Genetic resistance: tolerance to vector-borne diseases and the prospects and challenges of genomics.

Vector-borne diseases in cattle and small ruminants (e.g. trypanosomosis, Rift Valley fever and East Coast fever) are associated with major economic losses in tropical countries, and particularly on the African continent. A variety of control strategies (e.g. management, vaccination and/or acaricide treatments) are used to minimise their negative impacts. These strategies are often associated with environmental, technical and/or economic drawbacks. However, several indigenous livestock populations have been reported to show a level of genetic tolerance or resistance to such disease challenges (e.g. trypanotolerant N'Dama cattle and Djallonké sheep). Use of these populations represents a sustainable alternative approach to minimising the negative impact of such infection/infestation on livestock production. This review summarises the current understanding of the genetic control of these adaptations, identifies knowledge gaps and critically examines the possible impacts of genomics approaches to the genetic improvement of tolerance and/or resistance to vector-borne diseases.