Balancing functions of regulatory T cells in mosquito-borne viral infections

Mosquito-borne viral infections are on the rise worldwide and can lead to severe symptoms such as haemorrhage, encephalitis, arthritis or microcephaly. A protective immune response following mosquito-borne viral infections requires the generation of a controlled and balanced immune response leading to viral clearance without immunopathology. Here, regulatory T cells play a central role in restoring immune homeostasis. In current review, we aim to provide an overview and summary of the phenotypes of FOXP3+ Tregs in various mosquito-borne arboviral disease, their association with disease severity and their functional characteristics. Furthermore, we discuss the role of cytokines and Tregs in the immunopathogenesis of mosquito-borne infections. Lastly, we discuss possible novel lines of research which could provide additional insight into the role of Tregs in mosquito-borne viral infections in order to develop novel therapeutic approaches or vaccination strategies.

Assessing viral metagenomics for the diagnosis of acute undifferentiated fever in returned travellers: a multicenter cohort study

BACKGROUND

Up to 45% of febrile returning travellers remain undiagnosed after a thorough diagnostic work-up, even at referral centres. Although metagenomic next-generation sequencing (mNGS) has emerged as a promising tool, evidence of its usefulness in imported fever is very limited.

METHODS

Travellers returning with fever were prospectively recruited in three referral clinics from November 2017 to November 2019. Unbiased mNGS optimised for virus detection was performed on serum samples of participants with acute undifferentiated febrile illness (AUFI), and results were compared to those obtained by reference diagnostic methods (RDM).

RESULTS

Among 507 returned febrile travellers, 433(85.4%) presented with AUFI. Dengue virus (n = 86) and Plasmodium spp. (n = 83) were the most common causes of fever. 103/433(23.8%) AUFI remained undiagnosed at the end of the follow-up.Metagenomic next-generation sequencing unveiled potentially pathogenic microorganisms in 196/433(38.7%) AUFI. mNGS identifications were more common in patients with a shorter duration of fever (42.3% in ≤5 days vs 28.7% in >5 days, P = 0.005). Potential causes of fever were revealed in 25/103(24.2%) undiagnosed AUFI and 5/23(21.7%) travellers with severe undiagnosed AUFI. Missed severe aetiologies included eight bacterial identifications and one co-infection of B19 parvovirus and Aspergillus spp.Additional identifications indicating possible co-infections occurred in 29/316(9.2%) travellers with AUFI, and in 11/128(8.6%) travellers with severe AUFI, who had received a diagnosis through RDM. The most common co-infections detected in severe AUFI were caused by Gram-negative bacteria. Serum mNGS was unable to detect >50% of infectious diagnoses achieved by RDM and also yielded 607 non-pathogenic identifications.

DISCUSSION

mNGS of serum can be a valuable diagnostic tool for selected travellers with undiagnosed AUFI or severe disease in addition to reference diagnostic techniques, especially during the first days of symptoms. Nevertheless, mNGS results interpretation presents a great challenge. Further studies evaluating the performance of mNGS using different sample types and protocols tailored to non-viral agents are needed.

Use of Dengvaxia® in Australian Travellers: a case series

Dengvaxia is the only licensed dengue vaccine in Australia, but rarely used. We report the experience of using Dengvaxia in seven Australian travellers. Main reasons for opting for vaccination were travel to dengue-endemic regions and severe symptoms during the prior dengue infection. The vaccine was well tolerated by all travellers.

Molecular mechanisms in the pathogenesis of dengue infections

Dengue is the most rapidly emerging climate-sensitive infection, and morbidity/mortality and disease incidence are rising markedly, leading to healthcare systems being overwhelmed. There are currently no specific treatments for dengue or prognostic markers to identify those who will progress to severe disease. Owing to an increase in the burden of illness and a change in epidemiology, many patients experience severe disease. Our limited understanding of the complex mechanisms of disease pathogenesis has significantly hampered the development of safe and effective treatments, vaccines, and biomarkers. We discuss the molecular mechanisms of dengue pathogenesis, the gaps in our knowledge, and recent advances, as well as the most crucial questions to be answered to enable the development of therapeutics, biomarkers, and vaccines.

A rare case report

Dengue fever is a viral disease transmitted by the Aedes aegypti mosquitoes. In Argentina, dengue fever is an epidemic disease; most cases are reported during the hot months. Until epidemiological week (EW) 20/2023, 106 672 cases were reported across 18 of the 24 provinces of Argentina. Children younger than 2 years are among the main groups at risk. Recognizing signs and symptoms and identifying risk factors is fundamental for the management of cases at a higher risk of severity. Here we describe the case of a 32-day-old female patient who was hospitalized due to febrile syndrome without a source, who had a differential diagnosis of viral meningitis and sepsis and progressed to leukocytosis, thrombocytopenia, hypoalbuminemia in association with rash and edema. The diagnosis of dengue fever was established based on clinical, epidemiological, and positive IgM data.

Pediatric Profound Dengue Shock Syndrome and Use of Point-of-Care Ultrasound During Mechanical Ventilation to Guide Treatment: Single-Center Retrospective Study, 2013-2021

OBJECTIVES

Profound dengue shock syndrome (DSS) complicated by severe respiratory failure necessitating mechanical ventilation (MV) accounts for high case fatality rates among PICU-admitted patients. A major challenge to management is the assessment of intravascular volume, which can be hampered by severe plasma leakage and the use of MV.

DESIGN

Retrospective cohort, from 2013 to 2021.

PATIENTS

Sixty-seven children with profound DSS supported by MV, some of whom underwent bedside point-of-care ultrasound (POCUS) for assessment and monitoring of hemodynamics and fluid administration.

SETTING

PICU of the tertiary Children's Hospital No. 2 in Vietnam.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We analyzed data clinical and laboratory data during PICU stay. In particular, during use of MV (i.e., at times 0-, 6-, and 24-hr after commencement) and fluid resuscitation. The primary study outcome was 28-day in-hospital mortality, and the secondary outcomes were associations with changes in hemodynamics, blood lactate, and vasoactive-inotrope score (VIS). Patients had a median age of 7 years (interquartile range, 4-9). Use of POCUS during fluid management (39/67), as opposed to not using (28/67), was associated with lower mortality (6/39 [15%] vs. 18/28 [64%]; difference 49 % [95% CI, 28-70%], p < 0.001). Use of POCUS was associated with lower odds of death (adjusted odds ratio 0.17 [95% CI, 0.04-0.76], p = 0.02). The utilization of POCUS, versus not, was associated with greater use of resuscitation fluid, and reductions in VIS and pediatric logistic organ dysfunction (PELOD-2) score at 24 hours after MV and PICU discharge.

CONCLUSIONS

In our experience of pediatric patients with profound DSS and undergoing MV (2013-2021), POCUS use was associated with lower odds of death, a higher volume of resuscitation fluid, and improvements in the blood lactate levels, VIS, and PELOD-2 score.

Application of computer vision and deep learning models to automatically classify medically important mosquitoes in North Borneo, Malaysia

Mosquito-borne diseases have emerged in North Borneo in Malaysia due to rapid changes in the forest landscape, and mosquito surveillance is key to understanding disease transmission. However, surveillance programmes involving sampling and taxonomic identification require well-trained personnel, are time-consuming and labour-intensive. In this study, we aim to use a deep leaning model (DL) to develop an application capable of automatically detecting mosquito vectors collected from urban and suburban areas in North Borneo, Malaysia. Specifically, a DL model called MobileNetV2 was developed using a total of 4880 images of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus mosquitoes, which are widely distributed in Malaysia. More importantly, the model was deployed as an application that can be used in the field. The model was fine-tuned with hyperparameters of learning rate 0.0001, 0.0005, 0.001, 0.01 and the performance of the model was tested for accuracy, precision, recall and F1 score. Inference time was also considered during development to assess the feasibility of the model as an app in the real world. The model showed an accuracy of at least 97%, a precision of 96% and a recall of 97% on the test set. When used as an app in the field to detect mosquitoes with the elements of different background environments, the model was able to achieve an accuracy of 76% with an inference time of 47.33 ms. Our result demonstrates the practicality of computer vision and DL in the real world of vector and pest surveillance programmes. In the future, more image data and robust DL architecture can be explored to improve the prediction result.

Reemergence of Sylvatic Dengue Virus Serotype 2 in Kedougou, Senegal, 2020

In 2020, a sylvatic dengue virus serotype 2 infection outbreak resulted in 59 confirmed dengue cases in Kedougou, Senegal, suggesting those strains might not require adaptation to reemerge into urban transmission cycles. Large-scale genomic surveillance and updated molecular diagnostic tools are needed to effectively prevent dengue virus infections in Senegal.

[Dengue in Argentina: confirmation of our worst suspicions]

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Influence of microbiota-driven natural antibodies on dengue transmission

Dengue has had a significant global health impact, with a dramatic increase in incidence over the past 50 years, affecting more than 100 countries. The absence of a specific treatment or widely applicable vaccine emphasizes the urgent need for innovative strategies. This perspective reevaluates current evidence supporting the concept of dual protection against the dengue virus (DENV) through natural antibodies (NAbs), particularly anti-α-Gal antibodies induced by the host's gut microbiome (GM). These anti-α-Gal antibodies serve a dual purpose. Firstly, they can directly identify DENV, as mosquito-derived viral particles have been observed to carry α-Gal, thereby providing a safeguard against human infections. Secondly, they possess the potential to impede virus development in the vector by interacting with the vector's microbiome and triggering infection-refractory states. The intricate interplay between human GM and NAbs on one side and DENV and vector microbiome on the other suggests a novel approach, using NAbs to directly target DENV and simultaneously disrupt vector microbiome to decrease pathogen transmission and vector competence, thereby blocking DENV transmission cycles.

Two decades of endemic dengue in Bangladesh (2000-2022): trends, seasonality, and impact of temperature and rainfall patterns on transmission dynamics

The objectives of this study were to compare dengue virus (DENV) cases, deaths, case-fatality ratio [CFR], and meteorological parameters between the first and the recent decades of this century (2000-2010 vs. 2011-2022) and to describe the trends, seasonality, and impact of change of temperature and rainfall patterns on transmission dynamics of dengue in Bangladesh. For the period 2000-2022, dengue cases and death data from Bangladesh's Ministry of Health and Family Welfare's website, and meteorological data from the Bangladesh Meteorological Department were analyzed. A Poisson regression model was performed to identify the impact of meteorological parameters on the monthly dengue cases. A forecast of dengue cases was performed using an autoregressive integrated moving average model. Over the past 23 yr, a total of 244,246 dengue cases were reported including 849 deaths (CFR = 0.35%). The mean annual number of dengue cases increased 8 times during the second decade, with 2,216 cases during 2000-2010 vs. 18,321 cases during 2011-2022. The mean annual number of deaths doubled (21 vs. 46), but the overall CFR has decreased by one-third (0.69% vs. 0.23%). Concurrently, the annual mean temperature increased by 0.49 °C, and rainfall decreased by 314 mm with altered precipitation seasonality. Monthly mean temperature (Incidence risk ratio [IRR]: 1.26), first-lagged rainfall (IRR: 1.08), and second-lagged rainfall (IRR: 1.17) were significantly associated with monthly dengue cases. The increased local temperature and changes in rainfall seasonality might have contributed to the increased dengue cases in Bangladesh.

Optimising the surveillance of Aedes aegypti in Brazil by selecting smaller representative areas within an endemic city

OBJECTIVES

Arboviruses, such as dengue (DENV), zika (ZIKV), and chikungunya (CHIKV), constitute a growing urban public health threat. Focusing on Aedes aegypti mosquitoes, their primary vectors, is crucial for mitigation. While traditional immature-stage mosquito surveillance has limitations, capturing adult mosquitoes through traps yields more accurate data on disease transmission. However, deploying traps presents logistical and financial challenges, demonstrating effective temporal predictions but lacking spatial accuracy. Our goal is to identify smaller representative areas within cities to enhance the early warning system for DENV outbreaks.

METHODS

We created Sentinel Geographic Units (SGUs), smaller areas of 1 km2 within each stratum, larger areas, with the aim of aligning the Trap Positivity Index (TPI) and Adult Density Index (ADI) with their respective strata. We conducted a two-step evaluation of SGUs. First, we examined the equivalence of TPI and ADI between SGUs and strata from January 2017 to July 2022. Second, we assessed the ability of SGU's TPI and ADI to predict DENV outbreaks in comparison to Foz do Iguaçu's Early-Warning System, which forecasts outbreaks up to 4 weeks ahead. Spatial and temporal analyses were carried out, including data interpolation and model selection based on Akaike information criteria (AIC).

RESULTS

Entomological indicators produced in small SGUs can effectively replace larger sentinel areas to access dengue outbreaks. Based on historical data, the best predictive capability is achieved 2 weeks after infestation verification. Implementing the SGU strategy with more frequent sampling can provide more precise space-time estimates and enhance dengue control.

CONCLUSIONS

The implementation of SGUs offers an efficient way to monitor mosquito populations, reducing the need for extensive resources. This approach has the potential to improve dengue transmission management and enhance the public health response in endemic cities.

Literacy and attitude of Asian youths on dengue and its prevention in an endemic developed community

Background

Over the past few decades, the incidence of dengue fever has considerably increased. Effective vector control strategies and specific protection using dengue vaccine are thought to be the key elements to combat dengue. The dengue incidence among the Singapore youths (15-24 years) was second only to that of adults (25-44 years). This study evaluated the knowledge and attitude of Singapore youths on dengue and its preventive measures.

Methods

A cross-sectional study using online-based questionnaire survey was conducted among Singapore youths from September to November 2022. Data were analyzed for descriptive statistics whereas Chi-squared test, linear regression analysis and Pearson correlation were used to determine the association between demographic factors and youth's attitude on dengue prevention using Rstudio.

Results

A total of 624 respondents completed the survey out of 1822 surveys distributed nation-wide, with a response rate of 34.2% (mean age 17.4 years ± 1.84; 59.3% female; 89.9% Chinese). The mean dengue knowledge scores of participants were 14.1 ± 2.8. Univariate analysis showed that teenagers (15-19 years) had significantly higher knowledge score than the young adults (20-24 years) (β =0.82,95%CI = 0.13-1.51, p = 0.021). Majority of them were aware of the Mozzie Wipeout campaign (90.2%) followed by the release of Wolbachia mosquitos (69.1%). Two-thirds of the youths who were aware of Wolbachia and Gravitrap considered that it was effective in reducing dengue infection rates. Participants suggested information about the current dengue infection rate (71.9%) as the most effective of the five proposed strategies to improve uptake of dengue preventive measures. In comparison to young adults, teenagers were more likely to uptake dengue preventive measures if widespread mosquito control practices were implemented (69.1% vs. 42.3%).

Conclusion

The overall knowledge of the youths on dengue and its prevention was satisfactory. Future health promotion campaigns targeting the youths should focus on transforming the knowledge into practice.

Using Computational Simulations Based on Fuzzy Cognitive Maps to Detect Dengue Complications

Dengue remains a globally prevalent and potentially fatal disease, affecting millions of people worldwide each year. Early and accurate detection of dengue complications is crucial to improving clinical outcomes and reducing the burden on healthcare systems. In this study, we explore the use of computational simulations based on fuzzy cognitive maps (FCMs) to improve the detection of dengue complications. We propose an innovative approach that integrates clinical data into a computational model that mimics the decision-making process of a medical expert. Our method uses FCMs to model complexity and uncertainty in dengue. The model was evaluated in simulated scenarios with each of the dengue classifications. These maps allow us to represent and process vague and fuzzy information effectively, capturing relationships that often go unnoticed in conventional approaches. The results of the simulations show the potential of our approach to detecting dengue complications. This innovative strategy has the potential to transform the way clinical management of dengue is approached. This research is a starting point for further development of complication detection approaches for events of public health concern, such as dengue.

Posterior reversible encephalopathy syndrome associated with dengue fever induced intrauterine death: A case report

In recent years dengue fever has become a major health concern specifically due to its diverse presentation and adverse outcome. Progression from mild febrile illness to a severe systemic illness may occur in dengue fever including neurological disorder. Here, we report an unusual and rare case of a 20-year-old mother who developed posterior reversible encephalopathy syndrome (PRES) following dengue fever induced intrauterine death and septic shock.

Severe dengue infection unmasking drug-induced liver injury: Successful management with N-acetylcysteine

Key Clinical Message

Clinicians in tuberculosis and dengue endemic regions should have heightened vigilance for drug-induced liver injury (DILI) overlapping with active infections, enabling prompt recognition and life-saving conservative management.

Abstract

Severe dengue and drug-induced liver injury (DILI) are significant independent risk factors for acute liver failure. The co-occurrence of these conditions significantly complicates clinical management. Here, we describe the case of a 21-year-old Nepali female who developed acute liver failure during antitubercular therapy (ATT). The patient, presenting with fever and nausea after 3 weeks of ATT, subsequently received a diagnosis of severe dengue. Laboratory evidence indicated markedly elevated transaminases (AST 4335 U/L, ALT 1958 U/L), total bilirubin (72 μmol/L), and INR (>5). Prompt discontinuation of first-line ATT, initiation of a modified ATT regimen, and N-acetylcysteine (NAC) infusion facilitated the patient's recovery after a week of intensive care. This case underscores the potential for synergistic hepatotoxicity in regions where multiple endemic illnesses coincide. Early recognition of DILI, cessation of offending agents, and comprehensive intensive care are crucial interventions. While the definitive efficacy of NAC remains under investigation, its timely administration in these complex cases warrants exploration for its potential lifesaving benefits.

Seroprevalence of dengue, Japanese encephalitis and Zika among long-term expatriates in Thailand

BACKGROUND

Travel to Southeast Asia increases the likelihood of acquiring mosquito-borne Flavivirus infections such as dengue (DENV), Japanese encephalitis (JEV) and Zika viruses (ZIKV). Expatriates are long-term travellers who have a higher risk of mosquito-borne illness at their destination country. The purpose of this study was to evaluate the seroprevalence of DENV, JEV and ZIKV infections and the determinants contributing to seropositivity among expatriates living in Thailand.

METHODS

A cross-sectional study was performed from December 2017 to February 2020. Expatriates from non-Flavivirus endemic countries were recruited. 5 mL of blood was collected for DENV 1-4, JEV and ZIKV antibody testing by plaque reduction neutralization test (PRNT50). Individuals with vaccination histories or diagnoses for dengue, Japanese encephalitis, yellow fever and tick-borne encephalitis were excluded.

RESULTS

Among 254 participants, most participants (83.1%) were male, the mean age was 65 years and the median duration of stay in Thailand was 6 years. Seroprevalence rate of any Flavivirus, non-specific DENV, DENV1-4, JEV and ZIKV were 34.3, 30.7, 20.5, 18.1, 18.9, 10.6, 4.7 and 2.8%, respectively. The presence of neutralizing antibodies against DENV1-4 positively correlates with the duration of stay in Thailand. DENV seropositivity was associated with living in urban areas (aOR 2.75, 95% CI 1.36-5.57). Expatriates were unlikely to have detectable anti-JEV antibodies regardless of time spent in a JEV-endemic area. No risk factors were identified that were significantly associated with JEV or ZIKV seropositivity. Only 48.4% received pre-travel counselling services, while only 18.9% visited a travel medicine specialist.

CONCLUSIONS

A high proportion (34.3%) of long-term expatriates living in Thailand were seropositive for flavivirus, mainly from dengue (30.7%). To minimize risk, travel medicine practitioners should provide adequate pre-travel health risk information on mosquito-borne flavivirus infection and offer advice on mosquito bite prevention strategies. Dengue vaccine might be considered in high-risk travellers such as long-term expatriate.

Risk factors associated with severe dengue in Latin America: A systematic review and meta-analysis

OBJECTIVE

Severe dengue is a significant health problem in Latin America, with children being the most affected. Understanding risk factors for severe dengue is crucial for enhancing patient care. Therefore, this study aims to systematically review the literature to identify the risk factors associated with severe dengue in Latin America through systematic review and meta-analysis.

METHODS

PubMed, SciELO, LILACS and EMBASE databases were used to search for eligible scientific articles for the review. The outcomes considered were symptoms of severe dengue, hospitalisation and death. The Joanna Briggs Institute Critical Appraisal Checklist was used to assess the quality of the studies. Data analysis was performed using STATA v 13.0 software. The degree of heterogeneity between studies was quantified using the I2 measure, and statistically significant results were defined as those with p values <0.05.

RESULTS

Of the 1876 articles screened, 47 articles were included in the systematic review and 45 articles were analysed through meta-analysis. Identified risk factors associated with severe dengue included secondary dengue infection, female sex, white or Caucasian ethnicity and specific signs and symptoms such as headache, myalgia and/or arthralgia, vomiting/nausea, abdominal pain or tenderness, diarrhoea, prostration, lethargy, fatigue or similar. For the death outcome, respiratory symptoms and age <18 years were identified as risk factors. On the other hand, in women, the diagnosis of positive tourniquet test, platelet count <100,000 per μL and symptoms of capillary fragility were associated with a lower probability of death. These data highlight the importance of early screening of patients, to identify possible haemorrhagic signs and reduce deaths from dengue. This study has limitations, including possible publication bias, heterogeneity of results and study design biases.

CONCLUSION

These findings are significant for shaping strategies, management approaches and identifying high-risk groups, which will help establish future guidelines.

Molecular epidemiology identifies the expansion of the DENV2 epidemic lineage from the French Caribbean Islands to French Guiana and mainland France, 2023 to 2024

In 2023, dengue virus serotype 2 (DENV2) affected most French overseas territories. In the French Caribbean Islands, viral circulation continues with > 30,000 suspected infections by March 2024. Genome sequence analysis reveals that the epidemic lineage in the French Caribbean islands has also become established in French Guiana but not Réunion. It has moreover seeded autochthonous circulation events in mainland France. To guide prevention of further inter-territorial spread and DENV introduction in non-endemic settings, continued molecular surveillance and mosquito control are essential.

Dengue virus infection and neurological manifestations: an update

Dengue virus is a flavivirus transmitted by the mosquitoes, Aedes aegypti and Aedes albopictus. Dengue infection by all four serotypes (DEN 1 to 4) is endemic globally in regions with tropical and subtropical climates, with an estimated 100-400 million infections annually. Among those hospitalized, the mortality is about 1%. Neurological involvement has been reported to be about 5%. The spectrum of neurological manifestations spans both the peripheral and central nervous systems. These manifestations could possibly be categorized into those directly related to dengue infection, i.e. acute and chronic encephalitis, indirect complications leading to dengue encephalopathy, and post-infectious syndrome due to immune-mediated reactions, and manifestations with uncertain mechanisms, such as acute transverse myelitis, acute cerebellitis and myositis. The rising trend in global dengue incidence calls for attention to a more explicit definition of each neurological manifestation for more accurate epidemiological data. The actual global burden of dengue infection with neurological manifestation is essential for future planning and execution of strategies, especially in the development of effective antivirals and vaccines against the dengue virus. In this article, we discuss the recent findings of different spectrums of neurological manifestations in dengue infection and provide an update on antiviral and vaccine development and their challenges.

Clinical manifestations of dengue, Zika and chikungunya in the Pacific Islands: A systematic review and meta-analysis

Dengue, Zika and chikungunya outbreaks pose a significant public health risk to Pacific Island communities. Differential diagnosis is challenging due to overlapping clinical features and limited availability of laboratory diagnostic facilities. There is also insufficient information regarding the complications of these arboviruses, particularly for Zika and chikungunya. We conducted a systematic review and meta-analysis to calculate pooled prevalence estimates with 95% confidence intervals (CI) for the clinical manifestations of dengue, Zika and chikungunya in the Pacific Islands. Based on pooled prevalence estimates, clinical features that may help to differentiate between the arboviruses include headache, haemorrhage and hepatomegaly in dengue; rash, conjunctivitis and peripheral oedema in Zika; and the combination of fever and arthralgia in chikungunya infections. We estimated that the hospitalisation and mortality rates in dengue were 9.90% (95% CI 7.67-12.37) and 0.23% (95% CI 0.16-0.31), respectively. Severe forms of dengue occurred in 1.92% (95% CI 0.72-3.63) of reported cases and 23.23% (95% CI 13.58-34.53) of hospitalised patients. Complications associated with Zika virus included Guillain-Barré syndrome (GBS), estimated to occur in 14.08 (95% CI 11.71-16.66) per 10,000 reported cases, and congenital brain malformations such as microcephaly, particularly with first trimester maternal infection. For chikungunya, the hospitalisation rate was 2.57% (95% CI 1.30-4.25) and the risk of GBS was estimated at 1.70 (95% CI 1.06-2.48) per 10,000 reported cases. Whilst ongoing research is required, this systematic review enhances existing knowledge on the clinical manifestations of dengue, Zika and chikungunya infections and will assist Pacific Island clinicians during future arbovirus outbreaks.

The continuum of liver injury with severity of dengue fever: A retrospective observational study

BACKGROUND

Dengue is a major international health concern prevalent in tropical and sub-tropical countries. There are a paucity of studies on the relationship of hepatic complications with inflammatory parameters in dengue infection.

METHODS

Single-centre observational study was conducted at the tertiary care centre in North India. Patients (>12 years) diagnosed with dengue infection between August and November 2021 were enrolled in the study. The frequency of hepatic derangements and their associations with inflammatory severity was analysed.

RESULTS

Based on the clinical symptoms, 170 patients were classified into three categories, namely, dengue fever, warning dengue and severe dengue. Higher incidence of liver dysfunction was observed in severe dengue patients with median values of aspartate aminotransferase (AST) (3051 U/L, p < 0.001), alanine aminotransferase (ALT) (1792 U/L, p = 0.009), alkaline phosphatase (172 U/L, p = 0.001), T.Bil (34.2 µmol/L, p < 0.001), albumin (30 g/L, <0.001), and gamma-glutamyl transferase (152 U/L, p < 0.001) along with inflammatory marker C-reactive protein (CRP) (43 mg/dL, p < 0.001) highly deranged, in comparison to patients with/without warning signs. Median levels of CRP were found to be positively and significantly correlated with the median levels of AST and ALT (p < 0.05, r = 0.99) in all three categories of dengue patients. Liver injury was noted in 107 (63%) of the cohort, and mixed type of liver injury involving both hepatocellular and cholestatic patterns was observed as the most common type of injury (n = 50, 29.4%). Liver injury correlated with the severity of dengue illness as about 85% of severe dengue patients had significant liver injury (p = 0.014).

CONCLUSION

In dengue patients, the association of the liver injury with inflammatory severity suggests that the mechanism of liver injury may be related to inflammatory response apart from the hepatotropic nature of the virus.

Approaches of dengue control: vaccine strategies and future aspects

Dengue, caused by the dengue virus (DENV), affects millions of people worldwide every year. This virus has two distinct life cycles, one in the human and another in the mosquito, and both cycles are crucial to be controlled. To control the vector of DENV, the mosquito Aedes aegypti, scientists employed many techniques, which were later proved ineffective and harmful in many ways. Consequently, the attention shifted to the development of a vaccine; researchers have targeted the E protein, a surface protein of the virus and the NS1 protein, an extracellular protein. There are several types of vaccines developed so far, such as live attenuated vaccines, recombinant subunit vaccines, inactivated virus vaccines, viral vectored vaccines, DNA vaccines, and mRNA vaccines. Along with these, scientists are exploring new strategies of developing improved version of the vaccine by employing recombinant DNA plasmid against NS1 and also aiming to prevent the infection by blocking the DENV life cycle inside the mosquitoes. Here, we discussed the aspects of research in the field of vaccines until now and identified some prospects for future vaccine developments.

Climate change and the spread of Aedes mosquito-borne viruses in Europe

Several outbreaks of chikungunya and dengue occurred on Mediterranean coasts during the hot season in the last two decades. Aedes albopictus was the vector involved in all the events. As a consequence of climate change, the 'Tiger' mosquito is now spreading through central Europe, and in the summer of 2023, for the first time, mosquito control measures were implemented in Paris to prevent autochthonous transmission of dengue. Rapid changes in the distribution of tropical disease vectors need to be taken into account in future risk assessment activities.

Short report: unmanned aerial vehicle for wide area larvicide spraying (WALS) using Vectobac® WG at Kota Kinabalu, Sabah

INTRODUCTION

Given the stagnating progress in the fight against dengue in Kota Kinabalu, there is an urgent need to use other strategies to complement the existing vector control, focusing on larviciding. Unmanned aerial vehicle (UAV) technology has been used in vector control programs in many countries. The aim of this study was to determine the feasibility of using UAVs for larviciding to control Aedes mosquitoes in urban areas.

METHODOLOGY

The Hexarotor Agro Drone (Polardrone Sdn Bhd, Malaysia) was used to carry out larviciding using Vectobac® manufactured by Valent BioSciences LLC, Libertyville, USA. The drone flew at a height of 10 feet and at a speed of 5 m/s. A total of 32 items with 10 larvae in each item were placed to test the effectiveness of larviciding using UAV.

RESULTS

Out of 32 items used, 4 containers had a 100% larva mortality (13.3% mortality). The drone was not able to reach the designated spraying route that had been pre-programmed. This was due to interference with the electromagnetic waves emitted from the home satellite dishes, that were in front of the houses along the route.

CONCLUSIONS

This trial showed that UAVs will be more suitable for use in larviciding in an open area without electromagnetic disturbances from electric house poles and satellite TV dishes that are commonly present in urban areas.

Effectiveness of a Nursing Educational Intervention in Adults to Promote Control Behaviors Against Dengue: Protocol for a Randomized Controlled Trial

BACKGROUND

The increase in dengue cases can be attributed to social, demographic, environmental changes, or community-driven factors. In this regard, different strategies have been established in health education, using educational interventions as necessary tools for the reduction of the disease with the aim of reinforcing and stimulating the prevention and control of dengue.

OBJECTIVE

This study aims to evaluate the effectiveness of a nursing educational intervention for dengue control.

METHODS

A randomized controlled trial will be conducted with adults living in rural areas and participating in health promotion and disease prevention programs. We will enroll 116 adults. Adults will be randomized 1:1, with 58 adults assigned to the educational intervention group and 58 to the usual care group. Participants will receive 4 sessions over the course of a month, 1 week apart, and will be followed up for 1 month after the end of the educational intervention. Nursing Outcome Classification labels will be used to measure the outcomes: risk control (1902) and participation in health care decisions (1606).

RESULTS

The participants in the intervention group are expected to achieve better dengue control behaviors than those in the usual care group.

CONCLUSIONS

Risk factors are fostered by the community, largely caused by artificial reservoirs or unprotected tanks in homes; also, the lack of information hinders the identification of symptomatology and the poor implementation of effective measures, and the development of standardized educational strategies can contribute to efficient and cost-effective control of the disease.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05321264; https://clinicaltrials.gov/study/NCT05321264.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/54286.

Immunological signatures unveiled by integrative systems vaccinology characterization of dengue vaccination trials and natural infection

Introduction

Dengue virus infection is a global health problem lacking specific therapy, requiring an improved understanding of DENV immunity and vaccine responses. Considering the recent emerging of new dengue vaccines, here we performed an integrative systems vaccinology characterization of molecular signatures triggered by the natural DENV infection (NDI) and attenuated dengue virus infection models (DVTs).

Methods and results

We analyzed 955 samples of transcriptomic datasets of patients with NDI and attenuated dengue virus infection trials (DVT1, DVT2, and DVT3) using a systems vaccinology approach. Differential expression analysis identified 237 common differentially expressed genes (DEGs) between DVTs and NDI. Among them, 28 and 60 DEGs were up or downregulated by dengue vaccination during DVT2 and DVT3, respectively, with 20 DEGs intersecting across all three DVTs. Enriched biological processes of these genes included type I/II interferon signaling, cytokine regulation, apoptosis, and T-cell differentiation. Principal component analysis based on 20 common DEGs (overlapping between DVTs and our NDI validation dataset) distinguished dengue patients by disease severity, particularly in the late acute phase. Machine learning analysis ranked the ten most critical predictors of disease severity in NDI, crucial for the anti-viral immune response.

Conclusion

This work provides insights into the NDI and vaccine-induced overlapping immune response and suggests molecular markers (e.g., IFIT5, ISG15, and HERC5) for anti-dengue-specific therapies and effective vaccination development.

Antiviral Wolbachia strains associate with Aedes aegypti endoplasmic reticulum membranes and induce lipid droplet formation to restrict dengue virus replication

Wolbachia are a genus of insect endosymbiotic bacteria which includes strains wMel and wAlbB that are being utilized as a biocontrol tool to reduce the incidence of Aedes aegypti-transmitted viral diseases like dengue. However, the precise mechanisms underpinning the antiviral activity of these Wolbachia strains are not well defined. Here, we generated a panel of Ae. aegypti-derived cell lines infected with antiviral strains wMel and wAlbB or the non-antiviral Wolbachia strain wPip to understand host cell morphological changes specifically induced by antiviral strains. Antiviral strains were frequently found to be entirely wrapped by the host endoplasmic reticulum (ER) membrane, while wPip bacteria clustered separately in the host cell cytoplasm. ER-derived lipid droplets (LDs) increased in volume in wMel- and wAlbB-infected cell lines and mosquito tissues compared to cells infected with wPip or Wolbachia-free controls. Inhibition of fatty acid synthase (required for triacylglycerol biosynthesis) reduced LD formation and significantly restored ER-associated dengue virus replication in cells occupied by wMel. Together, this suggests that antiviral Wolbachia strains may specifically alter the lipid composition of the ER to preclude the establishment of dengue virus (DENV) replication complexes. Defining Wolbachia's antiviral mechanisms will support the application and longevity of this effective biocontrol tool that is already being used at scale.IMPORTANCEAedes aegypti transmits a range of important human pathogenic viruses like dengue. However, infection of Ae. aegypti with the insect endosymbiotic bacterium, Wolbachia, reduces the risk of mosquito to human viral transmission. Wolbachia is being utilized at field sites across more than 13 countries to reduce the incidence of viruses like dengue, but it is not well understood how Wolbachia induces its antiviral effects. To examine this at the subcellular level, we compared how different strains of Wolbachia with varying antiviral strengths associate with and modify host cell structures. Strongly antiviral strains were found to specifically associate with the host endoplasmic reticulum and induce striking impacts on host cell lipid droplets. Inhibiting Wolbachia-induced lipid redistribution partially restored dengue virus replication demonstrating this is a contributing role for Wolbachia's antiviral activity. These findings provide new insights into how antiviral Wolbachia strains associate with and modify Ae. aegypti host cells.

Dengue severity by serotype 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 influence of serotype and immune status on dengue severity. Study participants 6 months to 17 years old were followed during their hospital stay or as ambulatory patients, with dengue cases confirmed by molecular, serological, and/or virological methods.

Results

We enrolled a total of 14071 participants, of whom 2954 (21%) were positive for DENV infection. Of 2425 cases with serotype result by RT-PCR, 541 corresponded to DENV1, 996 to DENV2, 718 to DENV3 and 170 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 had a higher proportion of severe disease compared to other serotypes, whereas DENV3 had the greatest percentage of severity under the WHO-2009 classification. DENV2 was associated with pleural effusion and low platelet count, while DENV3 correlated with both hypotensive and compensated shock.

Conclusions

These findings emphasize the critical need for a dengue vaccine with balanced efficacy against all four serotypes, particularly as existing vaccines show variable efficacy by serotype and immune status, posing challenges for comprehensive protection, particularly in dengue-naïve individuals.

Sustainable Dengue Prevention and Management: Integrating Dengue Vaccination Strategies with Population Perspectives

The GEMKAP study (2023) unveiled consistent knowledge, attitude, and practice (KAP) levels across Asia-Pacific (APAC) and Latin America (LATAM) countries regarding dengue, with variations in the willingness to vaccinate. Despite an overall KAP parity, the disparities within and between the countries indicated the need for both overarching and tailored strategies. Population-wide gaps in dengue awareness result in suboptimal vaccination priorities and preventive measures. This commentary delves into identifying the drivers and barriers for implementing a multi-pronged dengue prevention and management program, emphasizing the pivotal role of vaccination alongside education and vector control. Drawing on expert interviews in APAC and LATAM, informed by the Consolidated Framework for Implementation Research (CFIR), four key themes emerged: prioritizing and continuously advocating for dengue on national health agendas, fostering stakeholder collaboration, incorporating population perspectives for behavioral change, and designing sustainable dengue prevention and management programs. Successful implementation requires evidence-based decision making and a comprehensive understanding of population dynamics to design adaptive education tailored to diverse population views. This commentary provides actionable strategies for enhancing dengue prevention and management, with a pronounced emphasis on dengue vaccination, advocating for a holistic, population-centric approach for sustained effectiveness.

Fully automated high-throughput immuno-µPlaque assay for live-attenuated tetravalent dengue vaccine development

Dengue fever has remained a continuing global medical threat that impacts half of the world's population. Developing a highly effective dengue vaccine, with live-attenuated tetravalent vaccines as leading candidates, remains essential in preventing this disease. For the development of live virus vaccines (LVVs), potency measurements play a vital role in quantifying the active components of vaccine drug substance as well as drug product during various stages of research, development, and post-licensure evaluations. Traditional plaque-based assays are one of the most common potency test methods, but they generally take up to weeks to complete. Less labor and time-intensive potency assays are thus called for to aid in the acceleration of vaccine development, especially for multivalent LVVs. Here, we introduce a fully automated, 96-well format µPlaque assay that has been optimized as a high-throughput tool to evaluate process and formulation development of a live-attenuated tetravalent dengue vaccine. To the best of our knowledge, this is the first report of a miniaturized viral plaque method for dengue with full automation via an integrated robotic system. Compared to the traditional manual plaque assay, this newly developed method substantially reduces testing time by approximately half and allows for the evaluation of over ten times more samples per run. The fully automated workflow, from cell culture to plaque counting, significantly minimizes analyst hands-on time and improves assay repeatability. The study presents a pioneering solution for the rapid measurement of LVV viral titers, offering promising prospects for advancing vaccine development through high-throughput analytics.

Epidemiology of Dengue in Argentina during the 2010/11 to 2019/20 Seasons: A Contribution to the Burden of Disease

BACKGROUND

Dengue is an important public health problem in Argentina, as in many other countries. We reviewed and updated information on the dengue disease burden in Argentina over a 10-year period.

METHODS

We conducted a retrospective descriptive study from 2010 to 2020 based on data from the National Health Surveillance System. The main outcomes included dengue cases, incidence rates, deaths, and serotype distribution by season, age group, and region.

RESULTS

A total of 109,998 confirmed cases of dengue were reported. Seasonality stands out, prevailing during summer and autumn. Two main outbreaks (seasons 2015/16 and 2019/20), with increasing magnitude, were observed. The 2019/20 season showed the highest number of cases (58,731) and incidence rate (135/100,000). The Northeast region had the highest number of cases and incidence rate. In 2020, for the first time, autochthonous cases were registered in the Cuyo region. The only region with no autochthonous cases was the South. Adolescents and young adults showed the highest incidence rate. The case fatality rate for the period was 0.05%. Four serotypes circulated, but the predominant one was DEN-1 (78%).

CONCLUSIONS

Dengue has been expanding temporally and spatially. Although the DEN-1 serotype widely predominated, the increasing circulation of other serotypes raises concerns regarding re-exposure and the severity of future cases. Understanding epidemiological trends is key to defining public prevention and control policies.

Plant Extracts and Phytochemicals from the Asteraceae Family with Antiviral Properties

Asteraceae (Compositae), commonly known as the sunflower family, is one of the largest plant families in the world and includes several species with pharmacological properties. In the search for new antiviral candidates, an in vitro screening against dengue virus (DENV) was performed on a series of dichloromethane and methanolic extracts prepared from six Asteraceae species, including Acmella bellidioides, Campuloclinium macrocephalum, Grindelia pulchella, Grindelia chiloensis, Helenium radiatum, and Viguiera tuberosa, along with pure phytochemicals isolated from Asteraceae: mikanolide (1), eupatoriopicrin (2), eupahakonenin B (3), minimolide (4), estafietin (5), 2-oxo-8-deoxyligustrin (6), santhemoidin C (7), euparin (8), jaceidin (9), nepetin (10), jaceosidin (11), eryodictiol (12), eupatorin (13), and 5-demethylsinensetin (14). Results showed that the dichloromethane extracts of C. macrocephalum and H. radiatum and the methanolic extracts prepared from C. macrocephalum and G. pulchella were highly active and selective against DENV-2, affording EC50 values of 0.11, 0.15, 1.80, and 3.85 µg/mL, respectively, and SIs of 171.0, 18.8, >17.36, and 64.9, respectively. From the pool of phytochemicals tested, compounds 6, 7, and 8 stand out as the most active (EC50 = 3.7, 3.1, and 6.8 µM, respectively; SI = 5.9, 6.7, and >73.4, respectively). These results demonstrate that Asteraceae species and their chemical constituents represent valuable sources of new antiviral molecules.

Investigating the Association Between ABO Blood Groups and Rhesus Factors with Dengue and Chikungunya Virus Infections During the 2017 Outbreak in Bangladesh

This retrospective study was conducted in 2017 during the dual dengue and chikungunya outbreak in Bangladesh. Febrile participants underwent blood tests for chikungunya, dengue, and ABO groups and rhesus (Rh) factors. Blood grouping information was gathered from healthy donors. Males and those aged between 18 and 49 years had a higher risk of contracting dengue and chikungunya. Blood group O exhibited the highest infection rates at ∼50%, whereas group AB had the lowest at ∼9% among the participants in the study. Yet, when considering the general population's blood group distribution, the combined odds of infection were 2.0, 3.5, and 1.4 times higher in groups B, O, and AB, respectively, than in group A. Infection rates were greater in Rh-negative people. Blood groups B, O, and AB showed higher susceptibility than blood group A according to adjusted odds ratios. Blood groups ABO and Rh factor hold significance in disease susceptibility and vaccine effectiveness. Keeping these implications in mind, further investigations are necessary to understand the mechanisms underlying these connections and their effects on the efficacy of dengue and chikungunya vaccines.

Potential Pathways and Pathophysiological Implications of Viral Infection-Driven Activation of Kallikrein-Kinin System (KKS)

Microcirculatory and coagulation disturbances commonly occur as pathological manifestations of systemic viral infections. Research exploring the role of the kallikrein-kinin system (KKS) in flavivirus infections has recently linked microvascular dysfunctions to bradykinin (BK)-induced signaling of B2R, a G protein-coupled receptor (GPCR) constitutively expressed by endothelial cells. The relevance of KKS activation as an innate response to viral infections has gained increasing attention, particularly after the reports regarding thrombogenic events during COVID-19. BK receptor (B2R and B1R) signal transduction results in vascular permeability, edema formation, angiogenesis, and pain. Recent findings unveiling the role of KKS in viral pathogenesis include evidence of increased activation of KKS with elevated levels of BK and its metabolites in both intravascular and tissue milieu, as well as reports demonstrating that virus replication stimulates BKR expression. In this review, we will discuss the mechanisms triggered by virus replication and by virus-induced inflammatory responses that may stimulate KKS. We also explore how KKS activation and BK signaling may impact virus pathogenesis and further discuss the potential therapeutic application of BKR antagonists in the treatment of hemorrhagic and respiratory diseases.

Molecular detection of dengue and chikungunya viruses in surveillance of wild-caught Aedes mosquitoes in Punjab, North India

BACKGROUND

Dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses are transmitted mainly by Aedes mosquitoes and are responsible for a significant global healthcare burden. The current study aimed to detect arboviruses in the Aedes mosquitoes in close proximity of patients during the transmission season.

METHODS

Both immature and adult mosquitoes were collected from in and around the patients' houses. Mosquito pools were homogenized and extracted RNA was subjected to reverse transcription polymerase chain reaction for arboviral detection. Transovarian transmission (TOT) was assessed by screening F0 adults. Mosquito positivity was correlated with the aetiological agents identified in patients.

RESULTS

Of 46 pools, 19 consisted of wild Aedes, with arboviral positivity in 53% (10/19) of pools. Among wild A. aegypti pools, positivity of DENV mono-infection, CHIKV mono-infection and DENV+CHIKV co-infection was noted in four, two and three pools, respectively. One wild pool of Aedes albopictus was positive for DENV-1. Similarly, A. aegypti F0 (adult Aedes developed from immatures) pools showed 59.2% (16/27) positivity for arboviruses. F0 Aedes showed positivity in three, six and seven pools for DENV-2, CHIKV and DENV+CHIKV, respectively, suggestive of TOT. DENV serotypes and CHIKV from 24 patients' serum samples were matched with strains isolated from Aedes and correlation was observed in four instances.

CONCLUSIONS

The study detected DENV and CHIKV from wild-caught Aedes and found evidence of DENV and CHIKV TOT in F0 adults.

Observational study of clinical, epidemiological, and laboratory characteristics of pediatric patients with dengue in the city of Córdoba

Introduction. Dengue has been the most widespread mosquito-borne disease worldwide in recent years. It develops with a broad spectrum of clinical manifestations and sometimes progresses to a critical condition known as severe dengue. It is managed with supportive treatment. Available information about its clinical, epidemiological, and laboratory characteristics in the pediatric population is limited. Objective. To describe the clinical, epidemiological, and laboratory characteristics of dengue. Population and methods. Descriptive, observational, and retrospective study. It included patients aged 1 to 180 months seen due to probable or confirmed dengue at a children's hospital between 1/1/2020 and 5/31/2020. Results. A total of 85 patients with positive microbiological or clinical-epidemiological criteria were included. Of these, 25 (29%) were confirmed by RT-PCR; all corresponded to DENV-1 serotype. Patients' median age was 108 months (interquartile range: 84-144). The main clinical manifestations were fever, headache, and myalgia. The most important laboratory findings were leukopenia, thrombocytopenia, and high transaminase levels. Conclusion. The recognition and understanding of clinical and laboratory alterations that occur during dengue disease may allow an effective approach and help to reduce the more severe clinical form in children.

Wastewater-based surveillance of vector-borne pathogens: a cautionary note

Diamond et al. recently identified malaria and dengue as high-priority diseases in wastewater surveillance for climate-change-driven shifts in pathogen dynamics. When employing wastewater surveillance for vector-borne pathogens it is essential to take into account the geographical context, pathogen biology, and the availability of sewage networks for meaningful interventions.

The Epidemiologic and Clinical Characteristics of the 2023 Dengue Outbreak in Bangladesh

The ongoing 2023 dengue outbreak is the worst ever case reported in Bangladesh. There is a lack of epidemiological studies on the outbreak. A 2-tailed t test was performed. Multivariable logistic regression analysis was conducted. We found about 277 801 cases and 1393 deaths from the 2023 dengue outbreak. About 52% of the cases were from outside of Dhaka. The male:female ratio was about 3:2. The highest frequency of cases was found among people aged 19-29 years (28.7%, 79 673 of 277 801; P = .001). The overall case fatality rate (CFR) was 0.5%. The highest CFR was found among children aged 0-10 years (12%). Fever (99%) was the most prevalent, followed by joint pain (86%). We found significantly higher odds of fatalities (adjusted odds ratio [aOR], 4.21; 95% CI, 3.93-4.74; P = .05), cases (aOR, 3.85; 95% CI, 3.25-4.12; P = .001) and hospitalizations (aOR, 3.26; 95% CI, 3.11-4.04; P = .006) during the 2023 outbreak compared with previous outbreaks during 2008-2022. This is one of the early reports of epidemiological and clinical characteristics of ongoing dengue outbreak.

APRI as a predictor of severe dengue fever

Introduction

The AST/platelet ratio index (APRI) is a well-researched indicator of liver fibrosis. Some studies have shown that APRI can be used as a predictor of severe dengue, but the data is limited. As dengue epidemics are common in our country with limited healthcare resources, we believe APRI can help emergency physicians/primary physicians in predicting the severity of dengue and plan for the appropriate use of limited healthcare resources.

Objective

1) To determine the utility of APRI as a predictor of severe dengue. 2) To determine the association of APRI with length of hospital stay and platelet requirement.

Materials and Methods

A retrospective cross-sectional study was done on patients presented to the Emergency Medicine department at Travancore Medicity Medical College with a positive Dengue NS1 antigen or IgM antibody.

Results

We found from the univariate analysis results that ALT > 74.5 IU/L has a sensitivity of 59.6 and a specificity of 76.3 (AUC: 0.696; 95% CI: 0.606-0.786), AST > 160.5 IU/L has a sensitivity of 42.3 and a specificity of 93.7 (AUC: 0.747; 95% CI: 0.665-0.829), and APRI > 3.2 has a sensitivity of 69.2 and a specificity of 84.2 (AUC: 0.806; 95% CI: 0.72-0.884) to predict severe dengue. Patients with an APRI of >3.2 required a mean hospital stay of 5.47 days (P = 0.005); 27 (81.8%) requiring platelet transfusion had an APRI of > 3.2 (P = 0.00).

Conclusion

APRI is a straightforward index that can be easily derived from AST and platelet values. APRI values of >3.2 can predict severe dengue with a sensitivity of 69.2 and a specificity of 84.2. APRI values of >3.2 are also associated with the length of hospital stay and requirement of platelet transfusion.

DENV-1 Titer Impacts Viral Blocking in wMel Aedes aegypti with Brazilian Genetic Background

Several countries have been using Wolbachia deployments to replace highly competent native Aedes aegypti populations with Wolbachia-carrying mosquitoes with lower susceptibility to arboviruses such as dengue, Zika, and chikungunya. In Rio de Janeiro, Wolbachia deployments started in 2015 and still present a moderate introgression with a modest reduction in dengue cases in humans (38%). Here, we evaluated the vector competence of wild-type and wMel-infected Ae. aegypti with a Brazilian genetic background to investigate whether virus leakage could contribute to the observed outcomes in Brazil. We collected the specimens in three areas of Rio de Janeiro with distinct frequencies of mosquitoes with wMel strain and two areas with wild Ae. aegypti. The mosquitoes were orally exposed to two titers of DENV-1 and the saliva of DENV-1-infected Ae. aegypti was microinjected into wMel-free mosquitoes to check their infectivity. When infected with the high DENV-1 titer, the presence of wMel did not avoid viral infection in mosquitoes' bodies and saliva but DENV-1-infected wMel mosquitoes produced lower viral loads than wMel-free mosquitoes. On the other hand, wMel mosquitoes infected with the low DENV-1 titer were less susceptible to virus infection than wMel-free mosquitoes, although once infected, wMel and wMel-free mosquitoes exhibited similar viral loads in the body and the saliva. Our results showed viral leakage in 60% of the saliva of wMel mosquitoes with Brazilian background; thus, sustained surveillance is imperative to monitor the presence of other circulating DENV-1 strains capable of overcoming the Wolbachia blocking phenotype, enabling timely implementation of action plans.

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.

Chemical Ecology and Management of Dengue Vectors

Dengue, caused by the dengue virus, is the most widespread arboviral infectious disease of public health significance globally. This review explores the communicative function of olfactory cues that mediate host-seeking, egg-laying, plant-feeding, and mating behaviors in Aedes aegypti and Aedes albopictus, two mosquito vectors that drive dengue virus transmission. Aedes aegypti has adapted to live in close association with humans, preferentially feeding on them and laying eggs in human-fabricated water containers and natural habitats. In contrast, Ae. albopictus is considered opportunistic in its feeding habits and tends to inhabit more vegetative areas. Additionally, the ability of both mosquito species to locate suitable host plants for sugars and find mates for reproduction contributes to their survival. Advances in chemical ecology, functional genomics, and behavioral analyses have improved our understanding of the underlying neural mechanisms and reveal novel and specific olfactory semiochemicals that these species use to locate and discriminate among resources in their environment. Physiological status; learning; and host- and habitat-associated factors, including microbial infection and abundance, shape olfactory responses of these vectors. Some of these semiochemicals can be integrated into the toolbox for dengue surveillance and control.

Challenges and epidemiological implications of the first outbreak of dengue and chikungunya in Sudan

Background

Dengue and chikungunya are mosquito-borne infections that are spreading rapidly worldwide. The highest burden lies in tropical and subtropical countries. In 2022 Sudan encountered the most widespread infection of both diseases.

Aim

To describe the magnitude of the first outbreak of dengue and chikungunya infections in Tandalti Town, White Nile State, southern part of Sudan.

Methods

Following the report of a high number of undifferentiated febrile illnesses in 32 health clinics in Tandalti Town, an area with high densities of Aedes aegypti, we collected blood samples from symptomatic suspected cases. The samples were tested for major arboviral infections using arboviral-specific enzyme-linked immunosorbent assays (IgM capture ELISA), and serologically positive samples were confirmed using commercially available Real Time RT-PCR Kits.

Results

Out of 773 suspected cases, 63 (8.15%) were confirmed. Eleven (17.46%) of the confirmed cases were DENV, 49 (77.77%) were CHIKV, and 3 (4.76%) were DENV and CHIKV co-infections. The outbreak started at the beginning of October and ended by mid December 2022. Both dengue and chikungunya infection was higher (41(65.08%)) among young females than males (22 (34.92%)).

Conclusions

White Nile State may experience larger outbreaks of dengue and chikungunya in the future, there is, therefore, an urgent need for proper vector control interventions in the state and nearby states.

Enabling countries to manage outbreaks: statistical, operational, and contextual analysis of the early warning and response system (EWARS-csd) for dengue outbreaks

Introduction

Dengue is currently the fastest-spreading mosquito-borne viral illness in the world, with over half of the world's population living in areas at risk of dengue. As dengue continues to spread and become more of a health burden, it is essential to have tools that can predict when and where outbreaks might occur to better prepare vector control operations and communities' responses. One such predictive tool, the Early Warning and Response System for climate-sensitive diseases (EWARS-csd), primarily uses climatic data to alert health systems of outbreaks weeks before they occur. EWARS-csd uses the robust Distribution Lag Non-linear Model in combination with the INLA Bayesian regression framework to predict outbreaks, utilizing historical data. This study seeks to validate the tool's performance in two states of Colombia, evaluating how well the tool performed in 11 municipalities of varying dengue endemicity levels.

Methods

The validation study used retrospective data with alarm indicators (mean temperature and rain sum) and an outbreak indicator (weekly hospitalizations) from 11 municipalities spanning two states in Colombia from 2015 to 2020. Calibrations of different variables were performed to find the optimal sensitivity and positive predictive value for each municipality.

Results

The study demonstrated that the tool produced overall reliable early outbreak alarms. The median of the most optimal calibration for each municipality was very high: sensitivity (97%), specificity (94%), positive predictive value (75%), and negative predictive value (99%; 95% CI).

Discussion

The tool worked well across all population sizes and all endemicity levels but had slightly poorer results in the highly endemic municipality at predicting non-outbreak weeks. Migration and/or socioeconomic status are factors that might impact predictive performance and should be further evaluated. Overall EWARS-csd performed very well, providing evidence that it should continue to be implemented in Colombia and other countries for outbreak prediction.

Harnessing Pentameric Scaffold of Cholera Toxin B (CTB) for Design of Subvirion Recombinant Dengue Virus Vaccine

Dengue virus is an enveloped virus with an icosahedral assembly of envelope proteins (E). The E proteins are arranged as a head-to-tail homodimer, and domain III (EDIII) is placed at the edge of the dimer, converging to a pentamer interface. For a structure-based approach, cholera toxin B (CTB) was harnessed as a structural scaffold for the five-fold symmetry of EDIII. Pivoted by an RNA-mediated chaperone for the protein folding and assembly, CTB-EDIII of dengue serotype 1 (DV1) was successfully produced as soluble pentamers in an E. coli host with a high yield of about 28 mg/L. Immunization of mice with CTB-DV1EDIII elicited increased levels of neutralizing antibodies against infectious viruses compared to the control group immunized with DV1EDIII without CTB fusion. IgG isotype switching into a balanced Th1/Th2 response was also observed, probably triggered by the intrinsic adjuvant activity of CTB. Confirming the immune-enhancing potential of CTB in stabilizing the pentamer assembly of EDIII, this study introduces a low-cost bacterial production platform designed to augment the soluble production of subunit vaccine candidates, particularly those targeting flaviviruses.

Seroprevalence of dengue and chikungunya viruses among urban refugees in Klang Valley, Malaysia

BACKGROUND

Mosquito-borne diseases pose a significant global public health threat, with Malaysia's Klang Valley experiencing numerous outbreaks in densely populated urban areas.

METHODS

This study aimed to estimate the seroprevalence of anti-dengue and anti-chikungunya antibodies among urban refugees in the Klang Valley, Malaysia, and identify associated risk factors.

RESULTS

High seroprevalence of anti-dengue immunoglobulin G (IgG) and IgM (60.0% [confidence interval {CI} 55.39 to 64.48] and 9.2% [CI 6.77 to 12.25], respectively) were observed among refugees >18 years of age (χ22=11.720, p=0.003), Kachin ethnicity (χ28=72.253, p<0.001), without formal education (χ21=3.856, p=0.050), homes near waste disposal sites (χ21=10.378, p=0.001) and refugees who have experienced flooding (χ21=5.460, p=0.019). Meanwhile, the overall seroprevalence of anti-chikungunya IgG and IgM was 9.7% (CI 7.15 to 12.73) and 10.8% (CI 8.09 to 13.93), respectively, with ages 12-18 years (χ22=6.075, p=0.048), Rohingya ethnicity (χ28=31.631, p<0.001) and homes close to waste disposal sites (χ21=3.912, p=0.048) being significant risk factors. Results showed a link to poor environmental living conditions, with an increase in the vector population with higher availability of breeding sites and thus exposure to dengue and chikungunya virus.

CONCLUSIONS

Health education among the community is the key to disease prevention, as there are no specific antiviral drugs for treatment and limited vaccine availability.

Development of Vaccines against Emerging Mosquito-Vectored Arbovirus Infections

Among emergent climate-sensitive infectious diseases, some mosquito-vectored arbovirus infections have epidemiological, social, and economic effects. Dengue virus (DENV), West Nile virus (WNV), and Chikungunya virus (CHIKV) disease, previously common only in the tropics, currently pose a major risk to global health and are expected to expand dramatically in the near future if adequate containment measures are not implemented. The lack of safe and effective vaccines is critical as it seems likely that emerging mosquito-vectored arbovirus infections will be con-trolled only when effective and safe vaccines against each of these infections become available. This paper discusses the clinical characteristics of DENV, WNV, and CHIKV infections and the state of development of vaccines against these viruses. An ideal vaccine should be able to evoke with a single administration a prompt activation of B and T cells, adequate concentrations of protecting/neutralizing antibodies, and the creation of a strong immune memory capable of triggering an effective secondary antibody response after new infection with a wild-type and/or mutated infectious agent. Moreover, the vaccine should be well tolerated, safe, easily administrated, cost-effective, and widely available throughout the world. However, the development of vaccines against emerging mosquito-vectored arbovirus diseases is far from being satisfactory, and it seems likely that it will take many years before effective and safe vaccines for all these infections are made available worldwide.

Innovations in dengue virus detection: An overview of conventional and electrochemical biosensor approaches

Globally, people are in great threat due to the highly spreading of viral infectious diseases. Every year like 100-300 million cases of infections are found, and among them, above 80% are not recognized and irrelevant. Dengue virus (DENV) is an arbovirus infection that currently infects people most frequently. DENV encompasses four viral serotypes, and they each express comparable sign. From a mild febrile sickness to a potentially fatal dengue hemorrhagic fever, dengue can induce a variety of symptoms. Presently, the globe is being challenged by the untimely identification of dengue infection. Therefore, this review summarizes advances in the detection of dengue from conventional methods (nucleic acid-based, polymerase chain reaction-based, and serological approaches) to novel biosensors. This work illustrates an extensive study of the current designs and fabrication approaches involved in the formation of electrochemical biosensors for untimely identifications of dengue. Additionally, in electrochemical sensing of DENV, we skimmed through significances of biorecognition molecules like lectins, nucleic acid, and antibodies. The introduction of emerging techniques such as the CRISPR/Cas' system and their integration with biosensing platforms has also been summarized. Furthermore, the review revealed the importance of electrochemical approach compared with traditional diagnostic methods.

Alarming Trends in Dengue Incidence and Mortality in Bangladesh

Bangladesh is currently experiencing the country's largest and deadliest dengue outbreak on record. This year's outbreak has been characterized by an early seasonal surge in cases, rapid geographic spread, and a high fatality rate. The alarming trends in dengue incidence and mortality this year is an urgent wake-up call for public health policymakers and researchers to pay closer attention to dengue dynamics in South Asia, to strengthen the surveillance system and diagnostic capabilities, and to develop tools and methods for guiding strategic resource allocation and control efforts.