was to investigate the role of ultrasonography as a tool in diagnosing and predicting the severity of dengue fever in children.

MATERIALS AND METHODS

This was a prospective study conducted in a tertiary pediatric centre from September 2010 to July 2012. Three hundred twenty-four children with confirmed dengue fever were compared with 422 children of suspected dengue fever. Severity of illness was graded as per WHO criteria and sonography findings were correlated to the grade of illness.

RESULTS

Gallbladder wall thickening was seen in 75% of the children with confirmed dengue fever. A significant difference was seen between survivors and non-survivors with respect to pericholecystic fluid collection (P = 0.002), hepatic intraparenchymal fluid (P < 0.001), splenomegaly (P = 0.002), splenic subcapsular fluid (P < 0.001), peripancreatic fluid (P < 0.001), perirenal fluid (P < 0.001) and pericardial fluid (P < 0.001). Other findings included ascites, pleural effusion, hepatomegaly and splenomegaly, which were present irrespective of grade of illness.

CONCLUSIONS

Ultrasonography can be used as a useful tool in developing countries to predict the severity of dengue fever in children.

The predictive diagnostic value of serial daily bedside ultrasonography for severe dengue in Indonesian adults

BACKGROUND

Identification of dengue patients at risk for progressing to severe disease is difficult. Significant plasma leakage is a hallmark of severe dengue infection which can suddenly lead to hypovolemic shock around the time of defervescence. We hypothesized that the detection of subclinical plasma leakage may identify those at risk for severe dengue. The aim of the study was to determine the predictive diagnostic value of serial ultrasonography for severe dengue.

METHODOLOGY/PRINCIPAL FINDINGS

Daily bedside ultrasounds were performed with a handheld ultrasound device in a prospective cohort of adult Indonesians with dengue. Timing, localization and relation to dengue severity of the ultrasonography findings were determined, as well as the relation with serial hematocrit and albumin values. The severity of dengue was retrospectively determined by WHO 2009 criteria. A total of 66 patients with proven dengue infection were included in the study of whom 11 developed severe dengue. Presence of subclinical plasma leakage at enrollment had a positive predictive value of 35% and a negative predictive value of 90% for severe dengue. At enrollment, 55% of severe dengue cases already had subclinical plasma leakage, which increased to 91% during the subsequent days. Gallbladder wall edema was more pronounced in severe than in non-severe dengue patients and often preceded ascites/pleural effusion. Serial hematocrit and albumin measurements failed to identify plasma leakage and patients at risk for severe dengue.

CONCLUSIONS/SIGNIFICANCE

Serial ultrasonography, in contrast to existing markers such as hematocrit, may better identify patients at risk for development of severe dengue. Patients with evidence of subclinical plasma leakage and/or an edematous gallbladder wall by ultrasonography merit intensive monitoring for development of complications.

Inflammatory and innate immune responses in dengue infection: protection versus disease induction

Dengue disease is a mosquito-borne viral disease of expanding geographical range and incidence. Infection by one of the four serotypes of dengue virus induces a spectrum of disease manifestations, ranging from asymptomatic to life-threatening Dengue hemorrhagic fever/dengue shock syndrome. Many efforts have been made to elucidate several aspects of dengue virus-induced disease, but the pathogenesis of disease is complex and remains unclear. Understanding the mechanisms involved in the early stages of infection is crucial to determine and develop safe therapeutics to prevent the severe outcomes of disease without interfering with control of infection. In this review, we discuss the dual role of the innate and inflammatory pathways activated during dengue disease in mediating both protection and exacerbation of disease. We show that some mediators involved in each of these responses differ substantially, suggesting that interfering in disease-associated immune pathways may represent a potential therapeutic opportunity for the treatment of severe dengue.

Genetic variants of MICB and PLCE1 and associations with non-severe dengue

BACKGROUND

A recent genome-wide association study (GWAS) identified susceptibility loci for dengue shock syndrome (DSS) at MICB rs3132468 and PLCE1 rs3740360. The aim of this study was to define the extent to which MICB (rs3132468) and PLCE1 (rs3740360) were associated with less severe clinical phenotypes of pediatric and adult dengue.

METHODS

3961 laboratory-confirmed dengue cases and 5968 controls were genotyped at MICB rs3132468 and PLCE1 rs3740360. Per-allele odds ratios (OR) with 95% confidence intervals (CI) were calculated for each patient cohort. Pooled analyses were performed for adults and paediatrics respectively using a fixed effects model.

RESULTS

Pooled analysis of the paediatric and adult cohorts indicated a significant association between MICB rs3132468 and dengue cases without shock (OR  =  1.15; 95%CI: 1.07 - 1.24; P  =  0.0012). Similarly, pooled analysis of pediatric and adult cohorts indicated a significant association between dengue cases without shock and PLCE1 rs3740360 (OR  =  0.92; 95%CI: 0.85 - 0.99; P  =  0.018). We also note significant association between both SNPs (OR  =  1.48; P  =  0.0075 for MICB rs3132468 and OR  =  0.75, P  =  0.041 for PLCE1 rs3740360) and dengue in infants.

DISCUSSION

This study confirms that the MICB rs3132468 and PLCE1 rs3740360 risk genotypes are not only associated with DSS, but are also associated with less severe clinical phenotypes of dengue, as well as with dengue in infants. These findings have implications for our understanding of dengue pathogenesis.

Genome-wide patterns of intrahuman dengue virus diversity reveal associations with viral phylogenetic clade and interhost diversity

Analogous to observations in RNA viruses such as human immunodeficiency virus, genetic variation associated with intrahost dengue virus (DENV) populations has been postulated to influence viral fitness and disease pathogenesis. Previous attempts to investigate intrahost genetic variation in DENV characterized only a few viral genes or a limited number of full-length genomes. We developed a whole-genome amplification approach coupled with deep sequencing to capture intrahost diversity across the entire coding region of DENV-2. Using this approach, we sequenced DENV-2 genomes from the serum of 22 Nicaraguan individuals with secondary DENV infection and captured ∼75% of the DENV genome in each sample (range, 40 to 98%). We identified and quantified variants using a highly sensitive and specific method and determined that the extent of diversity was considerably lower than previous estimates. Significant differences in intrahost diversity were detected between genes and also between antigenically distinct domains of the Envelope gene. Interestingly, a strong association was discerned between the extent of intrahost diversity in a few genes and viral clade identity. Additionally, the abundance of viral variants within a host, as well as the impact of viral mutations on amino acid encoding and predicted protein function, determined whether intrahost variants were observed at the interhost level in circulating Nicaraguan DENV-2 populations, strongly suggestive of purifying selection across transmission events. Our data illustrate the value of high-coverage genome-wide analysis of intrahost diversity for high-resolution mapping of the relationship between intrahost diversity and clinical, epidemiological, and virological parameters of viral infection.

Dynamics of dengue disease severity determined by the interplay between viral genetics and serotype-specific immunity

The rapid spread of dengue is a worldwide public health problem. In two clinical studies of dengue in Managua, Nicaragua, we observed an abrupt increase in disease severity across several epidemic seasons of dengue virus serotype 2 (DENV-2) transmission. Waning DENV-1 immunity appeared to increase the risk of severe disease in subsequent DENV-2 infections after a period of cross-protection. The increase in severity coincided with replacement of the Asian/American DENV-2 NI-1 clade with a new virus clade, NI-2B. In vitro analyses of viral isolates from the two clades and analysis of viremia in patient blood samples support the emergence of a fitter virus in later, relative to earlier, epidemic seasons. In addition, the NI-1 clade of viruses was more virulent specifically in children who were immune to DENV-1, whereas DENV-3 immunity was associated with more severe disease among NI-2B infections. Our data demonstrate that the complex interaction between viral genetics and population dynamics of serotype-specific immunity contributes to the risk of severe dengue disease. Furthermore, this work provides insights into viral evolution and the interaction between viral and immunological determinants of viral fitness and virulence.

Subcutaneous Infection with Non-mouse Adapted Dengue Virus D2Y98P Strain Induces Systemic Vascular Leakage in AG129 Mice

Introduction: Dengue (DEN) is a mosquito-borne viral disease which has become an increasing economic and health burden for the tropical and subtropical world. Plasma leakage is the most life threatening condition of DEN and may lead to hypovolaemic shock if not properly managed. Materials and Methods: We recently reported a unique dengue virus strain (D2Y98P) which upon intraperitoneal (IP) administration to immunocompromised mice led to systemic viral dissemination, intestine damage, liver dysfunction, and increased vascular permeability, hallmarks of severe DEN in patients (Tan et al, PLoS Negl Trop Dis 2010;4:e672). Results: Here we report the clinical manifestations and features observed in mice subcutaneously (SC) infected with D2Y98P, which is a route of administration closer to natural infection. Similar to the IP route, increased vascular permeability, intestine damage, liver dysfunction, transient lymphopenia (but no thrombocytopenia) were observed in the SC infected mice. Furthermore, the SC route of infection was found more potent than the IP route whereby higher viral titers and earlier time-of-death rates were measured. In addition, various staining approaches revealed structurally intact blood vessels in the moribund animals despite pronounced systemic vascular leakage, as reported in dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) patients. Interestingly, measurement of soluble mediators involved in vascular permeability indicated that vascular leakage may occur at an early stage of the disease, as proposed in DEN patients. Conclusion: We believe that this novel mouse model of DEN-associated vascular leakage will contribute to a better understanding of DEN pathogenesis and represents a relevant platform for testing novel therapeutic treatments and interventions. Key words: Dengue shock syndrome, Dengue hemorrhagic fever, Capillary leakage

Dengue reporter virus particles for measuring neutralizing antibodies against each of the four dengue serotypes

The lack of reliable, high-throughput tools for characterizing anti-dengue virus (DENV) antibodies in large numbers of serum samples has been an obstacle in understanding the impact of neutralizing antibodies on disease progression and vaccine efficacy. A reporter system using pseudoinfectious DENV reporter virus particles (RVPs) was previously developed by others to facilitate the genetic manipulation and biological characterization of DENV virions. In the current study, we demonstrate the diagnostic utility of DENV RVPs for measuring neutralizing antibodies in human serum samples against all four DENV serotypes, with attention to the suitability of DENV RVPs for large-scale, long-term studies. DENV RVPs used against human sera yielded serotype-specific responses and reproducible neutralization titers that were in statistical agreement with Plaque Reduction Neutralization Test (PRNT) results. DENV RVPs were also used to measure neutralization titers against the four DENV serotypes in a panel of human sera from a clinical study of dengue patients. The high-throughput capability, stability, rapidity, and reproducibility of assays using DENV RVPs offer advantages for detecting immune responses that can be applied to large-scale clinical studies of DENV infection and vaccination.

Unusual dengue virus 3 epidemic in Nicaragua, 2009

The four dengue virus serotypes (DENV1–4) cause the most prevalent mosquito-borne viral disease affecting humans worldwide. In 2009, Nicaragua experienced the largest dengue epidemic in over a decade, marked by unusual clinical presentation, as observed in two prospective studies of pediatric dengue in Managua. From August 2009–January 2010, 212 dengue cases were confirmed among 396 study participants at the National Pediatric Reference Hospital. In our parallel community-based cohort study, 170 dengue cases were recorded in 2009–10, compared to 13–65 cases in 2004–9. In both studies, significantly more patients experienced “compensated shock” (poor capillary refill plus cold extremities, tachycardia, tachypnea, and/or weak pulse) in 2009–10 than in previous years (42.5% [90/212] vs. 24.7% [82/332] in the hospital study (p<0.001) and 17% [29/170] vs. 2.2% [4/181] in the cohort study (p<0.001). Signs of poor peripheral perfusion presented significantly earlier (1–2 days) in 2009–10 than in previous years according to Kaplan-Meier survival analysis. In the hospital study, 19.8% of subjects were transferred to intensive care, compared to 7.1% in previous years – similar to the cohort study. DENV-3 predominated in 2008–9, 2009–10, and 2010–11, and full-length sequencing revealed no major genetic changes from 2008–9 to 2010–11. In 2008–9 and 2010–11, typical dengue was observed; only in 2009–10 was unusual presentation noted. Multivariate analysis revealed only “2009–10” as a significant risk factor for Dengue Fever with Compensated Shock. Interestingly, circulation of pandemic influenza A-H1N1 2009 in Managua was shifted such that it overlapped with the dengue epidemic. We hypothesize that prior influenza A H1N1 2009 infection may have modulated subsequent DENV infection, and initial results of an ongoing study suggest increased risk of shock among children with anti-H1N1-2009 antibodies. This study demonstrates that parameters other than serotype, viral genomic sequence, immune status, and sequence of serotypes can play a role in modulating dengue disease outcome.

Dengue is the most prevalent mosquito-borne viral disease affecting humans worldwide. The four dengue virus serotypes (DENV1–4) cause Dengue Fever and more severe life-threatening syndromes. In 2009, Nicaragua experienced the largest dengue epidemic in over a decade. In a hospital-based study and community-based prospective cohort study of pediatric dengue in the capital, Managua, we observed unusual clinical presentation of dengue. Significantly more patients experienced “compensated shock” (poor capillary refill plus cold extremities, rapid heartbeat, elevated respiratory rate, and/or weak pulse) in 2009–10 than in previous years. These signs of poor peripheral perfusion presented significantly earlier and more children were transferred to intensive care in 2009–10 than in previous years. DENV-3 was the predominant serotype in Managua in 2008–9, 2009–10 and 2010–11, but full-length sequencing revealed no major genetic changes. In 2008–9 and 2010–11, typical dengue was observed; only in 2009–10 was unusual presentation noted. Since pandemic influenza A H1N1-2009 overlapped with the dengue epidemic in Nicaragua, we hypothesize that prior influenza A H1N1-2009 infection may have modulated subsequent DENV infection, and preliminary results appear to support this hypothesis. This study demonstrates that parameters other than DENV serotype, viral genomic sequence, immune status, and sequence of serotypes can play a role in modulating dengue disease.

Sonographic evidence of ascites, pleura-pericardial effusion and gallbladder wall edema for dengue fever

INTRODUCTION

Radiographic findings of dengue fever have not yet been clearly elucidated in relation to clinical and serological findings, despite the fact that two-fifths of the world population lives in areas where the virus is endemic. The current study is a retrospective analysis of ultrasonographic (USG) features of patients presenting with probable dengue fever during the outbreak of DF of 2006 in North India.

METHODS

Case records of a 169 patients with probable dengue fever were included. Ten individual sonographic parameters were reviewed vis-à-vis ascites, hepatomegaly, splenomegaly, gall bladder wall edema (GBWE), pleural effusion (right or left or both), pericardial effusion, pericholecystic collection, perinephric collection. Subjects who had GB wall thickness >3 mm as measured on ultrasound were identified as positive for GBWE. The cases were analyzed in view of their serological profile.

RESULTS

The mean age of the subjects was 27.9 +/- 13.4 years. The mean value of the platelet count was 57.4 +/- 22.3 x 103/cmm. The most common ultrasonographic feature was ascites (126, 74.6%) followed by gall bladder wall edema (122, 72%), hepatomegaly (78, 46.2%), splenomegaly (66, 39.1%) and pericholecystic collection (63, 37.3%); 48 (28.4%) subjects demonstrated evidence of pleural effusion on the right side, while 19 (11.2%) had bilateral effusion. None of the subjects had an isolated left pleural effusion. Twenty-seven (16%) subjects reported bleeding manifestations in the form of petechiae and five (3%) developed renal dysfunction. Presence of pleural and pericardial effusions was found to be specific while ascites and GBWE were identified as highly sensitive markers for seropositive Primary DF.

CONCLUSIONS

Ultrasonographic evidence of ascites, pleuro-pericardial effusion, and gallbladder wall edema are rapidly acquired, non-invasive markers of dengue and can be helpful before serological investigations become available. These findings may indicate severity and may herald the onset of bleeding (petechiae) or predict the development of acute renal dysfunction.

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.

Valor da ultrassonografia em crianças com suspeita de febre hemorrágica do dengue: revisão da literatura

O dengue é doença endêmica em regiões tropicais e subtropicais. Quando sintomática, classifica-se em febre do dengue e febre hemorrágica do dengue, com tendência a síndrome do choque do dengue. A febre hemorrágica do dengue é marcada por manifestações hemorrágicas, trombocitopenia e aumento da permeabilidade capilar. A síndrome do choque do dengue apresenta os achados de febre hemorrágica do dengue com hipotensão. Muitos achados ultrassonográficos têm sido descritos, incluindo derrame pleural, ascite, espessamento da parede da vesícula biliar e derrame pericárdico. O objetivo desta revisão da literatura é descrever os achados ultrassonográficos e demonstrar o papel da ultrassonografia em crianças com suspeita de febre hemorrágica do dengue

Transient reticular gallbladder wall thickening in severe dengue fever: a reliable sign of plasma leakage

BACKGROUND

Dengue fever (DF) is an acute infection caused by a flavivirus. Although most patients present mild symptoms, some progress to a severe condition characterized by hypovolemic shock and hemorrhagic phenomena. The main feature of this severe form of DF is plasma leakage. Gallbladder wall thickening (GBWT), ascites and pleural effusion represent the sonographic triad of plasma leakage in DF.

OBJECTIVE

To evaluate the plasma leakage triad in severe DF with emphasis on the GBWT.

MATERIALS AND METHODS

Thirty-seven children with severe DF underwent abdominal US on the day of admittance and on the day of discharge, or 7 days after the first examination if the child was still hospitalized.

RESULTS

Of the 37 children, 33 (89.2%) presented GBWT, 29 (78.4%) ascites and 26 (70.3%) pleural effusion. All of these findings had resolved by the second examination. Of the 33 GBWTs, 29 (87.9%) presented a reticular pattern, which could be considered typical of plasma leakage in patients with severe DF.

CONCLUSION

GBWT, ascites and pleural effusion are transient findings in DF. The authors have described a typical reticular pattern of GBWT that can be used to diagnose and follow up on patients with severe DF and should not be considered an acalculous cholecystitis.

Systemic vascular leakage associated with dengue infections - the clinical perspective

Vascular leakage is the most serious complication of dengue infection. However, despite considerable progress in understanding the immunological derangements associated with dengue, the pathogenic mechanisms underlying the change in vascular permeability remain unclear. Lack of suitable model systems that manifest permeability characteristics similar to human vascular endothelium has seriously impeded research in this area. Similarly, limited knowledge of the factors regulating intrinsic microvascular permeability in health, together with limited understanding of the alterations seen in disease states in general, has also hampered progress. Fortunately considerable advances have been made in the field of endothelial biology in recent years, especially following appreciation of the crucial role played by the endothelial surface glycocalyx, acting in concert with underlying cellular structures, in regulating fluid flow across the microvasculature. We review what is known about vascular leakage during dengue infections, particularly in relation to current knowledge of vascular physiology, and discuss potential areas of research that may help to elucidate the complex nature of this singular phenomenon in the future.

Assessing the prognosis of dengue-infected patients

Dengue infections pose a huge burden to health care providers in most tropical countries. Careful clinical examination and history-taking supplemented by newer rapid diagnostic tests may lead to early etiological diagnosis. For severe dengue, early recognition of vascular permeability followed by rapid physiological replacement of fluids is life-saving. Prognosis of patients depends upon optimum management, an outcome that requires preparation via organization, training, and use of evidence-based practice guidelines.

Early clinical and biological features of severe clinical manifestations of dengue in Vietnamese adults

BACKGROUND

Dengue is a major public health problem in both children and adults in Vietnam, but dengue severity in adults has been poorly investigated.

OBJECTIVES

To describe severe manifestations of dengue in Vietnamese adults and to identify early indicators of these manifestations.

STUDY DESIGN

A prospective longitudinal study was carried out from July to October, 2007, in People's Hospital 115, Ho Chi Minh City, Vietnam.

RESULTS

One hundred ninety-five clinically suspected dengue patients were enrolled. 151 of these were laboratory-confirmed using serum samples on day 3 after onset of fever for RT-PCR and/or virus isolation. Dengue was associated with plasma leakage in 51 patients (33.8%), gallbladder thickening in 30 patients (20%), spontaneous bleeding in 127 patients (84.1%), and internal bleeding in 37 patients (24.5%). Several early indicators were associated with severe manifestations of dengue. Frequent vomiting (> or =3 times a day), marked lymphopenia, thrombocytopenia, and elevated liver enzymes on day 3 after onset of fever were significantly associated with plasma leakage and gallbladder thickening. Increased alanine aminotransferase level in plasma on day 3 was significantly associated with internal bleeding. Gallbladder thickening and internal bleeding were more common with specific serotypes.

CONCLUSION

Several severe manifestations of dengue were observed in Vietnamese adults. These manifestations were associated with early clinical and biological indicators. This information may be useful for clinicians to better monitor adult dengue patients, particularly in tropical areas where health resources may be limited.

Mosquito-borne diseases

Despite centuries of control efforts, mosquito-borne diseases are flourishing worldwide. With a disproportionate effect on children and adolescents, these conditions are responsible for substantial global morbidity and mortality. Malaria kills more than 1 million children annually, chiefly in sub-Saharan Africa. Dengue virus has expanded its range over the past several decades, following its principal vector, Aedes aegypti, back into regions from which it was eliminated in the mid-20th century and causing widespread epidemics of hemorrhagic fever. West Nile virus has become endemic throughout the Americas in the past 10 years, while chikungunya virus has emerged in the Indian Ocean basin and mainland Asia to affect millions. Japanese encephalitis virus, too, has expanded its range in the Indian subcontinent and Australasia, mainly affecting young children. Filariasis, on the other hand, is on the retreat, the subject of a global eradication campaign. Efforts to limit the effect of mosquito-borne diseases in endemic areas face the twin challenges of controlling mosquito populations and delivering effective public health interventions. Travelers to areas endemic for mosquito-borne diseases require special advice on mosquito avoidance, immunizations, and malaria prophylaxis.

Three-dimensional mapping of gallbladder wall thickness on computed tomography using Laplace's equation

RATIONALE AND OBJECTIVES

Traditionally, maximum gallbladder wall thickness is measured at a single point on ultrasonography. The purpose of this work was to develop an automated technique to measure the thickness of the gallbladder wall over the entire gallbladder surface using computer tomography (CT).

MATERIALS AND METHODS

Subjects who had (5-mm) thick and thin (2.5-mm) reconstruction through the abdomen were selected from a research database. Their volumetric computed tomographic images were acquired using a multidetector GE Medical Systems LightSpeed 16 scanner at 120 kVp, approximately 250 mAs, with standard filter reconstruction algorithm and segmented in three dimensions. Two segmentation boundaries were obtained, an inner and an outer boundary of the gallbladder wall. The thickness of the wall was quantified by computing the distance between the boundaries over the entire volume using Laplace's equation from mathematical physics. The distance between the surfaces is found by computing normalized gradients that form a vector field, representing tangent vectors along field lines connecting both boundaries. The Laplacian technique was compared with the well-known Euclidean distance transformation (EDT) technique that provides a three-dimensional Euclidean distance mapping between the two extracted surfaces.

RESULTS

The technique was tested on 10 subjects who had thin- and thick-section computed tomographic datasets reconstructed from a single scan. The mean thickness for the thick- and thin-section CT using Laplace was 3.18 and 2.93 mm, respectively. The smooth transition between surfaces resulting from the Laplace technique resulted in a coefficient of variation that was less than 1% compared to EDT.

CONCLUSIONS

EDT technique is very sensitive to imperfect segmentations, resulting in higher variation compared to the Laplacian technique. The smooth transition between surfaces makes the Laplacian technique more robust compared to EDT for the measurement of CT gallbladder thickness.

Dengue

The four dengue viruses are transmitted in tropical countries that circle the globe. All can cause syndromes that are self-limited or severe. The common severe syndrome--dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS)--is characterised by sudden vascular permeability generated by cytokines released when T cells attack dengue-infected cells. Dengue 1 virus became prevalent in Hawaii where it was transmitted by Aedes albopictus, producing a classic virgin soil epidemic, with clinical disease seen largely in adults. In Cuba and Singapore, sequential dengue infections at long intervals produced unusually severe disease in adults. Evidence suggests that enhancing and cross-reactive neutralising antibodies regulate dengue epidemics and disease severity. Classic DHF/DSS arises during initial dengue infections in infants with low circulating amounts of maternal dengue antibodies, an observation that precludes an exclusive causal role for secondary T-cell responses. Here, I review and discuss data on clinical diagnosis and pathophysiology of vascular permeability and coagulopathy, parenteral treatment of DHF/DSS, and new laboratory tests.

Sustainable transfer of biotechnology to developing countries: fighting poverty by bringing scientific tools to developing-country partners

Poverty and social inequalities have powerfully sculpted not only the distribution of infectious and other diseases but also the course of disease in those affected. The lack of proper diagnosis and access to adequate health services only compounds the problem. In low-resource settings, the burden of disease can be reduced if the basic human and material resources exist to support the use of low-cost interventions by appropriately trained personnel. For 20 years, the Sustainable Sciences Institute has built scientific capacity in developing countries to recognize, prevent, and respond to the threats posed by disease.