Mapping the global potential distributions of two arboviral vectors Aedes aegypti and Ae. albopictus under changing climate

Exploring spatiotemporal dynamics and climatic effects on dengue in Amazonas, Peru during 2000-2023

Peru experienced its most severe dengue outbreak on record, with the Amazonas region reporting 3502 dengue cases in 2022. This study aimed to examine the distribution of dengue cases across Amazonas from 2000 to 2023, while exploring the influence of climate factors. Monthly incidence was aggregated into four consecutive six-year blocks to identify incidence trends, and space-time scan statistics identified high and low-risk clusters. Spearman correlations with distributed lags (0 - 2 months) evaluated the association between incidence and climatic data from NASA-POWER, stratified by season. Until 2005, transmission was restricted to Bagua and Utcubamba provinces. A major increase in cases from 2008 to 2011 was recorded in the endemic provinces of Condorcanqui, Bagua, and Utcubamba forming a high-risk cluster in the latter two (LLR = 287.88, RR = 3.79). After a decrease during 2012-2017, incidence resurged creating a Bagua mega-cluster (LLR = 1112.28, RR = 3.20) and expanding to Jazán and Balsas districts, with the latter characterized by lower temperatures compared to endemic areas. Significant correlations were found between climatic variables and incidence. Specifically, minimum temperature significantly influenced dengue dynamics and expansion into Balsas (rho = 0.23, P = 0.03), with a two-month lag during the wet season. These findings underscore the importance of climate monitoring in guiding public health interventions. However, a comprehensive approach that considers environmental and behavioral factors, tailored to the specific conditions of each province, is essential for effective control of future outbreaks.

Current and Future Spatial Distribution of the Aedes aegypti in Peru Based on Topoclimatic Analysis and Climate Change Scenarios

Dengue, a febrile disease that has caused epidemics and deaths in South America, especially Peru, is vectored by the Aedes aegypti mosquito. Despite the seriousness of dengue fever, and the expanding range of Ae. aegypti, future distributions of the vector and disease in the context of climate change have not yet been clearly determined. Expanding on previous findings, our study employed bioclimatic and topographic variables to model both the present and future distribution of the Ae. aegypti mosquito using the Maximum Entropy algorithm (MaxEnt). The results indicate that 10.23% (132,053.96 km2) and 23.65% (305,253.82 km2) of Peru's surface area possess regions with high and moderate distribution probabilities, respectively, predominantly located in the departments of San Martín, Piura, Loreto, Lambayeque, Cajamarca, Amazonas, and Cusco. Moreover, based on projected future climate scenarios, it is anticipated that areas with a high probability of Ae. aegypti distribution will undergo expansion; specifically, the extent of these areas is estimated to increase by 4.47% and 2.99% by the years 2070 and 2100, respectively, under SSP2-4.5 in the HadGEM-GC31-LL model. Given the increasing dengue epidemic in Peru in recent years, our study seeks to identify tools for effectively addressing this pressing public health concern. Consequently, this research serves as a foundational framework for assessing areas with the highest likelihood of Ae. aegypti distribution in response to projected climate change in the second half of the 21st century.

Understanding the Effect of a Changing Climate on the Re-Emergence of Mosquito-Borne Diseases in Vulnerable Small Island Nations: A Systematic Review

INTRODUCTION

Drastic changes in meteorological variables due to climate change will likely have an implication on the proliferation of vectors such as mosquitoes. Extreme weather events may therefore promote the emergence/re-emergence of mosquito-borne diseases (MBDs) and potentiate the risk of endemicity, particularly, in small island nations.

METHOD

A systematic review was chosen to methodically ascertain the knowledge gaps that exist in determining the influence of the changing climate on MBDs in small islands with vulnerable public health systems. This review was conducted using the PRISMA guidelines.

RESULTS

Following extraction of 600 articles from the databases, 16 studies were determined to meet the selection criteria. The majority of these research papers were from Sri Lanka (n = 9) while the remaining articles were distributed between islands in the Pacific and Atlantic Ocean. Several of these studies used regression modelling techniques to discuss the effect of multiple meteorological variables on the incidence of MBDs. A positive relationship was observed between temperature and the relative risk of MBDs in 72% of the papers. Rainfall enhanced dengue transmission in 84% of the studies included. All the articles discussing the effect of humidity illustrated a similar trend while wind speed was the only climatic variable demonstrating a negative relationship with MBDs.

DISCUSSION

Considering the intricate nature of the non-linear exposure-response link is crucial when estimating the lagged effect of the changing climate on MBDs transmission. Other challenges associated with bias and confounders in the selected studies as well as meteorological data accessibility, were highlighted. Therefore, it was not possible to conclusively establish that the changing climatic variables do influence the spread of MBDs which accentuated the need for conducting further studies to illustrate the effect of changing weather variables on the incidence of MBDs, with an emphasis on vulnerable small island nations.

Future Climate Predicts Range Shifts and Increased Global Habitat Suitability for 29 Aedes Mosquito Species

Aedes mosquitoes (Diptera, Culicidae) are the major vectors for many mosquito-borne diseases. Here, we retrieved 878,954 global occurrences of 29 Aedes mosquito species and 30 candidate predictors at a global scale. We created a unified frame and built 29 multi-algorithm species distribution models to project the ranges and overlapped them to examine the range-overlap hotspots under future scenarios. We detected expanded ranges in most Aedes mosquito species, and a substantial increase in the index of habitat suitability overlap was detected in more than 70% of the global terrestrial area, particularly in Europe, North America, and Africa. We also identified extensive range overlap, which increased in future scenarios. Climatic factors had a more significant influence on range dynamics than other variables. The expanded ranges of most Aedes mosquito species and the substantial increase in the overlap index of habitat suitability in most regions suggest globally increasing threats of Aedes-borne epidemic transmission. Thus, much stricter strategies must be implemented, particularly in Europe, North America, and Africa. As climate change increases habitat suitability and expands ranges in most Aedes mosquito species, mitigating future climate change will be a key approach to combatting their impacts.

Understanding the Burden of Agriculturally Significant Vector-Borne and Parasitic Diseases in Kansas

Background: The state of Kansas (KS) has been called the "agricultural heartland" of the United States. Vector-borne and parasitic diseases (VBPD) have a major impact on the production of livestock, such as cattle, swine, goats and sheep, as well as crops, such as wheat, corn, and sorghum. The purpose of this review is to educate agricultural professionals in the state of KS about VBPD of current or potential concern and to inform the public about the challenges faced by the agricultural community. Methods: This review describes and discusses the endemic VBPD that currently impact agricultural production in KS and foreign VBPD of concern. In addition, we outline the major arthropod vectors of VBPD in KS, including ticks, mites, and various insects. In the context of this review, parasites are strictly limited to arthropod ectoparasites that negatively impact livestock production. Modern agricultural data for the state of KS were mostly sourced from the USDA National Agricultural Statistics Service, and current KS VBPD data were mostly sourced from the KS State Veterinary Diagnostic Laboratory. Conclusion: These VBPD have a large economic impact on the state and country, and we have concluded there is a need for updated estimates regarding the economic burden of VBPD in KS and throughout the United States to make better animal and crop health investment decisions.

Climate change and geographical distribution projections for major leaf beetles (Coleoptera: Chrysomelidae) in Saudi Arabia

Climate change has a substantial impact on the quality and diversity of insect pests, which may have adverse ecological and economic effects. The family Chrysomelidae represents one of the most economically and ecologically important groups within Coleoptera, with species acting as agricultural pests and contributing substantially to biodiversity in arid regions. Based on bioclimatic, topographic, and vegetation data, the current and future distributions of 4 chrysomelids (Caryedon acaciae (Gyllenhal, 1833), Chaetocnema pulla Chapuis, 1879, Phyllotreta cheiranthi Weise, 1903, and Spermophagus sericeus (Geoffroy, 1785)) in Saudi Arabia were predicted using MaxEnt modeling for 2050 under 2 Shared Socioeconomic Pathways (SSPs), SSP126 (low emission) and SSP585 (high emission) scenarios. The leaf beetle models showed strong performance, with average area under the curve (AUC) values ranging from 0.86 to 0.96 and average TSS values ranging from 0.52 to 0.65. Five predictors were chosen for each species from 21 environmental variables. The results show that the key ecological factors that influence species distributions varied, with vegetation being the most influential. According to habitat suitability maps, in the future, such distribution will be severely altered, mostly by climate change. More precisely, C. acaciae will face minor range shifts, while C. pulla, P. cheiranthi, and S. sericeus will expand their ranges substantially, especially in the Eastern Province. Our results confirm the importance of implementing adaptive pest-management strategies to address the potential range expansions of various agricultural pests, which could intensify local ecological challenges and pose a heightened threat to agricultural systems.

Assessing current and future areas of ecological suitability for Lutzomyia shannoni in North America

BACKGROUND

In the Americas, sand flies of the Lutzomyia genus are the vectors of pathogens of human and animal health significance. Lutzomyia shannoni is suspected to transmit vesicular stomatitis virus, along with Leishmania mexicana and Leishmania infantum (causative agents of leishmaniases). Despite the suspected vector potential of Lu. shannoni, significant knowledge gaps remain, including how ongoing climate changes could facilitate their range expansion. The objectives of this study were to predict the current and future ecological suitability of regions across North America for Lu. shannoni and to identify variables driving ecological suitability.

METHODS

Occurrence records were obtained from the Global Biodiversity Information Facility, Disease Vectors Database, the National Museum of Natural History (Smithsonian Institution) and published literature on Lu. shannoni surveillance and capture. Historical climate data from 1991-2020, along with projection data for Shared Socioeconomic Pathways 2-4.5 and 3-7.0 were obtained. An additional terrestrial ecoregions layer was applied. The ecological niche model was created using maximum entropy (MaxEnt) algorithms to identify regions which currently are or may become ecologically suitable for Lu. shannoni.

RESULTS

Currently, regions in eastern, western and southern Mexico, along with the Midwest, southeastern and eastern regions of the USA are ecologically suitable for Lu. shannoni. In the future, ecological suitability for Lu. shannoni is expected to increase slightly in the northeastern regions of the USA and in Atlantic Canada, and to decrease in the southeastern reaches of Mexico. Degree-days below 0 °C (spring and autumn), precipitation as snow (summer and winter), terrestrial ecoregions, number of frost-free days (summer), Hargreaves climatic moisture deficit (summer), degree-days above 5 °C (autumn) and Hogg's climatic moisture index (summer) were all identified as predictors of ecological suitability.

CONCLUSIONS

The findings from this study identified climate and environmental variables driving the ecological suitability of regions for Lu. shannoni and can be used to inform public health professionals of high-risk regions for exposure at present and into the future.

Mothers and mosquitoes: climate change contributes to the spread of vector-borne pathogens posing a substantial threat to pregnant women

Infectious diseases have threatened individuals and societies since the dawn of humanity. Certain population groups, including pregnant women, young children and the elderly, are particularly vulnerable to severe infections. Over the past few centuries, advances in medical standards and the availability of vaccines have reduced infection-related mortality and morbidity rates in industrialized countries. However, the global rise in temperatures and increased precipitation present a new challenge, facilitating the broader distribution of disease vectors, such as mosquitoes, bugs and ticks, to higher altitudes and latitudes. Consequently, epidemic and pandemic outbreaks associated with these vectors, such as Zika, West Nile, dengue, yellow fever, chikungunya and malaria, are increasingly impacting diverse populations. This review comprehensively examines how infections associated with climate change disproportionately affect the health and well-being of pregnant women and their unborn children. There has been a noticeable emergence of vector-borne diseases in Europe. Consequently, we stress the importance of implementing measures that effectively protect pregnant women from these increasing infections globally and regionally. We advocate for initiatives to safeguard pregnant women from these emerging threats, beginning with enhanced education to raise awareness about the evolving risks this particularly vulnerable population faces.

Vaccines Against Urban Epidemic Arboviruses: The State of the Art

Arboviruses represent a contemporary global challenge, prompting coordinated efforts from health organizations and governments worldwide. Dengue, chikungunya, and Zika viruses have become endemic in the tropics, resulting in the so-called "triple arbovirus epidemic". These viruses are transmitted typically through the bites of infected mosquitoes, especially A. aegypti and A. albopictus. These mosquito species are distributed across all continents and exhibit a high adaptive capacity in diverse environments. When combined with unplanned urbanization, uncontrolled population growth, and international travel-the so-called "triad of the modern world"-the maintenance and spread of these pathogens to new areas are favored. This review provides updated information on vaccine candidates targeting dengue, chikungunya, and Zika viruses. Additionally, we discuss the challenges, perspectives, and issues associated with their successful production, testing, and deployment within the context of public health.

Geospatial modeling of geographical spread of Aedes species, in relation to climatic and topographical factors in Lagos State, Nigeria

The ecology and biology of mosquito disease vectors of the genus Aedes are highly dynamic, adapting to various climatic and topographic factors which makes their control challenging. Evidence-based control of Aedes mosquitoes requires a detailed understanding of this adaptability, which is greatly influenced by environmental dynamics. Understanding the drivers of their distribution is hence pertinent to predict disease risk. To better understand drivers and dynamics, we studied the distribution of Aedes mosquitoes in Lagos State, Nigeria, and its connection to climatic and human factors. Aedes larvae and adults were collected from eight Local Government Areas (LGAs, four urban and four rural) in Lagos State, resulting in 98 occurrence points. Using 23 environmental variables, we modeled the geographic distribution of Aedes spp. under current climatic conditions. Human population density was overlaid to estimate the risk of arboviral diseases. Although Aedes mosquitoes were found in all the eight LGAs in different proportions, species distribution varied considerably. Both Aedes aegypti and Aedes albopictus were found across the LGAs with evidence of species partitioning. Virtually all the LGAs were predicted to be highly suitable environments for Aedes mosquitoes, with only two LGAs being moderately suitable. Anthropogenic factors including the extensive accumulation of tires contribute to larval habitat availability for both Aedes aegypti and Aedes albopictus. Urban areas with high population density were also associated with increased larval habitat availability when compared with rural areas. Furthermore, the model suggests that LGAs sharing border with Ogun State are highly suitable environments for Aedes spp. Our study highlights that the main contributing factors to Aedes distribution were precipitation and temperature in the coldest quarter. This paper aims to understand how human and climatic factors affect Aedes mosquitoes distribution in Lagos State, which is crucial to prevent disease transmission.

Assessing neighbourhood-scale BTI spray applications and laboratory-based mortality testing on Aedes aegypti larval development

Mosquitoes, particularly Aedes aegypti, pose significant public health risks by transmitting diseases like dengue, zika and chikungunya. Bacillus thuringiensis var. israelensis (BTI) is a crucial larvicide targeting mosquitoes while sparing other organisms and the environment. This study evaluated the effects of sublethal BTI doses on Ae. aegypti larvae regarding mortality, development, adult emergence and size, using a wide-area spray application in an urban neighbourhood. Laboratory experiments with four BTI concentrations (0, 0.008, 0.02 and 0.04 ppm) assessed compensatory and over compensatory responses. The spray achieved over 90% larval mortality within 48 h, but accumulating sublethal doses could trigger compensatory and over compensatory effects, enhancing the fitness of survivors. A dose-response relationship was evident, with higher BTI concentrations leading to increased mortality, reduced longevity and fewer pupae. BTI exposure also skewed the sex ratio towards males and altered adult sizes, potentially affecting population dynamics and vectorial capacity. These findings highlight the effectiveness of BTI in Ae. aegypti control and the importance of understanding compensation, overcompensation and density-dependent effects. While wide-area BTI applications can reach inaccessible breeding sites and offer potent mosquito control, careful consideration of ecological and evolutionary consequences is crucial.

Re-emergence of Aedes aegypti (Linnaeus) in Egypt: Predicting distribution shifts under climate changes

Aedes aegypti, the primary vector of several medically significant arboviruses-including dengue fever, yellow fever, chikungunya and Zika-was successfully eradicated from Egypt in 1963. However, since 2011, there have been increasing reports of its re-emergence, alongside dengue outbreaks in southern Egyptian governorates, raising significant public health concerns. This study aimed to model the current and future distribution of Ae. aegypti in Egypt. Local occurrence data were integrated with bioclimatic, anthropogenic and biological environmental variables to identify key factors influencing the distribution of Ae. aegypti. Maximum entropy (MaxEnt) modelling demonstrated strong predictive performance (area under the receiver operating characteristic curve [AUC] mean = 0.975; true skill statistic [TSS] mean = 0.789). The key determinants of habitat suitability were identified as human population density, annual precipitation and the normalised difference vegetation index (NDVI). Current predictions indicate that suitable habitats for Ae. aegypti are concentrated in the Nile Valley, Nile Delta, Fayoum Basin, Red Sea coast and South Sinai. Projections under future climate change scenarios suggest an expansion of suitable habitats, particularly in the Nile Delta region. By 2050, the model predicts a 61%-68% increase in suitable habitat area, with a further 64%-69% increase by 2070, depending on the future climate scenarios. These findings are crucial for informing vector control and disease prevention strategies, particularly considering Egypt's status as one of the world's leading tourist destinations.

Climate change influences on the potential geographic distribution of the invasive Asian longhorned tick, Haemaphysalis longicornis

The Asian long-horned tick, Haemaphysalis longicornis Neumann, 1901, is the competent vector for severe fever with thrombocytopenia syndrome virus (SFTSV). Haemaphysalis longicornis originated mainly in eastern Asia and invaded many areas like Australia, New Zealand, and the Pacific islands, and was recently introduced to eastern parts of the USA. This species is characterized by high adaptability to a wide range of temperatures and can reproduce parthenogenically under stressful conditions. Migratory birds are important hosts of H. longicornis and are thought to be responsible for its unexpected invasion and introduction into new areas worldwide. This study predicted the historical (near current) global environmental suitability and the possible shifts in environmental suitability for H. longicornis under the ongoing climate change between 2021 and 2100. The results demonstrated that Europe is at potential of high environmental suitability for H. longicornis invasion although this species has not been recorded in any regions of Europe yet. Our model also anticipated the environmental suitability for H. longicornis in eastern parts of the USA, although the recently recorded occurrences there were not used in the model calibration. Climate change is thought to affect and increase the range of suitable environments for H. longicornis. The different maps introduced in this study may help improve understanding of the global environmental suitability for this invasive disease vector and predict the areas at high environmental suitability for possible invasion to prioritize the control programs and enhance quarantine procedures in these areas.

PHYLOGENETIC ANALYSIS OF AEDES AEGYPTI IN TAIF AND JEDDAH GOVERNORATES, SAUDI ARABIA

With their diverse species, mosquitoes are known to transmit the causal agents of diseases such as malaria, dengue, and yellow fever. Their high adaptability, attraction to humans, and variable adult behaviors make them a significant health concern. The focus on Aedes aegypti is significant for reducing vector-human contacts, monitoring insecticide resistance, and developing innovative vector management strategies. Given the scarcity of studies on Ae. aegypti in the western region of Saudi Arabia, this research is a significant step forward. The study aims to analyze the genetic variations and conduct a phylogenetic study of forty Ae. aegypti samples collected from Taif and Jeddah governorates of Saudi Arabia. The mitochondrial cytochrome c oxidase subunit I (COI) locus was targeted for genetic variance and phylogenetic analysis. Sequences of COI of Ae. aegypti isolates were submitted to the DNA Data Bank of Japan (DDBJ) and National Center for Biotechnology Information (NCBI) Genbank and compared with other global Aedes species isolates. The phylogenetic analysis shows that Ae. aegypti samples from Jeddah have identities ranging from 96.9% to 99.8%, closely related to the Peru (MN299016) and Cambodia (MN299014) isolates. Taif isolates have genetic similarities ranging from 97.5% to 99.8%, closely related to the Germany (KY022526) isolate. Sequence alignment and pairwise comparison show variation among the populations of Ae. aegypti from Taif and Jeddah regions (74.24-98.84%) with a genetic divergence distance of 0.008-0.12. In comparison, ranges slightly change with other Ae. aegypti (79.92-95.96%, 0.008-0.01) as well as Ae. albopictus populations (74.13-83.58%, 0.13-0.20) found in the Genbank database. According to our findings, the present study provides information for a local variation of Ae. aegypti in the western region of Saudi Arabia that could help in disease mapping and risk mitigation, thereby enhancing our ability to manage disease vectors effectively.

Isolation and characterization of the midgut microbiota of Aedes albopictus to identify suitable candidates for paratransgenesis

Aedes albopictus is a widely recognized carrier of various pathogens. Its resilient characteristics enable it to easily spread across diverse climates. The microbiota in the midgut of mosquitoes plays a crucial role in the interactions between the host and pathogens and can either enhance or reduce the ability of the insect to transmit diseases. Hence, determining the microorganisms present in the mosquito's digestive system could be a promising approach to developing an effective method of controlling them. Hence, the aim of this study was to investigate the microbial compositions in the midguts of Ae. albopictus mosquitoes collected from the fields of Sistan and Baluchestan Province. The midguts of 60 female mosquitoes were dissected, and their related bacteria were determined using the culture-dependent method. Different colonies were differentiated using the biochemical tests followed by 16S rRNA gene sequencing. The isolated bacteria were identified as belonging to the Asaia, Delftia, Serratia, Aeromonas, Paracoccus, and Planomicrobium genera based on biochemical and molecular analysis. The findings obtained in this study were largely consistent with earlier studies conducted on mosquitoes gathered from different regions throughout the world. Overall, the findings could enhance our understanding of the microbial diversity in Ae. albopictus and aid in the identification of a potent and widespread bacterium for the development of a paratransgenesis tool to combat Aedes-borne infectious diseases.

Aedes albopictus colonies from different geographic origins differ in their sleep and activity levels but not in the time of peak activity

Mosquitoes occupy a wide range of habitats where they experience various environmental conditions. The ability of some species, such as the tiger mosquito, Aedes albopictus, to adapt to local conditions certainly contributes to their invasive success. Among traits that remain to be examined, mosquitoes' ability to time their activity with that of the local host population has been suggested to be of significant epidemiological importance. However, whether different populations display heritable differences in their chronotype has not been examined. Here, we compared laboratory strains originating from eight populations from three continents, monitored their spontaneous locomotor activity patterns and analysed their sleep-like states. Overall, all strains showed conserved diurnal activity concentrated in the hours preceding the crepuscule. Similarly, they all showed increased sleep levels during the morning and night hours. However, we observed strain-specific differences in the activity levels at each phase of the day. We also observed differences in the fraction of time that each strain spends in a sleep-like state, explained by variations in the sleep architecture across strains. Human population density and the latitude of the site of the geographic origin of the tested strain showed significant effects on sleep and activity patterns. Altogether, these results suggest that Ae. albopictus mosquitoes adapt to local environmental conditions via heritable adaptations of their chronotype.

The first record of the invasive mosquito species Aedes albopictus in Yemen

The invasive mosquito Aedes albopictus is regarded as a public health threat due to its ability to transmit pathogens such as dengue and chikungunya viruses, its wide range of hosts, and its ecological plasticity. Aedes albopictus has already invaded parts of the Middle East region and further expansion is expected. Twenty-two sites in three districts of Yemen (Al Ghaydha, Hawf, and Sayhout) were screened for the presence of mosquitoes. We surveyed water bodies and containers, and deployed Centers for Disease Control and Prevention (CDC) and Biogents Sentinel (BG) traps, spray catches, and aspiration for adult collection. Aedes albopictus was recorded for the first time in Yemen in September 2023, during routine surveillance in Al Mahrah Governorate. Adults and immature stages of Ae. albopictus were identified in Hawf, a city 17 m above sea level in the easternmost part of the Governorate of Al Mahrah, which is located less than 8 km from the border with Oman. Our findings showed that Ae. albopictus adults were coexisting with both Ae des aegypti and Anopheles stephensi in the same location and occupying the same containers with Ae. aegypti with a ratio of 1:2. This is the first report on the presence of Ae. albopictus in Yemen. The proximity, ongoing human activity and transportation exchanges between Al Mahrah and Oman may have played a role in the introduction of this species. Intensive efforts should be undertaken to monitor and manage Ae. albopictus spread in the country, in addition to coordinating cross-border surveillance with Oman. The presence of both Aedes spp. vectors together highlights the need for surveillance for associated diseases and consideration of countermeasures.

Quantitative modelling for dengue and Aedes mosquitoes in Africa: A systematic review of current approaches and future directions for Early Warning System development

The rapid spread and growing number of dengue cases worldwide, alongside the absence of comprehensive vaccines and medications, highlights the critical need for robust tools to monitor, prevent, and control the disease. This review aims to provide an updated overview of important covariates and quantitative modelling techniques used to predict or forecast dengue and/or its vector Aedes mosquitoes in Africa. A systematic search was conducted across multiple databases, including PubMed, EMBASE, EBSCOhost, and Scopus, restricted to studies conducted in Africa and published in English. Data management and extraction process followed the 'Preferred Reporting Items for Systematic Reviews and Meta-Analyses' (PRISMA) framework. The review identified 30 studies, with the majority (two-thirds) focused on models for predicting Aedes mosquito populations dynamics as a proxy for dengue risk. The remainder of the studies utilized human dengue cases, incidence or prevalence data as an outcome. Input data for mosquito and dengue risk models were mainly obtained from entomological studies and cross-sectional surveys, respectively. More than half of the studies (56.7%) incorporated climatic factors, such as rainfall, humidity, and temperature, alongside environmental, demographic, socio-economic, and larval/pupal abundance factors as covariates in their models. Regarding quantitative modelling techniques, traditional statistical regression methods like logistic and linear regression were preferred (60.0%), followed by machine learning models (16.7%) and mixed effects models (13.3%). Notably, only 36.7% of the models disclosed variable selection techniques, and a mere 20.0% conducted model validation, highlighting a significant gap in reporting methodology and assessing model performance. Overall, this review provides a comprehensive overview of potential covariates and methodological approaches currently applied in the African context for modelling dengue and/or its vector, Aedes mosquito. It also underscores the gaps and challenges posed by limited surveillance data availability, which hinder the development of predictive models to be used as early warning systems in Africa.

An update on the ocular manifestations of dengue

Dengue is the most common arboviral disease. It is typically spread by the bite of an infected female Aedes aegypti or Aedes albopictus mosquitoes. Dengue is endemic in subtropical and tropical regions, but its geographic reach keeps expanding. Ophthalmic manifestations of dengue are common and may present with a wide spectrum of ophthalmic findings. These may range from conjunctival petechiae, retinal hemorrhage, retinal vasculitis to panophthalmitis. Some of these may be vision threatening and may require urgent ophthalmic evaluation. The precise pathophysiologic mechanisms involved in dengue infection involve a complex interplay between host immune responses, virus, and host genes. There is no specific treatment for ocular dengue. Therefore, treatment is supportive. Despite the lack of proven efficacy, corticosteroids have been used in vision-threatening dengue-related ocular complications. Dengue must be considered in endemic areas, and a careful travel history needs to be elicited in nonendemic areas.

Potential climate change effects on the distribution of urban and sylvatic dengue and yellow fever vectors

Climate change may increase the risk of dengue and yellow fever transmission by urban and sylvatic mosquito vectors. Previous research primarily focused on Aedes aegypti and Aedes albopictus. However, dengue and yellow fever have a complex transmission cycle involving sylvatic vectors. Our aim was to analyze how the distribution of areas favorable to both urban and sylvatic vectors could be modified as a consequence of climate change. We projected, to future scenarios, baseline distribution models already published for these vectors based on the favorability function, and mapped the areas where mosquitoes' favorability could increase, decrease or remain stable in the near (2041-2060) and distant (2061-2080) future. Favorable areas for the presence of dengue and yellow fever vectors show little differences in the future compared to the baseline models, with changes being perceptible only at regional scales. The model projections predict dengue vectors expanding in West and Central Africa and in South-East Asia, reaching Borneo. Yellow fever vectors could spread in West and Central Africa and in the Amazon. In some locations of Europe, the models suggest a reestablishment of Ae. aegypti, while Ae. albopictus will continue to find new favorable areas. The results underline the need to focus more on vectors Ae. vittatus, Ae. luteocephalus and Ae. africanus in West and Central sub-Saharan Africa, especially Cameroon, Central Africa Republic, and northern Democratic Republic of Congo; and underscore the importance of enhancing entomological monitoring in areas where populations of often overlooked vectors may thrive as a result of climate changes.

Systematic Review of Impacts of Educational Interventions to Control Breeding Sites of Aedes aegypti and Aedes albopictus Mosquitoes

Community participation is a critical element in the management of Aedes aegypti and Aedes albopictus breeding sites. Many educational interventions have been conducted to encourage prevention and elimination of breeding sites among different community actors, such as government-run programs for vector surveillance aimed at preventing and eliminating breeding sites at the household level within a community. Getting people involved in prevention and elimination of vector breeding sites in their communities requires communication and social mobilization strategies to promote and reinforce those prevention actions that, in turn, should be effective from the entomological standpoint. Articles published in English, Spanish, and Portuguese, were reviewed to assess whether educational interventions targeting Ae. aegypti and Ae. albopictus were effective in reducing entomological indicators or in improving practices to prevent the presence of or eliminate breeding sites. The most widely used indicators were larval indices and the practices associated with reducing/eliminating breeding sites. We found that using a community-based approach adapted to eco-epidemiological and sociocultural scenarios explains the reduction of entomological indicators by educational interventions. Those who design or implement educational interventions should strengthen the evaluation of those interventions using qualitative approaches that provide a more complete picture of the social context and the barriers and facilitators to implementing vector control. Engaging school children in cross-sectorial collaboration involving the health and education spheres promotes the participation of the community in vector surveillance and reduces the risk of arboviral disease transmission.

Anopheles mosquitoes in Morocco: implication for public health and underlined challenges for malaria re-establishment prevention under current and future climate conditions

BACKGROUND

The potential reappearance and/or expansion of vector-borne diseases is one of the terrifying issues awaiting humanity in the context of climate change. The presence of competent Anopheles vectors, as well as suitable environmental circumstances, may result in the re-emergence of autochthonous Malaria, after years of absence. In Morocco, international travel and migration movements from Malaria-endemic areas have recently increased the number of imported cases, raising awareness of Malaria's possible reintroduction. Using machine learning we developed model predictions, under current and future (2050) climate, for the prospective distribution of Anopheles claviger, Anopheles labranchiae, Anopheles multicolor, and Anopheles sergentii implicated or incriminated in Malaria transmission.

RESULTS

All modelled species are expected to find suitable habitats and have the potential to become established in the northern and central parts of the country, under present-day conditions. Distinct changes in the distributions of the four mosquitoes are to be expected under climate change. Even under the most optimistic scenario, all investigated species are likely to acquire new habitats that are now unsuitable, placing further populations in danger. We also observed a northward and altitudinal shift in their distribution towards higher altitudes.

CONCLUSION

Climate change is expected to expand the potential range of malaria vectors in Morocco. Our maps and predictions offer a way to intelligently focus efforts on surveillance and control programmes. To reduce the threat of human infection, it is crucial for public health authorities, entomological surveillance teams, and control initiatives to collaborate and intensify their actions, continuously monitoring areas at risk. © 2023 Society of Chemical Industry.

Possible potential spread of Anopheles stephensi, the Asian malaria vector

BACKGROUND

Anopheles stephensi is native to Southeast Asia and the Arabian Peninsula and has emerged as an effective and invasive malaria vector. Since invasion was reported in Djibouti in 2012, the global invasion range of An. stephensi has been expanding, and its high adaptability to the environment and the ongoing development of drug resistance have created new challenges for malaria control. Climate change is an important factor affecting the distribution and transfer of species, and understanding the distribution of An. stephensi is an important part of malaria control measures, including vector control.

METHODS

In this study, we collected existing distribution data for An. stephensi, and based on the SSP1-2.6 future climate data, we used the Biomod2 package in R Studio through the use of multiple different model methods such as maximum entropy models (MAXENT) and random forest (RF) in this study to map the predicted global An. stephensi climatically suitable areas.

RESULTS

According to the predictions of this study, some areas where there are no current records of An. stephensi, showed significant areas of climatically suitable for An. stephensi. In addition, the global climatically suitability areas for An. stephensi are expanding with global climate change, with some areas changing from unsuitable to suitable, suggesting a greater risk of invasion of An. stephensi in these areas, with the attendant possibility of a resurgence of malaria, as has been the case in Djibouti.

CONCLUSIONS

This study provides evidence for the possible invasion and expansion of An. stephensi and serves as a reference for the optimization of targeted monitoring and control strategies for this malaria vector in potential invasion risk areas.

Aedes albopictus colonies from different geographic origins differ in their sleep and activity levels but not in the time of peak activity

Mosquitoes occupy a wide range of habitats where they experience various environmental conditions. The ability of some species, such as the tiger mosquito, Aedes albopictus, to adapt to local conditions certainly contributes to their invasive success. Among traits that remain to be examined, mosquitoes' ability to time their activity with that of the local host population has been suggested to be of significant epidemiological importance. However, whether different populations display heritable differences in their chronotype has not been examined. Here, we compared laboratory strains originating from 8 populations from 3 continents, monitored their spontaneous locomotor activity patterns, and analyzed their sleep-like states. Overall, all strains showed conserved diurnal activity concentrated in the hours preceding the crepuscule. Similarly, they all showed increased sleep levels during the morning and night hours. However, we observed strain-specific differences in the activity levels at each phase of the day. We also observed differences in the fraction of time that each strain spends in a sleep-like state, explained by variations in the sleep architecture across strains. Human population density and the latitude of the site of geographic origin of the tested strain showed significant effects on sleep and activity patterns. Altogether, these results suggest that Ae. albopictus mosquitoes adapt to local environmental conditions via heritable adaptations of their chronotype.

Aedes albopictus is present in the lowlands of southern Zambia

Identifying the current geographic range of disease vectors is a critical first step towards determining effective mechanisms for controlling and potentially eradicating them. This is particularly true given that historical vector ranges may expand due to changing climates and human activity. The Aedes subgenus Stegomyia contains over 100 species, and among them, Ae. aegypti and Ae. albopictus mosquitoes represent the largest concern for public health, spreading dengue, chikungunya, and zika viruses. While Ae. aegypti has been observed in the country of Zambia for decades, Ae. albopictus has not. In 2015 we sampled four urban and three rural areas in Zambia for Aedes species. Using DNA barcoding, we confirmed the presence of immature and adult Ae. albopictus at two sites: Siavonga and Livingstone. These genotypes seem most closely related to specimens previously collected in Mozambique based on mtDNA barcoding. We resampled Siavonga and Livingstone sites in 2019, again observing immature and adult Ae. albopictus at both sites. Relative Ae. albopictus frequencies were similar between sites, with the exception of immature life stages, which were higher in Siavonga than in Livingstone in 2019. While Ae. albopictus frequencies did not vary through time in Livingstone, both immature and adult frequencies increased through time in Siavonga. This report serves to document the presence of Ae. albopictus in Zambia, which will contribute to understanding the potential public health implications of this disease vector in southern Africa.

The spread of Aedes albopictus (Diptera: Culicidae) in the islands of São Tomé and Príncipe

The mosquito Aedes albopictus (Diptera: Culicidae) is a vector species of the causal agents of Dengue, yellow fever, and Zika among other diseases pathogens. The species originated in Southeast Asia and has spread widely and rapidly in the last century. The species has been reported in localities from the Gulf of Guinea since the early 2000s, but systematic sampling has been scant. We sampled Ae. albopictus twice, in 2013 and 2023 across the altitudinal gradient in São Tomé and found that the species was present in all sampled years at altitudes up to 680 m. We also found some evidence of increases in proportional representation compared to Ae. aegypti over time. We report the presence of the species in Príncipe for the first time, suggesting that the range of Ae. albopictus is larger than previously thought. Finally, we use bioclimatic niche modeling to infer the potential range of Ae. albopictus and infer that the species has the potential to spread across a large portion of São Tomé and Príncipe. Our results suggest that Ae. albopictus has established itself as a resident species of the islands of the Gulf of Guinea and should be incorporated into the list of potential vectors that need to be surveyed and controlled.

Global Prevalence of Zika and Chikungunya Coinfection: A Systematic Review and Meta-Analysis

Zika virus (ZIKV) and chikungunya virus (CHIKV) are arthropod-borne viruses with significant pathogenicity, posing a substantial health and economic burden on a global scale. Moreover, ZIKV-CHIKV coinfection imposes additional therapeutic challenges as there is no specific treatment for ZIKV or CHIKV infection. While a growing number of studies have documented the ZIKV-CHIKV coinfection, there is currently a lack of conclusive reports on this coinfection. Therefore, we performed a systematic review and meta-analysis to determine the true statistics of ZIKV-CHIKV coinfection in the global human population. Relevant studies were searched for in PubMed, Scopus, and Google Scholar without limitation in terms of language or publication date. A total of 33 studies containing 41,460 participants were included in this meta-analysis. The study protocol was registered with PROSPERO under the registration number CRD42020176409. The pooled prevalence and confidence intervals of ZIKV-CHIKV coinfection were computed using a random-effects model. The study estimated a combined global prevalence rate of 1.0% [95% CI: 0.7-1.2] for the occurrence of ZIKV-CHIKV coinfection. The region of North America (Mexico, Haiti, and Nicaragua) and the country of Haiti demonstrated maximum prevalence rates of 2.8% [95% CI: 1.5-4.1] and 3.5% [95% CI: 0.2-6.8], respectively. Moreover, the prevalence of coinfection was found to be higher in the paediatric group (2.1% [95% CI: 0.0-4.2]) in comparison with the adult group (0.7% [95% CI: 0.2-1.1]). These findings suggest that the occurrence of ZIKV-CHIKV coinfection varies geographically and by age group. The results of this meta-analysis will guide future investigations seeking to understand the underlying reasons for these variations and the causes of coinfection and to develop targeted prevention and control strategies.

The accumulation of modular serine protease mediated by a novel circRNA sponging miRNA increases Aedes aegypti immunity to fungus

BACKGROUND

Mosquitoes transmit many infectious diseases that affect human health. The fungus Beauveria bassiana is a biological pesticide that is pathogenic to mosquitoes but harmless to the environment.

RESULTS

We found a microRNA (miRNA) that can modulate the antifungal immunity of Aedes aegypti by inhibiting its cognate serine protease. Fungal infection can induce the expression of modular serine protease (ModSP), and ModSP knockdown mosquitoes were more sensitive to B. bassiana infection. The novel miRNA-novel-53 is linked to antifungal immune response and was greatly diminished in infected mosquitoes. The miRNA-novel-53 could bind to the coding sequences of ModSP and impede its expression. Double fluorescence in situ hybridization (FISH) showed that this inhibition occurred in the cytoplasm. The amount of miRNA-novel-53 increased after miRNA agomir injection. This resulted in a significant decrease in ModSP transcript and a significant increase in mortality after fungal infection. An opposite effect was produced after antagomir injection. The miRNA-novel-53 was also knocked out using CRISPR-Cas9, which increased mosquito resistance to the fungus B. bassiana. Moreover, mosquito novel-circ-930 can affect ModSP mRNA by interacting with miRNA-novel-53 during transfection with siRNA or overexpression plasmid.

CONCLUSIONS

Novel-circ-930 affects the expression level of ModSP by a novel-circ-930/miRNA-novel-53/ModSP mechanism to modulate antifungal immunity, revealing new information on innate immunity in insects.

Dengue and chikungunya: future threats for Northern Europe?

Arthropod-borne viral diseases are likely to be affected by the consequences of climate change with an increase in their distribution and intensity. Among these infectious diseases, chikungunya and dengue viruses are two (re)emergent arboviruses transmitted by Aedes species mosquitoes and which have recently demonstrated their capacity for rapid expansion. They most often cause mild diseases, but they can both be associated with complications and severe forms. In Europe, following the establishment of invasive Aedes spp, the first outbreaks of autochtonous dengue and chikungunya have already occurred. Northern Europe is currently relatively spared, but climatic projections show that the conditions are permissive for the establishment of Aedes albopictus (also known as the tiger mosquito) in the coming decades. It is therefore essential to question and improve the means of surveillance in northern Europe, at the dawn of inevitable future epidemics.

Automated analysis of feeding behaviors of females of the mosquito Aedes aegypti using a modified flyPAD system

Mosquitoes present a global health challenge due to their ability to transmit human and animal pathogens upon biting and blood feeding. The investigation of tastants detected by mosquitoes and their associated feeding behaviors is needed to answer physiological and ecological questions that could lead to novel control methods. A high-throughput system originally developed for research in fruit flies feeding behavior, the flyPAD, was adapted and tested for behaviors associated with the interaction or consumption of liquid diets offered to females of the mosquito Aedes aegypti Liverpool strain. Females were given water, sucrose solution and sheep blood in choice and non-choice assays. The volume ingested was evaluated with fluorescein. The placement of the system on a heated surface allowed blood consumption, and without females puncturing a membrane. The flyPAD system recorded nine feeding behavioral variables, of which the number of sips and number of activity bouts correlated with meal volume ingested for both sucrose solution and blood. The adaptation to mosquitoes of the flyPAD system differentiated feeding behavior variables between two feeding deterrents, capsaicin, and caffeine. The flyPAD has potential to quickly assess diverse tastants in both sucrose and blood and may contribute to characterizing more precisely their mode of action.

Niche and Range Shifts of Aedes aegypti and Ae. albopictus Suggest That the Latecomer Shows a Greater Invasiveness

The yellow fever (Aedes aegypti) and Asian tiger (Ae. albopictus) mosquitos are major vectors of global mosquito-borne pathogens. However, their niche and range shifts, the underlying mechanisms, and related relative invasion rates remain scarcely known. We examined the niche and range shifts between the native and invasive Ae. aegypti and Ae. albopictus populations through dynamic niche and range models and the largest occurrence record datasets to date. We detected substantial niche and range expansions in both species, probably because the introduced populations have more opportunities to acclimate to diverse environmental conditions than their native counterparts. Mitigating climate change could effectively control their future invasions, given that future climate changes could promote their invasiveness. Additionally, compared to the introduced Ae. aegypti, the more recent invader Ae. albopictus had greater niche and range expansion over its shorter invasion history. In terms of the range shifts, Ae. albopictus had an invasion rate approximately 13.3 times faster than that of Ae. aegypti, making it a more invasive vector of global mosquito-borne pathogens. Therefore, considering its higher invasion rate, much more attention should be paid to Ae. albopictus in devising our strategies against prevailing global mosquito-borne pathogens than Ae. aegypti. Since small niche shifts could result in their large range shifts, niche shifts might be a more important indicator for biological invasion assessments.

Potential Global Distribution of the Invasive Mosquito Aedes koreicus under a Changing Climate

Invasive alien species are a growing threat to natural systems, the economy, and human health. Active surveillance and responses that readily suppress newly established colonies are effective actions to mitigate the noxious consequences of biological invasions. Aedes (Hulecoeteomyia) koreicus (Edwards), a mosquito species native to East Asia, has spread to parts of Europe and Central Asia since 2008. In the last decade, Ae. koreicus has been shown to be a competent vector for chikungunya virus and Dirofilaria immitis. However, information about the current and potential distribution of Ae. koreicus is limited. Therefore, to understand the changes in their global distribution and to contribute to the monitoring and control of Ae. koreicus, in this study, the MaxEnt model was used to predict and analyze the current suitable distribution area of Ae. koreicus in the world to provide effective information.

Trends in mosquito species distribution modeling: insights for vector surveillance and disease control

Species distribution modeling (SDM) has become an increasingly common approach to explore questions about ecology, geography, outbreak risk, and global change as they relate to infectious disease vectors. Here, we conducted a systematic review of the scientific literature, screening 563 abstracts and identifying 204 studies that used SDMs to produce distribution estimates for mosquito species. While the number of studies employing SDM methods has increased markedly over the past decade, the overwhelming majority used a single method (maximum entropy modeling; MaxEnt) and focused on human infectious disease vectors or their close relatives. The majority of regional models were developed for areas in Africa and Asia, while more localized modeling efforts were most common for North America and Europe. Findings from this study highlight gaps in taxonomic, geographic, and methodological foci of current SDM literature for mosquitoes that can guide future efforts to study the geography of mosquito-borne disease risk.

New weapons against the disease vector Aedes aegypti: From natural products to nanoparticles

Despite the global burden of viral diseases transmitted by Aedes aegypti, there is a lack of effective means of prevention and treatment. Strategies for vector control include chemical and biological approaches such as organophosphates and Bacillus thuringiensis var. israelensis (Bti), among others. However, important concerns are associated, such as resistance in mosquito larvae and deleterious effects on non-target organisms. In this scenario, novel approaches against A. aegypti have been investigated, including natural products (e.g. vegetable oil and extracts) and nanostructured systems. This review focuses on potential strategies for fighting A. aegypti, highlighting plant-based materials and nanomaterials able to induce toxic effects on egg, larva, pupa and adult mosquitoes. Issues including aspects of conventional vector control strategies are presented, and finally new insights on development of eco-friendly nanoformulations against A. aegypti are discussed.

Non-target effects of chemical malaria vector control on other biological and mechanical infectious disease vectors

Public health insecticides play a crucial role in malaria control and elimination programmes. Many other arthropods, including mechanical and biological vectors of infectious diseases, have similar indoor feeding or resting behaviours, or both, as malaria mosquitoes, and could be exposed to the same insecticides. In this Personal View, we show that little is known about the insecticide susceptibility status and the extent of exposure to malaria interventions of other arthropod species. We highlight that there is an urgent need to better understand the selection pressure for insecticide resistance in those vectors, to ensure current and future active ingredients remain effective in targeting a broad range of arthropod species, allowing us to prevent and control future outbreaks of infectious diseases other than malaria.

Nanoliposomes containing three essential oils from the Artemisia genus as effective larvicides against Aedes aegypti and Anopheles stephensi

Aedes aegypti and Anopheles stephensi have challenged human health by transmitting several infectious disease agents, such as malaria, dengue fever, and yellow fever. Larvicides, especially in endemic regions, is an effective approach to the control of mosquito-borne diseases. In this study, the composition of three essential oil from the Artemisia L. family was analyzed by Gas Chromatography-Mass Spectrometry. Afterward, nanoliposomes containing essential oils of A. annua, A. dracunculus, and A. sieberi with particle sizes of 137 ± 5, 151 ± 6, and 92 ± 5 nm were prepared. Besides, their zeta potential values were obtained at 32 ± 0.5, 32 ± 0.6, and 43 ± 1.7 mV. ATR-FTIR analysis (Attenuated Total Reflection-Fourier Transform InfraRed) confirmed the successful loading of the essential oils. Moreover, The LC50 values of nanoliposomes against Ae. aegypti larvae were 34, 151, and 197 µg/mL. These values for An.stephensi were obtained as 23 and 90, and 140 µg/mL, respectively. The results revealed that nanoliposomes containing A. dracunculus exerted the highest potential larvicidal effect against Ae. aegypti and An. stephensi, which can be considered against other mosquitoes.

Equine Polyclonal Antibodies Prevent Acute Chikungunya Virus Infection in Mice

Chikungunya virus (CHIKV) is a mosquito-transmitted pathogen that causes chikungunya disease (CHIK); the disease is characterized by fever, muscle ache, rash, and arthralgia. This arthralgia can be debilitating and long-lasting, seriously impacting quality of life for years. Currently, there is no specific therapy available for CHIKV infection. We have developed a despeciated equine polyclonal antibody (CHIKV-EIG) treatment against CHIKV and evaluated its protective efficacy in mouse models of CHIKV infection. In immunocompromised (IFNAR^-/-) mice infected with CHIKV, daily treatment for five consecutive days with CHIKV-EIG administered at 100 mg/kg starting on the day of infection prevented mortality, reduced viremia, and improved clinical condition as measured by body weight loss. These beneficial effects were seen even when treatment was delayed to 1 day after infection. In immunocompetent mice, CHIKV-EIG treatment reduced virus induced arthritis (including footpad swelling), arthralgia-associated cytokines, viremia, and tissue virus loads in a dose-dependent fashion. Collectively, these results suggest that CHIKV-EIG is effective at preventing CHIK and could be a viable candidate for further development as a treatment for human disease.

Impact of regional climate change on the mosquito vector Aedes albopictus in a tropical island environment: La Réunion

The recent expansion of Aedes albopictus across continents in both tropical and temperate regions and the exponential growth of dengue cases over the past 50 years represent a significant risk to human health. Although climate change is not the only factor responsible for the increase and spread of dengue cases worldwide, it might increase the risk of disease transmission at global and regional scale. Here we show that regional and local variations in climate can induce differential impacts on the abundance of Ae. albopictus. We use the instructive example of Réunion Island with its varied climatic and environmental conditions and benefiting from the availability of meteorological, climatic, entomological and epidemiological data. Temperature and precipitation data based on regional climate model simulations (3 km × 3 km) are used as inputs to a mosquito population model for three different climate emission scenarios. Our objective is to study the impact of climate change on the life cycle dynamics of Ae. albopictus in the 2070-2100 time horizon. Our results show the joint influence of temperature and precipitation on Ae. albopictus abundance as a function of elevation and geographical subregion. At low-elevations areas, decreasing precipitation is expected to have a negative impact on environmental carrying capacity and, consequently, on Ae. albopictus abundance. At mid- and high-elevations, decreasing precipitation is expected to be counterbalanced by a significant warming, leading to faster development rates at all life stages, and consequently increasing the abundance of this important dengue vector in 2070-2100.

A Habitat Model for Disease Vector Aedes aegypti in the Tampa Bay Area, FloridA

Within the contiguous USA, Florida is unique in having tropical and subtropical climates, a great abundance and diversity of mosquito vectors, and high rates of human travel. These factors contribute to the state being the national ground zero for exotic mosquito-borne diseases, as evidenced by local transmission of viruses spread by Aedes aegypti, including outbreaks of dengue in 2022 and Zika in 2016. Because of limited treatment options, integrated vector management is a key part of mitigating these arboviruses. Practical knowledge of when and where mosquito populations of interest exist is critical for surveillance and control efforts, and habitat predictions at various geographic scales typically rely on ecological niche modeling. However, most of these models, usually created in partnership with academic institutions, demand resources that otherwise may be too time-demanding or difficult for mosquito control programs to replicate and use effectively. Such resources may include intensive computational requirements, high spatiotemporal resolutions of data not regularly available, and/or expert knowledge of statistical analysis. Therefore, our study aims to partner with mosquito control agencies in generating operationally useful mosquito abundance models. Given the increasing threat of mosquito-borne disease transmission in Florida, our analytic approach targets recent Ae. aegypti abundance in the Tampa Bay area. We investigate explanatory variables that: 1) are publicly available, 2) require little to no preprocessing for use, and 3) are known factors associated with Ae. aegypti ecology. Out of our 4 final models, none required more than 5 out of the 36 predictors assessed (13.9%). Similar to previous literature, the strongest predictors were consistently 3- and 4-wk temperature and precipitation lags, followed closely by 1 of 2 environmental predictors: land use/land cover or normalized difference vegetation index. Surprisingly, 3 of our 4 final models included one or more socioeconomic or demographic predictors. In general, larger sample sizes of trap collections and/or citizen science observations should result in greater confidence in model predictions and validation. However, given disparities in trap collections across jurisdictions, individual county models rather than a multicounty conglomerate model would likely yield stronger model fits. Ultimately, we hope that the results of our assessment will enable more accurate and precise mosquito surveillance and control of Ae. aegypti in Florida and beyond.

Entomological surveillance of invasive Aedes mosquitoes in Mazandaran Province, northern Iran from 2014 to 2020

Mosquitoes are the most important vectors of serious infectious diseases in the world. Dengue, Zika, chikungunya and yellow fever are emerging and re-emerging infectious diseases, associated with the distribution of two key vectors i.e. Aedes aegypti and Aedes albopictus throughout the world including countries neighbouring Iran. Entomological surveillance was planned and performed monthly from May to December during 2014-2020 in selected counties of Mazandaran Province, North of Iran, by ovitrap, larval collection, hand catch and human baited trap. Overall, 4410 Aedes specimens including 2376 larvae (53.9%) and 2034 (46.1%) adults belonging to six species, namely Aedes vexans, Aedes geniculatus, Aedes caspius, Aedes echinus, Aedes pulcritarsis and Aedes flavescence were collected and morphologically identified. Over the seven years of surveillance, Ae. aegypti and Ae. albopictus were not found by any sampling method. Aedes vexans and Ae. geniculatus were the most abundant species, their populations peaked in October and November and was positively correlated with precipitation and relative humidity. Aedes flavescence was a new species record for the province. A flowchart for planning and implementation of invasive mosquito surveillance for provincial health authorities in the country is proposed. These surveillance efforts provide basic and timely information for the health system to act promptly on integrated and intensified surveillance and control programs should Ae. aegypti and Ae. albopictus detected in the province.

Machine Learning Modeling of Aedes albopictus Habitat Suitability in the 21st Century

The Asian tiger mosquito, Aedes albopictus, is an important vector of arboviruses that cause diseases such as dengue, chikungunya, and zika. The vector is highly invasive and adapted to survive in temperate northern territories outside its native tropical and sub-tropical range. Climate and socio-economic change are expected to facilitate its range expansion and exacerbate the global vector-borne disease burden. To project shifts in the global habitat suitability of the vector, we developed an ensemble machine learning model, incorporating a combination of a Random Forest and XGBoost binary classifiers, trained with a global collection of vector surveillance data and an extensive set of climate and environmental constraints. We demonstrate the reliable performance and wide applicability of the ensemble model in comparison to the known global presence of the vector, and project that suitable habitats will expand globally, most significantly in the northern hemisphere, putting at least an additional billion people at risk of vector-borne diseases by the middle of the 21st century. We project several highly populated areas of the world will be suitable for Ae. albopictus populations, such as the northern parts of the USA, Europe, and India by the end of the century, which highlights the need for coordinated preventive surveillance efforts of potential entry points by local authorities and stakeholders.

A pH-dependent cluster of charges in a conserved cryptic pocket on flaviviral envelopes

Flaviviruses are enveloped viruses which include human pathogens that are predominantly transmitted by mosquitoes and ticks. Some, such as dengue virus, exhibit the phenomenon of antibody-dependent enhancement (ADE) of disease, making vaccine-based routes of fighting infections problematic. The pH-dependent conformational change of the envelope (E) protein required for fusion between the viral and endosomal membranes is an attractive point of inhibition by antivirals as it has the potential to diminish the effects of ADE. We examined six flaviviruses by employing large-scale molecular dynamics (MD) simulations of raft systems that represent a substantial portion of the flaviviral envelope. We utilised a benzene-mapping approach that led to a discovery of shared hotspots and conserved cryptic sites. A cryptic pocket previously shown to bind a detergent molecule exhibited strain-specific characteristics. An alternative conserved cryptic site at the E protein domain interfaces showed a consistent dynamic behaviour across flaviviruses and contained a conserved cluster of ionisable residues. Constant-pH simulations revealed cluster and domain-interface disruption under low pH conditions. Based on this, we propose a cluster-dependent mechanism that addresses inconsistencies in the histidine-switch hypothesis and highlights the role of cluster protonation in orchestrating the domain dissociation pivotal for the formation of the fusogenic trimer.

Egg-laying by female Aedes aegypti shapes the bacterial communities of breeding sites

BACKGROUND

Aedes aegypti, the main arboviral mosquito vector, is attracted to human dwellings and makes use of human-generated breeding sites. Past research has shown that bacterial communities associated with such sites undergo compositional shifts as larvae develop and that exposure to different bacteria during larval stages can have an impact on mosquito development and life-history traits. Based on these facts, we hypothesized that female Ae. aegypti shape the bacteria communities of breeding sites during oviposition as a form of niche construction to favor offspring fitness.

RESULTS

To test this hypothesis, we first verified that gravid females can act as mechanical vectors of bacteria. We then elaborated an experimental scheme to test the impact of oviposition on breeding site microbiota. Five different groups of experimental breeding sites were set up with a sterile aqueous solution of larval food, and subsequently exposed to (1) the environment alone, (2) surface-sterilized eggs, (3) unsterilized eggs, (4) a non-egg laying female, or (5) oviposition by a gravid female. The microbiota of these differently treated sites was assessed by amplicon-oriented DNA sequencing once the larvae from the sites with eggs had completed development and formed pupae. Microbial ecology analyses revealed significant differences between the five treatments in terms of diversity. In particular, between-treatment shifts in abundance profiles were detected, showing that females induce a significant decrease in microbial alpha diversity through oviposition. In addition, indicator species analysis pinpointed bacterial taxa with significant predicting values and fidelity coefficients for the samples in which single females laid eggs. Furthermore, we provide evidence regarding how one of these indicator taxa, Elizabethkingia, exerts a positive effect on the development and fitness of mosquito larvae.

CONCLUSIONS

Ovipositing females impact the composition of the microbial community associated with a breeding site, promoting certain bacterial taxa over those prevailing in the environment. Among these bacteria, we found known mosquito symbionts and showed that they can improve offspring fitness if present in the water where eggs are laid. We deem this oviposition-mediated bacterial community shaping as a form of niche construction initiated by the gravid female.

Chikungunya fever

Chikungunya virus is widespread throughout the tropics, where it causes recurrent outbreaks of chikungunya fever. In recent years, outbreaks have afflicted populations in East and Central Africa, South America and Southeast Asia. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Chikungunya fever is characterized by severe arthralgia and myalgia that can persist for years and have considerable detrimental effects on health, quality of life and economic productivity. The effects of climate change as well as increased globalization of commerce and travel have led to growth of the habitat of Aedes mosquitoes. As a result, increasing numbers of people will be at risk of chikungunya fever in the coming years. In the absence of specific antiviral treatments and with vaccines still in development, surveillance and vector control are essential to suppress re-emergence and epidemics.

Chikungunya: risks for travellers

RATIONALE FOR REVIEW

Chikungunya outbreaks continue to occur, with changing epidemiology. Awareness about chikungunya is low both among the at-risk travellers and healthcare professionals, which can result in underdiagnosis and underreporting. This review aims to improve awareness among healthcare professionals regarding the risks of chikungunya for travellers.

KEY FINDINGS

Chikungunya virus transmission to humans occurs mainly via daytime-active mosquitoes, Aedes aegypti and Aedes albopictus. The areas where these mosquitoes live is continuously expanding, partly due to climate changes. Chikungunya is characterized by an acute onset of fever with joint pain. These symptoms generally resolve within 1-3 weeks, but at least one-third of the patients suffer from debilitating rheumatologic symptoms for months to years. Large outbreaks in changing regions of the world since the turn of the 21st century (e.g. Caribbean, La Réunion; currently Brazil, India) have resulted in growing numbers of travellers importing chikungunya, mainly to Europe and North America. Viremic travellers with chikungunya infection have seeded chikungunya clusters (France, United States of America) and outbreaks (Italy in 2007 and 2017) in non-endemic countries where Ae. albopictus mosquitoes are present. Community preventive measures are important to prevent disease transmission by mosquitoes. Individual preventive options are limited to personal protection measures against mosquito bites, particularly the daytime-active mosquitos that transmit the chikungunya virus. Candidate vaccines are on the horizon and regulatory authorities will need to assess environmental and host risk factors for persistent sequelae, such as obesity, age (over 40 years) and history of arthritis or inflammatory rheumatologic disease to determine which populations should be targeted for these chikungunya vaccines.

CONCLUSIONS/RECOMMENDATIONS

Travellers planning to visit destinations with active CHIKV circulation should be advised about the risk for chikungunya, prevention strategies, the disease manifestations, possible chronic rheumatologic sequelae and, if symptomatic, seek medical evaluation and report potential exposures.

Aedes albopictus (Skuse) dispersion in Havana City, Cuba, 1995-2018

Various arboviruses are transmitted to humans by mosquitoes, particularly Aedes aegypti and Aedes albopictus, two invasive and frequently sympatric species. The objective of this study was to evaluate the dispersion and the behavior of Ae. albopictus in relation to houses and its association with other mosquitoes in the province of Havana, Cuba. All water-containing deposits in the houses or vacant lots in urban and peri‑urban municipalities of the province of Havana were sampled during the two study periods: 1995-1999 and 2010-2018. The following patterns in the presence of Ae. albopictus in the study area were observed: a persistent absence of Ae. albopictus in one of the municipalities; a rapid dispersion in the second period, staring from the absence of vector in the first period, in tow other municipalities; and a sustained decrease in the dispersion of Ae.albopictus in two other municipalities. The peripheral municipalities noted the highest presence of Ae. albopictus, but few associations with other mosquitoes. However, overall, we found an increase in this association when comparing the period 2010-2018 with the first period. Ae. albopictus was present in 8% (2016) to 21.5% (2013) inside the houses with an average of 15%, which evidences an initial domiciliation of the species. The results obtained in this work show an initiation of domiciliation of Ae. albopictus in the urban area of the province of Havana. This is important to alert the National Control Program to strengthen the entomological monitoring of Ae. albopictus, and not only Ae. aegypti. The follow-up of this domiciliation is important to guide control efforts, knowing its role as a vector of different arboviruses.

Climate change and Aedes albopictus risks in China: current impact and future projection

BACKGROUND

Future distribution of dengue risk is usually predicted based on predicted climate changes using general circulation models (GCMs). However, it is difficult to validate the GCM results and assess the uncertainty of the predictions. The observed changes in climate may be very different from the GCM results. We aim to utilize trends in observed climate dynamics to predict future risks of Aedes albopictus in China.

METHODS

We collected Ae. albopictus surveillance data and observed climate records from 80 meteorological stations from 1970 to 2021. We analyzed the trends in climate change in China and made predictions on future climate for the years 2050 and 2080 based on trend analyses. We analyzed the relationship between climatic variables and the prevalence of Ae. albopictus in different months/seasons. We built a classification tree model (based on the average of 999 runs of classification and regression tree analyses) to predict the monthly/seasonal Ae. albopictus distribution based on the average climate from 1970 to 2000 and assessed the contributions of different climatic variables to the Ae. albopictus distribution. Using these models, we projected the future distributions of Ae. albopictus for 2050 and 2080.

RESULTS

The study included Ae. albopictus surveillance from 259 sites in China found that winter to early spring (November-February) temperatures were strongly correlated with Ae. albopictus prevalence (prediction accuracy ranges 93.0-98.8%)-the higher the temperature the higher the prevalence, while precipitation in summer (June-September) was important predictor for Ae. albopictus prevalence. The machine learning tree models predicted the current prevalence of Ae. albopictus with high levels of agreement (accuracy > 90% and Kappa agreement > 80% for all 12 months). Overall, winter temperature contributed the most to Ae. albopictus distribution, followed by summer precipitation. An increase in temperature was observed from 1970 to 2021 in most places in China, and annual change rates varied substantially from -0.22 ºC/year to 0.58 ºC/year among sites, with the largest increase in temperature occurring from February to April (an annual increase of 1.4-4.7 ºC in monthly mean, 0.6-4.0 ºC in monthly minimum, and 1.3-4.3 ºC in monthly maximum temperature) and the smallest in November and December. Temperature increases were lower in the tropics/subtropics (1.5-2.3 ºC from February-April) compared to the high-latitude areas (2.6-4.6 ºC from February-April). The projected temperatures in 2050 and 2080 by this study were approximately 1-1.5 °C higher than those projected by GCMs. The estimated current Ae. albopictus risk distribution had a northern boundary of north-central China and the southern edge of northeastern China, with a risk period of June-September. The projected future Ae. albopictus risks in 2050 and 2080 cover nearly all of China, with an expanded risk period of April-October. The current at-risk population was estimated to be 960 million and the future at-risk population was projected to be 1.2 billion.

CONCLUSIONS

The magnitude of climate change in China is likely to surpass GCM predictions. Future dengue risks will expand to cover nearly all of China if current climate trends continue.

Sociodemographic and environmental factors associated with dengue, Zika, and chikungunya among adolescents from two Brazilian capitals

Among the emerging and reemerging arboviral diseases, Zika, dengue and chikungunya deserve special attention due to their wide geographical distribution and clinical severity. The three arboviruses are transmitted by the same vector and can present similar clinical syndromes, bringing challenges to their identification and register. Demographic characteristics and individual and contextual social factors have been associated with the three arboviral diseases. However, little is known about such associations among adolescents, whose relationships with the social environment are different from those of adult populations, implying potentially different places, types, and degrees of exposure to the vector, particularly in the school context. This study aims to identify sociodemographic and environmental risk factors for the occurrence of Zika, dengue, and chikungunya in a cohort of adolescents from the Study of Cardiovascular Risks in Adolescents-ERICA-in the cities of Rio de Janeiro/RJ and Fortaleza/CE, from January 2015 to March 2019. Cases were defined as adolescents with laboratory or clinical-epidemiological diagnosis of Zika, dengue, or chikungunya, notified and registered in the Information System for Notifiable Diseases (SINAN). The cases were identified by linkage between the databases of the ERICA cohort and of SINAN. Multilevel Cox regression was employed to estimate hazard ratios (HR) as measures of association and respective 95% confidence intervals (95%CI). In comparison with adolescents living in lower socioeconomic conditions, the risk of becoming ill due to any of the three studied arboviral diseases was lower among those living in better socioeconomic conditions (HR = 0.43; 95%CI: 0.19-0.99; p = 0.047) and in the adolescents who attended school in the afternoon period (HR = 0.17; 95%CI: 0.06-0.47; p<0.001). When compared to areas whose Building Infestation Index (BII) for Aedes aegypti was considered satisfactory, a BII in the school region classified as "alert" and "risk" was associated with a higher risk of arboviral diseases (HR = 1.62, 95%CI: 0.98-2.70; p = 0.062; HR = 3.72, 95%CI: 1.27-10.9; p = 0.017, respectively). These findings indicate that living in less favored socioeconomic conditions, attending school in the morning, and having a high BII for Ae. aegypti in school's region can contribute to an increased risk of infection by Zika, dengue, or chikungunya in adolescents. The identification of residential or school areas based on those variables can contribute to the implementation of control measures in population groups and priority locations.