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Arboviruses, transmitted by the Aedes and Culex mosquitoes, continue to threaten the health and lives of populations in areas where they are endemic and represent risks of emergence in new territories colonised by these vectors. The main objective of our work was i) to assess the level of exposure of populations to the bites of Aedes aegypti and Ae. albopictus and the risk of transmission of the diseases they transmit, in an urban environment in West Africa and in the South of metropolitan France and ii) to evaluate and validate the anti-EGS IgG and anti-recombinant 30 kDa protein responses of Culex quinquefasciatus as a potential biomarker of human exposure to Culex bites. We measured in the sera of exposed individuals, the antibody responses: i) IgG anti-Nterm-34 kDa and IgG anti arbovirus antigens (LUMINEX) in children from Anoumabo, Bromakoté and Petit-Bassam, in Abidjan, ii) IgG and IgM anti-Nterm-34 kDa of Ae. aegypti in Auvergne, Corsica, Occitania and PACA, France, and iii) anti-EGS IgG and recombinant 30 kDa protein in children from Dar-es-Salam, N'Gattakro, Kennedy in Bouaké.In Abidjan, anti-Nterm-34 kDa IgG was significantly different between the study districts with a high level in Bromakoté. Specific IgG was associated with sticky trap data. According to the LUMINEX technique, arboviruses were circulating in the districts, with a majority detection of DENV3. Petit-Bassam was the most affected. All these results showed that exposure to Aedes and thus the risk of transmission varied between neighbourhoods within the same African city.In metropolitan France, specific IgG was higher in the colonised areas than in the uncolonised area. The specific IgG response was higher in Occitania and PACA compared to Corsica. The anti-salivary peptide IgM, indicated a significant difference between the exposed regions. In Occitanie, the median levels of anti-peptide IgG responses in departments 30 and 34 were higher than those in departments 31 and 66. In PACA, a significant difference in the level of specific IgG was detected between departments 04 and 13 and between departments 05 and 13. IgG levels in departments 13 and 83 were higher than in the other departments. Departments colonised between 2010 and 2012 had statically higher anti-peptide IgG levels than non-colonised departments. IgM between individuals in the 4 regions was practically zero. These results indicated the relevance of the salivary anti-peptide IgG biomarker to discriminate the regions and departments most exposed to Ae. albopictus bites and thus to assess the heterogeneity of arbovirosis transmission risks in metropolitan France.For Culex, anti-EGS and anti-30 kDa IgG responses were significantly higher in children living in sites of high Culex quinquefasciatus density. Anti-30 kDa IgG was significantly higher in children not sleeping under insecticide-treated nets compared to those sleeping under them. In addition, a positive correlation was observed between anti-EGS IgG responses and anti-30 kDa IgG Ac in the total population.This study showed that the use of biomarkers of exposure to Aedes bites could be a relevant tool for the assessment of heterogeneity of exposure to arbovirus vectors in the African urban context and between departments of the same region in southern France. Anti-EGS IgG and anti-30 kDa protein responses would represent potential biomarker candidates for Culex bites. However further studies are needed, to validate them as a biomarker of Culex exposure, Les arboviroses, transmises par les moustiques Aedes et Culex, continuent de menacer la santé et la vie des populations des zones où elles sont endémiques et représentent des risques d’émergence dans nouveaux territoires colonisés par ces vecteurs. L’objectif principal de nos travaux était i) d’évaluer le niveau d’exposition des populations aux piqûres des Aedes aegypti et Ae. albopictus et le risque de transmission des maladies qu’ils transmettent, en milieu urbain en Afrique de l’Ouest et au Sud de la France métropolitaine et ii) d’évaluer et valider les réponses IgG anti-EGS et anti-protéine recombinante de 30 kDa de Culex quinquefasciatus comme biomarqueur d’exposition potentiel des Hommes aux piqûres des Culex. Nous avons dosé dans les sérums des individus exposés, les réponses anticorps : i) IgG anti-Nterm-34 kDa et les IgG anti- antigènes d’arbovirus (LUMINEX) chez les enfants d’Anoumabo, de Bromakoté et de Petit-Bassam, à d’Abidjan, , ii) IgG et IgM anti-Nterm-34 kDa d’Ae. aegypti à l’’Auvergne, de Corse, d’Occitanie et de PACA, en France, et iii) IgG anti-EGS et la protéine recombinante 30 kDa chez les enfants de Dar-es-Salam, N’Gattakro, Kennedy à Bouaké.A Abidjan, les IgG anti-Nterm-34 kDa étaient significativement différentes entres les quartiers d’étude avec un fort niveau à Bromakoté. Les IgG spécifiques étaient associées aux données des pièges collants. Selon la technique LUMINEX les arbovirus circulaient dans les quartiers, avec à une détection majoritaire de DENV3. Petit-Bassam était le plus affecté. L’ensemble de ces résultats démontraient que l’exposition aux Aedes et ainsi le risque de transmission étaient variables entre quartiers au sein d’une même ville africaine.En France métropolitaine, les IgG spécifiques étaient plus élevées dans les régions colonisées que dans la région non colonisée. La réponse IgG spécifique était plus élevée en Occitanie et en PACA par rapport à la Corse. Les IgM anti-peptide salivaire, indiquait une différence significative entre les régions exposées. En Occitanie, les niveaux médians des réponses IgG anti-peptide des départements 30 et 34, étaient plus élevés que celles des départements 31 et 66. En PACA, une différence significative du niveau des IgG spécifique était détectée entre le département 04 et 13 et entre les départements 05 et 13. Les IgG des départements 13 et 83 plus élevées que ceux des autres départements. Les départements colonisés entre 2010 et 2012 présentaient un taux d’IgG anti-peptide statiquement plus élevés que celui des départements non colonisés. Les IgM entre les individus des 4 régions était pratiquement nul. Ces résultats indiquaient la pertinence du biomarqueur IgG anti-peptide salivaire pour discriminer les régions et les départements les plus exposés aux piqûres d’Ae. albopictus et ainsi d’évaluer l’hétérogénéité des risques de transmission des arboviroses en France métropolitaine.Pour les Culex, les réponses IgG anti-EGS et anti-30 kDa étaient significativement plus élevées chez les enfants vivant dans les sites de forte densité de Culex quinquefasciatus. Les IgG anti-30 kDa étaient significativement plus élevées chez les enfants ne dormant pas sous les moustiquaires imprégnées d’insecticide par rapport à ceux dormant dessous. De plus, une corrélation positive a été observée entre les réponses IgG anti-EGS et les Ac IgG anti 30 kDa au sein de la population totale.Cette étude a montré que l’utilisation des biomarqueurs d’exposition aux piqûres des Aedes pourraient un outil pertinent pour l’évaluation de l’hétérogénéité d’exposition aux vecteurs d’arbovirus dans le contexte urbain africain et entre les départements d’une même région dans le Sud de la France métropolitaine. Les réponses IgG anti-EGS et anti-protéine 30 kDa représenteraient des candidats biomarqueurs potentiels aux piqûres de Culex. Toutefois, leur validation comme de ce biomarqueur d’exposition aux Culex, des études complémentaires sont nécessaires.

National audience; Les pesticides biologiques ou biopesticides sont de plus en plus utilisés pour lutter contre les nuisibles et les plantes adventices. Parmi ceux-ci figurent les bioinsecticides Btk. Or, une utilisation accrue de ces bioinsecticides pourrait avoir, sur le long terme, des conséquences sur la faune (l’environnement) et la santé publique (pathologies du tube digestif), malgré des doses relativement faibles retrouvées dans le biotope. Il est donc nécessaire d’analyser les risques environnementaux et sanitaires liés à l’ingestion chronique de Btk : ici, à partir du modèle Drosophila melanogaster ou mouche du vinaigre.

West nile virus infection: an emerging arbovirosis in france and europe. West Nile virus is a mosquito-borne flavivirus, transmitted to humans by mosquitoes of the genus Culex, from an avian reservoir. Humans are accidental hosts and there is no report of human-to-human transmission, except via blood transfusion or organ transplantation. In 2018, Europe experienced the largest outbreak of West Nile virus infection ever. In France, 27 cases were identified including 7 neuro invasive forms. This infection is asymptomatic in most cases but may also manifest as an isolated fever or flu-like syndrome. In about 1% of cases, neuro-invasive forms with meningitis, meningoencephalitis or flaccid paralysis can be observed. There is no specific treatment for this viral infection. Prevention is based on the prevention of mosquito bites, but also on enhanced epidemiological surveillance during the period of circulation of the virus in Europe (from spring to autumn).Infection à virus west nile : une arbovirose émergente en france et en europe. Le virus West Nile est un flavivirus transmis à l’homme par des moustiques du genre Culex, à partir d’un réservoir aviaire. L’être humain est un hôte accidentel, et il n’existe pas de transmission interhumaine connue, à l’exception du don de sang ou d’organes. En 2018, l’Europe a connu la plus importante épidémie d’infection à virus West Nile jamais observée. En France, 27 cas ont été recensés dont 7 formes neuro-invasives. Cette infection est asymptomatique dans la majorité des cas, mais peut également se manifester comme une fièvre isolée, une éruption cutanée ou un syndrome pseudo-grippal. Dans 1 % des cas environ, des formes neuro-invasives avec méningites, méningo-encéphalites ou paralysies flasques peuvent être observées. Il n’existe pas de traitement curatif de cette infection virale. La prévention repose sur la prévention des piqûres de moustiques mais également sur des mesures de surveillance épidémiologique renforcée pendant la période de circulation du virus en Europe (du printemps à l’automne).

Some arboviruses that originated in the Old World have been introduced by humans into the American continent. The first of them was the yellow fever virus, coming from the West African coast with slaves in the 17th-19th centuries, followed by dengue viruses, which were always prevalent within the Americas. Next was theWest Nile virus, introduced in New York in 1999, that spread in only a few years over the whole continent. Then, Chikungunya virus arrived on Saint Martin Island in 2013 after its outbreak in Polynesia; it is now widespread in the Caribbean Islands and on the American continent from the United States to Brazil. Finally, Zika virus, already active in Asia and in the South Pacific region, was introduced in Brazil and spread between the southern part of United States and south Brazil. These unexpected emergences are the consequence of the generalization of transoceanic trading; so, it is humans who are truly responsible for such transportation of viruses from the African and Asian continents. The mechanisms of virus establishment in unusual ecosystems have to be analyzed in order to understand the conditions for the circulation of the viruses, which supposes an adaptation to new hosts and vectors that are sometimes local species (like Culex vectors of West Nile virus) but mainly previously introduced mosquitoes (like Aedes aegypti and/or Aedes albopictus). Over time, all these vectors developed a strong anthropophily and, most of them, a remarkable adaptation to urban environment; hence, these arboviruses can disseminate both in rural and urban context. This type of arboviral emergences will certainly continue in the following years and we must imperatively develop preventive strategies by detecting virus mutations with capacity for emergence, enhancing the sensibility and rapidity of epidemiological surveillance, and becoming ready to face such events that cause a truly international health crisis.

Les maladies transmises par des insectes vecteurs ont un impact majeur sur la santé humaine et animale, mais également sur l'économie des sociétés. De par leurs modes de transmission, ces maladies, qu'elles soient zoonotiques ou non, sont particulièrement sensibles aux changements climatiques. En etfet, le climat et ses variations déterminent, et ce de manière parfois prépondérante, la présence des vecteurs à un endroit donné, mais également la densité et la capacité de ces derniers à transmettre les maladies. Le climat influe également sur la présence et la densité des animaux et des hommes, ainsi que sur les capacités de survie d'un pathogène dans un milieu donné. Ainsi, l'ensemble des acteurs, conditions et processus nécessaires à la transmission de ces maladies forme un système complexe et dynamique dont le comportement, sous influence du climat mais également d'autres variables environnementales, déterminera la possibilité ou non d'une transmission. Pour mieux comprendre les processus biologiques en jeu et mesurer l'impact des paramètres climatiques sur ces processus, des études expérimentales et épidémiologiques sont réalisées, en laboratoire ou en condition naturelle. La modélisation mathématique est utilisée pour représenter ces systèmes et en simuler le comportement sous ditférelltes conditions environnementales. C'est un outil majeur qui permet non seulement de mieux comprendre les phénomènes biologiques impliqués dans la transmission d'un pathogène donné, mais aussi de simuler, sur un pas de temps plus ou moins long, révolution dans r espace et le temps de l'intensité de cette transmission, et donc d'adapter la lutte contre ces maladies.

No case of autochthonous malaria has been detected in Morocco since 2004. This achievement is due to a national strategy to combat the disease by appropriate and well-organized disease detection and treatment, as well as control of the mosquito vector of the disease, the female Anopheles mosquito. Nonetheless, imported malaria cases have been increasing (75 in 2007), due to the rise in international travel and migration from countries where the disease is endemic. This work is divided into two parts: the first part is a retrospective study of the cases of imported malaria identified by optical microscopy in the Laboratory of Medical Entomology of the Khemisset Provincial Delegation of Health from 2000 to 2010. The second part is an entomological study conducted in 2010 of the Culicidae insect family, especially the Anopheles genus. The results show that of 176,457 requests for parasite testing, 14 were positive. All positive samples came from men older than 23 years. The cases identified are imported from two African countries: the Democratic Republic of Congo (86%) and Ivory Coast (14%). The years of high incidence were 2003 with four cases and 2000, 2004 and 2006 with two cases. The species found are Plasmodium falciparum in 13 cases (93%) and Plasmodium ovale in one case (7%). The vector of autochthonous malaria, which was eliminated in 2004, is Anopheles (Anopheles) labranchiae Fallerouni 1926, and it was the dominant species found in our entomological study (424 larvae). The other species were found in breeding sites in potential at-risk locations in the study area.

Rift Valley fever (RVF) is a zoonotic disease first described in 1930 in Kenya. Primarily transmitted between ruminant by mosquitoes of Aedes, Culex and Anopheles genus, it can also be transmitted to humans by direct contact with abortion products or body fluids of viraemic animals. This disease has been described in many African countries, in the Arabian Peninsula and the Indian Ocean. The circulation of RVF virus (RVFV) has been reported in three ecosystems: (i) semi-arid areas of South and East Africa, (ii) temporary ponds in arid areas, (iii) irrigated areas near large rivers. Within each of these ecosystems, the role of animal movements in the introduction of RVFV and that of mosquitoes in virus transmission has been strongly emphasized. Despite the existence of statistical models that predict the emergence of RVFV in East Africa based on rainfall level, the transmission mechanisms involved in other areas are still uncertain. The occurrence of an outbreak in a temperate and mountainous ecosystem of Madagascar, where the species and vector abundances are unfavorable to the persistence of RVFV, raises questions about these mechanisms.The objective of this thesis is to identify the factors and the epidemiological processes that support the RVFV recurrent circulation in a temperate ecosystem of Madagascar. The study took into account the socio-economic practices as well as major mosquito vectors of the area. The main modes of virus spread between cattle were studied during a three years serological follow-up. A mathematical model was elaborated and calibrated using empirical and field data collected in the area. Two cattle exchange practices could be distinguished: the usual trade and a traditional practice of barter. The results of the analysis suggest a different impact of these two practices in RVFV circulation. While trade may allow virus introduction, the barter practice would support its spread within the area. A deterministic model was built to compare four scenarios that could explain the recurrent virus circulation in this unfavorable ecosystem. Results suggest that, if the vector-based transmission remains the main transmission mode, direct transmission from viremic cows at calving could also play a role. RVFV circulation is favored by socio-economic practices of the area that led, despite the dry season, to the exposure of introduced, and potentially viremic, cattle to vectors.; La fièvre de la Vallée du Rift (FVR) est une arbovirose zoonotique décrite pour la première fois en 1930 au Kenya. Transmise principalement entre ruminants par des moustiques des genres Aedes, Culex et Anopheles, elle peut aussi se transmettre à l’homme par contact direct avec des produits d’avortement ou des fluides corporels d'animaux virémiques. Cette maladie a été décrite dans de nombreux pays d’Afrique ainsi que sur la péninsule arabique et dans l’Océan Indien. La circulation du virus de la FVR (VFVR) a été décrite dans 3 écosystèmes distincts : (i) les zones semi-arides sud- et est-africaines, (ii) les mares temporaires des zones arides, (iii) les zones irriguées adjacentes à de grands fleuves. Au sein de chacun de ces écosystèmes, le rôle des mouvements d’animaux dans l’introduction du VFVR et des moustiques vecteurs dans sa transmission ont fortement été mis en avant. Malgré l’existence de modèles statistiques pouvant prédire l’émergence du VFVR en Afrique de l’est notamment grâce au niveau de pluviométrie, les mécanismes de transmissions en jeu dans les autres régions sont encore incertains. L’apparition de foyers dans un écosystème tempéré et montagneux de Madagascar, où les espèces et abondances vectorielles ne sont pas favorables à la persistance du VFVR, suscite des interrogations quant à ces mécanismes.L’objectif de cette thèse est d’identifier les facteurs et les processus épidémiologiques permettant la circulation récurrente du VFVR dans un écosystème tempéré de Madagascar. L’étude a pris en considération les pratiques socio-économiques ainsi que les principaux moustiques vecteurs du virus de la zone tempérée des hautes terres malgaches. Les principaux modes de diffusion du virus entre bovins ont été étudiés au cours de 3 années de suivi sérologique. Un modèle mathématique calibré sur la base de nombreuses données empiriques collectées dans cette zone est proposé. Deux pratiques commerciales ont pu être distinguées : le commerce classique et une pratique traditionnelle de troc. Les résultats de l’analyse suggèrent une implication différente de ces deux pratiques dans la circulation du VFVR. Alors que le commerce pourrait permettre l’introduction du virus, la pratique du troc serait quant à elle le support de la circulation au sein de la zone. Un modèle déterministe est construit afin de comparer quatre scénarios pouvant expliquer la circulation virale dans cet écosystème peu favorable. Les résultats suggèrent que, si la transmission vectorielle reste la principale voie de transmission dans cet écosystème inhabituel, la transmission directe lors du vêlage de vaches virémiques pourrait également jouer un rôle. La circulation du VFVR est de plus favorisée par les pratiques socio-économiques de la zone qui permettent, malgré la saison sèche, l’exposition des bovins introduits et potentiellement virémiques aux moustiques vecteurs.

In Morocco, Culex pipiens plays a role in the high annoyance experienced by most urban cities, suburban and rural areas, especially since it was strongly suspected as the most likely vector in the transmission of West Nile virus epidemics that have hit Morocco in 1996. Chemical insecticides are generally the way in which they use the programs against harmful mosquitoes and disease vectors. However, the repeated and excessive use of these products regularly led to the emergence of the phenomenon of insect resistance. At the center of Morocco, information on the susceptibility or resistance to insecticides in mosquitoes (larvae and adults) vectors of diseases or pests, are almost nonexistent. This article reports the results of studies conducted between 2007 and 2010 with sensitivity tests WHO on larvae local populations of Culex pipiens collected in three lodging in the city of Fez, towards the insecticide mostly used by hygienic services: temephos. Five concentrations of insecticide (0.0025 mg/l, 0.005 mg/l, 0.0125 mg/l, 0.025 mg/l, 0.0625 mg/l) in addition to control, were used to determine the LC50 and LC 90 of Culex pipiens species towards temephos. Sensitivity tests were carried out at the entomology unit and monitoring of insect sensitivity towards insecticides installed at the Regional Diagnostic Laboratory Epidemiological and Environmental Hygiene (LRDEHM), Fez, under the Regional Directorate of Health in Fes Boulemane Region. The LC50 and LC90, concentrations corresponding to 50 and 90% mortality were determined graphically, by the linear relationship between the decimal logarithm of insecticide concentrations (x-axis) and the percentage of mortality transformed into probit values (ordinate) on logarithmic gausso paper. Resistance rates were determined on the basis of the sensitivity of a reference strain (S-Lab). The bioassay results affirmed the presence of resistance in larvae Culex pipiens towards temephos and that this species has also equally developed resistance levels similar and comparable in the three lodging studied, resistance rates recorded varying between 12.17 and 14.34. Facing such a situation, the surveillance of susceptibility of mosquitoes to insecticides used in mosquito control and anti-malarial fight has become imperative. This would undoubtedly allow a good management of the products available and consequently to adopt suitable measures for the best management of this resistance which must be an integral part of any program of vector control.

La fièvre West Nile est une arbovirose émergente endémique au Sénégal, surtout dans la région du fleuve Sénégal et dans le Ferlo. Les oiseaux sont les principaux hôtes-réservoirs et assurent la diffusion du virus des régions infectées vers des régions indemnes à travers les flux migratoires d'oiseaux. La transmission du virus d'un hôte infecté à un hôte sain se fait par le biais de vecteurs qui sont généralement des moustiques. Au Sénégal, bien que plusieurs études aient été faites sur la maladie, beaucoup de questions restent à être élucidées dans les cycles de transmission complexes qui dépendent largement des conditions climatiques et environnementales locales. La région du Ferlo et le Delta du fleuve Sénégal sont deux régions aux faciès écologiques différents. La région agropastorale du Ferlo est constituée de vallées fossiles inondables en saison des pluies et forme des mares temporaires qui disparaissent progressivement avec l'installation de la saison sèche. Tandis que le Delta du fleuve est constitué de vastes étendues aménagées pour la riziculture irriguée dont la principale source en eau est le fleuve Sénégal. Dans ces deux régions aux contextes géographiques et environnementaux différents, l'exploitation des terres par les populations humaines et animales est fortement liée à l'eau qui malheureusement permet le développement de vecteurs d'arbovirus comme ceux de la West Nile. La transmission du virus West Nile est complexe dans ces régions, car elle implique plusieurs intervenants dont des vecteurs (Aedes et/ou Culex) d'écologies différentes, des hôtes résidents ou migrateurs autour d'un environnement favorable (mare temporaire, fleuve). Il en est de même de l'endémisation du virus car les réservoirs sont peu étudiés. Afin de mieux comprendre l'écologie du virus de la West Nile dans ces écosystèmes, nous avons effectué des enquêtes entomologiques par différentes techniques (piège lumineux avec CO2, piège à appât poulet, piège à appât pigeon, piège à appât cheval, aspiration) et des enquêtes sérologiques sur les poulets sentinelles pendant la période à fort risque de transmission. Nous avons aussi, à partir d'observations faites sur le terrain, prélevé des échantillons de sol par raclage au niveau de potentiels gîtes de repos et de ponte du moustique Aedes vexans arabiensis que nous avons comparés avec des expériences effectuées au laboratoire. Les résultats obtenus sont assez encourageants et contribuent à une meilleure connaissance de l'écologie de ce virus dans ces écosystèmes et par conséquent de l'épidémiologie de la maladie. L'intérêt de ce travail est de mettre en évidence le rôle de chacun des acteurs étudiés impliqués dans le cycle épidémiologique de la maladie et les interactions qui peuvent exister entre ces différents intervenants et le milieu. Le schéma de surveillance que nous avons proposé pourra être utilisé pour la détection précoce de la circulation du virus au Sénégal dans le cadre d'un système de surveillance de la West Nile. Cependant, les efforts de recherche doivent être poursuivis pour mieux cerner son épidémiologie et développer des méthodes de prévention et de lutte efficientes.

Rift Valley fever (RVF) is a zoonotic disease first described in 1930 in Kenya. Primarily transmitted between ruminant by mosquitoes of Aedes, Culex and Anopheles genus, it can also be transmitted to humans by direct contact with abortion products or body fluids of viraemic animals. This disease has been described in many African countries, in the Arabian Peninsula and the Indian Ocean. The circulation of RVF virus (RVFV) has been reported in three ecosystems: (i) semi-arid areas of South and East Africa, (ii) temporary ponds in arid areas, (iii) irrigated areas near large rivers. Within each of these ecosystems, the role of animal movements in the introduction of RVFV and that of mosquitoes in virus transmission has been strongly emphasized. Despite the existence of statistical models that predict the emergence of RVFV in East Africa based on rainfall level, the transmission mechanisms involved in other areas are still uncertain. The occurrence of an outbreak in a temperate and mountainous ecosystem of Madagascar, where the species and vector abundances are unfavorable to the persistence of RVFV, raises questions about these mechanisms.The objective of this thesis is to identify the factors and the epidemiological processes that support the RVFV recurrent circulation in a temperate ecosystem of Madagascar. The study took into account the socio-economic practices as well as major mosquito vectors of the area. The main modes of virus spread between cattle were studied during a three years serological follow-up. A mathematical model was elaborated and calibrated using empirical and field data collected in the area. Two cattle exchange practices could be distinguished: the usual trade and a traditional practice of barter. The results of the analysis suggest a different impact of these two practices in RVFV circulation. While trade may allow virus introduction, the barter practice would support its spread within the area. A deterministic model was built to compare four scenarios that could explain the recurrent virus circulation in this unfavorable ecosystem. Results suggest that, if the vector-based transmission remains the main transmission mode, direct transmission from viremic cows at calving could also play a role. RVFV circulation is favored by socio-economic practices of the area that led, despite the dry season, to the exposure of introduced, and potentially viremic, cattle to vectors., La fièvre de la Vallée du Rift (FVR) est une arbovirose zoonotique décrite pour la première fois en 1930 au Kenya. Transmise principalement entre ruminants par des moustiques des genres Aedes, Culex et Anopheles, elle peut aussi se transmettre à l’homme par contact direct avec des produits d’avortement ou des fluides corporels d'animaux virémiques. Cette maladie a été décrite dans de nombreux pays d’Afrique ainsi que sur la péninsule arabique et dans l’Océan Indien. La circulation du virus de la FVR (VFVR) a été décrite dans 3 écosystèmes distincts : (i) les zones semi-arides sud- et est-africaines, (ii) les mares temporaires des zones arides, (iii) les zones irriguées adjacentes à de grands fleuves. Au sein de chacun de ces écosystèmes, le rôle des mouvements d’animaux dans l’introduction du VFVR et des moustiques vecteurs dans sa transmission ont fortement été mis en avant. Malgré l’existence de modèles statistiques pouvant prédire l’émergence du VFVR en Afrique de l’est notamment grâce au niveau de pluviométrie, les mécanismes de transmissions en jeu dans les autres régions sont encore incertains. L’apparition de foyers dans un écosystème tempéré et montagneux de Madagascar, où les espèces et abondances vectorielles ne sont pas favorables à la persistance du VFVR, suscite des interrogations quant à ces mécanismes.L’objectif de cette thèse est d’identifier les facteurs et les processus épidémiologiques permettant la circulation récurrente du VFVR dans un écosystème tempéré de Madagascar. L’étude a pris en considération les pratiques socio-économiques ainsi que les principaux moustiques vecteurs du virus de la zone tempérée des hautes terres malgaches. Les principaux modes de diffusion du virus entre bovins ont été étudiés au cours de 3 années de suivi sérologique. Un modèle mathématique calibré sur la base de nombreuses données empiriques collectées dans cette zone est proposé. Deux pratiques commerciales ont pu être distinguées : le commerce classique et une pratique traditionnelle de troc. Les résultats de l’analyse suggèrent une implication différente de ces deux pratiques dans la circulation du VFVR. Alors que le commerce pourrait permettre l’introduction du virus, la pratique du troc serait quant à elle le support de la circulation au sein de la zone. Un modèle déterministe est construit afin de comparer quatre scénarios pouvant expliquer la circulation virale dans cet écosystème peu favorable. Les résultats suggèrent que, si la transmission vectorielle reste la principale voie de transmission dans cet écosystème inhabituel, la transmission directe lors du vêlage de vaches virémiques pourrait également jouer un rôle. La circulation du VFVR est de plus favorisée par les pratiques socio-économiques de la zone qui permettent, malgré la saison sèche, l’exposition des bovins introduits et potentiellement virémiques aux moustiques vecteurs.

A literature analysis coupled with new entomological surveys conducted between 2009 and 2012 led to changes in the list of mosquito species present on the island of La Réunion. Using morphological criteria, Orthopodomyia arboricollis is replaced by Or. reunionensis. On the basis of morphometrical and genetic criteria, Culex univittatus is replaced by Cx. neavei. Cx. poicilipes, which was already reported missing 40 years ago, has not been found again. Anopheles arabiensis is confirmed as the only species of the Gambiae complex present on the island. Thus, twelve species are currently known. For each of them, elements of taxonomic, biological and medical interest are listed. An. arabiensis is a major vector of human Plasmodium (last case of indigenous malaria in 1967). In the Indian Ocean, Aedes albopictus and Ae. aegypti both are competent for transmitting dengue and chikungunya viruses. In Africa, Cx. quinquefasciatus transmits Wuchereria bancrofti and Cx. neavei transmits the Sindbis virus; both species also transmit the West Nile virus. Cx. tritaeniorhynchus is the major vector of Japanese Encephalitis virus in Asia. Two species are endemic (Ae. dufouri and Or. reunionensis), the ten other ones are also found in Madagascar and on the African continent (An. coustani, An. arabiensis, Ae. fowleri, Cx. tritaeniorhynchus, Cx. neavei, Cx. insignis, Lutzia tigripes), with three of them having also a cosmopolitan distribution (Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus). Among the twelve recorded taxa, eight species are anthropophilic, three are supposedly zoophilic and one is a predatory species. No new invasive anthropophilic species did settle on the island. Updated identification keys of larval and adult stages are proposed.

In order to better understand the nuisance that represents the development of mosquitoes in Constantine, a biodiversity study Culicidae was conducted over two years, from October 1995 to September 1997. Culicidae larvae were collected in different biotopes by the dipping method. A total of 24,190 mosquitoes belonging to four genera were captured, of which 24,139 were Culex, 47 Culiseta, 3 Anopheles, 1 Uranoteania. Culex pipiens L. 1758 represents 97.5% of the total fauna. This species is most frequent in open and closed urban biotope were the organic pollution is important. This high organic load in both urban biotopes types with regard to others would explain this preferential localization. This emergency intensity raised more during summer season where vegetation is totally absent, Culex pipiens represented 97.48% of the total fauna. The whole results obtained from measures of the main physico-chemical parameters of water, permitted to establish a typology of biotopes. It is in the context of larval control that our study was undertaken on the ecology of the principal nuisance at Constantine, represented by Culex pipiens., Dans le but de mieux cerner la nuisance que représente le développement des moustiques à Constantine, une étude sur la biodiversité culicidienne a été menée sur deux années, d’octobre 1995 à septembre 1997. Les larves de Culicidae ont été récoltées dans les différents gîtes par la méthode «dipping» . Au total, 24 190 moustiques appartenant à quatre genres ont été capturés, dont 24 139 Culex, 47 Culiseta, 3 Anopheles et 1 Uranoteania. Culex pipiens L. 1758 représente 97,5% de la faune totale. Cette espèce est la plus fréquente dans les gîtes urbains épigés et hypogés où la pollution d’origine organique est importante. Ce taux de pollution élevé dans les deux types de gîtes urbains serait la cause principale de cette localisation préférentielle. L’intensité d’émergence est très élevée durant la saison estivale aussi bien dans les gîtes urbains épigés qu’hypogés où la végétation est totalement absente. Les données obtenues à partir des mesures des principaux paramètres physico-chimiques de l’eau ont permis d’établir une typologie des gîtes. C’est dans une perspective de lutte que notre étude sur l’écologie de la principale nuisance culicidienne causée par Culex pipiens à Constantine a été entreprise., Berchi Selima, Aouati Amel, Louadi Kamel. Typologie des gîtes propices au développement larvaire de Culex pipiens L. 1758 (Diptera-Culicidae), source de nuisance à Constantine (Algérie). In: Ecologia mediterranea, tome 38 n°2, 2012. pp. 5-16.

The Rift Valley fever (RVF) is an arboviral zoonosis, first identified in Kenya in 1930, which has spread over many African countries. The RVF virus (RVFV) is a mosquito-borne virus member of the family Bunyaviridae, genus Phlebovirus. Statistical models that are used for predicting RVF outbreaks in East Africa do not work in West Africa where the factors and processes involved are still not well described. The aim of this thesis is to identify the factors and epidemiological processes that explain the emergence of RFV outbreaks in Senegal. To achieve that, we have chosen an eco-epidemiological approach targeted on the main candidate mosquito vectors of the RFV virus. By using the environmental and climatic variables and by their exploitation in mathematical models, we tried to answer two major epidemiological questions: (1) where are the potential zones at risk? And, (2) when are the periods favourable to RFV outbreaks?The study has been carried out at a local scale, in an area of about 10 km2 centred on the village of Barkedji in the pastoral Ferlo region in northern Senegal.When identifying risk areas for virus transmission, we used remote sensing and landscape analysis to characterize favourable environments fot the two main candidate vectors, Aedes vexans and Culex poicilipes (Diptera: Culicidae). For predicting risk of RVF outbreaks, we developed a mosquito population model for the two vector species taking into account the dynamics of the ponds as breeding sites. The results of the simulation have been validated with captured mosquito field data. This required the prior development of a temporary pond dynamics model that was calibrated and validated with field and remote sensing data.The results of the landscape analysis confirmed that favourable environments for the mosquito vectors of the RVF could be characterised by remote sensing. The importance of the ponds and the surrounding vegetation density was also highlighted, allowing to map the spatial heterogeneity of RVF circulation risk. The results of the mosquito model simulations showed that years of active virus circulation matched the years when both vector species were densely present. Indeed, the simulations showed high mosquito densities in 1987 and 2003, which correspond to the most important epidemic and epizootic events in that region.; La Fièvre de la Vallée du Rift (FVR) est une zoonose observée pour la première fois au Kenya en 1930 qui s'est peu à peu propagée à la plupart des pays d'Afrique. La FVR est une maladie à transmission vectorielle dont le virus appartient au genre Phlebovirus de la famille des Bunyaviridæ. En Afrique de l'Est, l'émergence de foyers est prédite par des modèles statistiques, ce qui n'est pas le cas en Afrique de l'Ouest où les facteurs et les mécanismes en jeu sont encore mal définis. L'objectif de cette thèse est d'identifier les facteurs et les processus épidémiologiques expliquant l'émergence de foyers de FVR au Sénégal, en mettant en œuvre une approche éco-épidémiologique centrée sur les principaux moustiques vecteurs du virus. Par l'étude de variables environnementales et climatiques et par leur exploitation dans des modèles mathématiques, nous avons tenté de répondre à deux questions épidémiologiques majeures : (1) quelles sont les zones potentiellement à risque, et (2) quelles sont les périodes favorables à l'apparition de foyers. L'étude a été menée à l'échelle locale, dans une zone d'environ 10 km2 autour du village de Barkedji situé dans la région sylvo-pastorale du Ferlo.Pour localiser les zones à risque de transmission du virus, nous utilisons la télédétection et l'analyse paysagère afin de caractériser l'environnement favorable aux deux principaux candidats vecteurs du virus, Aedes vexans et Culex poicilipes. Pour identifier les périodes à risque, nous avons développé un modèle d'abondance de populations de moustique des deux espèces vectrices prenant en compte la dynamique des gîtes larvaires (les mares), et dont les simulations ont été validées avec des données de terrain de capture de moustiques. Pour se faire, nous avons dû préalablement développé un modèle dynamique de hauteur d'eau des mares temporaires, modèle calibré et validé à partir de données de terrain et de données d'observation de la Terre.Les résultats de l'analyse paysagère ont confirmé que les milieux favorables aux vecteurs de la maladie pouvaient être caractérisés par télédétection. Ils ont aussi mis en évidence l'importance des mares et de la densité de végétation environnante, et ont abouti à une cartographie de l'hétérogénéité spatiale du risque de circulation de la FVR. Les résultats de l'analyse temporelle ont montré que les années de circulation active du virus coïncidaient avec les années pour lesquelles les deux espèces de moustiques étaient présentes en forte quantité. On observe ainsi deux années à très forte densité des deux moustiques vecteurs, en 1987 et en 2003, correspondant aux années d'épidémie/épizootie les plus importantes dans la région.

Dengue has emerged in Vietnam 50 years ago and since has become endemo-epidemic throughout the whole country. Each year, major epidemics of dengue fever (DF) and dengue hemorrhagic fever (DHF) hit South Vietnam during the rainy season, causing significant morbidity and mortality, especially among young children. The only preventive measure is vector control, but it is often implemented too late or indiscriminately. The aim of this study was to investigate, in the pre-epidemic stage, the existence of significant changes in vector indices, which will predict DF/DHF outbreaks. We conducted a descriptive transversal study, repeated once a month for four months (March to June) in the village of Locthuan (province Ben Tre) in the Mekong's delta. Adult mosquitoes were caught in 30 houses, and larvae were collected in water holding containers of 50 houses. The houses were randomly selected. Vector densities were calculated according to the indices recommended by WHO. Virological analysis was carried out on lots of female Aedes and larvae in order to determine viral infection rates. Catches of adult mosquitoes collected 496 specimens including 329 Aedes, 139 Culex and 28 Anopheles. Aedes aegypti was present in 63% of visited homes that is an average density of 1.8 mosquitoes per house. The increase in imaginal indices during the 4 months was not significant. The survey of breeding sites of Ae. aegypti identified 1292 water containers in which 71,569 larval specimens were collected. The values of house index, container index [CI] and Breteau index [BI] increased each month, the latter from 166 to 442. This increase was significant for CI and BI. Breeding sites were mostly intra-home, mainly consisting of large and small ceramic jars. Larval density of Ae. aegypti in the containers also increased significantly over the 4 months. It was correlated with the lack of cover and predators such as Mesocyclops spp., Micronecta spp. and larvivorous fishes. Cultivation of 15 pools of 10 adult females and 29 pools of larvae (ie 1088 specimens) of Ae. aegypti failed to isolate dengue virus. The high Stegomyia indices measured in this South Vietnamese village and their increase before the rainy season reflect a situation at high risk of epidemics but cannot predict the occurrence of an outbreak in the absence of virus isolation from mosquitoes. They justify conducting an integrated vector control throughout the year.

The mosquito Culex pipiens has been involved as vector of the West Nile virus in Tunisia. Its bio-ecological characteristics in combination with some environmental factors have favoured the emergence of this virus in a West-Nile free zone. This leads to question about the potential risk of introducing another arbovirus, the Rift Valley fever (RVF) virus, in Tunisia from neighbouring countries where RVF circulates. In this study, we have evaluated the vector competence of different populations of Cx. pipiens towards two strains of RVF virus, the virulent ZH548 and the avirulent Clone 13 by experimental infections and the genetic differentiation of these populations of Cx. pipiens using four microsatellite loci. We found disseminated infection rates ranging from 0% to 14.7% and a high genetic differentiation among populations without any geographical pattern (no isolation by distance). Thus, although Cx. pipiens is able to sustain an amplification of RVF virus, viral dissemination through mosquito dispersal would be unlikely. However, as RVF is an emerging disease transmitted by several other potential mosquito species (e.g. Ochlerotatus caspius), attention should be maintained to survey livestock and mosquitoes in Tunisia.

Field collections of the most common urban mosquito vectors Anopheles gambiae and Culex quinquefasciatus were carried out in June 2003, March 2004 and November 2005 to gather preliminary data on the insecticide susceptibility in mosquitoes from Lobito (Angola) using the WHO standard bioassays. Bioassays were performed on F0 adults emerging from the field larval collections and on unfed adults from landing catches on volunteers. Batches of mosquitoes from three selected locations (Alto Liro, San Jao and Bela Vista) were exposed for 1 hour to several insecticides such as DDT 4%, carbosulfan 0.4%, permethrin 1%, deltamethrin 0.05% and cyfluthrin 0.15%, in order to estimate the immediate knockdown times (kdT50 and kdT95) and the mortality rate after exposure. The results revealed that mosquito susceptibility to insecticides varied depending on the insecticide, the site and the period of collection. The main local malaria vector A. gambiae (both M and S forms) was basically resistant to DDT and susceptible to all pyrethoids, regardless of the period and the site of collections. The overall mortality rate due to DDT was 73% in Alto Liro, 89% in San Jao and varied depending on the period in Bela Vista between 95% in March 2004 and 100% in November 2005. The mortality due to pyrethoids was 100% at all locations, with the kdT50 and KdT95 times ranging between 9 and 16 minutes and between 18 and 29 minutes, respectively. Concerning the C. quinquefasciatus, populations from Yard and Caponte were resistant to all insecticides tested; the mortality rate was 40% with deltamethrin and 70% with permethrin, while no lethal effect was observed with DDT or carbosulfan. In conclusion, despite its probable high resistance to DDT, the main local malaria vector A. gambiae remained fully susceptible to pyrethroids. This could forecast a good biological efficacy of the scheduled vector control interventions in Angola, based on a large-scale distribution of long-lasting, insecticide-treated nets and on the implementation of indoor residual spraying. The local vector control programme must include well-adapted IEC campaigns and full participation of the community for better management of the insecticide resistance in targeted mosquitoes and for better control of malaria vector populations.

In November 2009, ten suspicious cases of yellow fever, including six deaths, were notified in the region of Denguélé, in the northwest of Côte-d'Ivoire. In order to evaluate the extent of yellow fever virus circulation and the risk for local people, a mission of entomological investigation was carried out by the Ministry of Health and Public Hygiene of Côte-d'Ivoire. Entomological investigations were conducted in the villages of confirmed cases (Banakoro and Tron-Touba) and the centers of consultation and hospitalization of cases during illness. Breteau index and recipient index were quasi nil. Aedes aegypti was absent among the captured mosquitoes. On the other hand, Aedes luteocephalus and Aedes opok were present at Banakoro and Tron-Touba with respective average biting rates of 0.8 and 0.6 bite/man/twilight. This situation of epidemic in the northwest of Côte-d'Ivoire could be explained by the deterioration of Denguélé region's health system which is a consequence of the war started in the country in 2002 and which has lowered the immunity of the population.

The following aspects are dealt with in this article: 1) current geographical distribution of Japanese encephalitis; 2) clinical patterns of Japanese encephalitis; 3) vertebrate hosts of Japanese encephalitis virus; 4) vectors of JE virus; 5) epidemiological locations (endemic area, endemoepidemic area, epidemic area); 6) unknown epidemiological aspects; 7) JE virus serotypes; 8) evolution of the disease and recent epidemiological changes; 9) phylogenetic origin of the JE virus; 10) ecological changes in the past, factors in the emergence of the disease; and 11) the future: Can we predict how the situation will evolve?

Rift Valley Fever (RVF) is a zoonotic arbovirosis. Among animals, it mainly affects ruminants, causing abortions in gravid females and mortality among young animals. In humans, RVF virus infection is usually asymptomatic or characterized by a moderate fever. However, in 1 to 3% of cases, more severe forms of the disease (hepatitis, encephalitis, retinitis, hemorrhagic fever) can lead to the death of infected individuals or to major sequels. The RVF virus (Bunyaviridae, genus Phlebovirus) was identified for the first time in the 1930s in Kenya. It then spread over almost all African countries, sometimes causing major epizootics/epidemics. In 2000, the virus was carried out of Africa, in the Middle East Arabian Peninsula. In 2007-2008, Eastern-African countries, including Madagascar, reported significant episodes of RVF virus, this was also the case for the Comoros archipelago and the French island of Mayotte. This ability to spread associated with many vectors, including in Europe, and high viral loads in infected animals led the health authorities worldwide to warn about the potential emergence of RVF virus in areas with a temperate climate. The awareness has increased in recent years with climate changes, which may possibly modify the vector distribution and competence, and prompted many RVF virus-free countries to better prepare for a potential implantation of RVF.

This survey, conducted from July 2003 to June 2004, was to assess the variation of the level of sensitivity of Cx. quinquefasciatus to the pyrethroids recommended for the impregnation of the mosquito nets, in the township of Yopougon situated in the Northwest of Abidjan city in relation with the bed of a drainage channel of sewage water that passes through the township from the north to the south. Five districts have been chosen along this channel according to the level of urbanization, for the withdrawal of the pre-imaginal populations of Cx. quinquefasciatus in collections of stagnant sewage water of this township. The female Cx. quinquefasciatus aged three to five days from the exits of the insectarium have been exposed to papers impregnated with deltamethrin 0.05%, permethrin 1% and DDT 4% in view of the diagnosis of a possible resistance of these populations to these insecticides. The populations of Cx. quinquefasciatus proved to be resistant to the three insecticides used, in four districts. On the other hand, the population of Cx. quinquefasciatus from the district "Zone industrielle," situated upstream of the channel, proved to be sensitive to permethrin 1%, and a drastic decrease of sensitivity of the same mosquito has been observed with deltamethrin 0.05% and DDT 4%.

This is the first description of Ae. albopictus in Grande Glorieuse and Juan de Nova, which are two isolated French islands of the Mozambique Channel. The recent introduction of this species is underlined by its absence in the inventories realised between 2000 and 2003. The last severe arbovirus epidemic of chikungunya (2005-2006), vectored by Ae. albopictus, which occurred in the area of the Indian Ocean emphasized the epidemiological role of this vector. So that, notifying its presence might help to target potential exotic arboviruses that could be introduced into the island. Furthermore this study allowed us to update the culicidae inventory, not only with this species, but also with the first observation of Culex sitiens in Europa and the confirmation of Ae. dufouri on this island. In order to determine the different species at the adult and/or at the larval stage, the authors propose keys of identification for mosquito species of the Eparse islands. All the described species on these islands are allochthonous species and some are being a nuisance. Sanitary recommendations together with biological and mechanical controls are proposed in order to reduce the nuisance and to prevent from any new introduction on these islands.

In April 2008, Abidjan was again faced with another case of yellow fever after the epidemic of 2001 causing mass immunization campaign. In order to evaluate the extent of amaril virus circulation and the risk for local people, an entomological investigation was carried out by the Ministry of Health and Public Hygiene of Côte d'Ivoire. At "Entent" area of Treichville, Breteau index was estimated at 34, recipient index at 20% and house index at 25%. Those indexes were respectively 53, 21 and 31% at "Vridi canal" of Port Bouet. In the both neighborhood, Aedes aegypti accounted for more than 80% of mosquitoes caught and more than 90% of mosquitoes adults obtained from larval breeding. This new situation of epidemic risk could be explained by several factors including the reception of 70% of forced migration people caused by the crisis in the country occurred in 2002, the probable drop of preventive immunization, the environment deterioration creating of more breeding sites of Ae. aegypti.

Despite the existence of antiamaril vaccine in the routine Expanded Program of Immunization (EPI) in Burkina Faso, yellow fever cases still occur in the country. In collaboration with WHO, the national health authorities set up a surveillance system through the national reference laboratory in Centre Muraz (Bobo-Dioulasso). All samples of feverish icterus cases of the 63 health districts of the country were analysed in this lab for M Immunoglobulin using Enzyme Linked Immunosorbent Assay (Elisa). Positive Elisa samples were sent to Pasteur Institute of Dakar (Senegal) for confirmation using a Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) assay. From 2003 to 2005, the number of confirmed cases of yellow fever was respectively of 1/413 (0.24%), 14/616 (2.27%) and 19/618 (3.07%). This increasing of the proportion was statistical different. Then, from 2006 to 2008, the confirmed case proportion was respectively 0.35%, 0.27 and 0.54% without significant difference (P = 0.69). The entomological investigations conducted in 2004 in Bobo-Dioulasso showed that the water pots constitute 48.11% mosquitoes lodgings, followed by metal drums with a strong representation of Culex quinquefasciatus (48.7%), followed by Aedes aegypti (43.3%), as vectors in domestic areas with sectorial variations. These results suggest that more attention must be paid by the national health authorities and international community regarding this disease.

Aedes albopictus a été observé pour la première fois dans les îles de Grande-Glorieuse et de Juan-de-Nova, îles Éparses françaises du canal du Mozambique. La présence de cette espèce n'a pas été mentionnée lors des derniers inventaires de la faune culicidienne réalisés entre 2000 et 2003, ce qui met en avant la vulnérabilité de ces milieux insulaires face aux nouvelles espèces invasives et l'intérêt de poursuivre la surveillance dans ces zones. L'inventaire de la faune culicidienne a de plus été enrichi de l'espèce Culex sitiens sur l'île d'Europa. Sur cette même île, la présence d'Ae. dufouri a été confirmée. Afin de faciliter la détermination des espèces culicidiennes, les auteurs proposent une clé dichotomique pour les larves et adultes. Toutes les espèces décrites sur ces îles étant allochtones, des recommandations sanitaires ainsi qu'une lutte biologique et mécanique ciblée contre les espèces les plus nuisibles sont proposées.

Description of Culex (Culex) sechani n. sp. from Tahiti (Society islands) (Diptera, Culicidae). Adults, pupa and larva of a new mosquito belonging to genus Culex, sitiens group, are described from Tahiti (Society Islands) : Culex (Culex) sechani n. sp. A key of larvae and males presents in Marquesas and Society islands is proposed., Les imagos, nymphe et larve d’une nouvelle espèce de moustique appartenant au genre Culex, groupe sitiens, sont décrits de Tahiti (Iles de la Société) : Culex (Culex) sechani n. sp. Il est proposé une clé d’identification des larves et des mâles des Culex présents aux Marquises et dans les îles de la Société., Brunhes Jacques, Bousses Philippe. Description de Culex (Culex) sechani n. sp. de Tahiti (îles de la Société) (Diptera, Culicidae). In: Bulletin de la Société entomologique de France, volume 114 (1),2009. pp. 21-28.

Histopathological studies relating to last instars larvae of mosquitoes treated with neem products are very few. The objective were to study the action of Neem products on larvae mosquitoes of Culex quinquefasciatus.The neem products (Neemix, Formulated neem oil, Pure neem oil and Neem powder) are tested on 4 instars larvae of Culex quinquefasciatus. Moribund and witness larvae were fixed, for histopathologic study.The results showed the following facts: an intestinal epithelium, a bross border, a fat body and others tissues are normals at the level of the untreated larva; Fat body and muscle are not touched during the treatment of the larva with Pure neem oil; Intestinal epithelial cells slightly hypertrophied with beaches of lysis on the level of the larva treated with Neem powder; a lysis of the microvilli of brush border on the level of the witness-solvent; a destruction of the epithelial cells recorded in larva treated with a Neemix; a disappearance of the food column and a destruction of the epithelial cells remarked on the level of the larva treated with Formulated neem oil.The neem products used in this study have a Larvaecidal action on Culex quinquefasciatus larvae.

Three surveys related to the knowledge, attitude and practices of populations towards mosquitoes were conducted in Côte d'Ivoire. The first survey was undertaken in June 1994 in the city of Bouaké and the other two respectively in January 1996 and in June 1999 in the village of Kafiné. The surveys have revealed that whatever the environment, nuisance due to mosquitoes constitutes a great concern for the population of the villages. The majority of people interviewed in urban (94%), peri-urban (68%) zones and in Kafiné (94%) associates mosquito with malaria against 18% only in Kabolo. Furthermore, these surveys have allowed the inventory of methods of controlling mosquito currently used by the communities in both urban and rural areas. Generally mosquito coils as well as insect sprays are currently used because of their cheapness and their availability on the local market. in Bouaké, insect sprays (97% to 99%) are used as much as mosquito coils (87% to 98%). However, in Kafiné and Kabolo, insect sprays are only used by respectively 76% and 69% and the mosquito coils by respectively 68% and 71%. In urban zones, the insect sprays are more common than mosquito coils. On the contrary mosquito coils are currently used in villages due to their low price (40 to 50 FCFA) and their constant availability on the local market. Furthermore, local plants characterized by a repulsive essence are known by 48% and 75% of people interviewed respectively in the urban and peri-urban area of the city of Bouak6, by 74 % of the population of Kafiné and 73% of people living in Kabolo. In the last village 57% of people who were interviewed do not use any means of orotection due to financial reason; only 14% use mosquito coils and 20% use local plants with a repulsive essence. Mosquito net is known by the majority of people interviewed (82 - 98%) as an excellent means of orotection against mosquito bites. However only 27%, 13%, 26% and 5% of people respectively living in the urban and peri-urban areas of Bouaké and in the villages of Kafiné and Kabolo own their mosquito net. Its cost is the main reason for not using it as mentionned by 25% of people interviewed in the urban neighborhood, by 48% in the peri-urban areas, respectively 46% and 89% in the villages of Kafiné and Kabolo. Although its effectiveness has been proved by the communities, mosquito net still remains less common. Its price is relatively high (3500 - 5000 FCFA). It is not constantly available on the local market. Other socio-cultural factors such as local beliefs and taboos hinder the use of mosquito nets by the communities.

Culex pipiens gonotrophic cycle has been studied, for the first time in Morocco, under experimental conditions. Its average duration was estimated at 5.54 +/- 1.73 days.

International audience; The islets of Europa, Juan-de-Nova and Grande-Glorieuse are French territories isolated in the Mozambique Channel (Indian Ocean) which have remained relatively preserved from anthropization all along their history These three islets have been classified entire nature reserves from 1975 and are today inhabited only by a permanent military detachment of about fifteen men even if they occasionally greet technical and scientific staff. Sanitary and environmental issues brought about assessment of the present culicid fauna. The authors propose a synthesis of the culicid knowledge from the islets and make an inventory of new species. The role played by humans in importation of culicids is discussed as well as sanitary consequences of their adaptation to environment; Les îlots français de Europa, Juan-de-Nova et Grande-Glorieuse, isolés dans le Canal du Mozambique (océan Indien), sont restés relativement préservés de l’anthropisation au cours de leur histoire. Classés réserves naturelles intégrales, ils ne sont aujourd’hui habités en permanence que par un détachement militaire et accueillent occasionnellement des personnels techniques et scientifiques. Des questions d’ordre sanitaire et environnemental ont amené à l’étude de la faune culicidienne présente. Les auteurs proposent une synthèse des connaissances sur les Culicidés de ces îlots, inventorient de nouvelles espèces et discutent du rôle de l’homme dans leur importation et les conséquences sanitaires de leur adaptation au milieu.

This study conducted from 1999 to 2000 in the suburbs of Bobo Dioulasso a town in the South of Burkina, aimed at investigating the susceptibility of the local population of Culex quinquefasciatus to various insecticides and proposing alternative strategies allowing a better management of insecticide resistance in the field. Eggs of C. quinquefasciatus were first collected in stagnant waste water places. The larvae were reared to early 4rth instar and tested by larval bioassays to determine the LC50/95 and the resistance ratios (RR50 and RR95) as well as their confidence intervals. A susceptible reference Strain "Slab" was used as control. Resistance was found to DDT and pyrethroids, but reduced susceptibility was found for carbamates, organophosphorates, phenyl pyrazole and in a less extend to Bacillus sphaericus. Resistance to pyrethroides is quite alarming since these insecticides are mainly used for bed net impregnation for the Roll Back malaria programme implemented in Africa. The high levels of insecticide resistance in C. quinquefasciatus suggest that alternative strategies have to be implemented to minimize the pressure of selection on resistant genes. The use of bio-larvicides (Bacillus sphaericus) alone or in rotation with different compounds may be a promising strategy for controlling C. quinquefasciatus in Bobo Dioulasso.

II existe, dans les mares du Ferlo, deux espèces de vecteurs potentiels du virus de la Rift Valley Fever possédant des modalités de développement différentes: Aedes vexans arabiensis et Culex poicilipes. De fortes pluies au début de la saison entraînent l'apparition soudaine d'une importante population d'Aedes, car les oeufs de cette espèce, pondus l'année précédente, sont présents en grand nombre sur les parois des mares, prêts à éclore dès qu'ils sont immergés. Pour peu que le virus soit présent dans la nature (la transmission transovarienne de virus chez les Aedes est un phénomène courant), une amplification virale suivie d'un début de diffusion est alors possible parmi des hôtes vertébrés non immuns. Des pluies légères, régulières, comme c'est souvent la règle en milieu de saison, auront tendance à favoriser d'autres espèces que les Aedes, en particulier Culex poicilipes dont la dynamique est liée à la stabilité du milieu aquatique, leurs oeufs ne supportant pas la dessiccation. Puis, en fin de saison, les pluies deviennent rares et les mares commencent à tarir. Les Aedes ont pratiquement disparu, leurs oeufs ne pouvant plus être recouverts par les rares pluies tombant alors. Mais des pluies tardives peuvent encore apparaître, de manière assez exceptionnelle. Si elles sont conséquentes, elles permettent alors aux Culex de maintenir leurs populations à un niveau élevé et aux oeufs d'Aedes de retrouver les conditions nécessaires pour éclore. Il y aura donc maintien des populations de Culex et apparition de femelles d'Aedes, donnant au virus la possibilité d'être à nouveau disséminé et amplifié. Après les pluies, les femelles de Culex vont disparaître et les oeufs d'Aedes - dont certains sont susceptibles d'héberger le virus RVF - entrer en diapause, jusqu'à l'année suivante.

Experimental study of efficiency of Gambusia affinis holbrooki (GIRARD, 1859) (Fish-Poecilidae). Gambusia affinis is a culiciphage fish which was introduced in Tunisia in 1929 to control mosquito larvae. In the present study, we confirm, under laboratory conditions, the good efficacy of Gambusia affinis against mosquito larvae. The consumption of larvae decreases with the evolution of larvae instars and increases, for the same instar, in relation with the fish size. In fact, the size of the prey is related to the predator's size: fish belonging to the length class [20-24 mm] prefer IIIrd instar, fish from class length [25-29 mm] prefer pupae and IVth instar. The trophic test shows that G. affinis has a clear preference for Culicidae larvae, except fish belonging to the 2 length classes [35-39 mm] and [40-44 mm] for which Culicidae and Ephemeroptera have similar preference. In addition, at high temperature (30 degrees C), Gambusia affinis has a higher efficiency.

The efficacy of pieces of nets treated with two formulations of deltamethrin (concentrated suspension at 1% and tablets at 25%) against two strains of Culex quinquefasciatus ("S-Lab", sensitive strain and "Bouaké", local strain) has been evaluated at the laboratory by experimental tunnels tests. The observed mortality of the sensitive strain has been 2-3 time more important than that of local strain. This observation seems to be linked to Culex quinquefasciatus of Bouaké pyrethrinoids-resistance. The excito-repellency effect of the two formulations has been lower for the local strain than for the sensitive strain. It has also been more important with the tablet at 25% than with concentrated suspension at 1%. The blood feeding rate has been more important for the local strain than for sensitive strain and it has been lower with the tablet at 25% than with the concentrated suspension at 1%.

The benzimidazolic and benzothiazolic derivatives with a (CH(2))n radical in 2 position of the heterocycle had been synthesized and then tested for their insecticidal activity on Culex pipiens larvae. The benzothiazolic derivatives were found to be the most active. The study has also showed that this activity was related to the nature of the substitute in 2 position of the heterocycle. This activity increased when (CH(2))n chain increased until n=6; above this value, the activity decreased.

West Nile (WN) virus is a common arbovirosis in sub-Saharian Africa. It has occasionally caused epidemics or epizootics in horses in Mediterranean regions and southern Europe. The virus is transmitted to humans by mosquitoes (primarily the Culex species) that are infected by biting viremic birds. Infections in humans are usually asymptomatic. Recently, however, a growing number of cases involving central nervous system manifestations and deaths have been reported in elderly people in Algeria and Romania. Deaths have also been recorded in migrating birds in zones where the virus is emerging. An outbreak of WN virus in an urban area of North America in 1999 underscored the ability of viruses to appear suddenly in unexpected places. Molecular biology techniques are required for positive identification of WN virus. Serological tests alone do not allow differentiation from other flavivirus in the encephalitis group including Japanese encephalitis in Asia and Saint Louis encephalitis in North America. Virological monitoring of sentinel birds should provide a better understanding of epidemiological factors and of the pathological potential of circulating strains.

This study, based on phenotype of green larvae colour, has enabled the selection of a genetically distinct line of Culex pipiens pipiens. The four loci under study were found to be homozygous to the 42nd generation. These loci were associated with an increased sensitivity to organochlorides in the progeny when compared to the parent strain. This observation, with possible expansion to other species, has potential practical applications in the identification of susceptible insect populations in insecticide campaigns.

The mortality of Culex quinquefasciatus mosquitoes having fed ten days earlier on a chicken treated by 2,000 micrograms/kg of ivermectin (about ten times the therapeutic dosage) is about 25% higher than the mortality recorded on mosquitoes having fed on a non treated chicken. This systemic effect occurs only if the blood meal takes place between 7 and 31 hours after the administration of the drug. However, no systemic effect is recorded either with the C. quinquefasciatus mosquito or with the Simulium squamosum black fly when they are fed on human beings treated at the therapeutic dose.

The aim of this paper is to indicate the main strengths which are involved in the spread of insecticide resistance genes. These forces are more or less well known in population genetics, there are: mutations which are involved in the creation of new alleles well adapted to insecticides; migration which is responsible for the geographical extension of resistance and selection which screened among the various alleles those which are best adapted in the geographical and ecological context. The biological model described in this paper is the mosquito Culex pipiens which is the best known model at that time. Many works have been done on the resistance to insecticides in this species. On the other hand, the molecular mechanisms involved in insecticide resistance have been described from various invertebrates.

Aedes aegypti control program in Martinique started en 1968. The Aedes aegypti major breeding sites are associated with flowers vases, drums, used tyres, artificial containers and watering places. However, Culex quinquefasciatus is the main nuisance mosquito in all the island. This species is unpleasant, especially in urban areas. Over 200 Culex quinquefasciatus bites per person per night have been observed in several localities of the island. Culex quinquefasciatus breeding sites are mostly associated with sewage treatment plants, septic tanks and stagnant drains. In order to reduce this nuisance and to improve the quality of life-the Conseil General initiated a large mosquito control program since 1991. This global mosquito control is based on: information and health education, environmental management (source reduction, drainage...), use of chemical insecticides.