Dengue in infants: an overview

Epidemiology of pediatric dengue virus infection, Scenario from a tertiary level hospital in Bangladesh

BACKGROUND

Dengue fever is the most rapidly spreading mosquito-borne disease and has grown to be a major public health issue, especially in tropical nations like Bangladesh. Globally, children, adolescents, and young adults bear the largest burden of Dengue; the infection rate is highest among infants. However, the epidemiology of pediatric dengue virus infection has been poorly explored in Bangladesh.

MATERIALS AND METHODS

This study was carried out at the Bangladesh Shishu Hospital & Institute from July to October 2023. Among 1102 admitted patients, 722 who were positive for dengue rapid test were enrolled.

RESULTS

The highest number of positive patients were 1-5 years old (38 %) followed by 5-10 years (32 %). Vomiting (49 %) was most common after fever (100 %). 71 % of patients showed warning signs, with 17 deaths. All patients received antibiotics, and the number of different antibiotics increased with hospital stay. Real-time RT-PCR was conducted on purposively selected 104 rapid test positives and 50 negatives for serotyping. DENV-2 was the most predominant serotype (80 %), followed by DENV-3 (20 %).

CONCLUSION

This study underscored the need for targeted public health interventions, especially for children with warning signs, to address the high burden of pediatric dengue infection in Bangladesh.

Age-specific kinetics of neutralizing antibodies and infection enhancement among ≤1 year-old Indian infants

Background

Infants born to dengue-immune mothers acquire maternal antibodies to dengue. Maternal antibodies decline over time, making infants susceptible to primary dengue infections. Another important concern is the role of maternal antibodies in causing antibody-dependent enhancement (ADE) during primary infections. In this study, we aimed to investigate the kinetics of dengue virus (DENV)-neutralizing antibodies and infection-enhancing activity in Indian infants.

Methods

Healthy infants at birth (cord blood), and at 3, 6, 9, and 12 months of age (n=32/group) were included in this cross-sectional study. Serum samples were tested for neutralizing antibodies using the foci-reduction neutralization test and enhancing antibodies using the ADE assay against DENV1-4 serotypes.

Results

Neutralizing antibody positivity declined with the increasing age of the infants. Undetectable levels of neutralizing antibodies to DENV1-4 serotypes were reported in 84% of infants by 9 months. Significantly lower neutralizing antibody titers were also reported in 9-month-old infants compared to that in 6-month-old infants and infants at birth. Comparable levels of enhancement of DENV1-4 infection at a particular dilution to at least one serotype were noted in infants at 3 and 6 months of age. Fold enhancement of DENV1-4 infection was found to be highest in 6-month-old infants at a dilution of 1:20. In summary, our data suggests that DENV infection-enhancing activity aligns with the decline of neutralizing antibodies.

Conclusion

Our study indicates that maternally acquired neutralizing antibodies could be protective until 6 months of age and capable of facilitating ADE on exposure to dengue infections in later months of life.

A non-structural protein 1 substitution of dengue virus enhances viral replication by interfering with the antiviral signaling pathway

BACKGROUND

The largest dengue virus 2 (DENV2) outbreak occurred in Taiwan in 2015, resulting in many fatalities. We therefore aim to identify crucial genetic variations which determine the virulence of the 2015 Taiwan outbreak strains.

METHODS

We compared the 2015 Taiwan DENV2 sequences to the pre-2015 sequences. Reverse genetics (rg) viruses with substitutions were produced and the viral growth kinetics were investigated. We treated A549 cells with interferon (IFN) to determine the interferon-stimulated genes (ISGs) expression and STAT1 phosphorylation in the rg viral infection and plasmid transfection systems. IFN and pro-inflammatory cytokines levels were measured upon DENV infection using ELISA.

RESULTS

The rgNS1-K272R mutant showed faster replication in IFN-I producing cells compared to wildtype (WT) virus. Results revealed that NS1-K272R substitution contributed to higher soluble NS1 secretion and evade the antiviral response by suppressing the expression of ISGs and STAT1 phosphorylation compared to NS1-WT. Infection with rgNS1-K272R induced higher secretion of pro-inflammatory cytokines through the activation of canonical nuclear factor-kappa B (NF-κB) signaling pathway.

CONCLUSIONS

Our results revealed that the DENV NS1 amino acid substitution affects the NS1 ability in immune evasion, which may contribute to the largest dengue outbreak in Taiwan since the 1990s.

Epidemiology of imported travelers with dengue fever in Taiwan from 2011 to 2020

We collected data on imported dengue cases between 2011 and 2020 from Taiwan's Centers for Disease Control to determine changes in the case number and importation rate of dengue. We used open data provided by Taiwan's Centers for Disease Control to extract the number of confirmed imported cases of dengue between 2011 and 2020. From 2011 to 2020, 2883 imported cases of dengue were reported in Taiwan. The importation rate was 25.8 to 46.4 per 100,000 inbound travelers from 2011 to 2020, peaking in 2020. Disease incidence varied between sexes, age groups, seasons (P < .001), and residence from 2011 to 2020. Numerous dengue cases were imported from Indonesia (548 cases), Vietnam (516 cases), and the Philippines (500). For travelers from Taiwan, the risk ratio of becoming infected by dengue was 31,712 for traveling to the Maldives, 3153 to Cambodia, and 996 to Myanmar. In this study, more serotype 1 and 2 strains were reported by Vietnam, and more serotype 3 and 4 strains were reported by Indonesia. Our data indicate that the rate of imported cases of dengue significantly increased annually from 2011 to 2020 in Taiwan, especially during the COVID-19 pandemic (46.4 per 100,000 inbound travelers).

Vertical dengue transmission complicated with neonatal encephalitis

Vertical transmission of the dengue virus is rare and infrequently reported in the literature. We report the case of a term newborn presented with high-grade fever, generalised petechial rash and hepatomegaly at the age of 5 days, with a history of dengue fever in the mother at 3 days before delivery. The diagnosis was nearly missed because the infant's dengue NS1 antigen test was initially negative and subsequently positive. After the convalescent phase, the infant developed a new-onset fever with lethargy and drowsiness. Dengue encephalitis was diagnosed with support from a positive dengue reverse-transcriptase PCR in the cerebrospinal fluid. This report has shown the importance of clinical awareness. Early recognition of congenital dengue and vigilant monitoring will contribute to appropriate early management and decrease neonatal morbidity and mortality.

Knowledge, attitude and practice (KAP) and risk factors on dengue fever among children in Brazil, Fortaleza: A cross-sectional study

BACKGROUND

Dengue fever is a mosquito-borne viral disease that is associated with four serotypes of the dengue virus. Children are vulnerable to infection with the dengue virus, particularly those who have been previously infected with a different dengue serotype. Sufficient knowledge, positive attitudes, and proper practices (KAP) are essential for dengue prevention and control. This study aims to estimate the dengue seropositivity for study participants and to examine the association between households' dengue-related knowledge, attitudes, and practices (KAP), and children's risk of dengue seropositivity, while accounting for socioeconomic and demographic differences in Brazil.

METHODOLOGY/PRINCIPAL FINDINGS

This analysis was based on a cross-sectional study from Fortaleza, Brazil between November 2019, and February 2020. There were 392 households and 483 participant children who provided a sample of sufficient quality for serological analysis. The main exposure was a household's dengue-related knowledge, attitudes, and practices, assessed through a questionnaire to construct a composite KAP score categorized into three levels: low, moderate, and high. The main outcome is dengue immunoglobulin G(IgG) antibodies, collected using dried blood spots and assessed with Panbio Dengue IgG indirect ELISA (enzyme-linked immunosorbent assays) test commercial kits. The estimated crude dengue seroprevalence among participating children (n = 483) was 25%. Five percent of households (n = 20) achieved a score over 75% for KAP, sixty-nine percent of households (n = 271) scored between 50% and 75%, and twenty-six percent of households (n = 101) scored lower than 50%. Each KAP domain was significantly and positively associated with the others. The mean percentage scores for the three domains are 74%, 63%, and 39% respectively. We found high household KAP scores were associated with an increased adjusted relative risk (aRR) of seropositivity (aRR: 2.11, 95% CI: 1.11-4.01, p = 0.023). Household adult respondents' education level of elementary school or higher was negatively associated with children's risk of being seropositive (aRR: 0.65, 95% CI: 0.48-0.87, p = 0.005). The risk of seropositivity in older children (6-12 years old) was over 6 times that of younger children (2-5 years old) (aRR: 6.08, 95% CI: 3.47-10.64, p<0.001). Children living in households with sealed water tanks or no water storage had a lower risk of being seropositive (aRR: 0.73, 95% CI: 0.54-0.98, p = 0.035).

CONCLUSIONS/SIGNIFICANCE

Our results provide insight into the prevalence of dengue seropositivity in Fortaleza, Brazil in children, and certain demographic and socioeconomic characteristics associated with children's risk of being seropositive. They also suggest that KAP may not identify those more at-risk for dengue, although understanding and enhancing households' KAP is crucial for effective community dengue control and prevention initiatives.

Interferome signature dynamics during the anti-dengue immune response: a systems biology characterization

Dengue virus (DENV) infection manifests as a febrile illness with three distinct phases: early acute, late acute, and convalescent. Dengue can result in clinical manifestations with different degrees of severity, dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. Interferons (IFNs) are antiviral cytokines central to the anti-DENV immune response. Notably, the distinct global signature of type I, II, and III interferon-regulated genes (the interferome) remains uncharacterized in dengue patients to date. Therefore, we performed an in-depth cross-study for the integrative analysis of transcriptome data related to DENV infection. Our systems biology analysis shows that the anti-dengue immune response is characterized by the modulation of numerous interferon-regulated genes (IRGs) enriching, for instance, cytokine-mediated signaling (e.g., type I and II IFNs) and chemotaxis, which is then followed by a transcriptional wave of genes associated with cell cycle, also regulated by the IFN cascade. The adjunct analysis of disease stratification potential, followed by a transcriptional meta-analysis of the interferome, indicated genes such as IFI27, ISG15, and CYBRD1 as potential suitable biomarkers of disease severity. Thus, this study characterizes the landscape of the interferome signature in DENV infection, indicating that interferome dynamics are a crucial and central part of the anti-dengue immune response.

Neurological Manifestations of Perinatal Dengue

Dengue viruses (DENVs) are single-stranded RNA viruses belonging to the family Flaviviridae. There are four distinct antigenically related serotypes, DENVs types 1, 2, 3, and 4. These are all mosquito-borne human pathogens. Congenital dengue disease occurs when there is mother-to-fetus transmission of the virus and should be suspected in endemic regions in neonates presenting with fever, maculopapular rash, and thrombocytopenia. Although most of the infected infants remain asymptomatic, some can develop clinical manifestations such as sepsis-like illness, gastric bleeding, circulatory failure, and death. Neurological manifestations include intracerebral hemorrhages, neurological malformations, and acute focal/disseminated encephalitis/encephalomyelitis. Dengue NS1Ag, a highly conserved glycoprotein, can help the detection of cases in the viremic stage. We do not have proven specific therapies yet; management is largely supportive and is focused on close monitoring and maintaining adequate intravascular volume.

Epidemiological profile of arboviruses in two different scenarios: dengue circulation vs. dengue, chikungunya and Zika co-circulation

BACKGROUND

The severity and distribution of dengue virus (DENV) infections have been attributed to a complex interaction among viral, host and environmental factors. Herein, we investigated the influence of chikungunya (CHIKV) and Zika (ZIKV) viruses on the epidemiological profile of dengue cases, using Recife, Pernambuco state, Brazil, as a study model. In addition, we described and compared the epidemiological profile related to each arbovirus (DENV vs. CHIKV vs. ZIKV).

METHODS

All cases of dengue, chikungunya and Zika reported to the Pernambuco Health Department in 2011-2013 (DENV circulation) and 2016-2018 (DENV, CHIKV and ZIKV co-circulation) were included in our study. The cases were classified by sex, age and race/color and their distribution was analyzed by the χ² test. Furthermore, the data were also analyzed for co-infections. Temperature, humidity and rainfall data were analyzed using one-way ANOVA and paired t-test.

RESULTS

During 2011-2013, 15,315 dengue cases were diagnosed, most of them female, brown and 20-29 age group. Between 2016 and 2018, 15,870 dengue cases were described, which presented the same profile described above. In the two triennia, the female/male dengue ratio fluctuated significantly, ranging from 1.07 to 1.52. Regarding chikungunya, 7076 cases were reported, most of them female and brown. The female/male ratio also fluctuated significantly, ranging from 1.62 to 2.1. Two main age groups were observed in chikungunya: ≤ 19 years (minority of diagnoses) and ≥ 20 years (majority of diagnoses). In the same triennium, 266 Zika cases were reported to the Pernambuco Health Department, mainly in females and in the 0-9 and 20-39 age groups. In general, 119 co-infections were identified: 117 DENV-CHIKV, 1 CHIKV-ZIKV and 1 DENV-CHIKV-ZIKV. Concerning climate data, only the humidity in 2011 was significantly different from the other years.

CONCLUSION

The epidemiological profile of dengue cases did not change after the introduction of CHIKV and ZIKV. Females were the most diagnosed with dengue, chikungunya or Zika, however we found important differences in the age profile of these arboviruses, which should be considered by public health policies, as well as investigated in future studies of virus-host interaction.

Arthropod-Borne Flaviviruses in Pregnancy

Flaviviruses are a diverse group of enveloped RNA viruses that cause significant clinical manifestations in the pregnancy and postpartum periods. This review highlights the epidemiology, pathophysiology, clinical features, diagnosis, and prevention of the key arthropod-borne flaviviruses of concern in pregnancy and the neonatal period-Zika, Dengue, Japanese encephalitis, West Nile, and Yellow fever viruses. Increased disease severity during pregnancy, risk of congenital malformations, and manifestations of postnatal infection vary widely amongst this virus family and may be quite marked. Laboratory confirmation of infection is complex, especially due to the reliance on serology for which flavivirus cross-reactivity challenges diagnostic specificity. As such, a thorough clinical history including relevant geographic exposures and prior vaccinations is paramount for accurate diagnosis. Novel vaccines are eagerly anticipated to ameliorate the impact of these flaviviruses, particularly neuroinvasive disease manifestations and congenital infection, with consideration of vaccine safety in pregnant women and children pivotal. Moving forward, the geographical spread of flaviviruses, as for other zoonoses, will be heavily influenced by climate change due to the potential expansion of vector and reservoir host habitats. Ongoing 'One Health' engagement across the human-animal-environment interface is critical to detect and responding to emergent flavivirus epidemics.

Does dengue and COVID-19 co-infection have worse outcomes? A systematic review of current evidence

In dengue-endemic regions, the co-infection with SARS-CoV-2 and dengue is a significant health concern. Therefore, we performed a literature search for relevant papers in seven databases on 26 Spetember 2021. Out of 24 articles, the mortality rate and intensive care unit (ICU) admission were 19.1% and 7.8%, respectively. The mean hospital stay was 11.4 days. In addition, we identified two pregnancies with dengue and COVID-19 co-infection; one ended with premature rupture of membrane and intrauterine growth restriction fetus, while the other one ended with maternal mortality and intrauterine fetal death. COVID-19 and dengue co-infection had worse outcomes regarding mortality rates, ICU admission, and prolonged hospital stay. Thus, wise-decision management approaches should be adequately offered to these patients to enhance their outcomes. Establishing an early diagnosis might be the answer to reducing the estimated significant burden of these conditions.

Mannose-binding lectin levels and MBL2 gene polymorphisms are associated to dengue infection in Brazilian children at the early ages

BACKGROUND

The mannose-binding lectin (MBL) plays an important role in innate immunity. Genetically determined variations in serum levels of MBL may influence the susceptibility and clinical outcome of dengue infection in early life.

METHODS

We investigated MBL2 gene polymorphisms and serum levels of MBL (total and functional) in children with asymptomatic (n=17) and symptomatic (n=29), primary dengue infections, and age-matched uninfected children (n=84) enrolled in a Brazilian dengue birth cohort. Polymorphisms of the MBL2 gene were assessed by RT-PCR, while ELISA were used to quantify serum levels of MBL.

RESULTS

We found that the X allele and YX genotype in the MBL2 were more frequent in dengue cases than controls. Likewise, the LXPA haplotype was exclusively found in dengue cases, thus probably related to dengue infection in our setting. Moreover, we found a higher frequency of the O allele and AO genotype in control group. Serum levels of total and functional MBL were higher in dengue naïve infants than dengue cases.

CONCLUSIONS

MBL2 variants related to lower production of serum MBL were associated to dengue infection in infants, while intermediate to high levels of total and functional serum MBL were associated with protection. These findings highlight the role of MBL2 variants and serum levels of MBL in the susceptibility to dengue disease at early ages.

Hydrocephalus secondary to dengue encephalitis in an infant: case report

BACKGROUND

Dengue is the leading cause of mosquito-borne viral infection. It is responsible for high morbidity and mortality in children living in endemic areas. Nowadays, neurological complications are progressively referred to and include a broad spectrum of symptoms. It can be secondary to metabolic alterations, direct invasion by the virus, and enhanced autoimmune response.

CASE PRESENTATION

Here, we report a rare case of hydrocephalus secondary to dengue encephalitis. A 13-day-old boy was diagnosed with dengue. He evolved with seizures and impaired consciousness being diagnosed with encephalitis. After clinical treatment, he was discharged fully recovered. Three months later, he presented with signs and symptoms of intracranial hypertension. Brain MRI revealed hydrocephalus secondary to acquired aqueduct stenosis. The patient underwent an endoscopic third ventriculocisternostomy.

CONCLUSION

Dengue infection is a differential diagnosis for acute febrile neurological impairment in children from endemic areas. Follow-up should be offered after dengue encephalitis to detect possible late-onset complications, as hydrocephalus.

Factors associated with clinical outcomes of pediatric dengue shock syndrome admitted to pediatric intensive care unit: A retrospective cohort study

Background

Dengue shock syndrome (DSS) in children is a challenging infectious disease due to its high mortality rate. Several factors can contribute to the DSS patients’ outcomes. Here we defined factors associated with clinical outcomes of patients with DSS in Pediatric Intensive Care Unit (PICU).

Methods

We retrospectively collected data from January 2016 to May 2020 of patients who had been diagnosed with DSS and admitted to PICU in our tertiary referral hospital. Bivariate analysis and logistic regression were used to evaluate independent predictors of the study outcomes.

Results

Overall, 146 patients were enrolled in this study, including 53.4% males and 46.6% females. The mortality rate during the study period was 5.5%. Fluid overload percentage, shock condition at PICU admission, DIC, and AKI were independent predictors for DSS mortality in logistic regression test with p < 0.05. There were several factors correlated with prolonged stay, including disseminated intravascular coagulation (DIC) (RR 15.26; 95% CI: 4.97–46.81), and nutritional status (RR 16.47; 95% CI: 3.72–72.9).

Conclusion

Fluid overload percentage, shock condition at PICU admission, DIC, and AKI are independent predictors for DSS mortality. Several factors contribute to prolonged PICU stay, including DIC and nutritional status.

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Dengue shock syndrome is still a major problem in childrens' health in Indonesia.

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Infection and fluid overload should to be concerned to prevent prolonged PICU stay.

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The importance of increasing referral response times from previous hospitals in dengue shock syndrome cases.

A novel anti-NS2BNS3pro antibody-based indirect ELISA test for the diagnosis of dengue virus infections

Dengue virus reportedly circulates as four genetically distinct serotypes for which there is no widely accepted vaccine or drug at present. Morbidity and mortality caused by this virus are alarming for the possible increased threat to human health. A suitable diagnostic test is the prerequisite for designing and developing control measures. But, the tests being employed at present possess one or the other drawback for this disease diagnosis. During the dengue virus infections, NS2B is essential for the stability and catalytic activity of the NS3 protease. N-terminal 185 amino acids of NS3 protease domain along with hydrophilic portion of NS2B (NS2BNS3pro) is being used to screen dengue inhibitors but not for diagnosis until now. In the present study, we have used purified NS2BNS3pro as an antigen to trap anti-NS2BNS3pro antibodies of the clinical samples. Antibodies were detected successfully in both Western blot analysis and enzyme-linked immunosorbent assay (ELISA) tests. In ELISA, antibodies were detected in both primary and secondary infections of all serotypes. Interestingly, 17 samples declared as other febrile infections by NS1 and IgM/IgG tests were found to be positive in present test, which were further confirmed by reverse-transcription polymerase chain reaction. In silico studies suggested the absence of conserved epitopes between NS2BNS3pro and the counterpart in JEV, Zika, and CHIKV, indicating less possibility of crossreaction, which was in turn confirmed by using synthetic peptides representing the above epitopes. Statistical analysis with 76% specificity, 87% sensitivity, and 95% concordance also supported the present test as a suitable test for large scale diagnosis of dengue virus infections.

Case Report: Severe COVID-19 and Dengue in an Indonesian Infant

We report a case of a 10-month infant with dual severe infection of COVID-19 and dengue fever who was admitted to the hospital with an influenza-like illness. The patient experienced severe conditions of COVID-19 and dengue fever with shock followed by disseminated intravascular coagulation. The standard of COVID-19 care was given coupled with fluid resuscitation and blood transfusion. The pitfalls of this case are how to differentiate the clinical manifestation of dengue fever in a patient with confirmed COVID-19; the difficulty to monitor the dengue course of illness of the patient in the COVID-19 isolation room; and to differentiate the severe dengue from the multisystem inflammatory syndrome-C when the patient was in critical condition. The infant recovered without sequale, but the management of new probable cases must be improved more thoroughly, especially during dengue peak period in tropical and developing countries such as Indonesia.

Clinical features and outcomes of neonatal dengue at the Children's Hospital 1, Ho Chi Minh, Vietnam

Objectives Neonatal dengue has been reported in the literature with contradictory findings of clinical characteristics and diagnosis; thereby, misdiagnosis of neonatal dengue has been frequently reported. We aim to delve into the epidemiology, clinical features, and outcomes of neonatal dengue, thus avoid misdiagnosis and obtain early intervention. Study design A retrospective study was conducted at Children's Hospital 1, Ho Chi Minh, Vietnam with laboratory-confirmed dengue in neonates by positive viral antigen nonstructural protein one rapid test (NS1) and positive IgM antibody for dengue by MAC-ELISA. Results We have included 32 neonates in this study with 25% cases were misdiagnosed with neonatal sepsis, and 12.5% cases were misdiagnosed with neonatal immune thrombocytopenia at the beginning. The median time between the first day of the mother's onset of fever and childbirth was -1 days (IQR: -2, 2). The patient's clinical manifestation included: petechiae 87.5% (28/32), pharyngeal mucosal hemorrhage 6.3% (2/32), and hepatomegaly occurred 75% (24/32). In the febrile phase (day of illness 1-3), the mean white blood cell (WBC) counts were 7800 ± 800/mm³ and platelets were 97,111 ± 37,826/mm³. In the critical phase (day of illness 4-6), the mean WBC counts were 13,400 ± 2800/mm³, and platelets were 30,100 ± 5749/mm³. All mothers (100%) had laboratory-confirmed dengue by NS1 positive in the perinatal period. Conclusions The findings emphasize that early diagnosis of neonatal dengue should be based on a history of maternal illness, NS1 rapid test, and clinical presentation such as petechiae, hepatomegaly, and low platelet counts in the febrile phase.

Vector-borne diseases in pregnancy

Vector-borne infections cause a significant proportion of world-wide morbidity and mortality and many are increasing in incidence. This is due to a combination of factors, primarily environmental change, encroachment of human habitats from urban to peri-urban areas and rural to previously uninhabited areas, persistence of poverty, malnutrition and resource limitation in geographical areas where these diseases are endemic. Pregnant women represent the single largest ‘at risk’ group, due to immune-modulation and a unique physiological state. Many of these diseases have not benefitted from the same level of drug development as other infectious and medical domains, a factor attributing to the ‘neglected tropical disease’ title many vector-borne diseases hold. Pregnancy compounds this issue as data for safety and efficacy for many drugs is practically non-existent, precluding exposure in pregnancy to many first-line therapeutic agents for ‘fear of the unknown’ or overstated adverse pregnancy-foetal outcomes. In this review, major vector-borne diseases, their impact on pregnancy outcomes, current treatment, vaccination and short-comings of current medical practice for pregnant women will be discussed.

Association between interferon lambda 3 rs12979860 polymorphism and clinical outcome in dengue virus-infected children

Single nucleotide polymorphisms (SNPs) in immune-related genes have been shown to play a role in driving the development of the severe phenotypes of dengue virus (DENV) infection. We assessed the association between IFNL3 gene SNP (rs12979860) and dengue clinical outcomes in children. Patients with dengue-related symptoms (aged 1-15 years) admitted at a public hospital in Northeast Brazil were invited to participate. The association between rs12979860 polymorphism and dengue classification and clinical signs and symptoms were analysed. A total of 206 DENV-infected children were included: 53.4% of the infections were classified as severe dengue. The T allele carriers had higher risk of developing severe dengue when compared to CC genotype carriers (OR: 1.81; 95% CI: 0.98-3.32 p = .054). The T allele carriers also showed longer fever episodes when compared to patients with the CC genotype (OR: 1.90; 95%CI: 1.07-3.38; p = .027). On the other hand, the ones carrying the CT/TT genotype had 70% lower chance of developing thrombocytopenia when compared to those with the CC genotype (OR: 0.30; 95%CI: 0.08-0.88; p = .042). Our findings demonstrated that the T allele carriers of the IFNL3 gene had higher risk of developing severe dengue, suggesting a link between IFN-λ expression and DENV immunopathogenesis.

The optimal age of vaccination against dengue in Brazil based on serotype-specific forces of infection derived from serological data

In this paper, we study a single serotype transmission model of dengue to determine the optimal vaccination age for Dengvaxia. The transmission dynamics are modelled with an age-dependent force of infection. The force of infection for each serotype is derived from the serological profile of dengue in Brazil without serotype distinction and from serotype-specific reported cases. The risk due to an infection is measured by the probability of requiring hospitalization based on Brazilian Ministry of Health data. The optimal vaccination age is determined for any number and combination of the four distinct dengue virus serotypes DENv1-4. The lifetime expected risk is adapted to include antibody dependent enhancement (ADE) and permanent cross-immunity after two heterologous infections. The risk is assumed to be serostatus-dependent. The optimal vaccination age is computed for constant, serostatus-specific vaccine efficacies. Additionally, the vaccination age is restricted to conform to the licence of Dengvaxia in Brazil and the achievable and minimal lifetime expected risks are compared. The optimal vaccination age obtained for the risk of hospitalization varies significantly with the assumptions relating to ADE and cross-immunity. Risk-free primary infections lead to higher optimal vaccination ages, as do asymptomatic third and fourth infections. Sometimes vaccination is not recommended at all, e.g. for any endemic area with a single serotype if primary infections are risk-free. Restricting the vaccination age to Dengvaxia licensed ages mostly leads to only a slightly higher lifetime expected risk and the vaccine should be administered as close as possible to the optimal vaccination age.

Retrospective cross-sectional observational study on the epidemiological profile of dengue cases in Pernambuco state, Brazil, between 2015 and 2017

BACKGROUND

The spread of Dengue virus (DENV) infections, as well as their signs and symptoms, are the result of a complex interaction between several factors. In Brazil, especially in the Northeastern, dengue is an important public health problem. Here, we report an epidemiological analysis of dengue cases in Pernambuco state, Northeastern Brazil, during 2015-2017.

METHODS

This work is a retrospective cross-sectional observational study on the epidemiological profile of all dengue cases confirmed and reported to the Health Secretary of Pernambuco between 2015 and 2017. These data cover all municipalities of Pernambuco, except Fernando de Noronha. DENV-positive individuals were classified according to the dengue type (without and with warning signs, or severe dengue), age, gender, ethnicity and intermediate geographic region of residence (Recife, Caruaru, Serra Talhada or Petrolina). The distribution of cases over the years was assessed by χ2 test. Temperature and rainfall data were evaluated by Unpaired t-test. p-value < 0.05 and CI 95% were considered in all analyses.

RESULTS

Most dengue cases was without warning signs. The most observed characteristics in the less severe dengue phenotypes were: female, mulatto ethnicity and age between 20 and 39 years old; this profile was more clearly observed in 2015. In 2016 and 2017, however, the numbers of dengue without and with warning signs were more evenly distributed and the difference in cases within groups decreased significantly. Regarding severe dengue, mulattoes were the most affected, but it is possible to note a trend towards a more uniform distribution between the genders and ages. Recife was the region with the highest numbers of both total cases and incidence rates and the highest rainfall levels. Overall, over the years, there has been a decrease in dengue cases in all regions of Pernambuco.

CONCLUSIONS

We identified the epidemiological profile of dengue in Pernambuco, Brazil, reporting the gender, age, ethnicity and regions most affected by different dengue types. In addition, we observed that these cases were probably more influenced by rainfall than by temperature. Finally, we believe that this epidemiological knowledge is important to direct public health policies to the reality of each population.

The Optimal Age of Vaccination Against Dengue with an Age-Dependent Biting Rate with Application to Brazil

In this paper we introduce a single serotype transmission model, including an age-dependent mosquito biting rate, to find the optimal vaccination age against dengue in Brazil with Dengvaxia. The optimal vaccination age and minimal lifetime expected risk of hospitalisation are found by adapting a method due to Hethcote (Math Biosci 89:29–52). Any number and combination of the four dengue serotypes DENv1–4 is considered. Successful vaccination against a serotype corresponds to a silent infection. The effects of antibody-dependent enhancement (ADE) and permanent cross-immunity after two heterologous infections are studied. ADE is assumed to imply risk-free primary infections, while permanent cross-immunity implies risk-free tertiary and quaternary infections. Data from trials of Dengvaxia indicate vaccine efficacy to be age and serostatus dependent and vaccination of seronegative individuals to induce an increased risk of hospitalisation. Some of the scenarios are therefore reconsidered taking these findings into account. The optimal vaccination age is compared to that achievable under the current age restriction of the vaccine. If vaccination is not considered to induce risk, optimal vaccination ages are very low. The assumption of ADE generally leads to a higher optimal vaccination age in this case. For a single serotype vaccination is not recommended in the case of ADE. Permanent cross-immunity results in a slightly lower optimal vaccination age. If vaccination induces a risk, the optimal vaccination ages are much higher, particularly for permanent cross-immunity. ADE has no effect on the optimal vaccination age when permanent cross-immunity is considered; otherwise, it leads to a slight increase in optimal vaccination age.

Profiling of Microrna Expression within the Cells of Peripheral Blood Mononuclear after an Infection with Serotype-2 of Dengue Virus: Preliminary Study

The role of microRiboNucleic Acids (miRNA), a small-non coding RNA has been associated with immune regulation in various viral infectionincluding dengue infection. The microRNA will bind a specific protein target in order to encourage an explosive expression of various cytokines, known as cytokines storm in Dengue infection.The objective of this study aimed to determine and evaluate themicroRNAs profile expression withinperipheral blood mononuclear cells having been infected with one of the dengue virus serotype.To obtained the PBMCs from a healthy donor, Ficoll density gradient centrifugation was used to isolate the PBMCs and then followed infecting it with a DENV-2 clinical isolate. Prior to PBMCs isolation, the virus has been propagated and having titration to get an optimal virus titer. We conducted the infection at the multiplication of infections 4 PFU/106 cells.MiRCURYLNATMExiqon was utilized on purpose to extract the RNA. Quantitative Real-Time PCR was applied in order for the miRNAs relative expression to be measured. The preliminary result reveals that miR-150, miR-146a, hsa-let-7e expression were increased 1.74 folds, 2 folds, and 1.49 foldsrespectively at 12 hours post-infection on PBMCs upon DENV-2 infection.The expression of microRNAswas discovered to behigher inPBMCsat the time of infection withDENV-2.ThemiRNAs expression in the uninfected PMBCs was lower than that of the miRNA. This high expression of miRNAsin dengue infection may proceedto dengue infection pathogenesis.

Development of a Prognostic Prediction Model to Determine Severe Dengue in Children

OBJECTIVE

To develop a prognostic prediction model using the seven warning signs highlighted by WHO revised Dengue fever classification 2009 to determine severe dengue in children.

METHODS

In this prospective analytical study conducted in a tertiary care centre, consecutive sampling of all children aged 1mo to 12y admitted with serologically confirmed Dengue was done from May 2015 through August 2016. After excluding 27 patients with co-infections and co-morbidities, 359 patients were followed up daily to assess clinical and laboratory progression till discharge/ death. Independent predictors were abdominal pain or tenderness, persistent vomiting, lethargy, mucosal bleed, clinical fluid accumulation, hepatomegaly >2 cm and rising hematocrit concurrent with platelet count <100 × 109/L. Outcome measure was severe dengue defined as per WHO guidelines 2009.

RESULTS

Among 359 children, 93 progressed to severe dengue. In univariate analysis, significant predictors were clinical fluid accumulation (OR 4.773, p = 0.000, 95%CI 2.511-9.075), persistent vomiting (OR 1.944, p = 0.010, 95%CI 1.170-3.225), mucosal bleed (OR 2.045, p = 0.019, 95%CI 1.127-3.711) and hematocrit ≥0.40 concurrent with platelet count <100 × 109/L (OR 2.985, p = 0.000, 95%CI 1.783-4.997). The final multivariable model included clinical fluid accumulation (aOR 3.717, p = 0.000, 95%CI 1.901-7.269), hematocrit ≥0.40 concurrent with platelet count <100 × 109/L (aOR 2.252, p = 0.004, 95%CI 1.302-3.894) and persistent vomiting (p = 0.056) as predictors of severe dengue.

CONCLUSIONS

Among seven WHO warning signs, predictors of severe dengue as suggested by the present multivariable prediction model include clinical fluid accumulation, persistent vomiting and hematocrit ≥0.40 concurrent with platelet count <100 × 109/L.

Assessing the effects of daily commuting in two-patch dengue dynamics: A case study of Cali, Colombia

There are many infectious diseases that can be spread by daily commuting of people and dengue fever is one of them. The absence of vaccine and irregularities in ongoing vector control programs make this disease the most frequent and persistent in many tropical and subtropical regions of the world. This paper targets to access the effects of daily commuting on dengue transmission dynamics by using a deterministic two-patch model fitted to observed data gathered in Cali, Colombia where dengue fever is highly persistent and exhibits endemo-epidemic patterns. The two-patch dengue transmission model with daily communing of human residents between patches (that is, between the city and its suburban areas) is presented using the concept of residence times, which certainly affect the disease transmission rates by inducing variability in human population sizes and vectorial densities at each patch. The same modeling framework is applied to two primary scenarios (epidemic outbreaks and endemic persistence of the disease) and for each scenario two coupling cases (one-way and asymmetric commuting) with different inflow and outflow intensities are analyzed. The concept of effective vectorial density, introduced in this paper, allows to explain in very simple terms why the daily commuting affects quite differently the dengue morbidity among human residents in both patches. In particular, residents of the patch with a greater share of incoming than outgoing commuters may actually "benefit" from inflow of daily commuter by avoiding a considerable number of infections. However, residents of the patch with a greater share of outgoing than incoming commuters, especially those who stay at home patch, incur more risk of getting infected. Additionally, the model shows that daily commuting enhance the total number of human infections acquired in both patches and may even provoke an epidemic outbreak in one patch while moderately lowering the level of the disease persistence in another patch.

Challenges in dengue research: A computational perspective

The dengue virus is now the most widespread arbovirus affecting human populations, causing significant economic and social impact in South America and South-East Asia. Increasing urbanization and globalization, coupled with insufficient resources for control, misguided policies or lack of political will, and expansion of its mosquito vectors are some of the reasons why interventions have so far failed to curb this major public health problem. Computational approaches have elucidated on dengue's population dynamics with the aim to provide not only a better understanding of the evolution and epidemiology of the virus but also robust intervention strategies. It is clear, however, that these have been insufficient to address key aspects of dengue's biology, many of which will play a crucial role for the success of future control programmes, including vaccination. Within a multiscale perspective on this biological system, with the aim of linking evolutionary, ecological and epidemiological thinking, as well as to expand on classic modelling assumptions, we here propose, discuss and exemplify a few major computational avenues-real-time computational analysis of genetic data, phylodynamic modelling frameworks, within-host model frameworks and GPU-accelerated computing. We argue that these emerging approaches should offer valuable research opportunities over the coming years, as previously applied and demonstrated in the context of other pathogens.

Incidence and risk factors for Dengue virus (DENV) infection in the first 2 years of life in a Brazilian prospective birth cohort

This study assessed the incidence and risk factors for dengue virus (DENV) infection among children in a prospective birth cohort conducted in the city of Recife, a hyperendemic dengue area in Northeast Brazil. Healthy pregnant women (n = 415) residing in Recife who agreed to have their children followed were enrolled. Children were followed during their first 24 months of age (May/2011-June/2014), before the 2015 Zika virus outbreak. DENV infection was detected by reverse-transcriptase polymerase chain reaction and/or serology (anti-DENV IgM/IgG). The incidence rates per 1000 person-years (py) and its association with risk factors by age bands (0-12, >12-30 months) were estimated through Poisson regression models. Forty-nine dengue infections were detected; none progressed to severe forms. The incidence rates were 107·6/1000py (95% CI 76·8-150·6) and 93·3/1000py (95% CI 56·1-154·4) in the first and second years of age, respectively. Male children (risk ratios (RR) = 2·33; 95% CI 1·09-4·98) and those born to DENV-naïve mothers (RR = 2·42; 95% CI 1·01-5·80) were at greater risk of infection in the first year of age. In the second year, children born to Caucasian/Asian descent skin colour mothers had a threefold higher risk of infection (RR = 3·34; 95% CI: 1·08-10·33). These data show the high exposure of children to DENV infection in our setting and highlight the role of biological factors in this population's susceptibility to infection.

Historical Perspectives on Flavivirus Research

The flaviviruses are small single-stranded RNA viruses that are typically transmitted by mosquito or tick vectors. These "arboviruses" are found around the world and account for a significant number of cases of human disease. The flaviviruses cause diseases ranging from mild or sub-clinical infections to lethal hemorrhagic fever or encephalitis. In many cases, survivors of neurologic flavivirus infections suffer long-term debilitating sequelae. Much like the emergence of West Nile virus in the United States in 1999, the recent emergence of Zika virus in the Americas has significantly increased the awareness of mosquito-borne viruses. The diseases caused by several flaviviruses have been recognized for decades, if not centuries. However, there is still a lot that is unknown about the flaviviruses as the recent experience with Zika virus has taught us. The objective of this review is to provide a general overview and some historical perspective on several flaviviruses that cause significant human disease. In addition, available medical countermeasures and significant gaps in our understanding of flavivirus biology are also discussed.

Complete genome characterization and evolutionary analysis of serotype-4 associated with severe dengue

Dengue virus circulates as four independent serotypes posing a major public health threat around the globe. In the recent years, frequent dengue outbreaks are being reported in many parts of the world including India. Among four serotypes, Den-4 is the least sampled and studied serotype until recent times, but the reported cases with Den-4 infections were mostly known to associate with severe dengue. In the past three decades, only one complete genome sequence of Den-4 has been published from India. Hence there is a deficit in information with reference to this serotype which would be required in deciphering its association with severe dengue. In this study, we have carried out the complete genome characterization of Den-4 virus, isolated from a dengue shock syndrome patient during the 2015 outbreak from Hyderabad, South India. Phylogenetic analysis revealed the circulation of genotype I (lineage C) which showed close relatedness to the reported virulent strains. The data also indicated few unique amino acid substitutions which are known to be important in virus replication and epitope presentation. This is the first report of complete genome characterization of Den-4 from South India, which may assist in shaping the genetic diversity of circulating strains in India.

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

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

Occurrence of severe dengue in Rio de Janeiro: an ecological study

INTRODUCTION

This study aimed to analyze the relationship between the incidence of severe dengue during the 2008 epidemic in Rio de Janeiro, Brazil, and socioeconomic indicators, as well as indicators of health service availability and previous circulation of the dengue virus serotype-3 (DENV-3).

METHODS

In this ecological study, the units of analysis were the districts of Rio de Janeiro. The data were incorporated into generalized linear models, and the incidence of severe dengue in each district was the outcome variable.

RESULTS

The districts with more cases of dengue fever in the 2001 epidemic and a higher percentage of residents who declared their skin color or race as black had higher incidence rates of severe dengue in the 2008 epidemic [incidence rate ratio (IRR)= 1.21; 95% confidence interval (95%CI)= 1.05-1.40 and IRR= 1.34; 95%CI= 1.16-1.54, respectively]. In contrast, the districts with Family Health Strategy (FHS) clinics were more likely to have lower incidence rates of severe dengue in the 2008 epidemic (IRR= 0.81; 95%CI= 0.70-0.93).

CONCLUSIONS

At the ecological level, our findings suggest the persistence of health inequalities in this region of Brazil that are possibly due to greater social vulnerability among the self-declared black population. Additionally, the protective effect of FHS clinics may be due to the ease of access to other levels of care in the health system or to a reduced vulnerability to dengue transmission that is afforded by local practices to promote health.

A Highly Sensitive Diagnostic System for Detecting Dengue Viruses Using the Interaction between a Sulfated Sugar Chain and a Virion

We propose a novel method of detecting trace amounts of dengue virus (DENVs) from serum. Our method is based on the interaction between a sulfated sugar chain and a DENV surface glycoprotein. After capturing DENV with the sulfated sugar chain-immobilized gold nanoparticles (SGNPs), the resulting complex is precipitated and viral RNA content is measured using the reverse-transcription quantitative polymerase chain reaction SYBR Green I (RT-qPCR-Syb) method. Sugar chains that bind to DENVs were identified using the array-type sugar chain immobilized chip (Sugar Chip) and surface plasmon resonance (SPR) imaging. Heparin and low-molecular-weight dextran sulfate were identified as binding partners, and immobilized on gold nanoparticles to prepare 3 types of SGNPs. The capacity of these SGNPs to capture and concentrate trace amounts of DENVs was evaluated in vitro. The SGNP with greatest sensitivity was tested using clinical samples in Indonesia in 2013-2014. As a result, the novel method was able to detect low concentrations of DENVs using only 6 μL of serum, with similar sensitivity to that of a Qiagen RNA extraction kit using 140 μL of serum. In addition, this method allows for multiplex-like identification of serotypes of DENVs. This feature is important for good healthcare management of DENV infection in order to safely diagnose the dangerous, highly contagious disease quickly, with high sensitivity.

Seroprevalence and seroconversion of dengue and implications for clinical diagnosis in amazonian children

This study aimed to evaluate the prevalence of serum IgG dengue in children in an Amazonian population, to assess the seroconversion rate in 12 months, and to estimate how many seropositive children had a prior clinical diagnosis of dengue. We conducted a population-based study between 2010 and 2011, with children aged 6 months to 12 years that were living in the urban area of a small town in the Brazilian Amazon. The prevalence of IgG antibodies against dengue antigens was determined by indirect ELISA technique, and seronegative children were reexamined after 12 months to determine seroconversion rates. Results showed seroprevalence of IgG antibodies against dengue type of 2.9%, with no significant association between age, race, and sex. In seropositive children, only 8.4% had received a clinical diagnosis of dengue, and the ratio of clinically diagnosed cases and subclinical cases was 1 : 11. The seroconversion rate between 2010 and 2011 was 1.4% (CI 3.8% to 35.1%). The seroprevalence of dengue in this pediatric population was low, and the vast majority of cases were not clinically detected, suggesting a difficulty in making the clinical diagnosis in children and a high frequency of asymptomatic infections.

Vaccine Development as a Means to Control Dengue Virus Pathogenesis: Do We Know Enough?

Dengue virus (DENV) is a mosquito-transmitted RNA virus responsible for 390 million infections each year and significant morbidity and mortality throughout tropical and subtropical regions of the world. Efforts to develop a DENV vaccine span 70 years and include the work of luminaries of the virus vaccine field. Although vaccines have been used to reduce the global health burden of other flaviviruses, the unique requirement for a single vaccine to protect against four different groups of dengue viruses, and the link between secondary infections and DENV disease pathogenesis, has limited success to date. In this review, we discuss several promising DENV vaccine candidates in clinical trials and assess how recent advances in understanding of DENV biology and immunity may expedite efforts toward the development of safe and effective vaccines.

Role of intracellular events in the pathogenesis of dengue; an overview

Dengue is one of the most important mosquito-borne viral diseases that are relentlessly spreading in newer areas in the tropical and subtropical regions of the World. In last fifty years, in spite of intensive and extensive investigations, pathogenesis of dengue is still not clearly understood. Recently, the research focus is on studying the role of intracellular events in pathogenesis of viral infections. Entry of virion in the host cell is followed by quick succession of events, unfolded protein response, lipid bodies and lipophagy, endoplasmic reticulum stress and recent demonstration of autophagy. The turbulence caused by these events may result in clearance of the virus/enhanced replication and survival of the host cell/apoptosis. Both, increased virus load and apoptosis of host cell may have pathological effects on the host. In the present review, we have summed up the role of various intracellular events in viral infections with special emphasis on Dengue virus infection.

Prevalence and incidence of dengue virus and antibody placental transfer during late pregnancy in central Brazil

Background

Maternal dengue antibodies are considered to play a significant role in dengue pathogenesis among infants. Determining the transplacental specific antibody transfer is invaluable for establishing the optimal vaccination age among infants in endemic regions.

Methods

We conducted a cross-sectional study among pairs of maternal and corresponding umbilical cord blood samples in public hospitals. The prevalence and incidence of dengue infection were determined in 505 pairs of pregnant women and neonates during a large outbreak (2009–2010) in central Brazil. The women were interviewed at late pregnancy to assess current or past symptoms of dengue. All parturients and their neonates were screened using Dengue IgG Indirect ELISA (Panbio) to assess previous dengue exposure. A semi-quantitative measurement of the IgG antibody expressed by the index ratio was calculated using optical density (OD) values according to the manufacturer’s instructions. The studied population of parturients and their offspring was also screened for recent dengue infection by the Dengue IgM-capture ELISA (Panbio). Those participants with history of fever and two or more symptoms of dengue at least 10 days before the delivery were also tested for the dengue NS1 antigen using the Dengue Early ELISA (Panbio) and RT-PCR.

Results

The mean maternal age was 25.8 (SD = 6.4), and 83.6% of deliveries were between 37 and 41 weeks. Approximately half of the 505 women and neonates were IgG-seropositive, yielding 99.3% co-positive mother-child frequency of antibody transfer (Kappa = 0.96). The incidence of dengue infection was 2.8% (95% CI 1.4–4.4%) among the women considering 14 IgM-positive results and one DENV2 detected by RT-PCR. The dengue NS1 antigen was undetectable in the matched pairs.

Conclusion

This study provides critical data on the prevalence of transplacental transferred maternal-infant anti-dengue antibodies and incidence of infection. The design of future vaccine trials should consider diverse regional epidemiological scenarios.

Developing a vulnerability mapping methodology: applying the water-associated disease index to dengue in Malaysia

The Water-associated Disease Index (WADI) was developed to identify and visualize vulnerability to different water-associated diseases by integrating a range of social and biophysical determinants in map format. In this study vulnerability is used to encompass conditions of exposure, susceptibility, and differential coping capacity to a water-associated health hazard. By assessing these conditions, the tool is designed to provide stakeholders with an integrated and long-term understanding of subnational vulnerabilities to water-associated disease and contribute to intervention strategies to reduce the burden of illness. The objective of this paper is to describe and validate the WADI tool by applying it to dengue. A systemic ecohealth framework that considers links between people, the environment and health was applied to identify secondary datasets, populating the index with components including climate conditions, land cover, education status and water use practices. Data were aggregated to create composite indicators of exposure and of susceptibility in a Geographic Information System (GIS). These indicators were weighted by their contribution to dengue vulnerability, and the output consisted of an overall index visualized in map format. The WADI was validated in this Malaysia case study, demonstrating a significant association with dengue rates at a sub-national level, and illustrating a range of factors that drive vulnerability to the disease within the country. The index output indicated high vulnerability to dengue in urban areas, especially in the capital Kuala Lumpur and surrounding region. However, in other regions, vulnerability to dengue varied throughout the year due to the influence of seasonal climate conditions, such as monsoon patterns. The WADI tool complements early warning models for water-associated disease by providing upstream information for planning prevention and control approaches, which increasingly require a comprehensive and geographically broad understanding of vulnerability for implementation.

Secondary infection as a risk factor for dengue hemorrhagic fever/dengue shock syndrome: an historical perspective and role of antibody-dependent enhancement of infection

Today, dengue viruses are the most prevalent arthropod-borne viruses in the world. Since the 1960s, numerous reports have identified a second heterologous dengue virus (DENV) infection as a principal risk factor for severe dengue disease (dengue hemorrhagic fever/dengue shock syndrome, DHF/DSS). Modifiers of dengue disease response include the specific sequence of two DENV infections, the interval between infections, and contributions from the human host, such as age, ethnicity, chronic illnesses and genetic background. Antibody-dependent enhancement (ADE) of dengue virus infection has been proposed as the early mechanism underlying DHF/DSS. Dengue cross-reactive antibodies raised following a first dengue infection combine with a second infecting virus to form infectious immune complexes that enter Fc-receptor-bearing cells. This results in an increased number of infected cells and increased viral output per cell. At the late illness stage, high levels of cytokines, possibly the result of T cell elimination of infected cells, result in vascular permeability, leading to shock and death. This review is focused on the etiological role of secondary infections (SI) and mechanisms of ADE.

Dengue em crianças: da notificação ao óbito

OBJETIVO: Descrever aspectos históricos, epidemiológicos e clínicos da dengue em crianças, demonstrando a importância das notificações e conhecimento destas para prevenir a evolução de gravidade e os óbitos nessa população. FONTES DE DADOS: Revisão narrativa dos principais trabalhos publicados sobre dengue e dengue em crianças. Buscaram-se estudos nas seguintes bases de dados: Lilacs, SciELO, Medline e Scopus, além de documentos oficiais do Ministério da Saúde. A busca incluiu trabalhos publicados no período de janeiro de 1980 a março de 2011. Os descritores utilizados foram: dengue, dengue em criança, dengue em pediatria e notificação de doenças. SÍNTESE DOS DADOS: Todos os artigos encontrados foram avaliados e procurou-se estabelecer uma linha de tempo e principais informações alusivas ao tema, fatores referentes ao vírus e ao vetor também foram incluídos; informações sobre as características clínicas e importância das notificações foram apontadas, além da relevante investigação e elucidação de todos os óbitos notificados. Existe um grande número de estudos sobre o assunto, porém foi dada maior ênfase àqueles pertinentes às crianças. CONCLUSÕES: O conhecimento desta doença, que se configura como principal doença emergente e reemergente na atualidade, é fundamental para diagnóstico precoce, tratamento oportuno e prevenção de óbitos. Há uma lacuna na notificação adequada em Pediatria, assim como no detalhamento dos óbitos em crianças vítimas de dengue.