title: Anopheles arabiensis seasonal densities and infection rates in relation to landscape classes and climatic parameters in a Sahelian area of Senegal.
abstract: BACKGROUND
  The influence of environmental and climatic factors on malaria vector bionomics and transmission is an important topic in the context of climatic change particularly at macro-geographical level. Sahelian areas could be particularly affected due to heterogeneous features including high inter-annual variability in rainfall and others associated parameters. Therefore, baseline information on the impact of environmental and climatic factors on malaria transmission at micro-geographical level is required for vector risk management and implementation of control strategies.
  
  
  METHODS
  Malaria vectors were collected indoors by pyrethrum spray catches in 14 villages belonging to 4 different landscape classes (wooded savanna, shrubby savanna, bare soils and steppe) in the sylvo-pastoral area of Senegal. Plasmodium falciparum infection rates were determined using an indirect enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  An. arabiensis was the predominant species in all landscape classes and was the only species collected at the end of the rainy season excepted in villages located in bare soils where it cohabited with An. coluzzii. Mean temperature and relative humidity showed similar variations in all the landscape classes covered whereas rainfall was more heterogeneous in terms of pattern, frequency and amount. The mean densities of An. arabiensis displayed high seasonal differences with peaks observed in August or September. A positive non-significant correlation was observed between An. arabiensis densities for rainfall and humidity whereas a negative non-significant correlation was reported for temperature. Plasmodium falciparum-infected mosquitoes were detected only in wooded savanna and bare soils villages.
  
  
  CONCLUSIONS
  These observations suggest key roles played by landscape classes and rainfall in malaria vector densities, infection rates and malaria transmission that could be more pronounced in villages situated in wooded savanna and bare soils. Due to the close relationship between environmental and meteorological parameters in this Sahelian region, additional studies on the impact of these parameters are required to further ascertain their association with entomological parameters involved in malaria transmission. From the public health point of view, such information could be useful for human population settlements as well as for monitoring and modelling purposes giving early warning system for implementation of interventions in these unstable transmission zones.
authors.affiliation: Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. emngom@pasteur.sn.|Université Cheikh Anta Diop de Dakar, Dakar, Sénégal. emngom@pasteur.sn.
authors.forename: El Hadji Malick
authors.initials: el HM
authors.lastname: Ngom
authors.affiliation: Université Cheikh Anta Diop de Dakar, Dakar, Sénégal. ndeyesatou_2@yahoo.fr.
authors.forename: Ndèye Diango
authors.initials: ND
authors.lastname: Faye
authors.affiliation: Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. ctalla@pasteur.sn.|Université Gaston Berger, Saint-Louis, Sénégal. ctalla@pasteur.sn.
authors.forename: Cheikh
authors.initials: C
authors.lastname: Talla
authors.affiliation: Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. elndiaye@pasteur.sn.|Université Cheikh Anta Diop de Dakar, Dakar, Sénégal. elndiaye@pasteur.sn.
authors.forename: El Hadji
authors.initials: el H
authors.lastname: Ndiaye
authors.affiliation: Centre de Suivi Ecologique, Dakar, Sénégal. jacques-andre.ndione@cse.sn.
authors.forename: Jacques-André
authors.initials: JA
authors.lastname: Ndione
authors.affiliation: Université Cheikh Anta Diop de Dakar, Dakar, Sénégal. fayeo@orange.sn.
authors.forename: Ousmane
authors.initials: O
authors.lastname: Faye
authors.affiliation: Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. ba@pasteur.sn.
authors.forename: Yamar
authors.initials: Y
authors.lastname: Ba
authors.affiliation: Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. diallo@pasteur.sn.
authors.forename: Mawlouth
authors.initials: M
authors.lastname: Diallo
authors.affiliation: Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. dia@pasteur.sn.
authors.forename: Ibrahima
authors.initials: I
authors.lastname: Dia
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D002980:Climate; D004772:Entomology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006813:Humidity; D007303:Insect Vectors / Q000469:parasitology*; D016778:Malaria, Falciparum / Q000635:transmission*; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D011891:Rain; D012621:Seasons; D012675:Senegal