Observations on the occurrence of African horsesickness amongst immunised horses

Abstract

During the course of an epizootic of African horsesickness it was possible to establish that:- (1) strains of virus apparently homologous with components of the polyvalent vaccine could be reisolated from clinically affected equines previously immunised; (2) infection by a specific immunological type of virus could be correlated with an absence of homologous antibody in the reacting animal; (3) animals failed to develop specific antibodies to certain components of the polyvalent vaccine in spite of repeated immunisation.