Dogs are a very significant host of bacteria that is harmful to humans
One gram of dog waste can contain 23 million fecal coliform bacteria. Dog waste can spread giardia and salmonella a well.
Parasites from dog waste can be passed on to children, other dogs, an even themselves
Some of the possible ways a dog or can obtain various parasites, viruses and stages of bacteria from their own poop include: rolling in their feces, pawing at it, and in some instances even eating it (coprophagy).
Some ailments that can affect humans are: Parvo virus, Trichinosis, Whipworms, Hookworms, Roundworms, Giardia and Coccidia.