Studies on Carrier State of Chlamydophila abortus in Naturally Infected Sheep

The purpose of the study was to establish whether or not C. abortus is shed through the reproductive tract following infection under natural conditions. Two farms where enzootic abortion was endemic were investigated by sequential collection of vaginal secretions, faeces and serum samples from ewes which had chlamydial abortion six months earlier.PCR was used as a confirmatory tool after extracting DNA from faeces and vaginal secretions‘ using primers specific to the MOMP gene.None of the samples tested were positive, suggesting that either there were no EBs of C. abortus in the samples or there were non infectious forms (RBs) which could not be detected by DNA amplification. Real-time PCR analysis of placental samples identified very few or no chlamydial genomes, which contrasted significantly with samples taken at the time of abortion. The C. abortus was detected by PCR for the first time in milk samples collected from ewes with EAE history using the IMS technique. The serum samples from these ewes showed significantly higher chlamydiaspecific IgG titre during the period of periovulation. In terms of flock management, the products of abortion should be considered the major and principal source of infection for transmission to naïve ewes.