• Parvovirus is spread to dogs by direct or indirect contact with dog feces, it is very contagious.  In fact, studies have shown that the virus can survive in feces and other organic material such as soil for over a year. It survives extremely cold and hot temperatures.
• Campylobacter germs are found in animal feces.  This germ causes gastrointestinal symptoms. It’s usually not dangerous, but can cause severe illness in people with weakened immune systems.

• Leptospira infection is caused from contact with water, food, or soil containing urine from infected animals. This can be very serious if left untreated.

• Salmonella infection. People get this often-severe gastrointestinal infection via contact with animal feces. It can cause severe kidney damage to young children. 

Other parasites of cats and dogs:

• Toxoplasmosis

• Tapeworm. A person can get tapeworm by swallowing an infected flea.

• Hookworm. Hookworms are common in tropical and subtropical areas. Hookworms infest soil contaminated by animal feces. Humans get infected by walking on contaminated soil and by having direct contact with the dog feces or worms. Heavy infections can be serious and can threaten the dogs’ life.

• Cryptosporidiosis. In humans, this parasite causes mild to severe intestinal symptoms like diarrhea. Crytosporidiosis is dangerous to people with weakened immune systems.

• Ringworm isn’t a parasite, but a fungal infection that forms a ring-shaped rash on the skin or a bald patch on the scalp. Ringworm is transmitted by contacting an infected animal directly.