title: Onchocerciasis transmission in Ghana: the human blood index of sibling species of the Simulium damnosum complex.
abstract: Vector-biting behaviour is important for vector-borne disease (VBD) epidemiology. The proportion of blood meals taken on humans (the human blood index, HBI), is a component of the biting rate per vector on humans in VBD transmission models. Humans are the definitive host of Onchocerca volvulus, but the simuliid vectors feed on a range of animals and HBI is a key indicator of the potential for human onchocerciasis transmission. Ghana has a diversity of Simulium damnosum complex members, which are likely to vary in their HBIs, an important consideration for parameterization of onchocerciasis control and elimination models.
  
  
  
  Host-seeking and ovipositing S. damnosum (sensu lato) (s.l.) were collected from seven villages in four Ghanaian regions. Taxa were morphologically and molecularly identified. Blood meals from individually stored blackfly abdomens were used for DNA profiling, to identify previous host choice. Household, domestic animal, wild mammal and bird surveys were performed to estimate the density and diversity of potential blood hosts of blackflies.
  
  
  
  A total of 11,107 abdomens of simuliid females (which would have obtained blood meal(s) previously) were tested, with blood meals successfully amplified in 3,772 (34 %). A single-host species was identified in 2,857 (75.7 %) of the blood meals, of which 2,162 (75.7 %) were human. Simulium soubrense Beffa form, S. squamosum C and S. sanctipauli Pra form were the most anthropophagic (HBI = 0.92, 0.86 and 0.70, respectively); S. squamosum E, S. yahense and S. damnosum (sensu stricto) (s.s.)/S. sirbanum were the most zoophagic (HBI = 0.44, 0.53 and 0.63, respectively). The degree of anthropophagy decreased (but not statistically significantly) with increasing ratio of non-human/human blood hosts. Vector to human ratios ranged from 139 to 1,198 blackflies/person.
  
  
  
  DNA profiling can successfully identify blood meals from host-seeking and ovipositing blackflies. Host choice varies according to sibling species, season and capture site/method. There was no evidence that HBI is vector and/or host density dependent. Transmission breakpoints will vary among locations due to differing cytospecies compositions and vector abundances.
authors: London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK.|Present address: Institute of Biodiversity, Animal Health and Comparative Medicine; Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, G12 8QQ, UK.
authors: Poppy H L
authors: PH
authors: Lamberton
authors: London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK.|Natural Resources Institute, University of Greenwich at Medway, Central Avenue, Chatham Maritime, Chatham, Kent, ME4 4 TB, UK.
authors: Robert A
authors: RA
authors: Cheke
authors: London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK.
authors: Martin
authors: M
authors: Walker
authors: MRC Centre for Outbreak Analysis and Modelling. Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK.
authors: Peter
authors: P
authors: Winskill
authors: Instituto Leônidas e Maria Deane, Fundação Oswaldo Cruz, Rua Terezina 476, Adrianopolis, AM, 69057-070, Manaus, Brazil.
authors: J Lee
authors: JL
authors: Crainey
authors: Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, PO Box LG581, Accra, Ghana.
authors: Daniel A
authors: DA
authors: Boakye
authors: Department of Environmental Biology and Health, Water Research Institute, Council for Scientific and Industrial Research, PO Box M32, Accra, Ghana.
authors: Mike Y
authors: MY
authors: Osei-Atweneboana
authors: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors: Iñaki
authors: I
authors: Tirados
authors: Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, PO Box LG581, Accra, Ghana.
authors: Michael D
authors: MD
authors: Wilson
authors: Ghana Health Service, P.O. Box MB-190, Accra, Ghana.
authors: Anthony
authors: A
authors: Tetteh-Kumah
authors: Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, PO Box LG581, Accra, Ghana.
authors: Sampson
authors: S
authors: Otoo
authors: School of Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AH, UK.
authors: Rory J
authors: RJ
authors: Post
authors: London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK. m.basanez@imperial.ac.uk.
authors: María-Gloria
authors: MG
authors: Basañez
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001769:Blood / Q000469:parasitology*; D002648:Child; D002675:Child, Preschool; D005247:Feeding Behavior; D005260:Female; D005869:Ghana / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007303:Insect Vectors / Q000145:classification* / Q000235:genetics / Q000469:parasitology / Q000502:physiology; D008297:Male; D008875:Middle Aged; D017181:Onchocerca volvulus / Q000502:physiology*; D009855:Onchocerciasis / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D012843:Simuliidae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000469:parasitology; D055815:Young Adult
keywords: Host choice; Host-seeking vectors; Human blood index; Onchocerca volvulus; Ovipositing vectors; Simulium damnosum (sensu lato); Vector abundance