Background: Immature stages of Aedes aegypti develop in many man-made aquatic habitats in which mosquito larvae are exposed to physicochemical elements and microorganisms that may influence their life cycle and their ability to transmit human arboviruses. Despite the omnipresence of Ae. aegypti in tropical and subtropical regions, little is known about the natural bacterial communities associated with this mosquito or their relation to the biotic and abiotic characteristics of their aquatic habitats. We comprehensively characterized the physicochemical properties and bacterial microbiome of Ae. aegypti breeding sites and larvae on Guadeloupe and in French Guiana. In addition, we explored whether geographical location, the type of breeding site and physicochemical parameters of the water influenced the microbiota associated with this mosquito species. Method:We used large-scale 16S rRNA gene sequencing of 160 breeding sites and 147 pools of Ae.aegypti larvae from sites widely distributed across Guadeloupe and French Guiana and recorded 13 physicochemical parameters at the sampled breeding sites. Ordination plots and multiple linear regression were used to assess the influence of environmental factors on the bacterial microbiome of water and larvae. Results:We found territory-specific differences in physicochemical properties (dissolved oxygen, conductivity and metal content) and the composition of bacterial communities in Ae. aegypti breeding sites that influenced the relative abundance of several bacteria genera (Methylobacterium, Roseoccocus) on the corresponding larvae. A significant fraction of the bacterial communities identified on Ae. aegypti larvae, dominated by Herbiconiux and Microvirga genera, were consistently enriched in mosquitoes regardless the location. Conclusion:Territory-specific differences observed in the biotic and abiotic properties of Ae. aegypti breeding sites influenced a fraction of the microbial communities of the corresponding larvae, raising concern about the impact of these changes on pathogen transmission by different Ae. aegypti populations. BackgroundAedes aegypti (Diptera: Culicidae) is a mosquito vector of arboviruses such as yellow fever, dengue, 4 chikungunya and Zika that constitute major global health problems and threaten the French overseas territories of Guadeloupe and French Guiana [1,2]. Besides the high susceptibility for these pathogens, this mosquito is a main vector of arboviruses because it is highly anthropophilic and thrives close to humans in urban and peri-urban areas [3,4]. The species breeds mainly in humanmade containers with volumes ranging from a few millilitres to hectolitres, such as drums, plastic buckets, cisterns, flower vases and rubber tyres [4,5].Water quality is critical for the choice of oviposition site for gravid females to ensure successful, complete development of their progeny from larvae to adults [6,7,8]. Females select breeding sites according to biotic and abiotic elements in the water, such as organic matter [8], bacteria [9, 10], phosp...

Background In 2017, inhabitants along the border between French Guiana and Brazil were affected by a malaria outbreak primarily due to Plasmodium vivax ( Pv ). While malaria cases have steadily declined between 2005-2016 in this Amazonian region, a resurgence was observed in 2017. Methods Two investigations were performed according to two different spatial scales and type of information details. Firstly, a local study on the French Guiana border, which enabled a thorough investigation of the malaria cases treated at the local village health center and of the entomological situation in the most affected neighborhood and secondly a regional and cross-border study, which enabled exploration of the regional spatial-temporal epidemic dynamic. Number and location of malaria cases were estimated using French and Brazilian surveillance systems. Results On the French Guiana side of the border in Saint-Georges de l’Oyapock, the attack rate was 5.5% (n=219/4000), reaching 51.4% (n=90/175) in one Amerindian neighborhood. Entomological findings suggest a peak of Anopheles darlingi density in August and September. Two female An. darlingi (n=2/1104, 0.18%) were found Pv -positive during this peak. During the same period, aggregated data from passive surveillance conducted by Brazilian and French Guianese border health centers identified 1,566 cases of Pv infection. Temporal distribution during the 2007-2018 period displayed seasonal patterns with a peak in November 2017. Four clusters were identified among the epidemic profiles of the localities of the cross-border area. All localities of the first two clusters were Brazilian. The localization of the first cluster suggests an onset of the outbreak in the Amerindian reservation, subsequently expanding to French Amerindian neighborhoods and to non-Native communities. Conclusions The current findings demonstrate a potential increase in malaria cases in an area with otherwise declining numbers. This is a transborder area where human mobility and remote populations challenge malaria control programs. This investigation illustrates the importance of international border surveillance and collaboration for malaria control, particularly in Amerindian villages and mobile populations.