[Latency of Brucella abortus causes problems in oriented control: a review].

This review on Brucella abortus in cattle covers the pathogenesis, the epidemiology and the diagnostics of brucellosis. Emphasis is given to the presence of latent infections in young stock. Calves infected by B. abortus in utero or after ingestion of infected milk may acquire a persistent infection. These animals might present a significant problem in brucellosis control and eradication schemes, since they are difficult to detect by the usual serological tests as they remain negative until near the first calving or abortion. The diagnostics must be improved: (new) tests need to be made more sensitive and herds and/or animals should be tested more frequently after introduction of cattle into a herd. Moreover more attention should be paid to cases of abortion. It is also suggested that if the slaughter of infected herds is limited to adult animals, the heifer calves could be a source of infection to the restocked herd.