Retrospective analysis of infectious agents in swine abortion materials in the years 2021 to 2023

Abortions in swine are caused by infectious and non-infectious factors and play an important economic role in the swine industry. Molecular biological testing for relevant pathogens is routine in state-of-the-art diagnostics. The aim of this study was to assess the prevalence of pathogens associated with abortions in central Europe to prioritize differential diagnoses. We report the detection rates of such pathogens in aborted material (fetuses, placenta) from 199 abortion cases sent to AniCon Labor GmbH/SAN Group Biotech Germany GmbH from January 2021 to July 2023. A key panel of pathogens that were tested in most abortion cases emerged, consisting of porcine reproductive and respiratory syndrome virus (PRRSV), Chlamydiaceae spp., porcine circovirus 2 (PCV2), porcine parvovirus (PPV) and Leptospira spp.. At least one of these pathogens was detected by real-time PCR in 38 of the 199 cases (19.1%). PRRSV (n=16) and Chlamydiaceae spp. (n=12) were most frequently found, whereas PCV2 (n=6), PPV (n=4) and Leptospira (n=2 cases) were detected less frequently. In 14 cases, potentially relevant pathogens outside the key panel were detected by molecular biological or culture methods. Three of those cases were additionally positive for a pathogen in the key panel. In total, pathogens associated with abortions were detected in 24.6% of cases. It is hypothesized that a more comprehensive diagnostic approach will lead to more frequent detection of pathogens not regularly tested by PCR in routine diagnostics.