Risk factors associated with Streptococcus suis cases on pig farms in Spain

Carlos Neila-Ibáñez, Sebastián Napp, Lola Pailler-García, Lorena Franco-Martínez, José Joaquín Cerón, Virginia Aragon, Jordi Casal*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

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Background: Streptococcus suis can cause meningitis, polyarthritis and acute death in piglets. However, the risk factors associated with S. suis infection remain incompletely understood. Therefore, a longitudinal study was carried out, in which six batches from two Spanish pig farms with S. suis problems were repeatedly examined to determine possible risk factors. Methods: A prospective case–control study was conducted, and potential risk factors were evaluated using mixed-effects logistic regression models. The explanatory variables included: (a) concomitant pathogens; (b) biomarkers associated with stress, inflammation and oxidative status; (c) farm environmental factors; and (d) parity and S. suis presence in sows. Three models were built to study the effect of these variables, including two to assess the risk factors involved in the subsequent development of disease. Results: Risk factors for S. suis-associated disease included porcine reproductive and respiratory syndrome virus co-infection at weaning (odds ratio [OR] = 6.69), sow parity (OR = 0.71), haptoglobin level before weaning (OR = 1.01), relative humidity (OR = 1.11) and temperature (OR = 0.13). Limitations: Laboratory diagnosis was done at the batch level, with individual diagnosis based on clinical signs only. Conclusions: This study confirms the multifactorial nature of S. suis-associated disease, with both environmental factors and factors related to the host involved in disease development. Controlling these factors may, therefore, help prevent the appearance of disease.

Original languageEnglish
Article numbere3056
Number of pages10
Issue number5
Publication statusPublished - 3 Jun 2023


  • animal stress
  • co-infection
  • environmental factors
  • risk factors
  • Streptococcus suis
  • Risk Factors
  • Streptococcal Infections/epidemiology
  • Case-Control Studies
  • Pregnancy
  • Animals
  • Swine Diseases/epidemiology
  • Farms
  • Swine
  • Female
  • Spain/epidemiology
  • Longitudinal Studies


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