Dengue Vector Research Articles

Lysinibacillus fusiformis: A novel mosquitocidal bacterium isolated from Western Ghats, Kerala, India

An extensive field survey was carried out from December 2021 to January 2022 for the collection of soil samples in the Western Ghat region of the Wayanad district of Kerala, India, to isolate potent novel mosquitocidal bacteria which could be used as efficient formulations to control mosquito vectors. Several bacterial colonies were isolated and screened, for mosquitocidal activity. Toxicity assay showed that only one bacterium isolated from forest loamy soil had promising larvicidal activity against Culex quinquefasciatus the lymphatic filariasis vector (LC50: 0.03 mg L-1 & LC90: 0.07 mg L-1) and moderate activity was shown against the dengue vector, Aedes aegypti (LC50: 1.03 mg L-1 & LC90: 1.8 mg L-1). The bacterium was identified as Lysnibacillus fusiformis by a phylogenetic tree constructed using 16S rRNA genome sequencing. This is the first report that L. fusiformis isolated from the forest loamy soil of the Western Ghats, Kerala, which showed proficient mosquitocidal activity against disease-transmitting mosquito vectors.

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

School and community driven dengue vector control and monitoring in Myanmar: Study protocol for a cluster randomized controlled trial.

Dengue is the most common and widespread mosquito-borne arboviral disease globally estimated to cause >390 million infections and >20,000 deaths annually. There are no effective preventive drugs and the newly introduced vaccines are not yet available. Control of dengue transmission still relies primarily on mosquito vector control. Although most vector control methods currently used by national dengue control programs may temporarily reduce mosquito populations, there is little evidence that they affect transmission. There is an urgent need for innovative, participatory, effective, and locally adapted approaches for sustainable vector control and monitoring in which students can be particularly relevant contributors and to demonstrate a clear link between vector reduction and dengue transmission reduction, using tools that are inexpensive and easy to use by local communities in a sustainable manner. Here we describe a cluster randomized controlled trial to be conducted in 46 school catchment areas in two townships in Yangon, Myanmar. The outcome measures are dengue cases confirmed by rapid diagnostic test in the townships, dengue incidence in schools, entomological indices, knowledge, attitudes and practice, behavior, and engagement. The trial involves middle school students that positions them to become actors in dengue knowledge transfer to their communities and take a leadership role in the delivery of vector control interventions and monitoring methods. Following this rationale, we believe that students can become change agents of decentralized vector surveillance and sustainable disease control in line with recent new paradigms in integrated and participatory vector surveillance and control. This provides an opportunity to operationalize transdisciplinary research towards sustainable health development. Due to the COVID-19 pandemic and political instability in Myanmar the project has been terminated by the donor, but the protocol will be helpful for potential future implementation of the project in Myanmar and/or elsewhere.Registration: This trial was registered in the ISRCTN Registry on 31 May 2022 ( https://doi.org/10.1186/ISRCTN78254298).

Arbovirus Detection of Adult Female <i>Aedes aegypti</i> for Dengue Surveillance: a Cohort Study in Bandung City, Indonesia

Dengue surveillance is an important activity to prevent dengue outbreaks. This activity becomes a significant challenge for the region with limited logistic capabilities. Developing a simple mathematical model to predict the possibility of dengue incidence provides a reliable early warning system. This study compared the correlation between vector (adult female Aedes aegypti) and arbovirus detection on a vector to dengue incidence, which generalized linear mixed models tested. The incidence of adult female Aedes aegypti and dengue fever cases were interpolated through third-power inverse distance weighting (IDW). A spatial correlation between female Aedes aegypti incidence and dengue incidence was obtained from polynomial regression. Collection sites were 16 villages in Bandung city, one of the significant dengue endemic areas in January–December 2017. A total of 8,402 mosquitoes of Aedes aegypti, Aedes albopictus, and Culex sp., with 17% belonging to Aedes aegypti as the subject of the dengue virus (DENV) infection test. Data analysis only showed a weak correlation between the numbers of adult female Aedes aegypti and dengue incidence. On the other hand, there is no correlation between positive dengue infection of vector and dengue incidence. This study highlights the importance of constant arbovirus surveillance and integrated surveillance methods on all possible dengue vectors to develop an early warning system for dengue incidence.

Community Empowerment in Household Clean and Healthy Behavior (PHBS), especially for Prevention and Early Action on Infectious Diseases and Cerebrocardiovascular Diseases in Pekan Village, Tanjung Beringin District, Serdang Bedagai

Infectious diseases, especially those transmitted by mosquitoes, are health problems that are often experienced by people in coastal areas. Cases of infection such as dengue hemorrhagic fever (DHF) and even malaria, were reported to be found in partner areas. The partner's location which is located on the beach with swamps around it allows breeding places for mosquitoes, especially Anopheles sp. which acts as the main vector of malaria and filarial. Breeding sites for Aedes aegypti and Aedes albopictus mosquitoes as dengue vectors are also possible to be found in partner locations because they are located not too far from the city of Medan and include tourist attractions. Cerebrocardiovascular disease, especially stroke and coronary heart, has high morbidity and mortality rates. This disease has almost the same risk factors because both are related to blood vessels, five main risk factors can be controlled, namely hypertension, diabetes mellitus, dyslipidemia, obesity, and smoking. The importance of public understanding of how to prevent and control these risk factors. Public Health Clinic Center as a front-line health service facility plays an important role in improving the health status of the community. One of the community service activities carried out by the Tanjung Beringin Health Center is counseling to cadres from community members this is related to stroke and coronary heart disease because these diseases are diseases that have a very close relationship and become a problem that requires proper and careful management. The risk factors for these two diseases, including hypertension, cause heart attacks, heart failure, and strokes and often lead to new DM in many cases. Due to the increase in the disease due to lifestyle changes, with this education, we can add to the public's knowledge to be responsive in conducting treatment and regular health checks.

First report of kdr mutations in the voltage-gated sodium channel gene in the arbovirus vector, Aedes aegypti, from Nouakchott, Mauritania

BackgroundSince 2014, dengue epidemics have occurred almost annually in Nouakchott, the capital city of Mauritania, coinciding with the recent establishment of Aedes aegypti, the primary vector of dengue, in the city. Anopheles arabiensis, the primary vector of malaria, is also abundant not only in Nouakchott but also in most areas of the country. Resistance to insecticides has been studied in An. arabiensis but not in Ae. aegypti in Mauritania. The objective of the present study was to establish the baseline data on the frequencies of knockdown resistance (kdr) mutations in the voltage-gated sodium channel (vgsc) gene in Ae. aegypti collected in Nouakchott to improve vector control.MethodsResting Ae. aegypti mosquitoes were collected in 2017 and 2018 in Teyarett and Dar Naim districts in Nouakchott using a battery-powered aspirator. Polymerase chain reaction (PCR) and DNA sequencing were performed to detect the presence of five kdr mutations known to be associated with pyrethroid resistance: L982W, S989P, I1011M/G, V1016G/I, and F1534C.ResultsA total of 100 female Ae. aegypti mosquitoes were identified among collected resting culicid fauna, of which 60% (60/100) were unfed, 12% (12/100) freshly blood-fed, and 28% (28/100) gravid. Among the mutations investigated in this study, 989P, 1016G, and 1534C were found to be widespread, with the frequencies of 0.43, 0.44, and 0.55, respectively. Mutations were not found in codons 982 and 1011. No other mutations were detected within the fragments analyzed in this study. Genotype distribution did not deviate from Hardy–Weinberg equilibrium. The most frequent co-occurring point mutation patterns among Ae. aegypti mosquitoes were the heterozygous individuals 989SP/1016VG/1534FC detected in 45.1% of mosquitoes. In addition, homozygous mutant 1534CC co-occurred simultaneously with homozygous wild type 989SS and 1016VV in 30.5% of mosquito specimens. Inversely, homozygous wild-type 1534FF co-occurred simultaneously with homozygous mutant 989PP and 1016GG in 19.5% of the mosquitoes.ConclusionsTo our knowledge, this is the first study reporting the presence of three point mutations in the vgsc gene of Ae. aegypti in Mauritania. The findings of the present study are alarming because they predict a high level of resistance to pyrethroid insecticides which are commonly used in vector control in the country. Therefore, further studies are urgently needed, in particular phenotypic characterization of insecticide resistance using the standardized test.Graphical

Effectiveness of Ovitrap as a Control Tool Population Aedes Spp. In Areas Endemic to Dengue Fever Ternate City

The mosquito ovitrap is often used in dengue fever (DF) vector surveillance, but it has never been reported in control programs to reduce the vector population. This study aims to determine the ovitrap effectiveness as a vector control instrument for DF. The research was carried out from January to March 2021 in Bastiong Talangame Village, one of the DF endemic villages, which is a densed settlement in Ternate City. This research was a quantitative pre-experimental design type one group pre-test and post-test . Measurement of the density of Aedes spp. larvae presented in the House Index (HI), Container Index (CI), and Breteau Index (BI) were carried out four times before and after ovitrap installation. The installation of ovitraps was carried out in 100 houses, where four ovitraps were installed in each house with an installation time of four weeks. The results showed that the ovitrap index value decreased until it reached the moderate category in the last week of observation. The density of larvae based on the calculation of HI, CI, BI showed a significant decrease (p = 0.0001) before and after ovitrap installation, with the density figure value of the high category being the medium category. The use of ovitrap was effective in reducing the population of Aedes spp. so it should be considered in the dengue vector control strategy

Societal knowledge, attitude, and practices towards dengue and associated factors in epidemic-hit areas: Geoinformation assisted empirical evidence

Dengue is one of Pakistan's major health concerns. In this study, we aimed to advance our understanding of the levels of knowledge, attitudes, and practices (KAPs) in Pakistan's Dengue Fever (DF) hotspots. Initially, at-risk communities were systematically identified via a well-known spatial modeling technique, named, Kernel Density Estimation, which was later targeted for a household-based cross-sectional survey of KAPs. To collect data on sociodemographic and KAPs, random sampling was utilized (n = 385, 5 % margin of error). Later, the association of different demographics (characteristics), knowledge, and attitude factors—potentially related to poor preventive practices was assessed using bivariate (individual) and multivariable (model) logistic regression analyses. Most respondents (>90 %) identified fever as a sign of DF; headache (73.8 %), joint pain (64.4 %), muscular pain (50.9 %), pain behind the eyes (41.8 %), bleeding (34.3 %), and skin rash (36.1 %) were identified relatively less. Regression results showed significant associations of poor knowledge/attitude with poor preventive practices; dengue vector (odds ratio [OR] = 3.733, 95 % confidence interval [CI ] = 2.377–5.861; P < 0.001), DF symptoms (OR = 3.088, 95 % CI = 1.949–4.894; P < 0.001), dengue transmission (OR = 1.933, 95 % CI = 1.265–2.956; P = 0.002), and attitude (OR = 3.813, 95 % CI = 1.548–9.395; P = 0.004). Moreover, education level was stronger in bivariate analysis and the strongest independent factor of poor preventive practices in multivariable analysis (illiterate: adjusted OR = 6.833, 95 % CI = 2.979–15.672; P < 0.001) and primary education (adjusted OR = 4.046, 95 % CI = 1.997–8.199; P < 0.001). This situation highlights knowledge gaps within urban communities, particularly in understanding dengue transmission and signs/symptoms. The level of education in urban communities also plays a substantial role in dengue control, as observed in this study, where poor preventive practices were more prevalent among illiterate and less educated respondents.

Measuring Oviposition Preference in Aedes aegypti Mosquitoes.

The female mosquito is endowed with the responsibility of gene transfer from one generation to another through careful delivery of her eggs to an appropriate environment. To guarantee a successful reproduction process, female mosquitoes use an evaluative approach to select an oviposition site that will ensure that their progeny successfully hatch and develop from larvae to pupa to adult. Specific conditions must be met during oviposition site selection before gravid females deposit eggs, including but not limited to appropriate temperature, salinity, and pH; the presence of nutrition; and a low risk of predation. Mosquito species exhibit a remarkable diversity in their oviposition site selection behaviors. For instance, Aedes aegypti, which is a vector for Zika, dengue, yellow fever, and chikungunya viruses, prefers to lay its eggs in natural depressions (e.g., tree holes) or artificial containers. In contrast, other mosquito species, like Anopheles, gravitate toward more open water bodies. Understanding the oviposition preference behavior of the Ae. aegypti mosquito will facilitate the development of surveillance and control efforts to hinder the successful progression of this vector. Here, we present information on some of the known behaviors and preferences of Ae. aegypti during oviposition site selection, techniques to measure these preferences, and some open questions.

Insecticidal Property of Plumeria obtusa L. (Apocynaceae) Leaf Extracts Against Aedes aegypti (Diptera: Culicidae)

Mosquitoes are one of the most lethal animals in the world and transmit many dangerous human pathogens, causing millions of deaths each year. Aedes aegypti is generally known to be a vector of dengue, chikungunya and zika. Mosquito control is a major challenge nowadays when they became resistant against commonly available insecticides. To reduce this, it is important to look for alternative that are easily biodegradable. One such alternative could be bioactive products from phytochemicals by systematically exploring the global floral biodiversity. Therefore the present study was to evaluate the ovipositional deterrent activity of the ethanol, hexane leaf extracts of Plumeria obtusa against Aedes aegypti and also observe various types of sensilla located on the antennae, maxillary palp, tarsi and ovipositor of the Ae. aegypti using scanning electron microscope. The effect of ethanol and hexane leaf extracts of P. obtusa on oviposition of Ae. aegypti was determined under two sets of conditions (Choice and no choice oviposition assay). Among the total number of eggs laid 33.83% (ethanol), 38.15(hexane) was present in control medium when placed along with ovitraps with 0.1, 0.3, 0.7, 0.010 and 0.013% ethanol and hexane leaf extracts of P. obtusa in which appeared 27.88, 23.27, 11.79, 9.371 and 0.038 % (ethanol), 26.09, 18.14, 13.19, 4.357 and 0.042% (hexane) of eggs respectively. This was also indicated by ODI values (9.649, 18.48, 48.30, 82.86 and 99.77) (ethanol) and (18.76, 35.53, 48.59, 79.50 and 99.77) (hexane) (choice oviposition assay). Percent oviposition in 0.1, 0.3, 0.7, 0.010 and 0.013 % ethanol and hexane of leaf extracts of P. obtusa was 43.11, 28.77, 19.51, 3.875 and 0.090% (ethanol), 36.36, 26.21, 18.03, 8.888 and 0.181% (hexane) which were less compared to their control counterparts 56.88, 71.22, 80.48, 96.12 and 99.90 (ethanol), 63.63, 73.78 , 81.96 , 91.11 and 99.81 (hexane) respectively (no choice oviposition assay). The findings also revealed that both extracts (ethanol, hexane) showed promising ovipositional deterrent activity against adult Ae. aegypti.

Phylogenetic analysis of Aedes species distributed in Taif Province, Saudi Arabia, based on mitochondrial COX1 sequences

AbstractAs Aedes mosquitoes are the predominant carriers of arboviruses responsible for global dengue fever and chikungunya outbreaks, understanding their genetic diversity and population structure can enhance dengue prevention and vector control efforts. Although sympatric cryptic species have been acknowledged in Aedes species subgroups in Southeast Asia, little information is available regarding the occurrence and dispersal of cryptic Aedes species in Saudi Arabia. In the present investigation, we intend to analyze genetic variations and perform a phylogenetic study of sympatric Aedes samples collected from various locations in Taif Province, Saudi Arabia. The locus of mitochondrial DNA cytochrome c oxidase subunit 1 (COX1, analyzed with DNA barcoding) was utilized to determine genetic variance and to build phylogenetic trees. For species identification, the COX1 sequences of Aedes samples from Taif Province were compared with those of Aedes samples from GenBank (National Center for Biotechnology Information, NCBI). To identify phylogenetic relationships and genetic variability, phylogenetic trees were created using Taif Province samples, GenBank A. albopictus samples, and GenBank A. aegypti samples. The phylogenetic analysis revealed that some Taif samples (A3, A7, F2, F4, F1, A4, A1, F9 and F6) were closer to A. aegypti and A. albopictus samples from Africa and East Asia, especially Kenya and Malaysia. Whereas other samples (F9, F6, A4, F1 and A1) were closer to the GenBank A. aegypti samples KP843383 (Thailand), HM399357(Australia), MK533632 (Kenya), KX420460 (Kenya), KU495081 (Australia) and MF179160 (China) than the remaining Taif samples. Overall, our findings demonstrate that examining the genetic diversity and phylogenetic linkages of Aedes samples can aid in understanding the evolution of Aedes cryptic species in the western regions of Saudi Arabia.

Wings geo-morphometrical differences based on geographic distance of Aedes aegypti from Southeast Aceh District Sumatra and Sleman District Java

Aedes aegypti is a mosquito species that is the main vector of dengue, zika, and chikungunya infection. Indonesia is a tropical country with great potential for transmission of Mosquito-Borne Disease. Geo-morphometric analysis is an approach method to evaluate the correlation between shape and the environmental variables that affect to mosquitoes, and to identify variations in mosquito populations by geographical conditions and various types of habitats. The purpose of this study was to determine the geomorphometric differences in the Ae. aegypti population from Southeast Aceh District and Sleman District Yogyakarta as well as examining the environmental conditions and factors that might be affecting wings geomorphometry variations. Eggs collection was carried out with ovitraps at both sampling locations. Eggs were hatched till the mature state, at the age of 3rd days, wings preparation is carried out. Digitization and analysis were performed using GM analysis program (Xyom.io). Significant differences (α; p<0.001) were shown in the size and shape of the wings and the distance of mahalanobis of the Ae. aegypti from Southeast Aceh and Sleman District. The results revealed that mosquitoes from the two districts are not closely related.

Dengue Infection Survey on Prevention and Control Strategies Among Community in Malaysia

Dengue is a vector-borne disease caused by a rapidly spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards prevention and control measures of Dengue infection. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: i) respondent profile ii) knowledge about prevention of Dengue Fever and insecticide use for mosquito control iii) knowledge about biological control.Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and Abate® (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel biocontrol and successful community programmes is significantly influenced by the perception of prevention and control measures for mosquitoes.

Essential oil-based nanoemulsion of Murraya koenigii is an efficient larvicidal against Aedes aegypti under field conditions

Murraya koenigii is a plant species with economic and cultural importance in Asian countries. Many studies have shown a wide biopotential of M. koenigii products, including for insect control. Aedes aegypti is the main vector of dengue, among other arboviruses. Estimates show that approximately 2.5 billion people are at risk of infection. Attempts at vector control favored the emergence of resistance to available chemical insecticides. Therefore, it is necessary to develop alternative formulations for vector control. This research aimed to evaluate the larvicidal activity of the essential oil from M. koenigii leaves against Ae. aegypti. The death time and bioavailability of the material in aqueous medium, as well as the influence of the type of breeding site on the lethal effect, were investigated. A nanoemulsion was developed as a dispersion system to increase the bioavailability of the essential oil. A test for evaluating the mutagenic potential of Allium cepa meristems was performed as a form of toxicological screening. It was observed that the essential oil from M. koenigii leaves was highly promising in terms of larvicidal activity against Ae. aegypti, both under controlled conditions and in the field. The nanoemulsion showed adequate stability and considerably increased the bioavailability time of the active ingredient in a liquid medium. No genotoxic events were observed in A. cepa cells, but the nanoemulsion showed antiproliferative effects.

Prevalence of dengue fever in Saudi Arabia: Jeddah as a case study

AbstractDengue fever is widespread in tropical and subtropical regions, including Saudi Arabia. Aedes aegypti (Diptera: Culicidae) transmits dengue and many other diseases, including chikungunya and Zika. This study provides an overview of dengue fever in Saudi Arabia since the first case was recorded in the early 1990s. In addition, it focuses on the epidemiological situation in Jeddah as a case study to study the spatial distribution of dengue cases using Geographic Information Systems (GIS) techniques over 5 years, from 2019 to 2023. The first recorded case in Saudi Arabia was in October 1993; however, daily data indicates that 2023 is a major epidemic year. The number of infections has reached 4099 so far during the first half of the year, which indicates a significant increase compared to previous years. GIS analysis has unveiled the locations of high infection rates across multiple municipalities, commonly called hotspots, and identified areas where dengue cases remain relatively low. The Inverse Distance Weighted (IDW) tool was used to determine the severity of infection in different areas of Jeddah. The study concluded that factors such as temperature, rainfall, and septic tanks in areas that lack a proper sanitation network are the most contributing factors to the spread of disease vectors and, thus, dengue. Winter rainfall creates conducive breeding environments for dengue mosquito vectors, increasing transmission rates. On the other hand, summer heat accelerates the mosquito life cycle and enhances viral replication, heightening the risk of dengue transmission.

Phenotypic adaptation to temperature in the mosquito vector, Aedes aegypti.

Most models exploring the effects of climate change on mosquito-borne disease ignore thermal adaptation. However, if local adaptation leads to changes in mosquito thermal responses, "one size fits all" models could fail to capture current variation between populations and future adaptive responses to changes in temperature. Here, we assess phenotypic adaptation to temperature in Aedes aegypti, the primary vector of dengue, Zika, and chikungunya viruses. First, to explore whether there is any difference in existing thermal response of mosquitoes between populations, we used a thermal knockdown assay to examine five populations of Ae. aegypti collected from climatically diverse locations in Mexico, together with a long-standing laboratory strain. We identified significant phenotypic variation in thermal tolerance between populations. Next, to explore whether such variation can be generated by differences in temperature, we conducted an experimental passage study by establishing six replicate lines from a single field-derived population of Ae. aegypti from Mexico, maintaining half at 27°C and the other half at 31°C. After 10 generations, we found a significant difference in mosquito performance, with the lines maintained under elevated temperatures showing greater thermal tolerance. Moreover, these differences in thermal tolerance translated to shifts in the thermal performance curves for multiple life-history traits, leading to differences in overall fitness. Together, these novel findings provide compelling evidence that Ae. aegypti populations can and do differ in thermal response, suggesting that simplified thermal performance models might be insufficient for predicting the effects of climate on vector-borne disease transmission.

Aedes aegypti D7 long salivary proteins modulate blood feeding and parasite infection.

During blood feeding, mosquitoes inject saliva into the host skin, preventing hemostasis and inflammatory responses. D7 proteins are among the most abundant components of the saliva of blood-feeding arthropods. Aedes aegypti, the vector of yellow fever and dengue, expresses two D7 long-form salivary proteins: D7L1 and D7L2. These proteins bind and counteract hemostatic agonists such as biogenic amines and leukotrienes. D7L1 and D7L2 knockout mosquitoes showed prolonged probing times and carried significantly less Plasmodium gallinaceum oocysts per midgut than wild-type mosquitoes. We hypothesize that reingested D7s play a vital role in the midgut microenvironment with important consequences for pathogen infection and transmission.

Spatial analysis for risk assessment of dengue in Spain

IntroductionThe establishment of Aedes albopictus in new areas in Europe has changed the risk of local dengue transmission represented by imported human cases. The risk of transmission is determined by the distribution of travelers arriving from dengue-endemic areas and the distribution of Ae. albopictus as potential vectors of dengue in Spain. MethodsEnvironmental, entomological, epidemiological, demographic, tourism and travel data were analyzed to produce a series of maps to represent: the distribution of Ae. albopictus across municipalities; the risk of expansion of Ae. albopictus based on a species distribution model; the calculated index of travelers from dengue-endemic areas (IDVZE) per province; the percentage contribution of each municipality to the total number of cases in Spain. The maps were then added using map algebra, to profile the spatial risk of autochthonous dengue in Spain at a municipal level from 2016 to 2018. ResultsAe. albopictus was detected in 983 municipalities. The calculated IDVZE varied from 0.23 to 10.38, with the highest IDVZE observed in Madrid. The overall risk of autochthonous cases oscillated between 0.234 and 115, with the very high risk and high risk areas detected in the Mediterranean region, mainly in the Levantine coast and some parts of the Balearic Islands. Most of the interior of the peninsula was characterized as low risk. ConclusionPrevention and control measures to mitigate the risk of autochthonous dengue should be prioritized for municipalities in the high risk areas integrating early detection of imported dengue cases and vector control.

The Key Associated Factor of the Emergence of the Dengue Vector in Peri-Urban and Rural Settlements

Introduction: The population density of Aedes mosquitoes is a risk factor for dengue in endemic areas. Therefore, it is necessary to understand the risk factors for mosquito vector emergence in settlements. This study aimed to determine the key factors associated with the occurrence and population density of dengue vectors in peri-urban and rural settlements. Methods: A cross-sectional study was conducted in two dengue-endemic villages, Bergas-Kidul and Gebugan, representing peri-urban and rural settlements, respectively. A cluster-based larval survey was conducted in the dengue-case house and in 18–20 houses around a radius of 100 m. All water containers and their characteristics and mosquito larvae emergence were recorded in each house to calculate Aedes indices. The geographic coordinates, altitude, air temperature, and humidity were mapped and analyzed using GIS and SPSS software. Results and Discussion: Dengue vectors were found in peri-urban and rural with HI, CI, BI, and DF indices of 29.3%, 32.2%, 35.4, 6.0; then 12.2%, 14.3%, 14.6, and 3.0, respectively. In peri-urban areas, larval occurrence was associated with air temperature, air humidity, container type, and open microhabitat, whereas in rural areas, it was associated with only open microhabitat. Conclusion: The Aedes indices represent a high density of mosquito populations, and the existence of open microhabitats is the key factor for larval occurrence in both peri-urban and rural settlements. Community participation in vector control needs to be increased in addition to studying the resistance of Aedes mosquitoes to a number of insecticide groups.