Coxiella burnetii and Co-Infections with Other Major Pathogens Causing Abortion in Small Ruminant Flocks in the Iberian Peninsula

SIMPLE SUMMARY: Abortions have a large economic impact in small ruminant flocks. Some abortions may be induced by non-infectious causes but most of them are due to a broad spectrum of abortifacient infectious agents. In this study, abortion cases from sheep (n: 1242) and goat (n: 371) flocks in the Iberian Peninsula were analyzed for the presence of Coxiella burnetii and other major abortifacients using molecular methods. C. burnetii and Chlamydia abortus were by far the most common pathogens circulating in sheep and goat flocks, since approximately 75% of cases from both hosts tested positive. C. burnetii infection was more prevalent in goats than sheep and was detected in almost half of caprine abortions. A significant proportion of C. burnetii PCR-positive cases were positive only for this bacterium in both ovine (33.1%) and caprine (63.2%) abortions, with the remaining cases harboring mixed infections. Toxoplasma gondii was the third most prevalent pathogen in both caprine (4.6%) and ovine (10.1%) abortions, followed by Campylobacter sp., Salmonella enterica, border disease virus and Neospora caninum. To the best of our knowledge, this is one of the most thorough studies reported in the literature regarding the presence of infectious agents in ovine and caprine abortions. ABSTRACT: Coxiella burnetii is an intracellular bacterium causing human Q fever and reproductive disorders in domestic ruminants. We analyzed the occurrence of C. burnetii and co-infections with six other major pathogens causing abortion in sheep (1242 cases) and goat (371 cases) flocks from Spain and Portugal. After real-time PCR detection, co-infections were established by principal component and cluster analysis that grouped cases based on the joint presence/absence of several microorganisms. C. burnetii and Chlamydia abortus were the most common abortifacient agents with approximately 75% of cases from both hosts testing positive, followed by Toxoplasma gondii, Campylobacter sp., Salmonella enterica, border disease virus and Neospora caninum. C. burnetii was significantly more common than C. abortus in goat abortions (p < 0.001). Co-infections with at least two pathogens were found in more than 66% cases of ovine abortions and 36% cases of caprine abortions testing positive for C. burnetii, mostly including mixed infections with only C. abortus. These findings indicate that both pathogens are the most significant ones to be readily prevented by vaccination in this geographical area. Biosecurity and biocontainment measures are also steadfastly recommended to prevent both the economic losses and public health risks associated with most of these abortifacient agents.