title: Early biting and insecticide resistance in the malaria vector Anopheles might compromise the effectiveness of vector control intervention in Southwestern Uganda.
abstract: BACKGROUND
  Southwestern Uganda has high malaria heterogeneity despite moderate vector control and other interventions. Moreover, the early biting transmission and increased resistance to insecticides might compromise strategies relying on vector control. Consequently, monitoring of vector behaviour and insecticide efficacy is needed to assess the effectiveness of strategies aiming at malaria control. This eventually led to an entomological survey in two villages with high malaria prevalence in this region.
  
  
  METHODS
  During rainy, 2011 and dry season 2012, mosquitoes were collected in Engari and Kigorogoro, Kazo subcounty, using human landing collection, morning indoor resting collection, pyrethrum spray collection and larval collection. Circumsporozoite protein of Plasmodium falciparum sporozoites in female Anopheles mosquitoes was detected using ELISA assay. Bioassays to monitor Anopheles resistance to insecticides were performed.
  
  
  RESULTS
  Of the 1,021 female Anopheles species captured, 62% (632) were Anopheles funestus and 36% (371) were Anopheles gambiae s.l. The most common species were Anopheles gambiae s.l. in Engari (75%) and A. funestus in Kigorogoro (83%). Overall, P. falciparum prevalence was 2.9% by ELISA. The daily entomological inoculation rates were estimated at 0.17 and 0.58 infected bites/person/night during rainy and dry season respectively in Engari, and 0.81 infected bites/person/night in Kigorogoro during dry season. In both areas and seasons, an unusually early evening biting peak was observed between 6 - 8 p.m. In Engari, insecticide bioassays showed 85%, 34% and 12% resistance to DDT during the rainy season, dry season and to deltamethrin during the dry season, respectively. In Kigorogoro, 13% resistance to DDT and to deltamethrin was recorded. There was no resistance observed to bendiocarb and pirimiphos methyl.
  
  
  CONCLUSIONS
  The heterogeneity of mosquito distribution, entomological indicators and resistance to insecticides in villages with high malaria prevalence highlight the need for a long-term vector control programme and monitoring of insecticide resistance in Uganda. The early evening biting habits of Anopheles combined with resistance to DDT and deltamethrin observed in this study suggest that use of impregnated bed nets alone is insufficient as a malaria control strategy, urging the need for additional interventions in this area of high transmission.
authors: Epicentre Mbarara Research Centre, Mbarara, Uganda. patrick.ojuka@epicentre.msf.org.
authors: Patrick
authors: P
authors: Ojuka
authors: Epicentre Mbarara Research Centre, Mbarara, Uganda. Yap.BOUM@epicentre.msf.org.|Mbarara University of Science and Technology, Mbarara, Uganda. Yap.BOUM@epicentre.msf.org.
authors: Yap
authors: Y
authors: Boum
authors: Epicentre, Paris, France. lise.denoeud@epicentre.msf.org.
authors: Lise
authors: L
authors: Denoeud-Ndam
authors: Epicentre Mbarara Research Centre, Mbarara, Uganda. Carolyn.NABASUMBA@epicentre.msf.org.
authors: Carolyn
authors: C
authors: Nabasumba
authors: Epicentre, Paris, France. Yolanda.MULLER@geneva.msf.org.
authors: Yolanda
authors: Y
authors: Muller
authors: National Malaria Control Programme Ministry of Health, Kampala, Uganda. blessedmike350@gmail.com.
authors: Michael
authors: M
authors: Okia
authors: Epicentre Mbarara Research Centre, Mbarara, Uganda. juliet.mwanga@epicentre.msf.org.|Mbarara University of Science and Technology, Mbarara, Uganda. juliet.mwanga@epicentre.msf.org.
authors: Juliet
authors: J
authors: Mwanga-Amumpaire
authors: TransVIHMI IRD UMI 233-INSERM U 1175-Montpellier University, Montpellier, France. pierre.debeaudrap@ird.fr.
authors: Pierre
authors: P
authors: De Beaudrap
authors: Department of Disease Control, London School of Tropical Medicine and Hygiene, Keppel Street, London, UK. Natacha.Protopopoff@lshtm.ac.uk.
authors: Natacha
authors: N
authors: Protopopoff
authors: Epicentre, Paris, France. jean-Francois.ETARD@epicentre.msf.org.|TransVIHMI IRD UMI 233-INSERM U 1175-Montpellier University, Montpellier, France. jean-Francois.ETARD@epicentre.msf.org.
authors: Jean-François
authors: JF
authors: Etard
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects / Q000469:parasitology / Q000502:physiology; D003430:Cross-Sectional Studies; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D007303:Insect Vectors / Q000187:drug effects / Q000469:parasitology / Q000502:physiology; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology; D016778:Malaria, Falciparum / Q000517:prevention & control*; D010963:Plasmodium falciparum; D014454:Uganda / Q000453:epidemiology
chemical_list: D007306:Insecticides