Significant Impact of Schmallenberg Virus in Three Ruminant Farms: A Laboratory Experience

Schmallenberg virus (SBV) is endemic in Europe and other parts of the world and represents an underestimated and under-diagnosed cause of abortion and economic losses for livestock farms. In the present study, we evaluated SBV’s impact on threeruminant farms, in particular, two dairy cattle farms with reproductive problems (including abortions, stillbirths, and mal-formations) and a clinically healthy bufalo farm involved in oocyte collection through ovum pick-up (OPU) for in vitro embryoproduction and commercial sale. All sampled animals were subjected to serological assays against the main infectious agentsresponsible for reproductive disorders in ruminants: SBV, bluetongue virus (BTV), Coxiella burnetii (C. burnetii), bovineherpesvirus type 1 (BHV-1), bovine viral diarrhea virus (BVDV), and Brucella abortus (B. abortus). Te frst herd with re-productive disorders had a high (78%) seroprevalence for SBV (considered to be the cause of reproductive problems), while theprevalence observed for BTV was modest (16.7%). Although free from B. abortus, the second dairy farm had only a few animalsthat were seropositive for C. burnetii and BTV (1/22 and 2/22, respectively), but a prevalence of 72.7% for SBV. Te bufalo farmhad several animals seropositive for C. burnetii (9/52), BTV (10/52), and SBV (12/52). Almost half of the sampled animals wereexposed to at least one pathogen (26/52). Seropositive animals were excluded from oocyte collection in compliance withregulatory health requirements. One month later, seronegative animals were retested, revealing the seroconversion of anotheranimal for SBV, which was also excluded. Tis study has described, through seroprevalence testing, the direct impact of SBV onlivestock (clinical impact) and how it afects the selection of animals for the trade of genetic material (indirect impact)