title: Mosquito host choices on livestock amplifiers of Rift Valley fever virus in Kenya.
abstract: BACKGROUND
  Animal hosts may vary in their attraction and acceptability as components of the host location process for assessing preference, and biting rates of vectors and risk of exposure to pathogens. However, these parameters remain poorly understood for mosquito vectors of the Rift Valley fever (RVF), an arboviral disease, and for a community of mosquitoes.
  
  
  METHODS
  Using three known livestock amplifiers of RVF virus including sheep, goat and cattle as bait in enclosure traps, we investigated the host-feeding patterns for a community of mosquitoes in Naivasha, an endemic area of Rift Valley fever (RVF), in a longitudinal study for six months (June-November 2015). We estimated the incidence rate ratios (IRR) where mosquitoes chose cow over the other livestock hosts by comparing their attraction (total number collected) and engorgement rate (proportion freshly blood-fed) on these hosts.
  
  
  RESULTS
  Overall, significant differences were observed in host preference parameters for attraction (F2,15 = 4.1314, P = 0.037) and engorgement (F2,15 = 6.24, P = 0.01) with cow consistently attracting about 3-fold as many mosquitoes as those engorged on sheep (attraction: IRR = 2.9, 95 % CI 1.24-7.96; engorgement: IRR = 3.2, 95 % CI = 1.38-7.38) or goat (attraction: IRR = 2.7, 95 % CI 1.18-7.16; engorgement: IRR = 3.28, 95 % CI 1.47-7.53). However, there was no difference between the attraction elicited by sheep and goat (IRR = 1.08; 95 % CI 0.35-3.33 or engorgement rate (IRR = 0.96, 95 % CI 0.36-2.57).
  
  
  CONCLUSIONS
  Despite the overall attractive pattern to feed preferentially on cows, the engorgement rate was clearly independent of the number attracted for certain mosquito species, notably among the flood water Aedes spp., largely incriminated previously as primary vectors of RVF. Our findings suggest that insecticide treated cattle (ITC) can be exploited in enclosure traps as contact bait in the monitoring and control of disease-causing mosquitoes in RVF endemic areas.
authors.affiliation: International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya. dtchouassi@icipe.org.
authors.forename: David P
authors.initials: DP
authors.lastname: Tchouassi
authors.affiliation: International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya.
authors.forename: Robinson O K
authors.initials: RO
authors.lastname: Okiro
authors.affiliation: International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya.|Centre for Virus Research, Kenya Medical Research Institute (KEMRI), P.O. Box 54840-00200, Nairobi, Kenya.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Sang
authors.affiliation: United States Department for Agriculture - Agricultural Research Station (USDA-ARS), Arthropod-Borne Animal Disease Research Unit, Center for Grain and Animal Health Research, 515 College Ave, Manhattan, KS 66502, KS, USA.
authors.forename: Lee W
authors.initials: LW
authors.lastname: Cohnstaedt
authors.affiliation: United States Department for Agriculture - Agricultural Research Station (USDA-ARS), Arthropod-Borne Animal Disease Research Unit, Center for Grain and Animal Health Research, 515 College Ave, Manhattan, KS 66502, KS, USA.
authors.forename: David Scott
authors.initials: DS
authors.lastname: McVey
authors.affiliation: International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya.
authors.forename: Baldwyn
authors.initials: B
authors.lastname: Torto
mesh_terms: D000818:Animals; D009033:Culicidae / Q000502:physiology* / Q000821:virology; D005247:Feeding Behavior; D007303:Insect Vectors; D007630:Kenya; D058751:Livestock / Q000469:parasitology*; D008137:Longitudinal Studies; D012295:Rift Valley Fever / Q000635:transmission; D012296:Rift Valley fever virus / Q000302:isolation & purification; D012418:Ruminants / Q000469:parasitology*
keywords: Attractancy; Enclosure trap; Engorgement rate; RVF livestock amplifiers; Surveillance