title: Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso.
abstract: BACKGROUND
  The Anopheles gambiae sensu lato (s.l.) species complex in Burkina Faso consists of Anopheles arabiensis, and molecular forms M and S of Anopheles gambiae sensu stricto (s.s.). Previous studies comparing the M and S forms for level of infection with Plasmodium falciparum have yielded conflicting results.
  
  
  METHODS
  Mosquito larvae were sampled from natural pools, reared to adulthood under controlled conditions, and challenged with natural P. falciparum by experimental feeding with blood from gametocyte carriers. Oocyst infection prevalence and intensity was determined one week after infection. DNA from carcasses was genotyped to identify species and molecular form.
  
  
  RESULTS
  In total, 7,400 adult mosquitoes grown from wild-caught larvae were challenged with gametocytes in 29 experimental infections spanning four transmission seasons. The overall infection prevalence averaged 40.7% for A. gambiae M form, 41.4% for A. gambiae S form, and 40.1% for A. arabiensis. There was no significant difference in infection prevalence or intensity between the three population groups. Notably, infection experiments in which the population groups were challenged in parallel on the same infective blood displayed less infection difference between population groups, while infections with less balanced composition of population groups had lower statistical power and displayed apparent differences that fluctuated more often from the null average.
  
  
  CONCLUSIONS
  The study clearly establishes that, at the study site in Burkina Faso, there is no difference in genetic susceptibility to P. falciparum infection between three sympatric population groups of the A. gambiae s.l. complex. Feeding the mosquito groups on the same infective blood meal greatly increases statistical power. Conversely, comparison of the different mosquito groups between, rather than within, infections yields larger apparent difference between mosquito groups, resulting from lower statistical power and greater noise, and could lead to false-positive results. In making infection comparisons between population groups, it is more accurate to compare the different groups after feeding simultaneously upon the same infective blood.
authors.affiliation: Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.
authors.forename: Awa
authors.initials: A
authors.lastname: Gnémé
authors.forename: Wamdaogo M
authors.initials: WM
authors.lastname: Guelbéogo
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Riehle
authors.forename: Antoine
authors.initials: A
authors.lastname: Sanou
authors.forename: Alphonse
authors.initials: A
authors.lastname: Traoré
authors.forename: Soumanaba
authors.initials: S
authors.lastname: Zongo
authors.forename: Karin
authors.initials: K
authors.lastname: Eiglmeier
authors.forename: Gustave B
authors.initials: GB
authors.lastname: Kabré
authors.forename: N'Falé
authors.initials: N
authors.lastname: Sagnon
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Vernick
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology* / Q000502:physiology*; D002050:Burkina Faso; D016054:DNA, Protozoan / Q000235:genetics / Q000302:isolation & purification; D005838:Genotype; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification
chemical_list: D016054:DNA, Protozoan