title: Transmission patterns of Plasmodium falciparum by Anopheles gambiae in Benin.
abstract: BACKGROUND
  To better control malaria, the clear and urgent need is for improved data to inform decision makers, but in several African countries, there is a lack of baseline data on vectors and variation in the intensity of malaria transmission. This has resulted in the implementation of vector control efforts that ignore variation in vector behaviour and intensity of transmission, an approach that is most often not cost-effective. This study presents a detailed entomological description of mosquito distribution and variation in potentially transmissible contacts of Plasmodium falciparum following a south to north transect in Benin.
  
  
  METHODS
  The study was conducted in five locations where environmental parameters were different and malaria prevalence ranged between 14 and 51%. The locations represent the main eco-epidemiological malaria areas in Benin. Mosquitoes were collected using human landing catches, pyrethrum spray catches and windows traps. They were taxonomically and molecularly identified. Head-thoraces of Anopheles gambiae s.l. were tested by enzyme-linked immunosorbent assay. Entomological indicators were estimated following WHO guidelines.
  
  
  RESULTS
  The results showed variation between location and period in distribution of Anopheles coluzzii, An. gambiae, and Anopheles arabiensis (p < 0.05). An extension of the reported range of An. arabiensis was also observed. Densities of malaria vectors varied significantly between rural and urban sites, however, indoor/outdoor biting ratios remained constant. Proportions of malaria vectors with circumsporozoite protein of P. falciparum were similar between locations. The entomological inoculation rates ranged between zero and eight bites/man/night with significant variations between areas.Four profiles of human exposure to infectious malaria vector bites were observed and included location with one season of high transmission (June - August), two seasons of lower transmission (March-August; October-November), moderate continuous transmission season, and high continuous transmission season of P. falciparum.
  
  
  CONCLUSIONS
  The study revealed several entomological patterns in transmission of P. falciparum in Benin. The data could be used for purposes of planning a more cost-effective vector control strategy, by stratifying the country into higher and lower transmission zones. The information could also be used to guide extension of indoor residual spray based on a targeted use of IRS at sites where the duration of insecticidal effect following spraying coincides with the peak transmission period.
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. amerusangel@yahoo.fr.
authors.forename: Virgile
authors.initials: V
authors.lastname: Gnanguenon
authors.forename: Renaud
authors.initials: R
authors.lastname: Govoetchan
authors.forename: Fiacre R
authors.initials: FR
authors.lastname: Agossa
authors.forename: Razaki
authors.initials: R
authors.lastname: Ossè
authors.forename: Frédéric
authors.initials: F
authors.lastname: Oke-Agbo
authors.forename: Roseric
authors.initials: R
authors.lastname: Azondekon
authors.forename: Arthur
authors.initials: A
authors.lastname: Sovi
authors.forename: Roseline
authors.initials: R
authors.lastname: Attolou
authors.forename: Kefilath
authors.initials: K
authors.lastname: Badirou
authors.forename: Filémon T
authors.initials: FT
authors.lastname: Tokponnon
authors.forename: Gil G
authors.initials: GG
authors.lastname: Padonou
authors.forename: Martin C
authors.initials: MC
authors.lastname: Akogbeto
mesh_terms: D000818:Animals; D000852:Anopheles / Q000145:classification / Q000235:genetics / Q000469:parasitology* / Q000502:physiology*; D000953:Antigens, Protozoan / Q000032:analysis; D001541:Benin / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005247:Feeding Behavior; D006801:Humans; D007303:Insect Vectors; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000635:transmission*; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D011156:Population Density; D015995:Prevalence
chemical_list: D000953:Antigens, Protozoan