Streptococcus suis

Streptococcus suis is a gram-positive coccus which causes severe disease in swine.  It has also been found to cause disease in humans, including a life-threatening meningitis.  A recent outbeak of the disease in China resulted in 38 deaths out of 235 total infections, for a 16% percent mortality rate.  The bacterium has caused sporadic illness in other countries as well, including Canada, and a human case of infection with the bacterium has recently been described in the United States.  Several investigators have suggested this low number of cases in the U.S. is due to under- or misdiagnosis, rather than a true absence of this disease in the human population. 

            S. suis isolates can be divided into 35 serotypes based on the type of capsule antigen.  Serotype 2 has been consistently associated with high virulence in both swine and humans, and was the serotype of the isolate implicated in the 2005 China outbreak.  Serotype 2 is also commonly isolated from swine in Iowa.  Current studies in our lab are examining sera from workers in close contact with swine, in order to test the hypothesis that they may have been asymptomatically infected with S. suis.