The Huffington Post
A long list of potentially infectious agents are known to live in dog and cat feces — from E. coli to tapeworms. But perhaps less well known is the fact that a lot of these parasites actually become more infectious as the poop ages.
“It takes many types of parasite eggs a while to ripen,” said Dr. Emily Beeler, an animal disease surveillance veterinarian for the Los Angeles County Department of Public Health. Toxoplasmosis, which is more common in cats than in dogs, typically takes more than 24 hours to become infectious, she explained. Roundworm can take up to three weeks, and then may remain infectious for years in contaminated soil and water. (A recent CDC study found 14 percent of Americans tested positive for roundworms.)