University of Iowa College of Public Health, Iowa City, Iowa 52242, USA. tara-smith@uiowa.edu
Despite numerous cases of human infection with Streptococcus suis worldwide, human disease is rarely diagnosed in North America. We studied 73 swine-exposed and 67 non-swine-exposed US adults for antibodies to S. suis serotype 2. Serologic data suggest that human infection with S. suis occurs more frequently than currently documented.