Salmonella Abortusovis: An Epidemiologically Relevant Pathogen

The ovine pathogen Salmonella enterica serovar Abortusovis (SAO), a pathogen strictly adapted to ovine hosts, is endemic in several European and Asian countries, where it causes significant economic losses due to the high rates of abortion in infected flocks. In some countries (i.e. Switzerland and Croatia), re-emergence of infection by SAO occurred after decades during which the disease has not been reported. The introduction of (SAO) epidemic strains in new areas is difficult to control due to the asymptomatic behaviors in infected adult lambs, rams, and nonpregnant ewes. Culture-based diagnosis may provide false-negative results. Moreover, the retrospective identification of Salmonella infection in ewes is challenging as excretion of the causative agent is transient and the serum antibodies fall to low titres soon after the abortion. Therefore, regular monitoring of pathogen exposure, mainly through seroconversion assessment, is advisable to prevent disease introduction and spread in SAO-free areas, especially in case of animal export, and to reduce abortion risk.