[1] Univ Nairobi, Dept Publ Hlth Pharmacol & Toxicol, POB 29053, Nairobi 00625, Kenya
[2] Int Livestock Res Inst, POB 30709, Nairobi 00100, Kenya
[3] Int Fund Agr Dev IFAD, 1191 Nile Corn, Cairo, Egypt
[4] Univ Liverpool, Inst Infect Vet & Ecol Sci, Liverpool L69 3BX, England
[5] Scotlands Rural Coll SRUC, Land Econ Environm & Soc, Edinburgh, Scotland