1. Correspondence: Department of Global Health and Bio-Medical Sciences, School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O Box 447, Arusha, Tanzania
2. International Livestock Research Institute (ILRI), Nairobi, Kenya
3. Centre for Tropical Livestock Genetics and Health, ILRI, Nairobi, Kenya
4. The Epidemiology, Economics and Risk Assessment (EERA) Group, The Roslin Institute, University of Edinburgh, Easter Bush, UK
5. Centre for Tropical Livestock Genetics and Health, The Roslin Institute, University of Edinburgh, Easter Bush, UK
6. Edinburgh Napier University, Sighthill Court, Edinburgh, UK