Did you know that some human sicknesses and aliments can be transmitted to our pets? Hamsters for example can catch a human cold and in severe cases, die from it. Even an aliment such as mesothelioma (also known as "white lung") can be found in our pets if they are exposed to asbestos in the home or if someone in the family works with asbestos at work and have particles on their clothing when they get home, thus exposing the pet to the danger.
We can also spread pet diseases among pets because we are unaware of what we are doing. I use to keep my horse at a public boarding stable and they had signs up all over the place that stated DO NOT TOUCH THE HORSE IF YOU ARE NOT THE OWNER. That was to keep people from spreading a horsey cold from one horse to another horse. This never did stop visitors that were unfamiliar with horses from petting every horse in the barn, one after the other. I wish people would stop and think before that touch an unfamiliar animal.
If you have a pet wash your hands before you handle or touch your pet after arriving home. You never can tell what animal disease you may carry on your hands and inadvertently contaminate your healthy pet.