It's likely you're thinking of Toxocara canis, which is a type of roundworm that can infect dogs and humans. However, it's not directly caused by dog dirt itself, but by the eggs of the Toxocara canis parasite found in dog feces.
Here's how the transmission works:
1. Infected dogs shed Toxocara canis eggs in their feces.
2. These eggs can survive in the environment for months.
3. Humans can become infected by accidentally ingesting these eggs. This can happen through contact with contaminated soil, by not washing hands thoroughly after handling dog feces, or by consuming contaminated food or water.
Toxocariasis, the disease caused by Toxocara canis, can cause various symptoms in humans, depending on the stage of infection and the number of larvae present.
It's crucial to remember that dog feces should always be disposed of properly to prevent the spread of parasites like Toxocara canis. Regular deworming of dogs, especially puppies, can also help reduce the risk of infection.