Serosurvey on Schmallenberg Virus and Selected Ovine Reproductive Pathogens in Culled Ewes From Southern Spain

Abstract

After the first case of Schmallenberg virus (SBV) was reported in southern Spain (March 2012), a retrospective serological study was carried out in extensive sheep flocks from nearby areas to assess the history of exposure to SBV and other selected ovine reproductive pathogens (Chlamydophila abortus, Coxiella burnetii, Border Disease virus 'BDV', Toxoplasma gondii and Neospora caninum). Secondly, the presence of antibodies was investigated in meat juice samples against selected pathogens to validate their use in serosurveys in sheep. A total of 209 Merina and cross-bred culled ewes belonging to 12 outdoor flocks managed in extensive breeding systems were sampled. Serum and meat juice samples were collected at the slaughterhouse and analysed using commercial ELISA kits. Chlamydophila abortus (62.68%, CI95 56.13-69.23) and Toxoplasma gondii (57.42%, CI95 50.72-64.12) were the most prevalent pathogens. The seroprevalence of BDV (16.27%, CI95 11.27-21.27) and Coxiella burnetii (13.88%, CI95 9.2-18.56) was moderate, and only 4 of 209 animals (1.91%, CI95 1.82-2.96) presented specific antibodies against Neospora caninum or SBV. All the examined ovine flocks were seropositive to three or more pathogens. The highest percentage of seropositive animals was detected for T.gondii-C.abortus coseropositive (25.36%) culled ewes. The concordance between serum and meat juice samples was moderate for T.gondii (κ=0.419) and BDV (κ=0.568), and fair for C.abortus (κ=0.311). Our results show evidence of circulation of SBV from summer 2011 in southern Spain. Furthermore, C.abortus and T.gondii were the most prevalent pathogens associated with sheep in outdoor rearing systems. Finally, these preliminary results point to meat juice samples as a potential biological sample for serosurveys studies on sheep.