title: The importance of considering community-level effects when selecting insecticidal malaria vector products.
abstract: BACKGROUND
  Insecticide treatment of nets, curtains or walls and ceilings of houses represent the primary means for malaria prevention worldwide. Direct personal protection of individuals and households arises from deterrent and insecticidal activities which divert or kill mosquitoes before they can feed. However, at high coverage, community-level reductions of mosquito density and survival prevent more transmission exposure than the personal protection acquired by using a net or living in a sprayed house.
  
  
  METHODS
  A process-explicit simulation of malaria transmission was applied to results of 4 recent Phase II experimental hut trials comparing a new mosaic long-lasting insecticidal net (LLIN) which combines deltamethrin and piperonyl butoxide with another LLIN product by the same manufacturer relying on deltamethrin alone.
  
  
  RESULTS
  Direct estimates of mean personal protection against insecticide-resistant vectors in Vietnam, Cameroon, Burkina Faso and Benin revealed no clear advantage for combination LLINs over deltamethrin-only LLINs (P = 0.973) unless both types of nets were extensively washed (Relative mean entomologic inoculation rate (EIR) ± standard error of the mean (SEM) for users of combination nets compared to users of deltamethrin only nets = 0.853 ± 0.056, P = 0.008). However, simulations of impact at high coverage (80% use) predicted consistently better impact for the combination net across all four sites (Relative mean EIR ± SEM in communities with combination nets, compared with those using deltamethrin only nets = 0.613 ± 0.076, P < 0.001), regardless of whether the nets were washed or not (P = 0.467). Nevertheless, the degree of advantage obtained with the combination varied substantially between sites and their associated resistant vector populations.
  
  
  CONCLUSIONS
  Process-explicit simulations of community-level protection, parameterized using locally-relevant experimental hut studies, should be explicitly considered when choosing vector control products for large-scale epidemiological trials or public health programme procurement, particularly as growing insecticide resistance necessitates the use of multiple active ingredients.
authors.affiliation: Ifakara Health Institute, Biomedical & Environmental Thematic Group, PO Box 53, Ifakara, Morogoro, United Republic of Tanzania. gkilleen@ihi.or.tz
authors.forename: Gerry F
authors.initials: GF
authors.lastname: Killeen
authors.forename: Fredros O
authors.initials: FO
authors.lastname: Okumu
authors.forename: Raphael
authors.initials: R
authors.lastname: N'Guessan
authors.forename: Marc
authors.initials: M
authors.lastname: Coosemans
authors.forename: Adedapo
authors.initials: A
authors.lastname: Adeogun
authors.forename: Sam
authors.initials: S
authors.lastname: Awolola
authors.forename: Josiane
authors.initials: J
authors.lastname: Etang
authors.forename: Roch K
authors.initials: RK
authors.lastname: Dabiré
authors.forename: Vincent
authors.initials: V
authors.lastname: Corbel
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007303:Insect Vectors / Q000187:drug effects* / Q000502:physiology; D057148:Insecticide-Treated Bednets / Q000706:statistics & numerical data*; D007306:Insecticides / Q000494:pharmacology*; D008288:Malaria / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission; D009032:Mosquito Control / Q000295:instrumentation* / Q000379:methods; D057147:Mosquito Nets / Q000706:statistics & numerical data*; D012111:Residence Characteristics; D014744:Vietnam / Q000453:epidemiology
chemical_list: D007306:Insecticides