Seroprevalence study of the main causes of abortion in dairy cattle in Morocco.

Sera from 221 cattle were collected in 25 farms in Morocco to investigate the evidence and circulation of some of the main bovine abortive agents in the dairy cattle farming, where abortions are often reported. All sera were examined for brucellosis, 176 for neosporosis, 88 for leptospirosis, and 42 for Bovine viral diarrhoea (BVD/MD), Bovine Herpesvirus 1 (BHV-1) (Infectious bovine rhinotracheitis, IBR/IPV), and Bovine Herpesvirus 4 (BHV-4) infections (at least 1 sample per herd). Abortions were reported in 23 (10.4%) of the 221 tested cattle. Antibodies against the investigated pathogens were detected in all samples tested, with an overall seroprevalence of 33.48% for Brucella, 9.09% for Leptospira, 8.52% for Neospora, 37.71% for BVDV, 50% for BHV-1, 9.52% for BHV-4. As for Leptospira antibodies against serovars Hardjo, Pomona, and Tarassovi were identified. Mixed infections were common. The lack of evidence of non-infectious factors epidemiologically related to abortions suggested that the investigated agents are to be considered important risk factors in the dynamic of the abortion syndrome, even if further investigations are necessary to identify the abortion cause. Particular attention should be paid on brucellosis, considering the high seroprevalence and its zoonotic relevance.