title: Exploring the potential of using cattle for malaria vector surveillance and control: a pilot study in western Kenya.
abstract: Malaria vector mosquitoes with exophilic and zoophilic tendencies, or with a high acceptance of alternative blood meal sources when preferred human blood-hosts are unavailable, may help maintain low but constant malaria transmission in areas where indoor vector control has been scaled up. This residual transmission might be addressed by targeting vectors outside the house. Here we investigated the potential of insecticide-treated cattle, as routinely used for control of tsetse and ticks in East Africa, for mosquito control.
  
  
  
  The malaria vector population in the study area was investigated weekly for 8 months using two different trapping tools: light traps indoors and cattle-baited traps (CBTs) outdoors. The effect of the application of the insecticide deltamethrin and the acaricide amitraz on cattle on host-seeking Anopheles arabiensis was tested experimentally in field-cages and the impact of deltamethrin-treated cattle explored under field conditions on mosquito densities on household level.
  
  
  
  CBTs collected on average 2.8 (95% CI: 1.8-4.2) primary [Anopheles gambiae (s.s.), An. arabiensis and An. funestus (s.s.)] and 6.3 (95% CI: 3.6-11.3) secondary malaria vectors [An. ivulorum and An. coustani (s.l.)] per trap night and revealed a distinct, complementary seasonality. At the same time on average only 1.4 (95% CI: 0.8-2.3) primary and 1.1 (95% CI: 0.6-2.0) secondary malaria vectors were collected per trap night with light traps indoors. Amitraz had no effect on survival of host-seeking An. arabiensis under experimental conditions but deltamethrin increased mosquito mortality (OR 19, 95% CI: 7-50), but only for 1 week. In the field, vector mortality in association with deltamethrin treatment was detected only with CBTs and only immediately after the treatment (OR 0.25, 95% CI: 0.13-0.52).
  
  
  
  Entomological sampling with CBTs highlights that targeting cattle for mosquito control has potential since it would not only target naturally zoophilic malaria vectors but also opportunistic feeders that lack access to human hosts as is expected in residual malaria transmission settings. However, the deltamethrin formulation tested here although used widely to treat cattle for tsetse and tick control, is not suitable for the control of malaria vectors since it causes only moderate initial mortality and has little residual activity.
authors.affiliation: International Centre of Insect Physiology and Ecology, Thomas Odhiambo Campus, 40305, Mbita, Kenya. mnjoroge@icipe.org.
authors.forename: Margaret M
authors.identifier: 0000-0002-9960-7982
authors.initials: MM
authors.lastname: Njoroge
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
authors.forename: Inaki
authors.initials: I
authors.lastname: Tirados
authors.affiliation: Schools of Biological and Biomedical Sciences, Durham University, Durham, DH1 3LE, UK.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Lindsay
authors.affiliation: South African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa.
authors.forename: Glyn A
authors.initials: GA
authors.lastname: Vale
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.|Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Torr
authors.affiliation: International Centre of Insect Physiology and Ecology, Thomas Odhiambo Campus, 40305, Mbita, Kenya.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Fillinger
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D000852:Anopheles / Q000187:drug effects / Q000502:physiology*; D001681:Biological Assay; D002417:Cattle; D005260:Female; D007303:Insect Vectors / Q000502:physiology*; D007306:Insecticides / Q000494:pharmacology; D007630:Kenya / Q000453:epidemiology*; D008288:Malaria / Q000453:epidemiology / Q000635:transmission*; D009570:Nitriles / Q000494:pharmacology; D010865:Pilot Projects; D011157:Population Dynamics; D011722:Pyrethrins / Q000494:pharmacology; D012621:Seasons; D013045:Species Specificity; D014370:Tsetse Flies / Q000187:drug effects
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin
keywords: Anopheles; Cattle-baited trap; Insecticide-treated cattle; Malaria; Vector control