Meta-Analysis of Dengue Severity during Infection by Different Dengue Virus Serotypes in Primary and Secondary Infections

Utilization of novel molecular multiplex methods for the detection and, epidemiological surveillance of dengue virus serotypes and chikungunya virus in Burkina Faso, West Africa

BACKGROUND

Dengue virus (DENV) and Chikungunya virus (CHIKV) are major arboviruses that are transmitted to humans by Aedes aegypti (A. aegypti) and Aedes Albopictus (A. Albopictus) mosquitoes. In absence of specific antivirals and vaccine against these two viruses, prompt diagnosis of acute infections and robust surveillance for outbreak identification remain crucial. Therefore, rapid, robust, high-throughput, accessible, and low-cost assays are essential for endemic countries. This study evaluated our recently developed multiplex RT-PCR and RT-qPCR assays to screen for DENV1-4 and CHIKV circulation in Burkina Faso.

METHODS AND RESULTS

This study, conducted between June to August 2023, enrolled patients with suspected arbovirus infection presenting at healthcare facilities in three Burkina Faso cities (Bobo-Dioulasso, Houndé, and Ouagadougou). Serum samples were collected and screened for DENV serotypes and CHIKV using our newly multiplex RT-PCR and RT-q PCR techniques recently developed. A total of 408 patients (age median = 33, range from 3 to 84 years) participated in this study. Of these, 13.7% (56/408) had DENV infection; DENV-1 was 32.1% (18/56) and DENV-3 was 67.9% (38/56). DENV-2, DENV-4 and CHIKV were not detected.

CONCLUSIONS

This study demonstrates the effectiveness of our molecular methods for DENV detection and serotyping in Burkina Faso. The affordability of our methods makes them valuable for implementing widespread routine clinical diagnostics or arbovirus surveillance in resource-limited settings.

Dengue severity by serotype and immune status in 19 years of pediatric clinical studies in Nicaragua

BACKGROUND

Dengue virus, a major global health threat, consists of four serotypes (DENV1-4) that cause a range of clinical manifestations from mild to severe and potentially fatal disease.

METHODS

This study, based on 19 years of data from the Pediatric Dengue Cohort Study and Pediatric Dengue Hospital-based Study in Managua, Nicaragua, investigates the relationship of serotype and immune status with dengue severity. Dengue cases were confirmed by molecular, serological, and/or virological methods, and sudy participants 6 months to 17 years old were followed during their hospital stay or as ambulatory patients.

RESULTS

We enrolled a total of 15,266 participants, of whom 3,227 (21%) were positive for DENV infection. Of 2,630 cases with serotype result by RT-PCR, 557 corresponded to DENV1, 992 to DENV2, 759 to DENV3 and 322 to DENV4. Severe disease was more prevalent among secondary DENV2 and DENV4 cases, while similar disease severity was observed in both primary and secondary DENV1 and DENV3 cases. According to the 1997 World Health Organization (WHO) severity classification, both DENV2 and DENV3 caused a higher proportion of severe disease compared to other serotypes, whereas DENV3 caused the greatest percentage of severity according to the WHO-2009 classification. DENV2 was associated with increased odds of pleural effusion and low platelet count, while DENV3 was associated with both hypotensive and compensated shock.

CONCLUSIONS

These findings demonstrate differences in dengue severity by serotype and immune status and emphasize the critical need for a dengue vaccine with balanced effectiveness against all four serotypes, particularly as existing vaccines show variable efficacy by serotype and serostatus.

Dengue outbreaks in Brazil and Latin America: The new and continuing challenges

Dengue is one of the most common zoonoses in Latin America. In 2023, Brazil registered a total of 1,658,814 suspected cases of dengue with 1094 deaths. For 2024, a total of 1,978,372 suspected cases of dengue were reported only until the 11th epidemiological week, with 656 deaths. When comparing dengue cases reported in 2024 and 2023, there is an increase in suspected cases, with 20% more cases reported during the first 11 epidemiological weeks of 2024 than in the entire 52 epidemiological weeks of 2023. At the same time, in 2024, the Pan American Health Organization reported suspected cases in 20 Latin American countries, with 3073 cases of severe dengue and 1187 deaths. In this sense, Brazil was responsible for more than 50% of suspected cases and deaths from dengue compared to the other Latin American countries in 2024. Furthermore, there is a different ethnic racial profile for dengue in Brazil, as Black people, Mixed individuals, and Indigenous peoples were more likely to be suspected cases of dengue in 2024 compared to 2023.

Duration of Fever in Patients with Dengue: A Systematic Review and Meta-Analysis

Dengue is an acute febrile illness endemic to tropical countries and associated with high mortality rates. Despite being a viral infection, there is rampant misuse of antibiotics in patients with dengue because of perceived delay in defervescence and fear of secondary bacterial infections. Therefore, there is a need to establish the average fever duration with a confidence interval among patients with dengue. Studies up to October 21, 2022 from two databases (PubMed and Embase) were included using the search terms related to dengue and duration of fever. All retrieved articles were screened for eligibility by two independent reviewers. Studies where the average duration of fever was available were included for systematic review. Articles with at least more than 20 patients where a mean and standard deviation for the total duration of fever was available were included for meta-analysis. A total of 643 articles were included from the two databases after duplicate deletion. After two rounds of screening, 31 articles (n = 7,905) were finally included. The mean duration of fever in the 20 articles included for meta-analysis was 5.1 (95% CI: 4.7-5.5) days. Longer duration of fever was seen in those with a higher grade of fever, those with higher disease severity, and those with concurrent bacterial infections. In the absence of risk factors for concurrent bacteremia, antimicrobials may be unnecessary in those with dengue fever duration of less than 5.5 days.

Serotype-Specific Epidemiological Patterns of Inapparent versus Symptomatic Primary Dengue Virus Infections: A 17-year cohort study in Nicaragua

Dengue is the most prevalent mosquito-borne viral disease and a major public health problem worldwide. Most primary infections with the four dengue virus serotypes (DENV1-4) are inapparent; nonetheless, whether the distribution of symptomatic versus inapparent infections by serotype varies remains unknown. Here, we present (1) the evaluation of a multiplex DENV1-4 envelope domain III multiplex microsphere-based assay (EDIII-MMBA) to serotype inapparent primary infections and (2) its application leveraging 17 years of prospective sample collection from the Nicaraguan Pediatric Dengue Cohort Study (PDCS). First, we evaluated the performance of the EDIII-MMBA with samples characterized by RT-PCR or focus reduction neutralization test. Next, we analyzed 46% (N=574) of total inapparent primary DENV infections in the PDCS with the EDIII-MMBA to evaluate the epidemiology of inapparent infections. Remaining infections were inferred using stochastic imputation, taking year and neighborhood into account. Infection incidence and percentage of inapparent, symptomatic, and severe infections were analyzed by serotype. The EDIII-MMBA demonstrated excellent overall accuracy (100%, 95.8-100%) for serotyping symptomatic and inapparent primary DENV infections when evaluated against gold-standard serotyping methods. We found that a significant majority of primary infections were inapparent, with DENV3 exhibiting the highest likelihood of symptomatic and severe primary infections (Pooled OR compared to DENV1 = 2.13, 95% CI 1.28-3.56, and 6.75, 2.01-22.62, respectively), whereas DENV2 was similar to DENV1 in both analyses. Significant within- and between-year variation in serotype distribution between symptomatic and inapparent infections and circulation of serotypes undetected in symptomatic cases were observed in multiple years. Our study indicates that case surveillance skews the perceived epidemiological footprint of DENV. We reveal a more complex and intricate pattern of serotype distribution in inapparent infections. The significant differences in infection outcomes by serotype emphasizes the need for vaccines with balanced immunogenicity and efficacy across serotypes.

Addressing the Dengue fever challenges in Nigeria: A narrative review and recommendations for control

Dengue fever is a mosquito-borne viral infection that continues to pose a significant public health threat globally, including Nigeria. Here, we provided a review of dengue fever outbreaks in Nigeria from 1972 to 2023, examining the epidemiology, prevention strategies, challenges faced in combating the disease, and recommendations to mitigate its spread and transmission. We utilized scholarly databases such as PubMed and Google Scholar in writing this paper. The search keywords like, "dengue fever", "break-bone fever", "dengue fever virus" "outbreak", "Nigeria", "prevalence", and "epidemiology", were used to get appropriate published articles about the subject areas. Over the past five decades, Nigeria has experienced intermittent outbreaks of dengue fever, with varying degrees of severity and geographic distribution. Factors such as urbanization, climate change, and inadequate healthcare infrastructure have contributed to the resurgence and spread of the disease in the country. Despite efforts to control dengue transmission through vector control measures and public health interventions, challenges persist, including limited surveillance capacity, diagnostic delays, and gaps in vector control strategies. The emergence of new dengue virus serotypes and the potential for co-circulation with other arboviruses further complicate control efforts. This review highlights the importance of strengthening surveillance systems, enhancing vector control measures, improving diagnostic capabilities, and increasing public awareness to effectively mitigate the burden of dengue fever in Nigeria. Collaboration between government agencies, healthcare providers, researchers, and international partners is crucial in addressing the growing threat of dengue fever and reducing its impact on public health in Nigeria.

Primary exposure to Zika virus is linked with increased risk of symptomatic dengue virus infection with serotypes 2, 3, and 4, but not 1

Infection with any of the four dengue virus serotypes (DENV1-4) can protect against or enhance subsequent dengue depending on preexisting antibodies and infecting serotype. Additionally, primary infection with the related flavivirus Zika virus (ZIKV) is associated with increased risk of DENV2 disease. Here, we measured how prior DENV and ZIKV immunity influenced risk of disease caused by DENV1-4 in a pediatric Nicaraguan cohort. Of 3412 participants in 2022, 10.6% experienced dengue cases caused by DENV1 (n = 139), DENV4 (n = 133), DENV3 (n = 54), DENV2 (n = 9), or an undetermined serotype (n = 39). Longitudinal clinical and serological data were used to define infection histories, and generalized linear and additive models adjusted for age, sex, time since last infection, and year, and repeat measurements were used to predict disease risk. Compared with flavivirus-naïve participants, primary ZIKV infection was associated with increased risk of disease caused by DENV4 (relative risk = 2.62, 95% confidence interval: 1.48 to 4.63) and DENV3 (2.90, 1.34 to 6.27), but not DENV1 infection. Primary DENV infection or DENV followed by ZIKV infection was also associated with increased risk of DENV4 disease. We reanalyzed 19 years of cohort data and demonstrated that prior flavivirus immunity and antibody titer had distinct associations with disease risk depending on incoming serotype. We thus find that prior ZIKV infection, like prior DENV infection, is associated with increased risk of disease with certain DENV serotypes. Cross-reactivity among flaviviruses should be considered when assessing vaccine safety and efficacy.

Retrospective Analysis of Severe Dengue by Dengue Virus Serotypes in a Population with Social Security, Mexico 2023

BACKGROUND

Risk factors for severe dengue manifestations have been attributed to various factors, including specific serotypes, sex, and age. Mexico has seen the re-emergence of DENV-3, which has not circulated in a decade.

OBJECTIVE

To describe dengue serotypes by age, sex, and their association with disease severity in dengue-positive serum samples from epidemiological surveillance system units.

MATERIALS AND METHODS

A descriptive analysis was conducted to evaluate the frequency of dengue severity by sex, age, disease quarter, geographical location, and dengue virus serotypes. The study was conducted using laboratory samples from confirmed dengue cases through RT-qPCR from the epidemiological surveillance laboratory network of the Mexican Social Security Institute, Mexico. Simple frequencies and proportions were calculated using the z-test for proportional differences between groups. Bivariate analysis with adjusted Chi2 was performed, and binary logistic regression models were constructed using the forward Wald method considering the model's predictive capacity. The measure of association was the odds ratio, with 95% confidence intervals. Statistical significance was set to an alpha level of <0.05.

RESULTS

In 2023, 10,441 samples were processed for dengue RT-qPCR at the IMSS, with a predominance of serotype DENV-3 (64.4%). The samples were mostly from women (52.0%) and outpatient cases (63.3%). The distribution of dengue severity showed significant variations by age, with a lower proportion of severe cases in young children and a higher proportion in the 5- to 14-year-old group. Hospitalizations increased significantly with severity. Warm regions had more cases overall and severity. Cases were most frequent from July to September. While DENV-2 was associated with severity, DENV-4 was not. Binary regression identified higher risk in women, age extremes, and DENV-2, with an overall predictive model of 58.5%.

CONCLUSIONS

Women, age groups at the extremes of life, and the DENV-2 serotype presented severe risk of dengue in a population with social security in Mexico during 2023.

Circulation of DENV-2 serotype associated with increased risk of cumulative incidence of severe dengue and dengue with warning signs: A 16-year retrospective study in Peru

Background

Dengue poses a significant public health challenge in Peru and other endemic countries worldwide. While severe dengue is known to be associated with secondary infection at the individual level, the factors that elevate the risk of severe dengue at the population level remain poorly understood. This study leverages over 16 years of secondary data from a Peruvian dengue surveillance system to assess which type of serotype-specific circulation is associated with an increased risk of cumulative incidence of severe dengue or dengue with warning signs (SD-DWS).

Methodology

This is a retrospective analysis of secondary data using the Peruvian Ministry of Health databases of dengue cases and serotyping. A mixed negative binomial regression model for repeated measures over time was employed to estimate the association between the cumulative incidence of reported SD-DWS cases per 100,000 inhabitants and serotype-specific circulation. Crude and adjusted incidence ratios (IRR) were estimated.

Principal findings

The study analyzed data from 2007 to 2022 across 19 regions of Peru, totaling 304 region-years. Data from nearly 58,000 serotype identification reports and 57,966 cases of SD-DWS were analyzed. The regions with most cumulative incidence of SD-DWS per 100,000 inhabitants during 2007 to 2022 were Madre de Dios (3859), Loreto (1518), Ucayali (1492), Tumbes (1335), and Piura (722). The adjusted model revealed a higher risk of cumulative incidence of SD-DWS when there was specific circulation of DENV-123 (aIRR 7.57 CI 4.00 - 14.31), DENV-12 (aIRR 4.66 CI 2.57 - 8.44), DENV-23 (aIRR 3.55 CI 1.75 - 7.21), or when there was circulation of DENV-2 alone or co-circulating with other serotypes (aIRR 27.7 CI 15.46 -49.63).

Conclusions

Circulation of DENV-2 was associated with higher average incidence rate ratios of SD-DWS.

Author summary

We investigated how the circulation of different dengue virus (DENV) serotypes are associated with the incidence of severe dengue and dengue with warning signs in Peru, a country where dengue is endemic. We analyzed 16 years of data from the dengue surveillance system, including nearly 58,000 serotype identification reports and 57,966 cases of severe dengue and dengue with warning signs. We found that regions with specific circulation of DENV-2, either alone or in combination with other serotypes, had higher incidence rates of severe dengue and dengue with warning signs. Our findings highlight the importance of monitoring DENV serotype circulation to manage and prevent severe dengue, especially in regions where DENV-2 is prevalent.

Diabetes as risk factor to severity of dengue in naïve patients

Background

Dengue cases can progress to severe ant life-threating forms particularly in subsequent heterologous infections. However, recent studies had explored additional risk factors, including underlying health conditions, even in individuals without prior exposure to dengue, notably, in patients with endothelial dysfunction and chronic inflammation. This study examines the link between diabetes and the development of severe dengue disease in dengue-naive patients during the 2019 dengue outbreak in São Jose do Rio Preto, Brazil.

Methodology

We enrolled 529 laboratory-confirmed dengue cases, identified through DENV RT-PCR or NS1 antigen assays in a hospital cohort of acute febrile illness. Subsequently, we investigated the presence of anti-dengue and anti-Zika IgG antibodies. Samples testing positive for Zika were excluded from the analyses. Two groups were analyzed: naïve (DV-), and dengue history (DV+).

Results

Initially, presence of diabetes and kidney disease, as well as being dengue-naive, were associated with a higher frequency of severe and potentially severe clinical outcomes. Multivariate analysis identified diabetes as a risk factor, while the presence of anti-dengue antibodies was considered protective. Analysis of dengue naïve samples, highlighted diabetes as an independent risk factor to severe forms of dengue disease. In DV+ patients, no condition was highlighted as a risk factor by univariate analysis or multivariate analysis.

Conclusions

We investigated and confirmed diabetes as a risk factor for severe dengue disease in individuals without prior dengue or Zika exposure. Our conclusions raise significant concerns given diabetes' ever increasing global prevalence and its potential impact on patients with or previous dengue exposure.

The burden of dengue and force of infection among children in Kerala, India; seroprevalence estimates from Government of Kerala-WHO Dengue study

Background

Dengue shows high geographic heterogeneity within and across endemic countries. In the context of increasing burden and predicted outbreaks due to climate change, understanding the heterogeneity will enable us to develop region specific targeted interventions, including vaccination. World Health Organisation (WHO) suggests standard methodologies to study the burden and heterogeneity at national and subnational levels. Regional studies with robust and standard methodology to capture heterogeneity are scarce. We estimated the seroprevalence of dengue in children aged 9-12 years and the force of infection in Kerala, India, from where Zika cases also have been reported recently.

Methods

We conducted a school-based cross-sectional survey in 38 clusters; selected by stratified random sampling, representing rural, urban, high burden and low-burden administrative units. Validation of Indirect IgG ELISA was done by Plaque Reduction Neutralization Test (PRNT90) using the local isolates of all four serotypes. Force of infection (FOI) was estimated using the WHO-FOI calculator. We conducted a follow-up survey among a subsample of seronegative children, to estimate the rate of sero-conversion.

Results

Among 5236 children tested, 1521 were positive for anti-dengue IgG antibody. The overall seroprevalence in the state was 29% (95% CI 24.1-33.9). The validity corrected seroprevalence was 30.9% in the overall sample, 46.9% in Thiruvananthapuram, 26.9% in Kozhikkode and 24.9% in Kollam. Age-specific seroprevalence increased with age; 25.7% at 9 years, 29.5% at 10 years, 30.9% at 11 years and 33.9% at 12 years. Seroprevalence varied widely across clusters (16.1%-71.4%). The estimated force of infection was 3.3/100 person-years and the seroconversion rate was 4.8/100 person-years. 90% of children who tested positive were not aware of dengue infection. All the four serotypes were identified in PRNT and 40% of positive samples had antibodies against multiple serotypes.

Interpretation

The study validates the WHO methodology for dengue serosurveys and confirms its feasibility in a community setting. The overall seroprevalence in the 9-12 year age group is low to moderate in Kerala; there are regional variations; high burden and low burden clusters co-exist in the same districts. The actual burden of dengue exceeds the reported numbers. Heterogeneity in prevalence, the high proportion of inapparent dengue and the hyperendemic situation suggest the need for region-specific and targeted interventions, including vaccination.

Funding

World Health Organization.

Dengue

Dengue, caused by four closely related viruses, is a growing global public health concern, with outbreaks capable of overwhelming health-care systems and disrupting economies. Dengue is endemic in more than 100 countries across tropical and subtropical regions worldwide, and the expanding range of the mosquito vector, affected in part by climate change, increases risk in new areas such as Spain, Portugal, and the southern USA, while emerging evidence points to silent epidemics in Africa. Substantial advances in our understanding of the virus, immune responses, and disease progression have been made within the past decade. Novel interventions have emerged, including partially effective vaccines and innovative mosquito control strategies, although a reliable immune correlate of protection remains a challenge for the assessment of vaccines. These developments mark the beginning of a new era in dengue prevention and control, offering promise in addressing this pressing global health issue.

Site-specific imprinting of dengue virus non-structural 1 antigen on a polydopamine-based sensing film for early detection and prognosis of dengue

Serum levels of dengue virus (DENV) non-structural 1 (NS1) antigen can serve as a valuable prognostic indicator of severe dengue infections. A quartz crystal microbalance (QCM)-based biosensor with a biomimetic recognition element was designed to quantitatively detect DENV NS1 as an early disease biomarker. To mitigate the reliance on costly viral antigens during the molecular imprinting process, a synthetic peptide mimicking a DENV NS1 epitope was used as a surrogate template for the synthesis of an epitope-imprinted polydopamine (EMIPDA) sensing film on the biosensor surface. The maximal frequency shift for DENV NS1 was obtained with an EMIPDA film synthesised using 5 mg mL-1 of dopamine monomer and 0.5 mg mL-1 of peptide template. The EMIPDA-QCM biosensor achieved low detection and quantitation limits of 0.091 μg mL-1 and 0.436 μg mL-1, respectively, allowing acute-phase detection of dengue and prognosis of the disease progression. The EMIPDA-QCM biosensor exhibited remarkable selectivity with up to 68-fold larger frequency responses towards DENV NS1 compared to a major serum protein. The site-specific imprinting approach not only enhanced the biosensing performance but also enabled a 26-fold cost reduction for biosensor functionalisation, providing a cost-effective strategy for label-free biosensing of the dengue biomarker via the biopolymer film.

Long-term efficacy and safety of a tetravalent dengue vaccine (TAK-003): 4·5-year results from a phase 3, randomised, double-blind, placebo-controlled trial

BACKGROUND

About half of the world's population lives in dengue-endemic areas. We aimed to evaluate the long-term efficacy and safety of two doses of the tetravalent dengue vaccine TAK-003 in preventing symptomatic dengue disease of any severity and due to any dengue virus (DENV) serotypes in children and adolescents.

METHODS

In this ongoing double-blind, randomised, placebo-controlled trial, we enrolled healthy participants aged 4-16 years at 26 medical and research centres across eight dengue-endemic countries (Brazil, Colombia, Dominican Republic, Nicaragua, Panama, Philippines, Sri Lanka, and Thailand). The main exclusion criteria were febrile illness (body temperature ≥38°C) at the time of randomisation, hypersensitivity or allergy to any of the vaccine components, pregnancy or breastfeeding, serious chronic or progressive disease, impaired or altered immune function, and previous receipt of a dengue vaccine. Participants were randomly assigned 2:1 (stratified by age and region) using an interactive web response system and dynamic block assignment to receive two subcutaneous doses of TAK-003 or placebo 3 months apart. Investigators, participants, and their parents or legal guardians were blinded to group assignments. Active febrile illness surveillance and RT-PCR testing of febrile illness episodes were performed for identification of virologically confirmed dengue. Efficacy outcomes were assessed in the safety analysis set (all randomly assigned participants who received ≥1 dose) and the per protocol set (all participants who had no major protocol violations), and included cumulative vaccine efficacy from first vaccination to approximately 4·5 years after the second vaccination. Serious adverse events were monitored throughout. This study is registered with ClinicalTrials.gov, NCT02747927.

FINDINGS

Between Sept 7, 2016, and March 31, 2017, 20 099 participants were randomly assigned (TAK-003, n=13 401; placebo, n=6698). 20 071 participants (10 142 [50·5%] males; 9929 [49·5%] females; safety set) received TAK-003 or placebo, with 18 257 (91·0%) completing approximately 4·5 years of follow-up after the second vaccination (TAK-003, 12 177/13 380; placebo, 6080/6687). Overall, 1007 (placebo: 560; TAK-003: 447) of 27 684 febrile illnesses reported were virologically confirmed dengue, with 188 cases (placebo: 142; TAK-003: 46) requiring hospitalisation. Cumulative vaccine efficacy was 61·2% (95% CI 56·0-65·8) against virologically confirmed dengue and 84·1% (77·8-88·6) against hospitalised virologically confirmed dengue; corresponding efficacies were 53·5% (41·6-62·9) and 79·3% (63·5-88·2) in baseline seronegative participants (safety set). In an exploratory analysis, vaccine efficacy was shown against all four serotypes in baseline seropositive participants. In baseline seronegative participants, vaccine efficacy was shown against DENV-1 and DENV-2 but was not observed against DENV-3 and low incidence precluded evaluation against DENV-4. During part 3 of the trial (approximately 22-57 months after the first vaccination), serious adverse events were reported for 664 (5·0%) of 13 380 TAK-003 recipients and 396 (5·9%) of 6687 placebo recipients; 17 deaths (6 in the placebo group and 11 in the TAK-003 group) were reported, none were considered study-vaccine related.

INTERPRETATION

TAK-003 demonstrated long-term efficacy and safety against all four DENV serotypes in previously exposed individuals and against DENV-1 and DENV-2 in dengue-naive individuals.

FUNDING

Takeda Vaccines.

TRANSLATIONS

For the Portuguese, Spanish translations and plain language summary of the abstract see Supplementary Materials section.

Characterization of Dengue Virus 4 Cases in Paraguay, 2019-2020

In 2019-2020, dengue virus (DENV) type 4 emerged to cause the largest DENV outbreak in Paraguay's history. This study sought to characterize dengue relative to other acute illness cases and use phylogenetic analysis to understand the outbreak's origin. Individuals with an acute illness (≤7 days) were enrolled and tested for DENV nonstructural protein 1 (NS1) and viral RNA by real-time RT-PCR. Near-complete genome sequences were obtained from 62 DENV-4 positive samples. From January 2019 to March 2020, 799 participants were enrolled: 253 dengue (14 severe dengue, 5.5%) and 546 other acute illness cases. DENV-4 was detected in 238 dengue cases (94.1%). NS1 detection by rapid test was 52.5% sensitive (53/101) and 96.5% specific (387/401) for dengue compared to rRT-PCR. DENV-4 sequences were grouped into two clades within genotype II. No clustering was observed based on dengue severity, location, or date. Sequences obtained here were most closely related to 2018 DENV-4 sequences from Paraguay, followed by a 2013 sequence from southern Brazil. DENV-4 can result in large outbreaks, including severe cases, and is poorly detected with available rapid diagnostics. Outbreak strains seem to have been circulating in Paraguay and Brazil prior to 2018, highlighting the importance of sustained DENV genomic surveillance.

Impact of secondary infections on dengue presentation: A cross-sectional study in a tertiary care hospital in Uttar Pradesh, India

BACKGROUND

Recently, a wide range variety of manifestations, including a self‑limiting to severe illness, has been increasingly reported in dengue. Few studies attract attention to severe dengue, mainly observed in secondary infection. With this background, this study aims to provide a comprehensive overview to differentiate primary from secondary dengue using serology (IgG) and the possible association of severity of illness in secondary dengue.

METHODS

Present retrospective cross-sectional study was conducted at a North Indian tertiary care center from September 2021 to January 2022. Clinical data of confirmed dengue patients from the medicine department were collected and assigned as primary and secondary dengue.

RESULTS

Of the 220 dengue patients, 22 (10 %) had secondary dengue infection. Hemorrhagic manifestations were reported in 58/220 (26.4 %) cases while 7/22 (31.8 %) in secondary dengue. Prevalent hemorrhagic manifestations in secondary dengue include purpura (27.3 %), vaginal bleeding (4.5 %), melaena (9.1 %), and epistaxis (4.5 %). In addition, 42 (19.1 %) patients had pancytopenia, and 8 (36.6 %) cases were of secondary dengue. Hepatic dysfunction was noted in 164 (74.5 %) cases. Notably, all secondary dengue cases (22;100 %) had hepatic dysfunction and severe in 9 (40.9 %) cases. In addition, in secondary dengue patients, evidence of plasma leakages such as hypoproteinemia 7 (31.8 %) and ascites (35 %) were statistically more frequent. Overall, two deaths (0.9 %) were reported, and were one in each group.

CONCLUSIONS

Many parameters, including hemorrhagic manifestation (melaena), hematological characteristic (pancytopenia), evidence of plasma leakage (hypoproteinemia and ascites), gastrointestinal (GB wall thickening and hepatic dysfunction) and reduction in mean hemoglobin and platelet count were found to be statistically significant in secondary dengue infection. Additionally, early classification of secondary dengue may help to anticipate its severity and allow for early strategic intervention/management to lower morbidity and mortality.

Primary exposure to Zika virus increases risk of symptomatic dengue virus infection with serotypes 2, 3, and 4 but not serotype 1

Infection with any of the four dengue virus serotypes (DENV1-4) can protect against or enhance subsequent dengue depending on pre-existing antibodies and the subsequent infecting serotype. Additionally, primary infection with the related flavivirus Zika virus (ZIKV) has been shown to increase DENV2 disease. Here, we measured how prior DENV and ZIKV immunity influenced risk of disease caused by all four serotypes in a pediatric Nicaraguan cohort. Of 3,412 participants in 2022, 10.6% experienced symptomatic DENV infections caused by DENV1 (n=139), DENV4 (n=133), DENV3 (n=54), DENV2 (n=9), or an undetermined serotype (n=39). Longitudinal clinical and serological data were used to define infection histories, and generalized linear and additive models adjusted for age, sex, time since the last infection, cohort year, and repeat measurements were used to predict disease risk. Compared to flavivirus-naïve participants, primary ZIKV infection increased disease risk of DENV4 (relative risk = 2.62, 95% confidence interval: 1.48-4.63) and DENV3 (2.90, 1.34-6.27) but not DENV1 (1.20, 0.72-1.99). Primary DENV infection or a DENV followed by ZIKV infection also increased DENV4 risk. We re-analyzed 19 years of cohort data and demonstrated that prior flavivirus-immunity and pre-existing antibody titer differentially affected disease risk for incoming serotypes, increasing risk of DENV2 and DENV4, protecting against DENV1, and protecting at high titers but enhancing at low titers against DENV3. We thus find that prior ZIKV infection, like prior DENV infection, increases risk of certain DENV serotypes. Cross-reactivity among flaviviruses should be carefully considered when assessing vaccine safety and efficacy.

Flying under the radar - impact and factors influencing asymptomatic DENV infections

The clinical outcome of DENV and other Flaviviruses infections represents a spectrum of severity that ranges from mild manifestations to severe disease, which can ultimately lead to death. Nonetheless, most of these infections result in an asymptomatic outcome that may play an important role in the persistent circulation of these viruses. Also, although little is known about the mechanisms that lead to these asymptomatic infections, they are likely the result of a complex interplay between viral and host factors. Specific characteristics of the infecting viral strain, such as its replicating efficiency, coupled with host factors, like gene expression of key molecules involved in the immune response or in the protection against disease, are among crucial factors to study. This review revisits recent data on factors that may contribute to the asymptomatic outcome of the world's widespread DENV, highlighting the importance of silent infections in the transmission of this pathogen and the immune status of the host.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Genetic Association Studies of MICB and PLCE1 with Severity of Dengue in Indonesian and Taiwanese Populations

Dengue is an arboviral disease that has spread globally and become a major public health concern. A small proportion of patients may progress from symptomatic dengue fever (DF) to dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). Findings from a previous genome-wide association study (GWAS) demonstrated that variations in the major histocompatibility complex (MHC) class I chain-related B (MICB) and the phospholipase C epsilon 1 (PLCE1) genes were related to DSS in a Vietnamese population. This study investigated associations of variations in MICB (rs3132468) and PLCE1 (rs3740360, rs3765524) with dengue severity and thrombocytopenia in both the Indonesian and Taiwanese populations. We sampled 160 patients from the Indonesian population and 273 patients from the Taiwanese population. None of the patients had DSS in the Taiwanese population. Based on age demographics, we found that dengue is more prevalent among younger individuals in the Indonesian population, whereas it has a greater impact on adults in the Taiwanese population. Our results showed the association between MICB rs3132468 and DSS. In addition, an association was identified between PLCE1 rs3740360 and DHF in secondary dengue in Indonesian patients. However, there is no association of MICB or PLCE1 variants with thrombocytopenia. This study highlights the value of genetic testing, which might be included in the clinical pathway for specific patients who can be protected from severe dengue.

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.

Direct and indirect effects of age on dengue severity: The mediating role of secondary infection

Severe dengue occurrence has been attributed to increasing age and different dengue virus (DENV) serotypes that cause secondary infections and immune-enhancing phenomena. Therefore, we examined if the effect of age on dengue severity was mediated by infectivity status while controlling for sex and region. Further, we assessed the spatial clustering of dengue severity for individuals with primary and secondary infection across Mexican municipalities. Health data from 2012 to 2017 was retrieved from Mexico's Ministry of Health. A mediation analysis was performed using multiple logistic regression models based on a directed acyclic graph. The models were explored for the direct effect of age on dengue severity and its indirect impact through secondary infection. In addition, severe dengue clusters were determined in some Northeastern and Southeastern municipalities through spatial analysis. We observed a nonlinear trend between age and severe dengue. There was a downward trend of severe dengue for individuals between 0 and 10 years and an upward trend above 10 years. The effect of age on dengue severity was no longer significant for individuals between 10 and 60 years after introducing infectivity status into the model. The mediating role of infectivity status in the causal model was 17%. Clustering of severe dengue among individuals with primary infection in the Northeastern region may point to the high prevalence of DENV-3 in the region. Public health efforts may prevent secondary infection among infants and the aged. In addition, there should be a further investigation into the effect of DENV-3 in individuals with primary disease.

The Effect of Age on Dengue Presentation and the Diagnostic Accuracy of the 2015 Pan American Health Organization Case Criteria in a Puerto Rican Cohort

Background

We evaluated dengue presentation by age, the performance of the 2015 Pan American Health Organization (PAHO) case criteria in identifying dengue cases, and variables to improve specificity.

Methods

Patients with fever ≤7 days (N = 10 408) were recruited from 2 emergency departments from May 2012 through December 2015. Serum samples were tested for dengue, chikungunya, and nasopharyngeal swabs for respiratory viruses. Smoothing splines assessed differences in the frequencies of signs/symptoms by age. Least absolute shrinkage and selection operator regressions identified the variables that best predicted dengue.

Results

Among 985 dengue cases, children aged <5 years were least likely to have leukopenia, but most likely to have rash and petechiae. Adults had the highest odds of aches/pains and headaches/retro-orbital pain. The 2015 PAHO criteria had sensitivity of 93% and specificity of 25%. Specificity could be improved by requiring at least 2 of the following criteria: vomiting/nausea, petechiae, rash, or leukopenia (specificity 68%, sensitivity 71%) or by using 2015 PAHO criteria plus either (1) aspartate aminotransferase >50 IU/L or platelet count <100 000 platelets/μL (specificity 81%, sensitivity 56%) or (2) itchy skin or absence of rhinorrhea or cough (specificity 51%, sensitivity 82%).

Conclusions

The 2015 PAHO dengue case criteria had excellent sensitivity but poor specificity. This can be improved by adding signs/symptoms associated with dengue diagnosis.

Mathematical modeling of Dengue virus serotypes propagation in Mexico

The Dengue virus (DENV) constitutes a major vector borne virus disease worldwide. Prediction of the DENV spread dynamics, prevalence and infection rates are crucial elements to guide the public health services effort towards meaningful actions. The existence of four DENV serotypes further complicates the virus proliferation forecast. The different serotypes have varying clinical impacts, and the symptomatology of the infection is dependent on the infection history of the patient. Therefore, changes in the prevalent DENV serotype found in one location have a profound impact on the regional public health. The prediction of the spread and intensity of infection of the individual DENV serotypes in specific locations would allow the authorities to plan local pesticide spray to control the vector as well as the purchase of specific antibody therapy. Here we used a mathematical model to predict serotype-specific DENV prevalence and overall case burden in Mexico.

Hyperimmune Globulins for the Management of Infectious Diseases

This review is focused on the use of hyperimmune globulin therapy to treat some infectious diseases of viral or bacterial origin. Despite the introduction of antibiotics and vaccines, plasma immunoglobulin therapy from whole blood donation can still play a key role. These treatments provide passive transfer of high-titer antibodies that either reduces the risk or the severity of the infection and offer immediate but short-term protection against specific diseases. Antibody preparations derived from immunized human donors are commonly used for the prophylaxis and treatment of rabies, hepatitis A and B viruses, varicella-zoster virus, and pneumonia caused by respiratory syncytial virus, Clostridium tetani, Clostridium botulinum. The use of hyperimmune globulin therapy is a promising challenge, especially for the treatment of emerging viral infections for which there are no specific therapies or licensed vaccines.

Insights into dengue immunity from vaccine trials

The quest for an effective dengue vaccine has culminated in two approved vaccines and another that has completed phase 3 clinical trials. However, shortcomings exist in each, suggesting that the knowledge on dengue immunity used to develop these vaccines was incomplete. Vaccine trial findings could refine our understanding of dengue immunity, because these are experimentally derived, placebo-controlled data. Results from these trials suggest that neutralizing antibody titers alone are insufficient to inform protection against symptomatic infection, implicating a role for cellular immunity in protection. These findings have relevance for both future dengue vaccine development and application of current vaccines for maximal public health benefit.

Twenty-two years of dengue outbreaks in Bangladesh: epidemiology, clinical spectrum, serotypes, and future disease risks

Dengue is the most rapidly spreading mosquito-borne disease and has become a major public health threat, particularly for tropical and subtropical countries including Bangladesh. This comprehensive review aims to summarize the overall scenario of dengue, including disease burden, clinical spectrum, seroprevalence, circulating serotypes/genotypes, and spatial distribution since the first recorded outbreak in Bangladesh. Since the first recorded outbreak in 2000, dengue epidemiology has shown the typical epidemic pattern with more frequent and bigger outbreaks and gradual geographic expansion to non-endemic regions in Bangladesh. For instance, highly confined Rohingya refugee camps that provide shelters to nearly 1.2 million forcibly displaced vulnerable Myanmar nationals in Cox's Bazar district confronted a massive outbreak in 2022. Recent major outbreaks are found to be associated with the emergence of serotype DENV-3, which was undetected for a long time. Consequently, changes in serotypes might be attributed to increased severity in clinical manifestation in recent years. The existing weak surveillance and risk management systems are inadequate to deal with impending dengue risks. The healthcare system, particularly at the district level, is not prepared to manage impending large-scale dengue outbreaks in Bangladesh. Our findings would contribute to the development of strategies for dengue control and management in Bangladesh as well as other similar settings elsewhere in the world.

Dengue virus NS5 degrades ERC1 during infection to antagonize NF-kB activation

Dengue virus (DENV) is the most important human virus transmitted by mosquitos. Dengue pathogenesis is characterized by a large induction of proinflammatory cytokines. This cytokine induction varies among the four DENV serotypes (DENV1 to 4) and poses a challenge for live DENV vaccine design. Here, we identify a viral mechanism to limit NF-κB activation and cytokine secretion by the DENV protein NS5. Using proteomics, we found that NS5 binds and degrades the host protein ERC1 to antagonize NF-κB activation, limit proinflammatory cytokine secretion, and reduce cell migration. We found that ERC1 degradation involves unique properties of the methyltransferase domain of NS5 that are not conserved among the four DENV serotypes. By obtaining chimeric DENV2 and DENV4 viruses, we map the residues in NS5 for ERC1 degradation, and generate recombinant DENVs exchanging serotype properties by single amino acid substitutions. This work uncovers a function of the viral protein NS5 to limit cytokine production, critical to dengue pathogenesis. Importantly, the information provided about the serotype-specific mechanism for counteracting the antiviral response can be applied to improve live attenuated vaccines.

Aminotransferases in Relation to the Severity of Dengue: A Systematic Review

A systematic review was conducted to investigate the relationship between aminotransferases and the severity of dengue infection, which is a prevalent and significant infection in tropical and subtropical regions. Aminotransferases are enzymes that are often elevated in dengue due to the liver's physiological and immunological response to the infection. This review focused on analyzing various studies that examined the correlation between aminotransferase levels and the severity of dengue. Extensive literature searches were performed using ("dengue*" OR "dengue fever*" OR "dengue haemorrhagic fever*" OR "dengue shock syndrome*") AND ("alanine aminotransferase*" OR "aspartate aminotransferase*") on PubMed. The selected articles were thoroughly reviewed, encompassing epidemiology, pathogenesis, and clinical manifestations of dengue. The consistent findings across the studies indicated that aminotransferases can serve as predictive markers for dengue severity. Therefore, early assessment of liver enzyme levels is crucial in dengue cases, and elevated levels should be closely monitored to prevent adverse outcomes.

Demographic characteristics, clinical symptoms, biochemical markers and probability of occurrence of severe dengue: A multicenter hospital-based study in Bangladesh

Establishing reliable early warning models for severe dengue cases is a high priority to facilitate triage in dengue-endemic areas and optimal use of limited resources. However, few studies have identified the complex interactive relationship between potential risk factors and severe dengue. This research aimed to assess the potential risk factors and detect their high-order combinative effects on severe dengue. A structured questionnaire was used to collect detailed dengue outbreak data from eight representative hospitals in Dhaka, Bangladesh, in 2019. Logistic regression and machine learning models were used to examine the complex effects of demographic characteristics, clinical symptoms, and biochemical markers on severe dengue. A total of 1,090 dengue cases (158 severe and 932 non-severe) were included in this study. Dyspnoea (Odds Ratio [OR] = 2.87, 95% Confidence Interval [CI]: 1.72 to 4.77), plasma leakage (OR = 3.61, 95% CI: 2.12 to 6.15), and hemorrhage (OR = 2.33, 95% CI: 1.46 to 3.73) were positively and significantly associated with the occurrence of severe dengue. Classification and regression tree models showed that the probability of occurrence of severe dengue cases ranged from 7% (age >12.5 years without plasma leakage) to 92.9% (age ≤12.5 years with dyspnoea and plasma leakage). The random forest model indicated that age was the most important factor in predicting severe dengue, followed by education, plasma leakage, platelet, and dyspnoea. The research provides new evidence to identify key risk factors contributing to severe dengue cases, which could be beneficial to clinical doctors to identify and predict the severity of dengue early.

Discrepant Activation Pattern of Inflammation and Pyroptosis Induced in Dermal Fibroblasts in Response to Dengue Virus Serotypes 1 and 2 and Nonstructural Protein 1

Four serotypes of dengue virus (DENV-1 to DENV-4) cause mild to severe disease in humans through infected mosquito bites. Dermal fibroblasts were found to be susceptible to DENV, and this may play a critical role in establishing the initial infection stage. However, the cellular response induced by the different DENV serotypes in dermal fibroblasts during the early stage of infection remains unclear. To determine this, normal human dermal fibroblast WS1 cells were infected with DENV-1 or DENV-2. Compared with the response elicited by DENV-1 infection, DENV-2 induced a stronger innate inflammatory response and cell death in the WS1 cells. However, DENV-1 activated a higher level of pyroptosis signaling than did DENV-2, which was associated with higher virion production. Caspase-1 inhibitor Ac-YVAD-cmk and imipramine, an antidepressant drug, reduced DENV-mediated caspase-1 and interleukin 1β (IL-β) cleavage in the pyroptosis pathway. Ac-YVAD-cmk and imipramine downregulated DENV virion production in WS1 cells. Furthermore, DENV-1 and DENV-2 NS1 proteins promoted diverse activation levels of cell death, inflammatory response, and activation of caspase-1 and IL-β in dermal fibroblasts at different time points. Collectively, these data suggest that DENV-1, DENV-2, and their nonstructural protein 1 (NS1) induce discrepant activation patterns of inflammation and pyroptosis in dermal fibroblasts. The pyroptosis caused by virus and NS1 may facilitate DENV replication in dermal fibroblasts. IMPORTANCE Skin fibroblasts are the primary cells of DENV infection through mosquito bites. Establishing a successful infection in dermal fibroblasts might be critical for dengue disease. However, the cellular response induced by DENV in dermal fibroblasts remains unclear. In this in vitro study, we found that DENV-2 and DENV-1 showed different time course patterns of virus replication and inflammation in dermal fibroblasts. We demonstrated that DENV-1 and DNEV-2 and their viral protein NS1 activate the cellular pyroptosis response to regulate virus replication in dermal fibroblasts. This finding suggests that pyroptosis activation in the DENV primary inoculation site plays a role in the establishment of a DENV infection.

A Six Years (2010-2016) Longitudinal Survey of the Four Serotypes of Dengue Viruses in Lao PDR

Dengue fever is the most prevalent arthropod-borne viral infection of humans in tropical and subtropical countries. Since 1979, dengue has been reported to be endemic in the Lao People's Democratic Republic (PDR), as in many countries in Southeast Asia, with a complex circulation of the four dengue viruses' serotypes (DENV-1 to DENV-4). By sequencing the complete envelope protein, we explored a panel of samples from five Lao Provinces (Vientiane capital, Luangprabang, Bolikhamxay, Saravane, Attapeu) to enrich knowledge about the co-circulation of DENVs in Lao PDR between 2010 and 2016. Phylogenetic analyses highlighted the specific circulation of DENV-1 genotype I, DENV-2 genotype Asian I, DENV-4 genotype I and the co-circulation of DENV-3 genotype II and III. The continuous co-circulation of the four serotypes was underlined, with genotype or cluster shifts among DENV-3 and DENV-1. These data suggested the emergence or re-emergence of DENV strains associated with epidemic events, potentially linked to the exchanges within the territory and with neighboring countries. Indeed, the increasing local or regional connections favored the dissemination of new isolates or new clusters around the country. Since 2012, the surveillance and alert system created in Vientiane capital by the Institut Pasteur du Laos appears to be a strategic tool for monitoring the circulation of the four serotypes, especially in this endemic country, and allows for improving dengue epidemiological knowledge to anticipate epidemic events better.

Increasing Dengue Burden and Severe Dengue Risk in Bangladesh: An Overview

Dengue is a prevalent and rapidly spreading mosquito-borne viral disease affecting humans. The geographic range of dengue is expanding, and much like in many other tropical regions of the world, dengue has become a major public health issue in Bangladesh. Until a large epidemic dengue outbreak in 2000, sporadic outbreaks have occurred in Bangladesh since 1964. After 2000, varying intensities of dengue activity were observed each year until 2018. However, in 2019, Bangladesh experienced the largest dengue epidemic in its history, with 101,354 dengue cases and 164 dengue-related deaths. Notably, this outbreak occurred in many regions that were previously considered free of the disease. As of 10 December 2022, a total of 60,078 dengue cases and 266 dengue-related deaths were reported in Bangladesh, with the 2022 outbreak being the second largest since 2000. There is an increased genetic diversity of the dengue virus (DENV) in Bangladesh and all four DENV serotypes are prevalent and co-circulating, which increases the risk for severe dengue owing to the antibody-dependent enhancement effect. Vector control remains the mainstay of dengue outbreak prevention; however, the vector control programs adopted in Bangladesh seem inadequate, requiring improved vector control strategies. In this review, we provide an overview of the epidemiology of DENV infection and the risks for a severe dengue outbreak in Bangladesh. Additionally, we discuss different dengue vector control strategies, from which the most suitable and effective measures can be applied in the context of Bangladesh for tackling future dengue epidemics.

Association of viral kinetics, infection history, NS1 protein with plasma leakage among Indonesian dengue infected patients

OBJECTIVES

Plasma leakage, a hallmark of disease in Dengue virus (DENV) infection, is an important clinical manifestation and is often associated with numerous factors such as viral factors. The aim of this study is to investigate the association of virus serotype, viral load kinetics, history of infection, and NS1 protein with plasma leakage.

METHODS

Subjects with fever ≤ 48 hours and positive DENV infection were included. Serial laboratory tests, viral load measurements, and ultrasonography examination to assess plasma leakage were performed.

RESULTS

DENV-3 was the most common serotype found in the plasma leakage group (35%). Patients with plasma leakage demonstrated a trend of higher viral load and a longer duration of viremia compared to those without. This was significantly observed on the fourth day of fever (p = 0.037). We found higher viral loads on specific days in patients with plasma leakage in both primary and secondary infections compared to those without. In addition, we also observed more rapid viral clearance in patients with secondary infection. NS1 protein, especially after 4 days of fever, was associated with higher peak viral load level, even though it was not statistically significant (p = 0.470). However, pairwise comparison demonstrated that peak viral load level in the group of patients with circulating NS1 detected for 7 days was significantly higher than the 5-day group (p = 0.037).

CONCLUSION

DENV-3 was the most common serotype to cause plasma leakage. Patients with plasma leakage showed a trend of higher viral load and a longer duration of viremia. Higher level of viral load was observed significantly on day 5 in patients with primary infection and more rapid viral clearance was observed in patients with secondary infection. Longer duration of circulating NS1 protein was also seen to be positively correlated with higher peak viral load level although not statistically significant.

Spin-Enhanced Lateral Flow Immunoassay for High-Sensitivity Detection of Nonstructural Protein NS1 Serotypes of the Dengue Virus

Dengue fever is a global mosquito-borne viral infectious disease that has, in recent years, rapidly spread to almost all regions of the world. Lack of vaccination and directed treatment makes detection at the infection's early stages extremely important for disease prevention and clinical care. In this paper, we developed a rapid and highly sensitive dengue detection tool using a novel platform of diagnosis, called spin-enhanced lateral flow immunoassay (SELFIA) with a fluorescent nanodiamond (FND) as a reporter. Taking advantage of the unique magneto-optical properties of negatively charged nitrogen-vacancy centers in the FND, the SELFIA platform utilizes alternating electromagnetic fields to modulate signals from FND's fluorescence to provide sensitive and specific results. With sandwich SELFIA, we could efficiently detect all four dengue non-structural protein (NS1) serotypes (DV1, DV2, DV3, and DV4). The lowest detection concentration of the dengue NS1 antigens varied from 0.1 to 1.3 ng/mL, which is among the lowest limits of detection to date. The FND-based SELFIA technique is up to 500 and 5000 times more sensitive than carbon black and conventional gold nanoparticles, respectively. By using different anti-NS1 antibodies, we could differentiate the NS1 antigen serotypes contained in the tested samples via three simultaneous assays. Proposed SELFIA allows for both qualitative and quantitative differentiation between different NS1 protein serotypes, which will assist in the development of a highly sensitive and specific detection platform for dengue screening that has the potential to detect the disease at its early stages, especially in high-risk and limited-resource areas.

Re-Emergence of Dengue Serotype 3 in the Context of a Large Religious Gathering Event in Touba, Senegal

Dengue virus (DENV) was detected in Senegal in 1979 for the first time. Since 2017, unprecedented frequent outbreaks of DENV were noticed yearly. In this context, epidemiological and molecular evolution data are paramount to decipher the virus diffusion route. In the current study, we focused on a dengue outbreak which occurred in Senegal in 2018 in the context of a large religious gathering with 263 confirmed DENV cases out of 832 collected samples, including 25 life-threatening cases and 2 deaths. It was characterized by a co-circulation of dengue serotypes 1 and 3. Phylogenetic analysis based on the E gene revealed that the main detected serotype in Touba was DENV-3 and belonged to Genotype III. Bayesian phylogeographic analysis was performed and suggested one viral introduction around 2017.07 (95% HPD = 2016.61-2017.57) followed by cryptic circulation before the identification of the first case on 1 October 2018. DENV-3 strains are phylogenetically related, with strong phylogenetic links between strains retrieved from Burkina Faso and other West African countries. These phylogenetic data substantiate epidemiological data of the origin of DENV-3 and its spread between African countries and subsequent diffusion after religious mass events. The study also highlighted the usefulness of a mobile laboratory during the outbreak response, allowing rapid diagnosis and resulting in improved patient management.

Predictive Factors for the Complications of Dengue Fever in Children: A Retrospective Analysis

Background and objective Dengue fever (DF) and its complications - dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) - are major public health problems in Southeast Asia. Predicting the development of DHF and DSS using hematological parameters and ultrasonic signs of vascular leakage will help in reducing morbidity and mortality associated with these diseases. Hence, this study aimed to test the association of platelets and packed cell volume (PCV) on day one (D1) of admission with gallbladder wall thickness (GWT) and ascites, which herald the onset of DHF and DSS. Methods The electronic health records of 52 pediatric patients admitted during a mini-outbreak were analyzed to assess platelets and PCV on D1, laboratory and ultrasonography findings, and outcomes. Correlations between D1 hematological parameters and GWT and ascites were tested. Results There was a positive correlation between GWT of more than 5 mm and ascites. However, there was no significant correlation of platelets and PCV on D1 with either GWT or ascites and consequently DHF or DSS. All the patients responded to fluid, blood, and supportive therapy. There were no mortalities. Conclusion Patients who develop GWT after DF are at an increased risk of developing ascites that deteriorate to DHF and DSS. D1 platelets and PCV are not reliable indicators for predicting the progression or worsening of the disease in the pediatric population.

A Comparative Study on Dengue-related Knowledge, Attitude, and Practice in Hotspot and Non-Hotspot Areas in Selangor

Dengue fever is a deadly vector-borne disease. Prevention strategies without specific drugs or vaccines emphasise community involvement in dengue vector control. Identifying dengue-related knowledge, attitudes, and behaviours is critical to developing more effective intervention strategies. A cross-sectional study compared the knowledge, attitudes, and practices on dengue in selected dengue hotspots and non-hotspot areas in Selangor, Malaysia. A self-administered questionnaire was distributed among 320 randomly selected residents. Data were analysed using an independent t-test and Spearman’s rank-order correlation. Despite having a good understanding of the dengue virus, most respondents (83.1%) from both hotspot and non-hotspot areas were unaware that a person could be infected with the virus more than once in their lifetime, and 62.8% agreed that dengue patients could recover without treatment. Most respondents (76.9%) agreed that buying mosquito repellent is a waste of money, and most reported not sleeping under the insecticide net at night (74.7%). Respondents from dengue hotspot areas had significantly higher attitude scores (32.00±4.60) compared to those of non-hotspot regions (28.78±5.51), t (307) = 5.674, <i>p</i><0.05. There was a significant positive correlation between knowledge and attitude scores (r_s=0.214, p<0.01), between knowledge and practices (r_s=0.563, p<0.01), and attitude and practices (r_s=0.374, p<0.01). In addition to the high levels of knowledge and practice, attitudes toward dengue must be improved to implement proper prevention measures.

Immuno-dominant dengue NS1 peptides as antigens for production of monoclonal antibodies

Synthetic peptides have recently become common as antigens for antibody production. Peptides are short chains of amino acids that can be used to elicit an immune response. The immunogenicity of the peptide antigens varies depending on the length, charge, solubility, and amino acids contained in the peptide sequence. Dengue NS1 protein is an important target antigen in the early detection of dengue infection. In this study, peptides corresponding to a highly conserved region from the dengue NS1 region were designed and synthesized. Balb/C mice were immunized against each peptide and spleen cells extracted from the immunized mice were fused with NS0 murine myeloma cells. Hybridoma clones obtained from the fusions were tested against peptides using ELISA. Out of 1,830 growing clones, 28 clones produced antibodies reacting with dengue NS1 peptides. A purified monoclonal antibody reacting with all four peptides was tested for reactivity with dengue NS1 native protein using dengue-confirmed serum and urine samples. The monoclonal antibody shows significant reactivity with both serum and urine. The findings of the current research can be used to detect dengue infection using urine, which ultimately results in the prevention of dengue epidemics through painless diagnosis, following treatment, and patient management to safeguard human and economic wellness.

Contribution of phylogenetics to understanding the evolution and epidemiology of dengue virus

Dengue virus (DENV) is one of the most important arboviral pathogens in the tropics and subtropics, and nearly one‐third of the world's population is at risk of infection. The transmission of DENV involves a sylvatic cycle between nonhuman primates (NHP) and Aedes genus mosquitoes, and an endemic cycle between human hosts and predominantly Aedes aegypti. DENV belongs to the genus Flavivirus of the family Flaviviridae and consists of four antigenically distinct serotypes (DENV‐1‐4). Phylogenetic analyses of DENV have revealed its origin, epidemiology, and the drivers that determine its molecular evolution in nature. This review discusses how phylogenetic research has improved our understanding of DENV evolution and how it affects viral ecology and improved our ability to analyze and predict future DENV emergence.

Determining the optimum cut-off IgM/ IgG ratio for predicting secondary dengue infections: An observational hospital based study from Central India

PURPOSE

The present study was conducted to determine an optimum cut-off IgM/IgG ratio for differentiating between primary and secondary Dengue. The calculated cut-off was used to estimate the relative prevalence of primary and secondary Dengue in central India during the 2021 outbreak.

METHODS

To differentiate between primary and secondary Dengue, optimum cut-off IgM/IgG ratio was determined using ROC curve analysis and Area under the curve (AUC) was calculated. For this 84 IgM positive samples were selected during the study period and Dengue IgM and IgG testing was performed.

RESULTS

Based on sero-positivity for IgG antibodies, we observed a prevalence of 77.4% for secondary Dengue during this outbreak. IgM/IgG ratio of 1.59 delivered a sensitivity of 100% and specificity of 90.8%. Comparison of clinical characteristics revealed significant differences in rigors (p ​= ​0.04) and haemorrhagic manifestations (p ​= ​0.01) between the two types of infection.

CONCLUSIONS

This study revealed an overwhelming predominance of secondary Dengue during the reported outbreak, which hints at increasing endemicity in this region and raises the risk of severe clinical manifestations. An optimal IgM/IgG cut-off ratio, tailored according to the endemicity of this geographical region, is therefore suggested in this study.

Dengue outbreak in the times of COVID-19 pandemic: Common myths associated with the dengue

With the sharp rise in dengue cases across the state and the ongoing COVID-19 pandemic, it is crucial to pay attention to the common misbelieves among the population about dengue. It should be considered to actively spread awareness about the disease to bust the common myths associated with it. A few common myths include that it is a contagious disease, or it is a milder infection than COVID-19, so it's not taken more seriously, or that one cannot be coinfected with both dengue and COVID-19 at one time. We propose that accurate information about dengue can be spread through community education through televisions and social media to cater to the targeted audience. In addition to that, awareness campaigns in rural areas should be planned to help the masses understand the pathogenesis of the diseases and play a role in limiting the transmission.

Intra-genomic heterogeneity in CpG dinucleotide composition in dengue virus

PURPOSE

Dengue virus is a life-threatening virus and cases of dengue infection have been increasing steadily in the past decades causing millions of deaths every year. So far, there is no vaccine that works effectively on all serotypes. Recently, CpG-recoded vaccines have proved to be effective against few viruses.

METHODS

In this study, evaluation and interpretation of more than 4547 Dengue virus genome sequences were included for analyzing novel CpG dinucleotides rich regions which are shared amid all serotypes. Genomic regions of DENV were synonymously CpG recoded using in silico methods and analyzed for adaptation in both human and Aedes spp. hosts based on CAI scores.

RESULTS

The analysis mirrored that serotypes 1, 3, and 4 shared CpG islands present in common regions. DENV-2 CpG islands showed no similarity with any of the CpG islands present in other serotypes. While DENV-3 sequences were found to possess the maximum number of conserved CpG islands stretches; DENV-2 was found to possess the lowest number. We found that all serotypes (with an exception of serotype 2) have CpG island in their 3' UTR. In silico CpG recoding of DENV genomic regions resulted in ∼ 3 fold increase of CpG dinucleotide frequency and comparative analysis based on CAI scores showed decreased adaptive fitness of CpG recoded DENV inside human host.

CONCLUSION

These CG-dinucleotide-enriched RNA sequences can be targeted by ZAP (zinc-finger antiviral protein) which can differentiate between host mRNA and viral mRNA. Our in silico findings can further be exploited for CpG-recoding of DENV genomes which can evoke cellular and humoral immune responses by recruiting ZAP-induced RNA degradation machinery and hence providing a promising approach for vaccine development.

Prognostic Indicators for the Early Prediction of Severe Dengue Infection: A Retrospective Study in a University Hospital in Thailand

This study aimed to develop simple diagnostic guidelines which would be useful for the early detection of severe dengue infections. Retrospective data of patients with dengue infection were reviewed. Patients with diagnosed dengue infection were categorized in line with the International Statistical Classification of Diseases (ICD-10): A90, dengue fever; A91, dengue hemorrhagic fever; and A910, dengue hemorrhagic fever with shock. A total of 302 dengue-infected patients were enrolled, of which 136 (45%) were male and 166 (55%) were female. Multivariate analysis was conducted to determine independent diagnostic predictors of severe dengue infection and to convert simple diagnostic guidelines into a scoring system for disease severity. Coefficients for significant predictors of disease severity generated by ordinal multivariable logistic regression analysis were transformed into item scores. The derived total scores ranged from 0 to 38.6. The cut-off score for predicting dengue severity was higher than 14, with an area under the receiver operating curve (AUROC) of 0.902. The predicted positive value (PPV) was 68.7% and the negative predictive value (NPV) was 94.1%. Our study demonstrates that several diagnostic parameters can be effectively combined into a simple score sheet with predictive value for the severity evaluation of dengue infection.

A cross-sectional study to assess the epidemiological situation and associated risk factors of dengue fever; knowledge, attitudes, and practices about dengue prevention in Khyber Pakhtunkhwa Province, Pakistan

Background

Dengue fever has been responsible for around 12 countrywide large outbreaks in Pakistan, resulting in 286,262 morbidities and 1,108 deaths. Khyber Pakhtunkhwa (KP) is the most recently impacted province. This study aimed to investigate the molecular, epidemiological, and potential elements that contribute to increasing dengue transmission patterns, and knowledge, attitude, and practice (KAP) toward dengue in KP province.

Method

This cross-sectional community-based study was conducted (June-December, 2021) in two phases. Phase I involved the epidemiological (n = 5,242) and molecular analysis of DENV in 500 randomly collected blood samples of the 2021 dengue outbreak in KP. Phase II focused on assessing dengue-KAP levels in healthy communities (n = 14,745, aged >18 years), adopting a cross-sectional clustered multistage sampling in eight districts (dengue-hotspot vs. non-hotspot) of KP. Chi-square tests and logistic regression analysis were applied.

Results

Peshawar district had the highest dengue cases (60.0%) associated with the predominant co-circulation of DENV-2 (45.8%) and DENV-3 (50.4%) serotypes. A rise in cases was reported in October (41.8%) followed by September (27.9%) and August (14.4%; p < 0.001). Males (63.7%, p < 0.001) and individuals aged 16–30 years (37.0%, p < 0.001) were highly affected. General workers (18.0%), families with a monthly income of 10,000–20,000 Pak rupees (50.5%), unmarried (71.0%), uneducated (31%), families with higher human density (>10 individuals per household), and those (29.0%) who faced power outages for more than 7/24 h were the most affected. Moreover, co-morbidities like renal failure and bronchial asthma were associated with disease severity. A community survey on KAP revealed that an average of 74, 60, and 43% of the participants demonstrated good knowledge, attitudes, and dengue preventive practices, respectively.

Conclusion

Multiple poor socioeconomic elements are influencing dengue fever transmission in the province. Higher KAP levels may explain the low frequency of dengue in non-hotspot districts. Our study emphasizes the need for effective and long-term public health education, strengthened vector surveillance, and expanded laboratory capacity for better diagnosis and management of dengue cases to better predict the burden and seasonality of disease in the country.

Severity and Outcomes of Dengue in Hospitalized Jamaican Children in 2018-2019 During an Epidemic Surge in the Americas

Objective

In 2019, dengue was among the "top-ten threats to global health," with 3.1 million cases reported from the Americas, the highest ever. Simultaneously, Jamaica reported its largest dengue outbreak in 40 years, following Chikungunya and Zika virus epidemics, in 2014 and 2016-2017, respectively. We describe dengue in children admitted to five hospitals in Jamaica during August 2018 through September 2019.

Methods

Hospitalized children and adolescents aged 0 to 15 years with dengue were managed using PAHO/WHO criteria. Data were extracted from questionnaires, entered into a dataset on Microsoft Excel version 2016, exported to SPSS version 20 and analyzed. Groups were compared using Student's t-test for normally distributed parametric data. Chi-square analysis, or Fisher's exact test was used for categorical variables. A p-value < 0.05 was considered statistically significant.

Results

There were 339 children, 245 (72.3%) aged 1-10 years, males:females 1:1. Classification was "dengue without warning signs" 53 (15.3%), "dengue with warning signs" 218 (64.3%) and "severe dengue" 68 (20%). Co-morbidities were reported in 88 (26%). Hemoglobin SC disease was associated with severe dengue with hemorrhage (p = 0.005). Organ-system involvement occurred in 334 (98.5%) including gastrointestinal 317 (93.5%), hematologic 311 (91.7%) and musculoskeletal 180 (53.1%). Thirty-nine (11.5%) had 5-7 organ-systems involved. Metabolomics emphasized increased hepatic transaminases 245 (72.3%), lactate dehydrogenase 164 (48.4%) and creatine phosphokinase 84 (24.8%) approaching the high thousands (121,560 u/L), both were markers for severe disease (p < 0.002). Thirteen (3.8%) received intensive care. Dengue was laboratory-confirmed in 220 (78.9%): NS1 antigen-positive (218); RT-PCR-positive (23), with an overlap of NS1 antigen and RT-PCR positive (21); DENV-3 serotype (20). Seventeen (5%) died, 16 (94.1%) had severe dengue and 11 (64.7%) succumbed within 24 to 48 h of admission despite resuscitation and transfusion of blood products.

Conclusion

Severe dengue with increased attributable mortality occurred in hospitalized children after Jamaica's maiden Zika epidemic.

Immunogenicity and safety of booster CYD-TDV dengue vaccine after alternative primary vaccination schedules in healthy individuals aged 9-50 years: a randomised, controlled, phase 2, non-inferiority study

BACKGROUND

Dengue is endemic in many countries throughout the tropics and subtropics, and the disease causes substantial morbidity and health-care burdens in these regions. We previously compared antibody responses after one-dose, two-dose, or three-dose primary regimens with the only approved dengue vaccine CYD-TDV (Dengvaxia; Sanofi Pasteur, Lyon, France) in individuals aged 9 years and older with previous dengue exposure. In this study, we assessed the need for a CYD-TDV booster after these primary vaccination regimens.

METHODS

In this randomised, controlled, phase 2, non-inferiority study, healthy individuals aged 9-50 years recruited from three sites in Colombia and three sites in the Philippines (excluding those with the usual contraindications to vaccinations) were randomly assigned 1:1:1 via a permuted block method with stratification by site and by age group using an independent voice response system to receive, at 6-month intervals, three doses of CYD-TDV (three-dose group), one dose of placebo followed by two doses of CYD-TDV (two-dose group), or two doses of placebo followed by one dose of CYD-TDV (one-dose group). Participants were also randomly assigned (1:1) to receive a CYD-TDV booster at 1 year or 2 years after the last primary dose. Each CYD-TDV dose was 0·5 mL and administered subcutaneously in the deltoid region of the upper arm. The investigators and sponsor, study staff interacting with the investigators, and participants and their parents or legally acceptable representatives were masked to group assignment. Neutralising antibodies were measured by 50% plaque reduction neutralisation testing, and geometric mean titres (GMTs) were calculated. Due to a change in study protocol, only participants who were dengue seropositive at baseline in the Colombian cohort received a booster vaccination. The primary outcome was to show non-inferiority of the booster dose administered at 1 year or 2 years after the two-dose and three-dose primary regimens; non-inferiority was shown if the lower limit of the two-sided adjusted 95% CI of the between-group (day 28 post-booster dose GMT from the three-dose or two-dose group vs day 28 GMT post-dose three of the three-dose primary regimen [three-dose group]) geometric mean ratio (GMR) was higher than 0·5 for each serotype. Non-inferiority of the 1-year or 2-year booster was shown if all four serotypes achieved non-inferiority. Safety was assessed among all participants who received the booster. This trial is registered with ClinicalTrials.gov, NCT02628444, and is closed to accrual.

FINDINGS

Between May 2 and Sept 16, 2016, we recruited and enrolled 1050 individuals who received either vaccine or placebo. Of the 350, 348, and 352 individuals randomly assigned to three-dose, two-dose, and one-dose groups, respectively, 108, 115, and 115 from the Colombian cohort were dengue seropositive at baseline and received a booster; 55 and 53 in the three-dose group received a booster after 1 year and 2 years, respectively, as did 59 and 56 in the two-dose group, and 62 and 53 in the one-dose group. After the three-dose primary schedule, non-inferiority was shown for serotypes 2 (GMR 0·746; 95% CI 0·550-1·010) and 3 (1·040; 0·686-1·570) but not serotypes 1 (0·567; 0·399-0·805) and 4 (0·647; 0·434-0·963) for the 1-year booster, and again for serotypes 2 (0·871; 0·673-1·130) and 3 (1·150; 0·887-1·490) but not serotypes 1 (0·688; 0·479-0·989) and 4 (0·655; 0·471-0·911) for the 2-year booster. Similarly, after the two-dose primary schedule, non-inferiority was shown for serotypes 2 (0·809; 0·505-1·300) and 3 (1·19; 0·732-1·940) but not serotypes 1 (0·627; 0·342-1·150) and 4 (0·499; 0·331-0·754) for the 1-year booster, and for serotype 3 (0·911; 0·573-1·450) but not serotypes 1 (0·889; 0·462-1·710), 2 (0·677; 0·402-1·140), and 4 (0·702; 0·447-1·100) for the 2-year booster. Thus, non-inferiority of the 1-year or 2-year booster was not shown after the three-dose or two-dose primary vaccination regimen in dengue-seropositive participants. No safety concerns occurred with the 1-year or 2-year CYD-TDV booster.

INTERPRETATION

CYD-TDV booster 1 year or 2 years after the two-dose or three-dose primary vaccination regimen does not elicit a consistent, meaningful booster effect against all dengue serotypes in participants who are seropositive for dengue at baseline.

FUNDING

Sanofi Pasteur.

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.