title: High mosquito burden and malaria transmission in a district of the city of Douala, Cameroon.
abstract: BACKGROUND
  Rapid demographic growth in Douala city, Cameroon, has resulted in profound ecological and environmental changes. Although demographic changes can affect anopheline mosquito breeding sites, there is a lack of understanding about the epidemiological impact that such changes might have on vector ecology and malaria transmission.
  
  
  METHODS
  A 12-month entomological study was conducted in a highly populated district of Douala called Ndogpassi. Adult mosquitoes were collected using two methods: 1) human landing catches (HLC); and 2) Centers for Disease Control and Prevention (CDC) light traps; these methods were used twice monthly from January to December 2011. Mosquito genus and species were identified with morphological and molecular diagnostic tools. The sampling efficiency of the CDC light trap and HLC were compared. Anopheles gambiae infection with Plasmodium falciparum was detected using ELISA. Susceptibility to DDT, permethrin, and deltamethrin insecticides were also determined.
  
  
  RESULTS
  A total of 6923 mosquitoes were collected by HLC (5198) and CDC light traps (1725). There was no equivalence in the sampling efficiency between light traps and human landing catches (P > 0.01). With 51% of the total, Culex was the most common, followed by Anopheles (26.14%), Mansonia (22.7%) and Aedes (0.1%). An. gambiae ss (M form) comprised ~98% of the total anophelines collected. An. gambiae had a biting rate of 0.25 to 49.25 bites per human per night, and was the only species found to be infected with P. falciparum. A P. falciparum infection rate of 0.5% was calculated (based on enzyme-linked immunosorbent assays using the circumsporozoite surface protein). The entomological inoculation rate was estimated at 31 infective bites per annum. Insecticide susceptibility tests on An. gambiae females revealed a mortality rate of 33%, 76% and 98% for DDT, permethrin and deltamethrin, respectively. The West African kdr allele (L1014F) was detected in 38 of the 61 An. gambiae analyzed (62.3%).
  
  
  CONCLUSIONS
  The present study revealed seasonal malaria transmission in Douala. High levels of An. gambiae were detected along with a high prevalence of insecticide resistance in this vector population. These findings highlight the need to promote use of insecticide-impregnated bed nets in Douala.
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun. antonio_nk@yahoo.fr
authors.forename: Christophe
authors.initials: C
authors.lastname: Antonio-Nkondjio
authors.forename: Blaise
authors.initials: B
authors.lastname: Defo-Talom
authors.forename: Romuald
authors.initials: R
authors.lastname: Tagne-Fotso
authors.forename: Billy
authors.initials: B
authors.lastname: Tene-Fossog
authors.forename: Cyrille
authors.initials: C
authors.lastname: Ndo
authors.forename: Leopold Gustave
authors.initials: LG
authors.lastname: Lehman
authors.forename: Timoléon
authors.initials: T
authors.lastname: Tchuinkam
authors.forename: Pierre
authors.initials: P
authors.lastname: Kengne
authors.forename: Parfait
authors.initials: P
authors.lastname: Awono-Ambene
mesh_terms: D000818:Animals; D002163:Cameroon / Q000453:epidemiology; D002947:Cities; D009033:Culicidae / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000469:parasitology*; D004199:Disease Vectors; D017753:Ecosystem; D005260:Female; D006801:Humans; D007305:Insecticide Resistance; D008297:Male; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D012621:Seasons