Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom. peter.gething@zoo.ox.ac.uk|Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom. peter.gething@zoo.ox.ac.uk|Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom. peter.gething@zoo.ox.ac.uk