title: Investigating the Contribution of Peri-domestic Transmission to Risk of Zoonotic Malaria Infection in Humans.
abstract: BACKGROUND
  In recent years, the primate malaria Plasmodium knowlesi has emerged in human populations throughout South East Asia, with the largest hotspot being in Sabah, Malaysian Borneo. Control efforts are hindered by limited knowledge of where and when people get exposed to mosquito vectors. It is assumed that exposure occurs primarily when people are working in forest areas, but the role of other potential exposure routes (including domestic or peri-domestic transmission) has not been thoroughly investigated.
  
  
  RESULTS
  We integrated entomological surveillance within a comprehensive case-control study occurring within a large hotspot of transmission in Sabah, Malaysia. Mosquitoes were collected at 28 pairs households composed of one where an occupant had a confirmed P. knowlesi infection within the preceding 3 weeks ("case") and an associated "control" where no infection was reported. Human landing catches were conducted to measure the number and diversity of mosquitoes host seeking inside houses and in the surrounding peri-domestic (outdoors but around the household) areas. The predominant malaria vector species was Anopheles balabacensis, most of which were caught outdoors in the early evening (6pm - 9pm). It was significantly more abundant in the peri-domestic area than inside houses (5.5-fold), and also higher at case than control households (0.28±0.194 vs 0.17±0.127, p<0.001). Ten out of 641 An. balabacensis tested were positive for simian malaria parasites, but none for P. knowlesi.
  
  
  CONCLUSIONS
  This study shows there is a possibility that humans can be exposed to P. knowlesi infection around their homes. The vector is highly exophagic and few were caught indoors indicating interventions using bednets inside households may have relatively little impact.
authors.affiliation: Department of Pathobiology and Medical Diagnostics, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia.
authors.forename: Benny O
authors.initials: BO
authors.lastname: Manin
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, United Kingdom.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Ferguson
authors.affiliation: Parasitology Department, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Indra
authors.initials: I
authors.lastname: Vythilingam
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Kim
authors.initials: K
authors.lastname: Fornace
authors.affiliation: Jesselton Medical Centre, Kota Kinabalu, Sabah, Malaysia.
authors.forename: Timothy
authors.initials: T
authors.lastname: William
authors.affiliation: Department of Vector Biology, Liverpool School of Tropical Medicine, United Kingdom.
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Torr
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Drakeley
authors.affiliation: Department of Pathobiology and Medical Diagnostics, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia.
authors.forename: Tock H
authors.initials: TH
authors.lastname: Chua
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology / Q000502:physiology*; D016022:Case-Control Studies; D006798:Housing; D006801:Humans; D007303:Insect Vectors / Q000469:parasitology / Q000502:physiology*; D008288:Malaria / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D008296:Malaysia / Q000453:epidemiology; D009032:Mosquito Control; D016790:Plasmodium knowlesi / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D015047:Zoonoses / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*