Chlamydia abortus and Coxiella burnetii- Related Abortions in Small Ruminants in Bulgaria during a Five-Year Period (2013-2018)

The results of the polymerase chain reaction (PCR) and serological testing for Chlamydia abortus and Coxiella burnetii of abortion submissions (placentaе or foetal organ samples) and sera from 56 sheep and 54 goats are presented. The samples were submitted for routine diagnostic procedures at the Laboratory for Chlamydial and Rickettsial Diseases, National Diagnostic and Research Veterinary Medical Institute (NDRVMI), during a five-year period (2013-2018). Samples from 48 sheep and 28 goats were tested by conventional PCR for the presence of one or both infections, while other 34 small ruminants were investigated only serologically by ELISA. In some cases one and the same animal was tested both serologically and by PCR. Of the 43 ovine and 24 caprine samples tested for C. abortus by PCR, positive results were obtained in 24 (35.8%), 18 (41.9%) ovine and 6 (25%) caprine samples, respectively. Five of the 12 PCR-tested goat samples were positive for C. burnetii, whereas no sample of the 17 sheep tested showed presence of this agent. Antibodies against these two intracellular bacteria were detected in 20 (23%) out of 87 sera from aborted animals, suggesting, or confirming their probable etiological role. The results show that C. abortus plays a leading role as a cause of abortions in small ruminants as a whole, but C. burnetii, too, should not be ignored, especially presuming its zoonotic potential.