According to the Companion Animal Parasite Council, roundworm spreads to humans through their contact with dog feces and contaminated soil. Children and pregnant women are particularly vulnerable to roundworms.
Puppies are the most common receptor of roundworms. Almost every dog has roundworms at one point in its life. Roundworms are passed from the mother dog or are ingested from eating other animals or contaminated soil. If a human directly touches infected feces or the soil the feces was near, the human ingests the roundworms. A roundworm infection can cause eye, heart, lung and neurological problems. Humans must always wash their hands after handling feces, notes CAPC.