[Ovine salmonellosis caused by Salmonella abortus ovis]

Salmonella enteritidis subsp. enteritidis ser. abortus ovis, a sheep-adapted serotype, causes a contagious infectious disease with abortion as the main symptom, sometimes accompanied with mortality of lambs. This auxotrophic gram-negative bacterium ranks among the main causes of ovine abortions in some countries of Europe and of western Asia. The disease tends toward an endemic pattern with a multi-annual rhythm in the frequency of abortions. Bacteremia leads to bacterial colonization of the feto-placental unit, the principal site of salmonella multiplication. Peripartum vaginal excretion, coming with abortion or sometimes with lambing of living lamb at term, is massive. Fecal excretion remains generally undetectable, except during septicemic complication of placental retention. Rams develop a serological response to contamination but remain clinically normal. Frequency of carriers of abortus ovis is reported as low-to-relatively-high. Diagnosis rests on laboratory findings. A sero-agglutination test may offer a strong presumption at the flock level. Isolation of abortus ovis confirms the diagnosis; vaginal discharges, placentas or organs of aborted fetus or of dead animals are plated directly on selective media. Differential diagnosis requires consideration of other salmonelloses and other abortifacient diseases predominating in the area. Introduction of sheep from an infected area to a clean area should be avoided. Isolation of aborting ewes and destruction of contaminated bedding and of all products of abortion reduce contamination. Antibiotic treatment during an outbreak is sometimes disappointing. Annual vaccination with dead or living vaccines is advisable in endemic areas.