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The Aedes aegypti mosquito is the primary vector of arboviruses such as dengue (DENV), Zika (ZIKV), chikungunya (CHIKV), and yellow fever. This mosquito species is common in urbanized areas in [...]

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. [ABSTRACT FROM AUTHOR]

Abstract Background The survival of adult female Aedes mosquitoes is a critical component of their ability to transmit pathogens such as dengue viruses. One of the principal determinants of Aedes survival is temperature, which has been associated with seasonal changes in Aedes populations and limits their geographical distribution. The effects of temperature and other sources of mortality have been studied in the field, often via mark-release-recapture experiments, and under controlled conditions in the laboratory. Survival results differ and reconciling predictions between the two settings has been hindered by variable measurements from different experimental protocols, lack of precision in measuring survival of free-ranging mosquitoes, and uncertainty about the role of age-dependent mortality in the field. Methods Here we apply generalised additive models to data from 351 published adult Ae. aegypti and Ae. albopictus survival experiments in the laboratory to create survival models for each species across their range of viable temperatures. These models are then adjusted to estimate survival at different temperatures in the field using data from 59 Ae. aegypti and Ae. albopictus field survivorship experiments. The uncertainty at each stage of the modelling process is propagated through to provide confidence intervals around our predictions. Results Our results indicate that adult Ae. albopictus has higher survival than Ae. aegypti in the laboratory and field, however, Ae. aegypti can tolerate a wider range of temperatures. A full breakdown of survival by age and temperature is given for both species. The differences between laboratory and field models also give insight into the relative contributions to mortality from temperature, other environmental factors, and senescence and over what ranges these factors can be important. Conclusions Our results support the importance of producing site-specific mosquito survival estimates. By including fluctuating temperature regimes, our models provide insight into seasonal patterns of Ae. aegypti and Ae. albopictus population dynamics that may be relevant to seasonal changes in dengue virus transmission. Our models can be integrated with Aedes and dengue modelling efforts to guide and evaluate vector control, better map the distribution of disease and produce early warning systems for dengue epidemics.

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. [ABSTRACT FROM AUTHOR]

Background: The mosquito microbiota impacts different parameters in host biology, such as development, metabolism, immune response and vector competence to pathogens. As the environment is an important source of acquisition of host associate microbes, we described the microbiota and the vector competence to Zika virus (ZIKV) of Aedes albopictus from three areas with distinct landscapes. Methods: Adult females were collected during two different seasons, while eggs were used to rear F1 colonies. Midgut bacterial communities were described in field and F1 mosquitoes as well as in insects from a laboratory colony (>30 generations, LAB) using 16S rRNA gene sequencing. F1 mosquitoes were infected with ZIKV to determine virus infection rates (IRs) and dissemination rates (DRs). Collection season significantly affected the bacterial microbiota diversity and composition, e.g., diversity levels decreased from the wet to the dry season. Field-collected and LAB mosquitoes' microbiota had similar diversity levels, which were higher compared to F1 mosquitoes. However, the gut microbiota composition of field mosquitoes was distinct from that of laboratory-reared mosquitoes (LAB and F1), regardless of the collection season and location. A possible negative correlation was detected between Acetobacteraceae and Wolbachia, with the former dominating the gut microbiota of F1 Ae. albopictus, while the latter was absent/undetectable. Furthermore, we detected significant differences in infection and dissemination rates (but not in the viral load) between the mosquito populations, but it does not seem to be related to gut microbiota composition, as it was similar between F1 mosquitoes regardless of their population. Conclusions: Our results indicate that the environment and the collection season play a significant role in shaping mosquitoes' bacterial microbiota. [ABSTRACT FROM AUTHOR]

Problem In 2010, dengue virus (DENV) serotype-4 was detected during a dengue outbreak in the Amazonian city of Boa Vista. At that time Brazil was already endemic for DENV-1, DENV-2 and DENV-3.This was the first time DENV-4 was observed in the country after it was initially detected and eliminated in 1981. Approach To hinder the spread of DENV-4 throughout Brazil, standard vector control measures were intensified. Vector control professionals visited 56 837 households in 22 out of 31 districts of Boa Vista, to eliminate mosquito-breeding sites. Water storage containers were treated with the larvicide diflubenzuron, and deltamethrin was sprayed for adult Aedes aegypti mosquitoes. Fifteen days later, a second larvae survey and additional deltamethrin applications were performed. Local setting In Brazil, dengue vector control is managed at all three government levels. Regular surveillance of Aedes aegypti is done four to six times a year to strengthen mosquito control activities in areas with high-vector density. Educational dengue control campaigns In communities are scarce, especially between outbreaks. Relevant changes In spite of extensive implementation of all standard control actions recommended by the Brazilian dengue control programme, only a slight decrease in mosquito density was detected. Lessons learnt There Is a need to redesign all levels of dengue control. Public consultation and engagement, behaviour change and actions that go beyond technical Impositions are required. Vector control programme managers need to reflect on what constitutes good practices and whether intermittent information campaigns are effective measures for dengue prevention and control. [TEXT NOT REPRODUCIBLE IN ASCII] [TEXT NOT REPRODUCIBLE IN ASCII] Probleme En 2010, le serotype-4 du virus de la dengue (DENV) a ete detecte pendant une epidemie de dengue dans la ville amazonienne de Boa Vista. A l'epoque, le Bresil etait deja endemique pour les serotypes DENV-1, DENV-2 et DENV-3. C'etait la premiere fois que le serotype DENV-4 etait observe dans le pays apres avoir ete initialement detecte et elimine en 1981. Approche Pour empecher la propagation de DENV-4 dans tout le Bresil, les mesures standard de lutte antivectorielle ont ete intensifiees. Des professionnels de la lutte antivectorielle ont rendu visite a 56837 menages dans 22 des 31 districts de Boa Vista pour eliminer les sites de reproduction des moustiques. Les reservoirs d'eau ont ete traites avec le larvicide diflubenzuron, et de la deltamethrine a ete pulverisee pour eliminer les moustiques adultes Aedes aegypti. Quinze jours plus tard, une deuxieme evaluation des larves et des applications supplementaires de deltamethrine ont ete effectuees. Environnement local Au Bresil, la lutte antivectorielle de la dengue est geree aux trois niveaux gouvernementaux. La surveillance reguliere des moustiques Aedes aegypti est effectuee4 a 6 fois paran pour renforcer les activites de lutte contre les moustiques dans les zones a densite elevee de vecteurs. Les campagnes d'information pour I utter contre la dengue dans les communautes sont rares, en particulier entre les epidemies. Changements significatifs Malgre la mise en ceuvre etendue de toutes les actions standard de lutte recommandees par le programme bresilien de lutte contre la dengue, seule une legere diminution de la densite des moustiques a ete detectee. Lecons tirees II est necessaire de redessiner tous les niveaux de la lutte contre la dengue. La consultation et l'engagement du public, le changement de comportement et des actions qui vont au-dela des impositions techniques sont requis. Les directeurs des programmes de lutte antivectorielle doivent reflechir sur ce qui constitue de bonnes pratiques et evaluer si les campagnes intermittentes d'information sont des mesures efficaces pour la prevention et la lutte contre la dengue. [TEXT NOT REPRODUCIBLE IN ASCII] Situacion En el ano 2010 se detecto el serotlpo 4 del virus del dengue (DENV) durante un brote de dengue en la ciudad amazonica de Boa Vista. En aquel momento, en Brasil ya eran endemicos los serotlpos DENV-1, DENV-2 y DENV-3.Tras su deteccion inicial y eliminacion en 1981, esta fue la primera vez que se volvia a observar el DENV-4 en el pais. Enfoque Con objeto de impedir la propagacion del DENV-4 por todo Brasil, se intensificaron las medidas de control vectorial estandar. Profesionales del control vectorial visitaron 56 837 hogares en 22 de los 31 distritos de Boa Vista para eliminar los criaderos de mosquitos. Los recipientes de almacenamiento de agua se trataron con el larvicida diflubenzuron, y se rocio deltametrina contra los mosquitos adultos Aedes aegypti. Quince dias mas tarde se llevo a cabo una segunda encuesta de larvas y se realizaron aplicaciones adicionales de deltametrina. Marco regional En Brasil, el control vectorial del dengue se gestiona en los tres niveles gubernamentales. El control regular de Aedes aegypti se realiza de cuatro a seis veces al ano para reforzar las actividades de control de los mosquitos en areas con una densidad vectorial elevada. Las campanas educativas en las comunidades sobre el control del dengue son escasas, especialmente entre los brotes. Cambios importantes A pesar de la amplia aplicacion de todas las acciones de control estandar recomendadas por el programa de control del dengue brasileno, unicamente se detecto una disminucion leve en la densidad de mosquitos. Lecciones aprendidas Hay una necesidad de redisenar todos los niveles de control del dengue. Son necesarios una consulta y compromiso publicos, un cambio en el comportamiento y acciones que vayan mas alla de las Imposiciones tecnicas. Los directores de los programas de control vectorial deben reflexionar sobre que constituye las buenas practicas y si las campanas de Informacion Intermitentes son medidas eficaces para controlar y prevenir el dengue., Introduction Dengue is currently the arbovirus affecting the highest number of people worldwide. The World Health Organization (WHO) estimates that 50-100 million dengue infections occur annually, and that about 2.5 [...]

Currently, DENV transmitted primarily by Aedes aegypti affects approximately one in three people annually. The spatio-temporal heterogeneity of vector infestation and the intensity of arbovirus transmission require surveillance capable of predicting an outbreak. In this work, we used data from 4 years of reported dengue cases and entomological indicators of adult Aedes collected from approximately 3500 traps installed in the city of Foz do Iguaçu, Brazil, to evaluate the spatial and temporal association between vector infestation and the occurrence of dengue cases. Entomological (TPI, ADI and MII) and entomo-virological (EVI) indexes were generated with the goal to provide local health managers with a transmission risk stratification that allows targeting areas for vector control activities. We observed a dynamic pattern in the evaluation; however, it was a low spatio-temporal correlation of Ae. aegypti and incidence of dengue. Independent temporal and spatial effects capture a significant portion of the signal given by human arbovirus cases. The entomo-virological index (EVI) significantly signaled risk in a few areas, whereas entomological indexes were not effective in providing dengue risk alert. Investigating the variation of biotic and abiotic factors between areas with and without correlation should provide more information about the local epidemiology of dengue. [ABSTRACT FROM AUTHOR]

The transmission of dengue (DENV) and Zika (ZIKV) has been continuously increasing worldwide. An efficient arbovirus surveillance system is critical to designing early-warning systems to increase preparedness of future outbreaks in endemic countries. The Near Infrared Spectroscopy (NIRS) is a promising high throughput technique to detect arbovirus infection in Ae. aegypti with remarkable advantages such as cost and time effectiveness, reagent-free, and non-invasive nature over existing molecular tools for similar purposes, enabling timely decision making through rapid detection of potential disease. Our aim was to determine whether NIRS can differentiate Ae. aegypti females infected with either ZIKV or DENV single infection, and those coinfected with ZIKV/DENV from uninfected ones. Using 200 Ae. aegypti females reared and infected in laboratory conditions, the training model differentiated mosquitoes into the four treatments with 100% accuracy. DENV-, ZIKV-, and ZIKV/DENV-coinfected mosquitoes that were used to validate the model could be correctly classified into their actual infection group with a predictive accuracy of 100%, 84%, and 80%, respectively. When compared with mosquitoes from the uninfected group, the three infected groups were predicted as belonging to the infected group with 100%, 97%, and 100% accuracy for DENV-infected, ZIKV-infected, and the co-infected group, respectively. Preliminary lab-based results are encouraging and indicate that NIRS should be tested in field settings to evaluate its potential role to monitor natural infection in field-caught mosquitoes. [ABSTRACT FROM AUTHOR]