A: The Environmental Protection Agency (EPA) estimates that a single gram of dog waste contains as much as 23 million fecal coliform bacteria, including Escherichia coli (E. coli) which can cause a range of illnesses in people including stomach cramps, diarrhea, intestinal problems and kidney disorders. Other harmful things that pet waste contains include parasites such as hookworms, ringworms, tapeworms and Salmonella. Roundworm larvae in pet waste can trigger disease in the brain, lungs kidneys, liver, heart or eyes if it comes in contact with people. Pet feces also carries Campylobacter bacteria. If people touch fecal matter contaminated with this bacteria, they can get campylobacteriosis and experience severe stomach illness and complications from infection, especially those with compromised immune systems.