This is interesting in that sows had always been considered to be the carriers of S. suis, and that they in turn infected their young. Apparently, a much more significant source of infection is contact with older infected piglets after weaning.

Bas Swildens, studied Streptococcus suis (S. suis) the common bacteria that can cause outbreaks of meningitis in piglets and its vectors of infection. His study provides a number of useful management and research recommendations that can be immediately implemented for combating S. Suis. The goal is to completely free pig farming operations of harmful strains of S. suis.

In order to conduct his research, Swildens first evaluated the characteristics of a simple test (Polymerase-Chain-Reaction, PCR) as it is used in practice. Using the PCR test of tonsil samples, he was able to detect 65% of the actual carriers. Using more thorough tests, he was able to detect 80% of the actual carriers in the test population. The test results showed very few false positives – less than 4%.

Swildens also showed that, in addition to the familiar lung infection, S. Suis infection via the intestines presents a serious risk in the period following weaning. During this period the piglets’ intestinal barrier (the system that protects the body against unwanted invaders through food) is more susceptible to infection due to the changes in the piglets’ feed and the effects of stress.

Thesis
Title: Detection and transmission of extracellular factor producing streptococcus suis serotype 2 strains in pigs 
PhD candidate: Bas Swildens 
 

Related website: Utrecht University, Faculty of Veterinary Medicine