Learn More About a Disease

Streptococcosis or Streptococcus suis disease

Streptococcus suis infections are among the leading infections in swine production. They can be primary, and associated with clinical infections such as meningitis, septicemia, endocarditis, osteoarthritis or pneumonia, or secondary, and follow viral infections such as PRRS, PCVD or influenza. Porcine streptococcus is seen mostly in weaned and growing pigs.

There are 35 identified serotypes of Streptococcus suis in the world today. All serotypes do not have the same significance or virulence; S. suis type 2, for example, is often associated with meningitis, endocarditis and epicarditis.

Clinical Signs +

The first sign of infection is usually a high fever, which may occur initially without other obvious symptoms. It is accompanied by a bacteremia or septicemia that may persist for several days if untreated. During this period, fluctuating fever and variable degrees of inappetence, listlessness, shifting lameness and nervous signs of meningitis can be observed. Endocarditis is also common in older piglets.

Affected pigs may die suddenly or show varying degrees of dyspnea, cyanosis and wasting. Septicemia, arthrosis and pneumonia are less common signs. Rhinitis, abortions and vaginitis may also develop.1

Transmission +

Most clinically healthy pigs are carriers of multiple serotypes of Streptococcus suis. Piglets become colonized with S. suis by vaginal secretions during birth or while nursing.

Infected piglets are carriers of S. suis in the nursery. Transmission between herds usually occurs by moving healthy carrier pigs from place to place. The introduction of these individuals into an uninfected herd usually leads to the subsequent development of the disease in post-weaning and/or fattening animals. However, some infected herds not showing clinical signs of the disease may develop a clinical form in the presence of other predisposing factors, such as PRRS. Streptococcus suis can also be transmitted through objects or flies.1

Diagnosis +

Clinical diagnosis may suggest a Streptococcus suis infection. However, isolation and serotyping of S. suis lesions are also necessary. Simply isolating S. suis in nasal cavities is not advised given the large number of pigs who are infected, but without clinical signs.2

Treatment +

Early intervention with antibiotics from the penicillin family is necessary to treat S suis. In cases of meningitis, it is highly recommended that anti-inflammatories be administered at the same time as the antibiotic. Infected animals should also be isolated and provided with plenty of water.2

Protection through vaccination is possible, but seems limited to date, especially because the innate immune system seems to be the main target.2

Consult your veterinarian before administering antibiotics and vaccines to animals. Your veterinarian is the best source of recommendations that are truly adapted to your farm.

Prevention +

Antibioprophylaxis may be used in combination with sanitary measures.


1 The Merck Veterinary Manual, Third Edition

2 Maladies d’élevage des porcs, Second Edition, Guy Pierre Martineau