title: What is a vector?
abstract: Many important and rapidly emerging pathogens of humans, livestock and wildlife are 'vector-borne'. However, the term 'vector' has been applied to diverse agents in a broad range of epidemiological systems. In this perspective, we briefly review some common definitions, identify the strengths and weaknesses of each and consider the functional differences between vectors and other hosts from a range of ecological, evolutionary and public health perspectives. We then consider how the use of designations can afford insights into our understanding of epidemiological and evolutionary processes that are not otherwise apparent. We conclude that from a medical and veterinary perspective, a combination of the 'haematophagous arthropod' and 'mobility' definitions is most useful because it offers important insights into contact structure and control and emphasizes the opportunities for pathogen shifts among taxonomically similar species with similar feeding modes and internal environments. From a population dynamics and evolutionary perspective, we suggest that a combination of the 'micropredator' and 'sequential' definition is most appropriate because it captures the key aspects of transmission biology and fitness consequences for the pathogen and vector itself. However, we explicitly recognize that the value of a definition always depends on the research question under study.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.
authors.affiliation: Vector-borne Viral Diseases Programme, The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK anthony.wilson@pirbright.ac.uk.
authors.forename: Anthony James
authors.identifier: http://orcid.org/0000-0002-2000-2914
authors.initials: AJ
authors.lastname: Wilson
authors.affiliation: School of Veterinary Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.
authors.forename: Eric René
authors.initials: ER
authors.lastname: Morgan
authors.affiliation: School of Medicine, Pharmacy and Health, Durham University, Thornaby TS17 6BH, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Booth
authors.affiliation: School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Norman
authors.affiliation: School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK.|Department of Biodiversity and Molecular Ecology, Centre for Research and Innovation, Fondazione Edmund Mach, Via E. Mach 1, 38010 S Michele all'Adige (TN), Italy.
authors.forename: Sarah Elizabeth
authors.identifier: http://orcid.org/0000-0002-7457-2699
authors.initials: SE
authors.lastname: Perkins
authors.affiliation: Department of Biodiversity and Molecular Ecology, Centre for Research and Innovation, Fondazione Edmund Mach, Via E. Mach 1, 38010 S Michele all'Adige (TN), Italy.
authors.forename: Heidi Christine
authors.identifier: http://orcid.org/0000-0003-3098-8964
authors.initials: HC
authors.lastname: Hauffe
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3B2.
authors.forename: Nicole
authors.initials: N
authors.lastname: Mideo
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, VA 22904, USA.
authors.forename: Janis
authors.identifier: http://orcid.org/0000-0002-5189-1611
authors.initials: J
authors.lastname: Antonovics
authors.affiliation: Environmental Futures Research Institute, Griffith University, Nathan 4111, Queensland, Australia.
authors.forename: Hamish
authors.initials: H
authors.lastname: McCallum
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
authors.forename: Andy
authors.initials: A
authors.lastname: Fenton
mesh_terms: D000820:Animal Diseases / Q000635:transmission*; D000818:Animals; D000835:Animals, Wild; D004199:Disease Vectors; D011157:Population Dynamics
keywords: arbovirus; disease ecology; host–pathogen interactions; public health; transmission; vector