Streptococcus equi subsp. zooepidemicus által okozott hirtelen elhullás és vetélés kocákban – az első dokumentált eset Magyarországon

Background: Outbreaks of Streptococcus equi subsp. zooepidemicus (SEZ) – a zoonotic pathogen – have caused severe epidemics in the pig sector since the 1970s in South-Eastern Asia, especially in China and more recently in North America. Cases of high mortality caused by peracute septicaemia were all attributed to strains of a highly virulent clonal lineage belonging to the sequence type (ST) 194. In Europe, only two outbreaks have been reported with similar features, but caused by other sequence types. Case description: In August 2023 afebrile disease with abortion and subsequent deaths were observed among sows kept on a small-scale organic pig farm in West Hungary. Materials and Methods: Serum samples from affected sows were serologically tested and microagglutination tests as well as real-time PCR tests were carried out to exclude common infectious agents causing abortion and sudden death. Organs collected from selected animals were examined with the routine bacteriology as well as with the routine abortion panel of the Production Animal Diagnostic Centre (Üllő, Hungary). Two selected strains were whole genome sequenced and tested for antibiotic susceptibility against 19 antimicrobial agents. Results and Discussion: Clinical signs, pathological lesions, and microbiological findings were suggestive of septicaemia of bacterial origin caused by SEZ. According to the results of the routine laboratory testing no other relevant infectious agents than SEZ were involved. Whole genome sequence analysis assigned the examined strains, unrelated to any of the European isolates. A sudden weather change and subsequent extremely high average daily temperature before the outbreak could be identified as the only predisposing factor. The abrupt antibiotic treatment and applied biosecurity measures can help to restrict and terminate the outbreak. To our knowledge, this is the first report on abortion and lethal septicaemia in sows from the Eastern part of Central Europe, especially Hungary. The results call attention to the potential of non-ST194 SEZ strains to cause outbreaks on pig farms.