Generally, this test determines both Streptococcus equi equi and Streptococcus equi zooepidemicus. However, the detected surface antigen SeM is considered a virulence factor which mainly occurs in Streptococcus equi equi.
In case of a positive result, the antibodies will always be quantified. Knowing the titre level can be particularly helpful if purpura haemorrhagica or metastasising abscesses are suspected; these animals have high titres.
The level of the titre does not give any information on the immunisation or the carrier status of a horse.