1. Boyd Orr Centre for Population and Ecosystem Health Institute of Biodiversity Animal Health and Comparative Medicine University of Glasgow Graham Kerr Building Glasgow G12 8QQ UK
2. Robertson Centre for Biostatistics University of Glasgow Boyd Orr Building Glasgow G12 8QQ UK
3. Department of Epidemiology and Public Health Swiss Tropical and Public Health Institute Socinstrasse 57, PO Box Basel CH‐4002 Switzerland
4. University of Basel Petersplatz 1 Basel CH‐4003 Switzerland