While it's not all that common, your dog can catch some human diseases through direct or indirect contact with you or someone else who is infected. Normally, the parasites and viruses that infect humans won't affect dogs, but some of them, along with some types of bacteria, can. These infectious agents are zoonotic, meaning that they can affect more than one species, passing between humans and canines and vice versa.
The most common type of fungal infection to affect both humans and canines is ringworm. If you have ringworm, you can give it to your pooch. Ringworm is highly contagious and causes red, flaky rings on the skin and can turn your fingernails or toenails yellow. Fido can catch ringworm from you if you touch him. He can get it indirectly from objects that you've touched, which carry the fungal spores, according to WebMD. While other types of fungi like Cryptococcus can affect both people and pets, it isn't directly communicable between you and your dog.
A type of antibiotic-resistant bacteria known as Methicillin-resistant Staphylococcus aureus can live harmlessly on the skin of people, dogs and other animals. Unfortunately, if this type of bacteria enters a skin wound, it can cause a serious infection, especially if the immune system of either a pooch or person is compromised. If you've been diagnosed with MRSA, you can give it to your dog and he can give it back to you, warns the American Veterinary Medical Association. Although rare, people can transmit the plague to dogs. The bacteria that cause this disease, Yersinia pestis, becomes airborne when people with plague pneumonia cough or sneeze; a dog could become infected with pneumonic plague as well.
While both people and their canine companions can contract the flu, usually it's due to different, species-specific types of viruses. Unfortunately, the H1N1 virus, commonly known as the swine flu, can be passed from humans to canines, according to the Centers for Disease Control and Prevention. While humans can't catch this virus from their dogs, they can give it to them through direct contact. Rabies is another virus, which can infect both people and dogs, although it's mainly spread through contact with the bodily fluids of an infected animal or person, usually through a bite. It's very unlikely that a person with rabies would infect a dog, but it's theoretically possible.
While some parasites like roundworms, hookworms and tapeworms infect both people and pups, most types are species-specific. Sarcoptes scabiei mites, though, are highly contagious parasites, which cause a skin rash and can infect humans and canines. You can pass these mites to your pooch with direct contact or indirect contact with contaminated items around your home. Protozoan parasites such as giardia also infect both people and pets. They are spread through the feces of an infected person.
To prevent the spread of disease from humans to pups, keep your pooch isolated from people with flu-like symptoms or skin conditions. Keep your pup's environment clean. Wash your hands regularly, especially before and after interacting with your pup or handling any of his food.