Etude de la dynamique des populations de vecteurs de la fièvre de la Vallée du Rift au Sénégal : premiers résultats

La Fièvre de la Vallée du Rift est une arbovirose, d'importance sanitaire et économique. Des recherches s'orientent vers l'élaboration de modèles prédictifs intégrant les différents facteurs favorisant son émergence, dont la dynamique des populations vectrices. Ce travail présente l'étude de la dynamique des populations d'Aedes vexans adultes, vecteur potentiel de FVR au Sénégal en début de saison des pluies.Des captures sur hommes ont été réalisées du 9 au 21 juillet 2002 dans le Ferlo, zone de mares temporaires. Aedes vexans représente 71% des captures. Les premières femelles nullipares commencent à piquer 6 jours après une pluie remplissant les mares. Le pic de femelles pares agressives apparaît 10 jours après cette dernière et le cycle trophogonique est estimé à 3-4 jours.Ces résultats devront être précisés et étendus à l'étude des stades larvaire

A quantitative risk assessment approach for mosquito-borne diseases: malaria re-emergence in southern France

Contains fulltext : 69138.pdf (publisher's version ) (Open Access)BACKGROUND: The Camargue region is a former malaria endemic area, where potential Anopheles vectors are still abundant. Considering the importation of Plasmodium due to the high number of imported malaria cases in France, the aim of this article was to make some predictions regarding the risk of malaria re-emergence in the Camargue. METHODS: Receptivity (vectorial capacity) and infectivity (vector susceptibility) were inferred using an innovative probabilistic approach and considering both Plasmodium falciparum and Plasmodium vivax. Each parameter of receptivity (human biting rate, anthropophily, length of trophogonic cycle, survival rate, length of sporogonic cycle) and infectivity were estimated based on field survey, bibliographic data and expert knowledge and fitted with probability distributions taking into account the variability and the uncertainty of the estimation. Spatial and temporal variations of the parameters were determined using environmental factors derived from satellite imagery, meteorological data and entomological field data. The entomological risk (receptivity/infectivity) was calculated using 10,000 different randomly selected sets of values extracted from the probability distributions. The result was mapped in the Camargue area. Finally, vulnerability (number of malaria imported cases) was inferred using data collected in regional hospitals. RESULTS: The entomological risk presented large spatial, temporal and Plasmodium species-dependent variations. The sensitivity analysis showed that susceptibility, survival rate and human biting rate were the three most influential parameters for entomological risk. Assessment of vulnerability showed that among the imported cases in the region, only very few were imported in at-risk areas. CONCLUSION: The current risk of malaria re-emergence seems negligible due to the very low number of imported Plasmodium. This model demonstrated its efficiency for mosquito-borne diseases risk assessment

Environmental changes and emergence of vector-borne diseases in Europe : improving risk surveillance and management

Vector-borne diseases are highly sensitive to environment and to environmental changes. Faced with their recrudescence and public concern about the possible consequences of climate and other environmental changes, the European commission has launched a large, integrative research project called EDEN (Emerging diseases in a changing European environment), involving 24 countries and 49 scientific partners from Europe, the Middle East and Africa. The goals of EDEN are to identify ecosystems exposed to a high risk of vector-borne disease emergence, and to explain and model the underlying epidemiological processes. For this purpose, an inter-disciplinary approach was adopted to ensure close interaction between biology, ecology, geography and modelling. The expected result is the development of new methods to help public-health agencies create disease-monitoring, early-warning and decision-making tools for the prevention and control of vector-borne diseases. After a general presentation of EDEN, we show results obtained with the Malaria sub-project, focusing on the Camargue ecosystem, to assess the risk of resurgence of disease previously eradicated from this region.Les maladies à transmission vectorielle sont par nature très sensibles à l'environnement et aux changements environnementaux. Devant leur recrudescence et les craintes liées aux conséquences de ces changements, la Commission européenne a financé un vaste projet de recherche intégrée: EDEN (Emerging diseases in a changing European environment). Ce projet concerne 24 pays et 49 partenaires d'Europe, du Moyen Orient et d'Afrique. Il vise à identifier les écosystèmes soumis à un risque élevé d'émergence de ces maladies, à expliquer et modéliser les processus épidémiologiques en cause. Pour atteindre cet objectif, une démarche inter-disciplinaire a été entreprise permettant une interaction optimale entre biologie, écologie, géographie et modélisation. Le résultat attendu est la mise au point de méthodes utilisables par les agences de santé publique pour développer des outils de surveillance, d'alerte précoce et d'aide à la décision pour la prévention et le contrôle des maladies à transmission vectorielle. Après une présentation générale du projet, nous exposons les résultats obtenus dans le domaine du paludisme, plus particulièrement dans l'écosystème de Camargue, pour évaluer le risque de résurgence de cette maladie éradiquée naguère de cette région

Using remote sensing to map larval and adult populations of Anopheles hyrcanus (Diptera: Culicidae) a potential malaria vector in Southern France

Although malaria disappeared from southern France more than 60 years ago, suspicions of recent autochthonous transmission in the French Mediterranean coast support the idea that the area could still be subject to malaria transmission. The main potential vector of malaria in the Camargue area, the largest river delta in southern France, is the mosquito Anopheles hyrcanus (Diptera: Culicidae). In the context of recent climatic and landscape changes, the evaluation of the risk of emergence or re-emergence of such a major disease is of great importance in Europe. When assessing the risk of emergence of vector-borne diseases, it is crucial to be able to characterize the arthropod vector's spatial distribution. Given that remote sensing techniques can describe some of the environmental parameters which drive this distribution, satellite imagery or aerial photographs could be used for vector mapping.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Effects of Local Anthropogenic Changes on Potential Malaria Vector Anopheles hyrcanus and West Nile Virus Vector Culex modestus, Camargue, France

Sixty years of environmental modifications have led to strong and rapid effects on the abundance of vector populations

Possible Autochthonous Malaria from Marseille to Minneapolis

We report 2 cases of Plasmodium falciparum malaria in southern France in a French woman and an American man of Togolese origin who reported no recent travel to malaria-endemic countries. Both infections occurred after a stay near Marseille, which raises the possibility of autochthonous transmission. Entomologic and genotypic investigations are described

Biology and dynamics of potential malaria vectors in Southern France

BACKGROUND: Malaria is a former endemic problem in the Camargue, South East France, an area from where very few recent data concerning Anopheles are available. A study was undertaken in 2005 to establish potential malaria vector biology and dynamics and evaluate the risk of malaria re-emergence. METHODS: Mosquitoes were collected in two study areas, from March to October 2005, one week every two weeks, using light traps+CO(2), horse bait traps, human bait catch, and by collecting females in resting sites. RESULTS: Anopheles hyrcanus was the most abundant Anopheles species. Anopheles melanoon was less abundant, and Anopheles atroparvus and Anopheles algeriensis were rare. Anopheles hyrcanus and An. melanoon were present in summer, whereas An. atroparvus was present in autumn and winter. A large number of An. hyrcanus females was collected on humans, whereas almost exclusively animals attracted An. melanoon. Based on an enzyme-linked immunosorbent assay, almost 90% of An. melanoon blood meals analysed had been taken on horse or bovine. Anopheles hyrcanus and An. melanoon parity rates showed huge variations according to the date and the trapping method. CONCLUSION: Anopheles hyrcanus seems to be the only Culicidae likely to play a role in malaria transmission in the Camargue, as it is abundant and anthropophilic