Risk factors for infection with Toxoplasma gondii for residents and workers on swine farms in Illinois

Risk factors for Toxoplasma gondii infection in workers and residents of sw ine farms were studied on 43 farms in Illinois. Blood samples were collecte d from 174 adults in 1993. The T. gondii seroprevalence was 31%. An intervi ew was conducted with each participant, obtaining information on demographi c characteristics and behaviors suspected to affect the risk of T. gondii i nfection. Factors associated with increased risk of T. gondii seropositivit y were a higher number of seropositive cats trapped on the farm, male sex, rearing pigs on pasture, and gardening. Factors associated with a decreased risk were handling of pig feed and presence of cats inside the pig facilit ies. Thus, infection of cats with T. gondii increased the risk of human inf ection, and contact with soil was a likely mechanism for transmission. The increased risk of seropositivity in males is attributed to less attention p aid to cleanliness in food preparation and eating.