Toxocariasis is sometimes called visceral larva migrans (VLM) because the larval form of the organism hatches inside the intestines and migrates throughout the body to other organs (viscera).

Roundworm infections are diseases of the digestive tract and other organ systems caused by nematodes. Nematodes are parasitic worms with long, cylindrical bodies.

Infections that are transmitted from animals to humans are called zoonoses. Some zoonoses may be transferred through casual contact, but others are much more readily transferred by activities that expose humans to the semen, vaginal fluids, urine, saliva, fecesand blood of animals. Examples of zoonoses are Brucellosis, Q fever, leptospirosis, and toxocariasis. Therefore sexual activity with animals is, in some instances, a high risk activity. Allergic reactions to animal semen may occur, including anaphylaxis. Bites and other trauma from penetration or trampling may occur.

well its only if young children stick their hand in it and rub it in their eyes. its definitely a known disease but i don't know how common it is. I suppose if a child is in the park and it rubs its eye after playing near dogs mess then it then the parasites in the poo could make them go blind.