Brucella as the main cause of abortion among livestock in Armenia

Abortion in livestock can have a significant impact on animal husbandry, as well as raise public health concerns when caused by zoonotic pathogens. Thus, the involvement of bacterial (e.g., Brucella spp. and Enterobacteriaceae) and fungal infections in livestock abortions in Armenia was explored.

From 2018 to 2022, 168 aborted foetal tissues from cattle and small ruminants in Armenia were tested for fungal and Enterobacteriaceae infections by culture. The API 20E biochemical test was performed on bacteria-positive samples. Culture-negative samples were further tested by qPCR to detect Brucella DNA. In all qPCR-positive aborted foetuses, maternal blood samples (n = 129) were collected ≥ 30 days post-abortion for serological diagnosis.

Overall, 33 foetal samples were positive by culture: 28 for Aspergillus spp. and 5 for Salmonella spp. Brucella DNA was detected in 129 out of 135 culture-negative samples; in addition, anti-Brucella antibodies were found in 124 maternal blood samples. A total of 6 (3.5%) samples were classified as indeterminate by any assay.

Our results suggest that Brucella is the major cause of abortions in cattle and small ruminants in Armenia, while other bacterial and fungal infections were involved in less than 20% of cases. Based on these findings, it is recommended to test all samples first by serology and qPCR to detect Brucella infections. For Brucella-negative samples, additional methods can be used to detect other abortifacient agents. This protocol will be useful for laboratories that operate at Biosafety Level 2 and are unable to isolate this bacterium.