Streptococcus suis (S. suis) infection is a common problem in North America and can cause problems in all stages of pig production. It is often found co-infecting with other pathogens and its effects are worsened by the presence of PRRS, as is the case for may bacterial pathogens. S. suis causes arthritis, pneumonia, septicemia, endocarditis and meningitis. It is easily isolated in the laboratory from joint and brain swabs as well as from tissues such as spleen, heart and lung.
There are 35 known serotypes of S. suis and isolation of multiple serotypes from any one herd is seen frequently. Traditionally, serotypes 2, 3 and 1/2 have been most commonly associated with disease in Canada, but other serotypes certainly can be pathogenic.
At Gallant Custom Laboratories we serotype for types 1 through 9 and type ½ using a slide agglutination test. The graph seen above depicts the serovar trends seen in 2003 in our laboratory.
When disease symptoms are seen in piglets of 3 weeks of age or less, maternal vaccination is likely to be sufficient for disease control. However, when disease symptoms occur in the nursery and beyond, vaccination of the pigs is advised. Vaccination of the weaned pigs must be carefully timed in some cases to allow enough time for immunity to develop before disease exposure. Use of serology and diagnostic investigation may aid in this process.
Autogenous bacterins for S. suis control can be very effective, however, thorough diagnostics to identify the serovars impacting the herd is essential.
It is also recommended that follow-up diagnostics be conducted when breaks are seen. New serotypes can become significant within a herd, either through introduction from an outside source, or, a strain that was present but not predominant before commencing the vaccination program may come to the front as the initial strains are controlled. This process of on-going diagnostics and bacterin evolution is depicted in the following illustration.