1. School of Biology, Newcastle University, Ridley Building, Newcastle upon Tyne NE1 7RU, UK
2. Department of Infection Biology, Institute of Global Health, University of Liverpool, Leahurst Campus, Neston, Chester CH64 7TE, UK
3. The Roslin Institute and Royal (Dick) School of Veterinary Science, University of Edinburgh, Midlothian EH25 9RG, UK
4. Department of Epidemiology and Population Health, Institute of Global Health, University of Liverpool, Leahurst Campus, Neston, Chester CH64 7TE, UK
5. College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK