Your poor little one. I did a bit of reading and this seems helpful:
http://www.peteducation.com/article....&articleid=739
It describes good hygiene methods for animals/humans to prevent infection. I would ask your vet about your yard regarding preventing future infections, since your dog must elimate there.
Good luck I hope your little one can be cured! In humans it can be cured quite easily but can make children quite sick, and is problematic for those who are pregnant.
http://www.cdc.gov/ncidod/dpd/parasi....htm#treatment
Just work with your vet, and I'm sure things will work out!