It could come from the soil if the surface is in contact with soil, such as a retaining wall. (thebalance.com)
Throughout history, humans have spent time outdoors much more than we do in modern time and have been in direct contact with the soil. (wellnessmama.com)
These diseases can be spread to people by direct contact with the feces of an infected cat or by contact with soil that has been contaminated by the feces of an infected cat. (brittonroadveterinaryclinic.com)