This document was prepared as a review paper for the FAO Animal Production and Health Division (AGA) and draws on an earlier review that the author undertook for the International Livestock Research Institute in 2000. The invaluable inputs and comments of Dr J.E.O. Rege in the latter review are gratefully acknowledged.
I am grateful to FAO for supporting this study and sponsoring two missions to Ouagadougou to give workshop presentations based on this paper. I am particularly grateful to Prof. Raffaele Mattioli of AGA for his encouragement and comments.
Finally, I am indebted to Ms Florence Muthigani Pobee of the International Trypanotolerance Centre for her excellent secretarial skills and hard work in putting this manuscript together.