Detection of Anaplasma phagocytophilum in fetal and placental tissue of bovine abortions and perinatal mortalities.

Background: Anaplasma phagocytophilum is a tick-borne zoonotic bacterium that is the aetiologic pathogen of tick-borne fever (TBF) in ruminants. In clinical bovine cases of TBF, abortion and stillbirth may be observed. However, in this regard, the pathophysiology of TBF has not yet been completely elucidated, and no clear guidelines to diagnose A. phagocytophilum-related abortions and perinatal mortalities (APM) are available.

Methods: This exploratory study aimed to investigate the presence of A. phagocytophilum in bovine cases of APM and determine whether placental or fetal spleen tissue has the greatest sensitivity for A. phagocytophilum identification. The placenta and fetal spleen of 150 late-term bovine APM cases were analysed using real-time PCR to detect A. phagocytophilum.

Results: A total of 2.7% of sampled placentas were positive for A. phagocytophilum, while none of the fetal spleen samples was.

Limitations: No histopathology to detect associated lesions was performed. Consequently, no evidence of causality between the detection of A. phagocytophilum and APM events could be achieved.

Conclusion: The detection of A. phagocytophilum suggests a potential role of this pathogen in bovine APM, and placental tissue seems to be the most suitable tissue for its identification.