A perspective on equine infectious anemia with an emphasis on vector transmission and genetic analysis

Knowledge of equine infectious anaemia (EIA) and its diagnosis is reviewed, with particular emphasis on comparative genetic analysis of the virus and the dynamics of vector transmission (which, incidentally, will be of comparative value in assessing human immunodeficiency virus (HIV) transmission by insects). Stomoxys calcitrans, Chrysops spp., Tabanus spp. and Hybomitra spp. have been shown to be capable of mechanical transmission of EIA virus. The clinical status and corresponding viraemia of positive horses and the amount of blood transferred between virus-positive and -negative horses are the most important factors affecting transmission. Distance between infected and susceptible animals, and the total vector populations, affect the amount of blood transferred.