Highly focused anopheline breeding sites and malaria transmission in Dakar

<p>Abstract</p> <p>Background</p> <p>Urbanization has a great impact on the composition of the vector system and malaria transmission dynamics. In Dakar, some malaria cases are autochthonous but parasite rates and incidences of clinical malaria attacks have been recorded at low levels. Ecological heterogeneity of malaria transmission was investigated in Dakar, in order to characterize the <it>Anopheles </it>breeding sites in the city and to study the dynamics of larval density and adult aggressiveness in ten characteristically different urban areas.</p> <p>Methods</p> <p>Ten study areas were sampled in Dakar and Pikine. Mosquitoes were collected by human landing collection during four nights in each area (120 person-nights). The <it>Plasmodium falciparum </it>circumsporozoite (CSP) index was measured by ELISA and the entomological inoculation rates (EIR) were calculated. Open water collections in the study areas were monitored weekly for physico-chemical characterization and the presence of anopheline larvae. Adult mosquitoes and hatched larvae were identified morphologically and by molecular methods.</p> <p>Results</p> <p>In September-October 2007, 19,451 adult mosquitoes were caught among which, 1,101 were <it>Anopheles gambiae s.l</it>. The Human Biting Rate ranged from 0.1 bites per person per night in Yoff Village to 43.7 in Almadies. Seven out of 1,101 <it>An. gambiae s.l</it>. were found to be positive for <it>P. falciparum </it>(CSP index = 0.64%). EIR ranged from 0 infected bites per person per year in Yoff Village to 16.8 in Almadies. The <it>An</it>. <it>gambiae </it>complex population was composed of <it>Anopheles arabiensis </it>(94.8%) and <it>Anopheles melas </it>(5.2%). None of the <it>An. melas </it>were infected with <it>P. falciparum</it>. Of the 54 water collection sites monitored, 33 (61.1%) served as anopheline breeding sites on at least one observation. No <it>An</it>. <it>melas </it>was identified among the larval samples. Some physico-chemical characteristics of water bodies were associated with the presence/absence of anopheline larvae and with larval density. A very close parallel between larval and adult densities was found in six of the ten study areas.</p> <p>Conclusion</p> <p>The results provide evidence of malaria transmission in downtown Dakar and its surrounding suburbs. Spatial heterogeneity of human biting rates was very marked and malaria transmission was highly focal. In Dakar, mean figures for transmission would not provide a comprehensive picture of the entomological situation; risk evaluation should therefore be undertaken on a small scale.</p

L'initiative européenne "Suivi global pour l'environnement et la sécurité'' et le protocole de Kyoto

International audienceEn 1992 la Convention Cadre des Nations Unies pour le Contrôle du Changement du Climat (UNFCCC) a montré la prise de conscience internationale des effets néfastes de l'accumulation dans l'atmosphère des gaz à effet de serre, conduisant à un réchauffement climatique, sous l'effet direct ou indirect des activités anthropiques. Le Protocole de Kyoto, adopté en 1997, a fixé des engagements quantitatifs que les parties signataires s'engageaient à respecter. Ceci suppose des moyens d'observation afin de comprendre, modéliser, mesurer l'évolution des sources et des puits de gaz à effet de serre, et tout particulièrement celles sur lesquelles l'Homme peut avoir une influence directe. Conjointement aux mesures in situ, l'observation de la Terre par satellite s'avère un moyen puissant pour répondre à cet objectif. L'Europe, comme le rappelle le "Manifeste de Baveno" adopté par un certain nombre d'agences impliquées dans les activités spatiales, dispose d'atouts majeurs pour remplir de tels objectifs. Le présent article s'efforce de donner une vue synthétique des différentes informations à rassembler pour le suivi des clauses du Protocole de Kyoto, de l'UNFCCC et de leurs conséquences globales sur le changement climatique, mettant en évidence les résultats obtenus, les moyens à entreprendre, les recherches restant à mener, pour atteindre ces buts

INSTRUMENTATION POUR LA MESURE DES NOYAUX DE CONDENSATION DE NUAGE AUX FAIBLES SURSATURATIONS CRITIQUES (APPLICATION A L'AEROSOL URBAIN EN REGION TOULOUSAINE)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

A Rose Analysis Method Relating Air Chemistry to Fire Distribution in Tropical Africa.

Emissions from vegetation fires in tropics contribute significantly to atmospheric chemistry at continental and global scales. africa is the continent where the largest number of vegetation fires annually occurs.The use of Global Area Coverage (GAC) data, from the Advanced Very High Resolution Radiometer (AVHRR) sensor onboard the NOAA satellites, allows a good description at continental level of the spatial distribution of intense active fire patterns and a unique temporal perspective over multiannual periods of time. in this study five years of active fire maps, from November 1984 to October 1989, derived from GAC data for the African continent were considered. in order to enhance the relationships between spatially distributed phenomena, such as regional patterns of active fires, and point data, such as experimental sites of atmospheric chemistry measurements, the rose diagram technique as derived from directional statistic was exploited. This methodological approach allowed the spatial characteristics of vegetation fires, which is considered the main source of atmospheric pollutants in Africa, to be described using measures of frequency and distance for each reference point. Comparison between rose diagrams of fires and nitrate (NO3) content in precipitation as measured at Enyele (Congo), at the heart of the equatorial forest during both dry and wet seasons, confirmed the usefulness of satellite observations and the spatial analysis technique proposed.JRC.(SAI)-Space Application Institut

Etude expérimentale de gaz azotés, du dioxyde de soufre et de l'ozone à l'échelle des écosystèmes de l'Afrique tropicale (application à l'estimation des dépôts secs gazeux dans le cadre du réseau IDAF)

TOULOUSE3-BU Sciences (315552104) / SudocTOULOUSE-Observ. Midi Pyréné (315552299) / SudocSudocFranceF

Remote Sensing of Bush Fire Dynamics in Central Africa from 1984 to 1988. Analysis in Relation to Regional Vegetation and Pluviometric Patterns

Abstract not availableJRC.(IRSA)-Institute For Remote Sensing Application

Domestic Biomass Combustion and Associated Atmospheric Emissions in West Africa.

Abstract not availableJRC.(SAI)-Space Application Institut