My dog had a 6 month long battle with Girardia and explosive poops. It is HIGHLY contagious to other animals and people. Original infection is usually spread through contaminated water or eating fecal matter. BUT, once they have it, everything needs to be disinfected. You need to clean up his poop right away and disinfect that area with bleach/water. I used 1 part bleach to 3 parts water (ask your vet what proportions). Keep in mind we are talking about bacteria. The pups toys also need to be disinfected daily and YOU need to wash your hands every time you touch your pup, his toys or his dishes. I also learned that they can implant eggs on the fur/skin which at a later date can reinfect pups so they also need to be bathed at least every other day.