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The importance of Streptococcus suis as a zoonotic agent
  • Dr. Claude Boissonneault
  • Chief, Red Meat Programs
  • Meat Program Section
  • Food of Animal Origin Division
  • Canadian Food Inspection Agency
  • October 2005
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This presentation
  • Streptococcal Diseases:
    • Etiology and Prevalence
    • Epidemiology
    • Clinical Signs & Lesions, Pathogenesis, Diagnosis and Treatment
  • Prevention Measures:
    • Biosecurity and On-Farm Food Safety Programs
    • Farm Gate to the Plate Interventions & Measures
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Streptococcus suis
  • Streptococcus suis is a species of bacterium found in many parts of the world where pigs are raised


  • Several streptococcal species can be found in the tonsils, intestines, or feces of clinically healthy pigs – some are potential pathogens


  •  S. suis is a zoonotic agent that requires our attention – cases in humans are rare but serious
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Streptococcal Diseases
Etiology and Prevalence
    • Gram + enterococci


    • Initial reports of infection with S. suis in the swine industry published in early 1950’s.
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Streptococcal Diseases
Etiology and Prevalence
    • Since reported in all countries where the swine industry is important


    • Infection associated with this microorganism has been observed in both traditional and modern intensive swine operations
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Streptococcal Diseases
Etiology and Prevalence
    • In diseased pigs, capsular type 2 predominates in almost all countries


    • S. suis type 2 can be isolated from apparently healthy looking pigs, but the prevalence may be low:
      • Clifton-Hadley et al. 1984, England – 2 herds out of 4 clinically healthy – 1.5 % and 20 % of animals
      • Brisebois et al. 1990, Canada – 12 % of clinically healthy herds, of which prevalence of 4% in the animals
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Streptococcal Diseases
Epidemiology
  • Natural habitat - upper respiratory tract (particularly the tonsils and nasal cavities), and the genital and alimentary tracts of pigs – feces


  • S. suis is frequently isolated from a wide range of animal species and birds


  • Presence in environment transitory
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Streptococcal Diseases
Epidemiology

  • Transmission – between herds usually occurs by the movement of healthy carrier pigs


  • Sows presumably infect piglets via respiratory route – also exposed at birth and when feeding (S. suis genital and alimentary tracts)
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Streptococcal Diseases
Epidemiology
  • Transmission - S. suis  appears to be easily transmitted via fomites
    • feed (piglet-sows);
    • flies - can carry S. suis type 2 for at least 5 days and contaminate materials on which they feed for at least 4 days; spreading infection within and between farms;
    • Hardware (equipment …) and software (people …)


  • Importance of other animals & birds as reservoirs or vectors of infection to be determined
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Streptococcal Diseases
Epidemiology
  • Survival in the Environment - S. suis type 2 results from experiments:


  • In water - at least 1-2 weeks at 4oC


  • At 0oC, 9oC , and 22-25oC survives in FECES - for 104, 10 and 8 days respectively, and in DUST 54, 25, and 0 days respectively:
    • Thus summer time or weaner-accommodation temperatures of 22-25oC, survival in feces for about 8 days, but in dust less than 24 hrs
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Streptococcal Diseases
Epidemiology
  • Survival in the Environment


  • Pig carcasses left rotting on farms – 6 weeks at 4oC and 12 days at 22-25oC – potential spread through birds, cats, dogs, and pests (rats, mice)


  • Cleaning and Desinfection of infected pens – commonly utilized disinfectants – kills in less than 1 minute.
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Streptococcal Diseases in Pigs
 Clinical Signs, Lesions, Pathogenesis, Diagnosis, Treatment and Prevention
  • Clinical Signs
  • Lesions
  • Pathogenesis
  • Diagnosis
  • Treatment
  • Prevention
  • Eradication
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 Generic consideration on zoonosis
 and foodborne illnesses
  • THE HUMAN FACTOR – SOFTWARE:


  • 1- KNOWLEDGE – AWARENESS: informing, communicating and training


  • 2- THE BIG BROTHER EFFECT – MONITORING, VERIFYING, INSPECTING, AUDITING


  • 3- THE CONSEQUENCES OF OUR ACTIONS – carrot-stick; farm employee & biosecurity; consumer food handling & food safety
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Zoonosis and Foodborne Illnesses
  • SHARED RESPONSIBILITY
    • SAFETY AT WORK
    • FOOD SAFETY


  • THE ROLE OF EVERY PLAYER FROM THE FARM TO THE PLATE IS CRITICAL FOR ACHIEVING THE INTENDED RESULTS
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References
  • Streptococcal Diseases, R. Higgins and M. Gottschalk, Chapter 41 Diseases of Swine, 8 th edition, ISU, 1999
  • Meat Hygiene, 10th edition, J. Gracey, D. S. Collins, R. Huey, 1999