High-resolution mapping of urban Aedes aegypti immature abundance through breeding site detection based on satellite and street view imagery.

Identification of Aedes aegypti breeding hotspots is essential for the implementation of targeted vector control strategies and thus the prevention of several mosquito-borne diseases worldwide. Training computer vision models on satellite and street view imagery in the municipality of Rio de Janeiro, we analyzed the correlation between the density of common breeding grounds and Aedes aegypti infestation measured by ovitraps on a monthly basis between 2019 and 2022. Our findings emphasized the significance (p ≤ 0.05) of micro-habitat proxies generated through object detection, allowing to explain high spatial variance in urban abundance of Aedes aegypti immatures. Water tanks, non-mounted car tires, plastic bags, potted plants, and storm drains positively correlated with Aedes aegypti egg and larva counts considering a 1000 m mosquito flight range buffer around 2700 ovitrap locations, while dumpsters, small trash bins, and large trash bins exhibited a negative association. This complementary application of satellite and street view imagery opens the pathway for high-resolution interpolation of entomological surveillance data and has the potential to optimize vector control strategies. Consequently it supports the mitigation of emerging infectious diseases transmitted by Aedes aegypti, such as dengue, chikungunya, and Zika, which cause thousands of deaths each year.

Comparison of Aedes aegypti arbovirus transmission thresholds in two communities with differing water supply infrastructure.

BACKGROUND: To assess whether the 'economic boom' in the tropical seaport city of Barranquilla improved tapped water supplies to socio-economically poor neighbourhoods resulting in: (1) their reduced use for domestic water-storage in large (> 1,000-litre) custom-made cement tanks which are their principal Aedes aegypti breeding sites and (2) their pupae/person index (PPI) values to below their established 0.5-1.5 PPI arbovirus transmission-threshold value, compared to matched neighbourhoods in the: (a) pre-economic boom (2004) period in Barranquilla and (b) economically-neglected seaport city of Buenaventura. METHODS: The simple, accurate and robust water surface sweep-net/calibration factor or total count methods were used to determine the total Ae. aegypti pupae numbers in greater or less than 20-litre water-holding container types located 'inside' or 'outside' these neighbourhood premises. The women residents also participated in questionnaire-based responses about their domestic water supplies, water-storage and maintenance and mosquito life stages and disease transmission knowledge, to subsequently plan appropriate resident education programmes. Microsoft Excel 8.0 with OpenEpi was used to determine the samples sizes and the statistical values. RESULTS: Tapped water supplies to the three poor Barranquilla neighbourhoods were dramatically increased from 2004 to 2023 resulting in their residents significantly reducing their: (a) large cement water-storage tanks from 1 per 6.9 (2004) to 1 per 31.2 (2020) premises (z = 10.5: p = 0) and (b) PPI values to 0.16, 0.19 and 0.53 (mean: 0.29: 95% CI ± 0.4) in each study neighbourhood. In contrast, tapped water supplies remained inadequate in the Buenaventura neighborhoods, thereby resulting in their continued use of many large (> 1,000-litre) water-storage containers (Barranquilla: 1 per 31.2 and Buenaventura: 1 per 1.5 premises: z = - 9.26: p = 0), with unacceptably high 0.81, 0.88 and 0.99 PPI values in each study neighbourhood (mean 0.89: 95% CI ± 0.12). CONCLUSIONS: Improved tapped water supplies resulted in reduced numbers of large custom-made stoneware water-containers, as are employed by poor residents throughout the world, as well as their Ae. aegypti PPI transmission threshold values which, together with appropriate residents' education programmes, are also urgently to reduce to prevent/reduce Ae. aegypti transmitted human diseases globally.

Effectiveness of mass trapping interventions using autocidal gravid ovitraps (AGO) for the control of the dengue vector, Aedes (Stegomyia) aegypti, in Northern Mexico.

BACKGROUND: Mosquito-borne diseases, such as malaria, dengue, Zika and chikungunya, pose significant public health threats in tropical and subtropical regions worldwide. To mitigate the impact of these diseases on human health, effective vector surveillance and control strategies are necessary. Traditional vector control methods, which rely on chemical agents such as insecticides and larvicides, face challenges such as resistance and environmental concerns. Consequently, there has been a push to explore novel surveillance and control tools. Mass trapping interventions have emerged as a promising and environmentally friendly approach to reducing the burden of mosquito-borne diseases. This study assessed mass-trapping interventions using autocidal gravid ovitraps (AGOs) on Aedes aegypti populations in Reynosa, Tamaulipas, Mexico. METHODS: Four neighborhoods were selected to evaluate the effects of three treatments: AGO mass-trapping, integrated vector control (IVC), which included source reduction and the application of chemical larvicide and adulticide, and AGO + IVC on Ae. aegypti populations. A control area with no interventions was also included. The effectiveness of the interventions was evaluated by comparing Ae. aegypti abundance between the pre-treatment period (9 weeks) and the post-treatment period (11 weeks) for each treatment. RESULTS: Only treatment using AGO mass trapping with an 84% coverage significantly reduced Ae. aegypti female populations by 47%, from 3.75 ± 0.32 to 1.96 ± 0.15 females/trap/week. As expected, the abundance of Ae. aegypti in the control area did not differ from the pre- and post-treatment period (range of 4.97 ± 0.59 to 5.78 ± 0.53); Ae. aegypti abundance in the IVC treatment was 3.47 ± 0.30 before and 4.13 ± 0.35 after, which was not significantly different. However, Ae. aegypti abundance in the AGO + IVC treatment increased from 1.43 ± 0.21 before to 2.11 ± 0.20 after interventions; this increase may be explained in part by the low AGO (56%) coverage. CONCLUSIONS: This is the first report to our knowledge on the effectiveness of mass-trapping interventions with AGOs in Mexico, establishing AGOs as a potential tool for controlling Ae. aegypti in Northeastern Mexico when deployed with sufficient coverage.

RNA-seq validation: software for selection of reference and variable candidate genes for RT-qPCR.

BACKGROUND: Real-time quantitative PCR (RT-qPCR) is one of the most widely used gene expression analyses for validating RNA-seq data. This technique requires reference genes that are stable and highly expressed, at least across the different biological conditions present in the transcriptome. Reference and variable candidate gene selection is often neglected, leading to misinterpretation of the results. RESULTS: We developed a software named "Gene Selector for Validation" (GSV), which identifies the best reference and variable candidate genes for validation within a quantitative transcriptome. This tool also filters the candidate genes concerning the RT-qPCR assay detection limit. GSV was compared with other software using synthetic datasets and performed better, removing stable low-expression genes from the reference candidate list and creating the variable-expression validation list. GSV software was used on a real case, an Aedes aegypti transcriptome. The top GSV reference candidate genes were selected for RT-qPCR analysis, confirming that eiF1A and eiF3j were the most stable genes tested. The tool also confirmed that traditional mosquito reference genes were less stable in the analyzed samples, highlighting the possibility of inappropriate choices. A meta-transcriptome dataset with more than ninety thousand genes was also processed successfully. CONCLUSION: The GSV tool is a time and cost-effective tool that can be used to select reference and validation candidate genes from the biological conditions present in transcriptomic data.

Severity of papular urticaria in children is associated with specific IgG4 anti-salivary gland antigens from Aedes aegypti.

Summary: Background. Papular Urticaria (PU) is a cutaneous hypersensitivity disorder triggered by hematophagous arthropod bites. Despite being a common condition, especially in tropical environments, many knowledge gaps are observed for this disease. The main objective of this study was to investigate the patterns of humoral immune response to mosquito antigens in children with PU and establish a correlation between this response and the severity of clinical symptoms. Methods. An analytical cross-sectional observational study was carried out. Clinical and sociodemographic data and children's blood samples were collected to measure the specific antibodies from: 1. A. aegypti salivary gland antigens; 2. A. aegypti whole body antigens (both produced in the laboratory of the Center for Health Sciences at the Federal University of Rio de Janeiro). A PU severity score based on clinical data is proposed to correlate disease severity with antibody reactivity signatures. Results. According to the clinical data, 58.9% of children received high severity scores. A significant statistical correlation was found between patients with high PU severity score and the development of symptoms before the age of two (p = 0.0326) and high IgG4 anti-salivary gland antigens concentration (p less than 0.05). Conclusion. It is suggested that PU severity in children is associated with a high concentration of IgG4 anti-salivary gland antigens from Aedes aegypti. Further studies are recommended to deepen the understanding of the mechanisms involved.

Exploring fine-scale urban landscapes using satellite data to predict the distribution of Aedes mosquito breeding sites.

BACKGROUND: The spread of mosquito-transmitted diseases such as dengue is a major public health issue worldwide. The Aedes aegypti mosquito, a primary vector for dengue, thrives in urban environments and breeds mainly in artificial or natural water containers. While the relationship between urban landscapes and potential breeding sites remains poorly understood, such a knowledge could help mitigate the risks associated with these diseases. This study aimed to analyze the relationships between urban landscape characteristics and potential breeding site abundance and type in cities of French Guiana (South America), and to evaluate the potential of such variables to be used in predictive models. METHODS: We use Multifactorial Analysis to explore the relationship between urban landscape characteristics derived from very high resolution satellite imagery, and potential breeding sites recorded from in-situ surveys. We then applied Random Forest models with different sets of urban variables to predict the number of potential breeding sites where entomological data are not available. RESULTS: Landscape analyses applied to satellite images showed that urban types can be clearly identified using texture indices. The Multiple Factor Analysis helped identify variables related to the distribution of potential breeding sites, such as buildings class area, landscape shape index, building number, and the first component of texture indices. Models predicting the number of potential breeding sites using the entire dataset provided an R² of 0.90, possibly influenced by overfitting, but allowing the prediction over all the study sites. Predictions of potential breeding sites varied highly depending on their type, with better results on breeding sites types commonly found in urban landscapes, such as containers of less than 200 L, large volumes and barrels. The study also outlined the limitation offered by the entomological data, whose sampling was not specifically designed for this study. Model outputs could be used as input to a mosquito dynamics model when no accurate field data are available. CONCLUSION: This study offers a first use of routinely collected data on potential breeding sites in a research study. It highlights the potential benefits of including satellite-based characterizations of the urban environment to improve vector control strategies.

Dengue Virus Serotype 1 Effects on Mosquito Survival Differ among Geographically Distinct Aedes aegypti Populations.

The mosquito Aedes aegypti is distributed worldwide and is recognized as the primary vector for dengue in numerous countries. To investigate whether the fitness cost of a single DENV-1 isolate varies among populations, we selected four Ae. aegypti populations from distinct localities: Australia (AUS), Brazil (BRA), Pakistan (PAK), and Peru (PER). Utilizing simple methodologies, we concurrently assessed survival rates and fecundity. Overall, DENV-1 infection led to a significant decrease in mosquito survival rates, with the exception of the PER population. Furthermore, infected Ae. aegypti from PAK, the population with the lowest infection rate among those tested, exhibited a noteworthy reduction in egg laying. These findings collectively suggest that local mosquito-virus adaptations may influence dengue transmission in endemic settings.

Spatial and temporal analysis on the impact of ultra-low volume indoor insecticide spraying on Aedes aegypti household density.

BACKGROUND: Aedes aegypti is the primary mosquito vector for several arboviruses, such as dengue, chikungunya and Zika viruses, which cause frequent outbreaks of human disease in tropical and subtropical regions. Control of these outbreaks relies on vector control, commonly in the form of insecticide sprays that target adult female mosquitoes. However, the spatial coverage and frequency of sprays needed to optimize effectiveness are unclear. In this study, we characterize the effect of ultra-low-volume (ULV) indoor spraying of pyrethroid insecticides on Ae. aegypti abundance within households. We also evaluate the effects of spray events during recent time periods or in neighboring households. Improved understanding of the duration and distance of the impact of a spray intervention on Ae. aegypti populations can inform vector control interventions, in addition to modeling efforts that contrast vector control strategies. METHODS: This project analyzes data from two large-scale experiments that involved six cycles of indoor pyrethroid spray applications in 2 years in the Amazonian city of Iquitos, Peru. We developed spatial multi-level models to disentangle the reduction in Ae. aegypti abundance that resulted from (i) recent ULV treatment within households and (ii) ULV treatment of adjacent or nearby households. We compared fits of models across a range of candidate weighting schemes for the spray effect, based on different temporal and spatial decay functions to understand lagged ULV effects. RESULTS: Our results suggested that the reduction of Ae. aegypti in a household was mainly due to spray events occurring within the same household, with no additional effect of sprays that occurred in neighboring households. Effectiveness of a spray intervention should be measured based on time since the most recent spray event, as we found no cumulative effect of sequential sprays. Based on our model, we estimated the spray effect is reduced by 50% approximately 28 days after the spray event. CONCLUSIONS: The reduction of Ae. aegypti in a household was mainly determined by the number of days since the last spray intervention in that same household, highlighting the importance of spray coverage in high-risk areas with a spray frequency determined by local viral transmission dynamics.

Dengue, chikungunya y el mosquito vector en el límite Sur de distribución durante la epidemia 2023, Argentina / Dengue, chikungunya and the mosquito vector at the Southern limit of distribution during the 2023 epidemic, Argentina

Resumen Objetivos : Monitorear la actividad de oviposición del mosquito Aedes aegypti y de casos de dengue y chikun gunya en cuatro localidades de Argentina templada, durante la epidemia del 2023. Métodos : Durante el verano y otoño del 2023, se mo nitoreó semanalmente mediante ovitrampas la actividad de oviposición del mosquito vector, y se registró el arribo de casos con dengue o chikungunya a Tandil, Olavarría, Bahía Blanca y Laprida. Resultados : La variación mensual del porcentaje de trampas positivas fue similar en las tres primeras localidades; en Laprida no se detectó el mosquito. Por el contrario, se observó una diferencia significativa del porcentaje de trampas que alguna vez resultó positiva en cada localidad, siendo mayor en Olavarría (83%), que en Bahía Blanca (67%) y Tandil (49%). Respecto a las enfermedades, se registraron 18 casos importados de dengue y 3 de chikungunya. Además, se registró el primer caso autóctono de dengue en la región, siendo el más austral hasta el momento. Conclusión : Es imprescindible sensibilizar y capacitar a los integrantes de los sistemas de salud de las nue vas regiones expuestas al Ae. aegypti para la detección temprana de casos, y a la población en general para potenciar las acciones de prevención.

Abstract Objectives : To monitor the oviposition activity of the mosquito Aedes aegypti and of dengue and chikungunya cases in four localities of temperate Argentina, during the 2023 epidemic. Methods : During the summer and autumn of 2023, the oviposition activity of the mosquito vector was monitored weekly using ovitraps, and the arrival of cases with dengue or chikungunya in Tandil, Olavarría, Bahía Blanca and Laprida were registered. Results : Monthly variations of the percentage of positive traps were similar in the first three locations; in Laprida the mosquito was not detected. On the con trary, a significant difference was observed in the per centage of total traps that ever tested positive in each locality, being higher in Olavarría (83.3%) than in Bahía Blanca (68.6%) and Tandil (48.7%). Regarding diseases, 18 imported cases of dengue and 3 of chikungunya were registered. In addition, the first autochthonous case of dengue in the region was recorded, being the southern most until known. Conclusion : It is essential to raise awareness and train the members of the health systems of the new regions exposed to Ae. aegypti for early detection of cases, and to the general population to enhance pre vention actions.

Colonización del Aedes aegypti en la región Metropolitana de Cochabamba / Colonization of Aedes aegypti in the Metropolitan Region of Cochabamba / Colonização do Aedes aegypti na Região Metropolitana de Cochabamba

El Aedes aegypti transmite enfermedades graves como dengue, zika, chikungunya y fiebre amarilla, representando una amenaza para la salud pública. En Cochabamba, Bolivia, su proliferación es favorecida por el clima y la urbanización. Estudiar su colonización es crucial para desarrollar estrategias efectivas de control y prevención. Metodología: para revisar la colonización del Aedes aegypti en Cochabamba, se usaron bases de datos como Scielo, PubMed y Google Scholar. Se seleccionaron estudios relevantes con palabras clave como Aedes aegypti, Cochabamba y salud pública. Zotero se utilizó para organizar las referencias. Se llevó a cabo un análisis cualitativo y sistemático de los hallazgos. Desarrollo: el Aedes aegypti es un mosquito pequeño, identificado por sus marcas blancas en las patas y una marca en forma de lira en el tórax. Prefiere áreas urbanas con agua estancada para depositar sus huevos. Su ciclo de vida incluye etapas de huevo, larva, pupa y adulto, completándose en 8 a 10 días. La presencia del mosquito en Cochabamba ha sido documentada desde los años 80, con una expansión asociada a la densidad poblacional y la disponibilidad de hábitats adecuados. Estrategias de control incluyen campañas de educación pública, uso de insecticidas y vigilancia entomológica. Discusión: los estudios sobre la colonización del Aedes aegypti en Cochabamba muestran su adaptación a nuevas altitudes y áreas urbanas, influenciada por variaciones climáticas y urbanización desordenada. Factores como la escasez de agua y el almacenamiento inadecuado facilitan su proliferación. Se recomienda intensificar la educación pública y la participación comunitaria para eliminar criaderos.

Introduction: aedes aegypti transmits severe diseases such as dengue, Zika, chikungunya, and yellow fever, representing a significant public health threat. In Cochabamba, Bolivia, its proliferation is favored by the climate and urbanization. Studying its colonization is crucial for developing effective control and prevention strategies. Methodology: to review the colonization of Aedes aegypti in Cochabamba, databases such as Scielo, PubMed, and Google Scholar were used. Relevant studies were selected using keywords like Aedes aegypti, Cochabamba, and public health. Zotero was used to organize the references. A qualitative and systematic analysis of the findings was conducted. Development: Aedes aegypti is a small mosquito, identified by its white markings on the legs and a lyre-shaped marking on the thorax. It prefers urban areas with stagnant water to lay its eggs. Its life cycle includes the egg, larva, pupa, and adult stages, which it completes in 8 to 10 days. The presence of the mosquito in Cochabamba has been documented since the 1980s, with expansion associated with population density and the availability of suitable habitats. Control strategies include public education campaigns, insecticide use, and entomological surveillance. Discussion: studies on the colonization of Aedes aegypti in Cochabamba show its adaptation to new altitudes and urban areas, influenced by climate variations and unplanned urbanization. Factors such as water scarcity and inadequate storage facilitate its proliferation. It is recommended to intensify public education and community participation to eliminate breeding sites

Introdução: o Aedes aegypti transmite doenças graves como dengue, zika, chikungunya e febre-amarela, representando uma ameaça significativa à saúde pública. Em Cochabamba, Bolívia, sua proliferação é favorecida pelo clima e pela urbanização. Estudar sua colonização é crucial para desenvolver estratégias eficazes de controle e prevenção. Metodologia: para revisar a colonização do Aedes aegypti em Cochabamba, foram utilizadas bases de dados como Scielo, PubMed e Google Scholar. Estudos relevantes foram selecionados usando palavras-chave como Aedes aegypti, Cochabamba e saúde pública. O Zotero foi utilizado para organizar as referências. Foi realizada uma análise qualitativa e sistemática dos achados. Desenvolvimento: o Aedes aegypti é um mosquito pequeno, identificado por suas marcas brancas nas patas e uma marca em forma de lira no tórax. Prefere áreas urbanas com água estagnada para depositar seus ovos. Seu ciclo de vida inclui as fases de ovo, larva, pupa e adulto, completando-se em 8 a 10 dias. A presença do mosquito em Cochabamba é documentada desde a década de 1980, com uma expansão associada à densidade populacional e à disponibilidade de habitats adequados. As estratégias de controle incluem campanhas de educação pública, uso de inseticidas e vigilância entomológica. Discussão: os estudos sobre a colonização do Aedes aegypti em Cochabamba mostram sua adaptação a novas altitudes e áreas urbanas, influenciada por variações climáticas e urbanização desordenada. Fatores como a escassez de água e o armazenamento inadequado facilitam sua proliferação. Recomenda-se intensificar a educação pública e a participação comunitária para eliminar criadouros

Genomic Analysis of Aedes aegypti in the Northern Chihuahuan Desert of Texas and Mexico.

Background: Aedes aegypti, is the primary vector of dengue, Chikungunya, Zika, and yellow fever viruses. Both natural and human-impacted landscapes have selective pressures on Ae. aegypti, resulting in strong genomic structure even within close geographical distances. Materials and Methods: We assess the genetic structure of this medically important mosquito species at the northern leading edge of their distribution in Southwestern USA. Ae. aegypti were collected during 2017 in the urban communities of El Paso and Sparks, Texas (USA) and in the city of Ciudad Juárez, Mexico. Results: Thousands of nuclear loci were sequenced across 260 captured Ae. aegypti. First, we recovered the genetic structure of Ae. aegypti following geography, with all four major collection communities being genetically distinct. Importantly, we found population structure and genetic diversity that suggest rapid expansion through active-short distance dispersals, with Anapra being the likely source for the others. Next, tests of selection recovered eight functional genes across six outliers: calmodulin with olfactory receptor function; the protein superfamily C-type lectin with function in mosquito immune system and development; and TATA box binding protein with function in gene regulation. Conclusion: Despite these populations being documented in the early 2000s, we find that selective pressures on specific genes have already occurred and likely facilitate Ae. aegypti range expansion.

Genetic variability of Aedes aegypti (Diptera: Culicidae) in El Salvador and Honduras: presence of a widespread haplotype and implications for mosquito control.

BACKGROUND: This study examined population genetics of Aedes aegypti in El Salvador and Honduras, two adjacent countries in Central America. Aedes aegypti is associated with yellow fever, dengue, chikungunya, and Zika. Each year, thousands of cases of dengue are typically reported in El Salvador and Honduras. METHODS: In El Salvador, collections were obtained from five Departments. In Honduras, samples were obtained from six municipalities in four Departments. Mitochondrial DNA cytochrome oxidase I (COI) was sequenced, and consensus sequences were combined with available sequences from El Salvador to determine haplotype number, haplotype diversity, nucleotide diversity, and Tajima's D. A haplotype network was produced to examine the relationship between genotypes. RESULTS: In El Salvador, there were 17 haplotypes, while in Honduras there were 4 haplotypes. In both El Salvador and Honduras, Haplotype 1 is most abundant and widespread. In El Salvador, haplotype H2 was also widespread in 10 of 11 sampled municipalities, but it was not present in Honduras. The capital of El Salvador (San Salvador) and the eastern region of ES had the highest haplotype diversity of regions sampled. CONCLUSIONS: Haplotype 1 and H2 each belong to different phylogenetic lineages of Ae. aegypti. The most geographically widespread haplotype (H1) may have been present the longest and could be a remnant from previous eradication programs. These data may contribute to future control programs for Ae. aegypti in the two countries.

A numbers game: Mosquito-based arbovirus surveillance in two distinct geographic regions of Latin America.

Aedes mosquitoes, as vectors of medically important arthropod-borne viruses (arboviruses), constitute a major public health threat that requires entomological and epidemiological surveillance to guide vector control programs to prevent and reduce disease transmission. In this study, we present the collaborative effort of one year of mosquito-based arbovirus surveillance in two geographically distinct regions of Latin America (Nicaragua and Ecuador). Adult female mosquitoes were collected using backpack aspirators in over 2,800 randomly selected households (Nicaragua, Ecuador) and 100 key sites (Nicaragua) from eight distinct communities (Nicaragua: 2, Ecuador: 6). A total of 1,358 mosquito female pools were processed for RNA extraction and viral RNA detection using real-time RT-PCR. Ten positive dengue virus (DENV) pools were detected (3 in Nicaragua and 7 in Ecuador), all of which were found during the rainy season and matched the serotypes found in humans (Nicaragua: DENV-1 and DENV-4; Ecuador: DENV-2). Infection rates ranged from 1.13 to 23.13, with the Nicaraguan communities having the lowest infection rates. Our results demonstrate the feasibility of detecting DENV-infected Aedes mosquitoes in low-resource settings and underscore the need for targeted mosquito arbovirus sampling and testing, providing valuable insights for future surveillance programs in the Latin American region.

Comparing the long-term persistence of different Wolbachia strains after the release of bacteria-carrying mosquitoes.

This paper proposes a bidimensional modeling framework for Wolbachia invasion, assuming imperfect maternal transmission, incomplete cytoplasmic incompatibility, and direct infection loss due to thermal stress. Our model adapts to various Wolbachia strains and retains all properties of higher-dimensional models. The conditions for the durable coexistence of Wolbachia-carrying and wild mosquitoes are expressed using the model's parameters in a compact closed form. When the Wolbachia bacterium is locally established, the size of the remanent wild population can be assessed by a direct formula derived from the model. The model was tested for four Wolbachia strains undergoing laboratory and field trials to control mosquito-borne diseases: wMel, wMelPop, wAlbB, and wAu. As all these bacterial strains affect the individual fitness of mosquito hosts differently and exhibit different levels of resistance to temperature variations, the model helped to conclude that: (1) the wMel strain spreads faster in wild mosquito populations; (2) the wMelPop exhibits lower resilience but also guarantees the smallest size of the remanent wild population; (3) the wAlbB strain performs better at higher ambient temperatures than others; (4) the wAu strain is not sustainable and cannot persist in the wild mosquito population despite its resistance to high temperatures.

The High Capacity of Brazilian Aedes aegypti Populations to Transmit a Locally Circulating Lineage of Chikungunya Virus.

The incidence of chikungunya has dramatically surged worldwide in recent decades, imposing an expanding burden on public health. In recent years, South America, particularly Brazil, has experienced outbreaks that have ravaged populations following the rapid dissemination of the chikungunya virus (CHIKV), which was first detected in 2014. The primary vector for CHIKV transmission is the urban mosquito species Aedes aegypti, which is highly prevalent throughout Brazil. However, the impact of the locally circulating CHIKV genotypes and specific combinations of local mosquito populations on vector competence remains unexplored. Here, we experimentally analyzed and compared the infectivity and transmissibility of the CHIKV-ECSA lineage recently isolated in Brazil among four Ae. aegypti populations collected from different regions of the country. When exposed to CHIKV-infected AG129 mice for blood feeding, all the mosquito populations displayed high infection rates and dissemination efficiency. Furthermore, we observed that all the populations were highly efficient in transmitting CHIKV to a vertebrate host (naïve AG129 mice) as early as eight days post-infection. These results demonstrate the high capacity of Brazilian Ae. aegypti populations to transmit the locally circulating CHIKV-ECSA lineage. This observation could help to explain the high prevalence of the CHIKV-ECSA lineage over the Asian lineage, which was also detected in Brazil in 2014. However, further studies comparing both lineages are necessary to gain a better understanding of the vector's importance in the epidemiology of CHIKV in the Americas.

[Dengue, chikungunya and the mosquito vector at the Southern limit of distribution during the 2023 epidemic, Argentina]. / Dengue, chikungunya y el mosquito vector en el límite sur de distribución durante la epidemia 2023, Argentina.

OBJECTIVES: To monitor the oviposition activity of the mosquito Aedes aegypti and of dengue and chikungunya cases in four localities of temperate Argentina, during the 2023 epidemic. METHODS: During the summer and autumn of 2023, the oviposition activity of the mosquito vector was monitored weekly using ovitraps, and the arrival of cases with dengue or chikungunya in Tandil, Olavarría, Bahía Blanca and Laprida were registered. RESULTS: Monthly variations of the percentage of positive traps were similar in the first three locations; in Laprida the mosquito was not detected. On the contrary, a significant difference was observed in the percentage of total traps that ever tested positive in each locality, being higher in Olavarría (83.3%) than in Bahía Blanca (68.6%) and Tandil (48.7%). Regarding diseases, 18 imported cases of dengue and 3 of chikungunya were registered. In addition, the first autochthonous case of dengue in the region was recorded, being the southernmost until known. CONCLUSION: It is essential to raise awareness and train the members of the health systems of the new regions exposed to Ae. aegypti for early detection of cases, and to the general population to enhance prevention actions.

OBJETIVOS: Monitorear la actividad de oviposición del mosquito Aedes aegypti y de casos de dengue y chikungunya en cuatro localidades de Argentina templada, durante la epidemia del 2023. Métodos: Durante el verano y otoño del 2023, se monitoreó semanalmente mediante ovitrampas la actividad de oviposición del mosquito vector, y se registró el arribo de casos con dengue o chikungunya a Tandil, Olavarría, Bahía Blanca y Laprida. RESULTADOS: La variación mensual del porcentaje de trampas positivas fue similar en las tres primeras localidades; en Laprida no se detectó el mosquito. Por el contrario, se observó una diferencia significativa del porcentaje de trampas que alguna vez resultó positiva en cada localidad, siendo mayor en Olavarría (83%), que en Bahía Blanca (67%) y Tandil (49%). Respecto a las enfermedades, se registraron 18 casos importados de dengue y 3 de chikungunya. Además, se registró el primer caso autóctono de dengue en la región, siendo el más austral hasta el momento. Conclusión: Es imprescindible sensibilizar y capacitar a los integrantes de los sistemas de salud de las nuevas regiones expuestas al Ae. aegypti para la detección temprana de casos, y a la población en general para potenciar las acciones de prevención.

Increased threat of urban arboviral diseases from Aedes aegypti mosquitoes in Colombia.

Objectives: Our study targets the potential of the local urban mosquito Aedes aegypti to experimentally transmit chikungunya virus (CHIKV), dengue virus (DENV), yellow fever virus (YFV), and Zika virus (ZIKV). Methods: We collected eggs and adults of Ae. aegypti in Medellín, Colombia (from February to March 2020) for mosquito experimental infections with DENV, CHIKV, YFV and ZIKV and viral detection using the BioMark Dynamic arrays system. Results: We show that Ae. aegypti from Medellín was more prone to become infected, to disseminate and transmit CHIKV and ZIKV than DENV and YFV. Conclusions: Thus, in Colombia, chikungunya is the most serious threat to public health based on our vector competence data.

Development of an Enzyme-Linked Immunosorbent Assay (ELISA) as a tool to detect NS1 of dengue virus serotype 2 in female Aedes aegypti eggs for the surveillance of dengue fever transmission.

Dengue is a significant disease transmitted by Aedes mosquitoes in the tropics and subtropics worldwide. The disease is caused by four virus (DENV) serotypes and is transmitted to humans by female Aedes aegypti mosquito bites infected with the virus and vertically to their progeny. Current strategies to control dengue transmission focus on the vector. In this study, we describe an indirect Enzyme-Linked Immunosorbent Assay (ELISA), using a monoclonal antibody against the non-structural dengue virus protein 1 (NS1), to detect DENV2 in Ae. aegypti eggs. The assay detects NS1 in eggs homogenates with 87.5% sensitivity and 75.0% specificity and it is proposed as a tool for the routine entomovirological surveillance of DENV 2 in field mosquito populations.

Aedes aegypti Knockdown Resistance Mutations and Dengue Virus Infection in Haiti.

Haiti is home to approximately 11 million people and has a high incidence of vector-borne disease, including more than 70,000 cases of dengue per year. Vector control is difficult in Haiti and adulticide spray of malathion is the main method of control employed during the outbreak of disease although pyrethroids are used in both bed net campaigns and in widely available aerosol cans for personal use. However, limited pathogen or insecticide resistance surveillance data are available for making operational decisions. In this study, we assessed Aedes aegypti from serial surveillance collections from 3 locations for the presence of dengue virus serotypes 1-3 (DENV1-3) by polymerase chain reaction and assessed, by melt curve analysis, samples from 10 locations in 2 departments for the presence of two mutations (V1016I and F1534C), that in combination, are linked to strong pyrethroid insecticide resistance. Only one of the 32 tested pools was positive for the presence of dengue virus. The two knockdown resistance (kdr) mutations were present in all locations. The 1016I mutation frequency varied from 0.29 to 0.91 and was in all sites lower than the 0.58-1.00 frequency of the 1534C mutation. We also observed that the genotype homozygous for both mutations (IICC), which has been linked to strong pyrethroid resistance, varied from 13 to 86% in each population. Notably, 3 locations - Ti Cousin and Christianville in Ouest department and Camp Coq in Nord department had more than 30% of the tested population without the presence of kdr mutations. These results indicate that the kdr markers of pyrethroid resistance are present in Haiti, at high frequency in several locations and, based on previous studies linking kdr genotypes and phenotypic resistance, that operational interventions with pyrethroids are not likely to be as effective as expected.