While there are many zoonotic diseases -- diseases your pets can have and give to you -- there are also diseases which are pet-specific and that do not travel between humans and animals. Here is a list of some of those diseases which are pet-specific, but are sometimes misunderstood as a threat to humans:
FIV
Commonly known as Feline AIDS, this is a virus that cats can have which affects their immune system. It is the result of a lentivirus and will cause infected cats to become vulnerable to other diseases, such as lymphoma. However, some cats can have FIV and not have any long term effects.
Canine Distemper Virus
This virus can be very devastating for dogs. It starts as a respiratory infection, becomes an intestinal disease, and can ultimately cause seizures. Fortunately, wide spread vaccination has done a wonderful job of eliminating the disease in dogs who are vaccinated. Although humans can pick up the virus, it does not cause any diseases in humans.
Feline Leukemia Virus (FeLV)
FeLV decreases the immune system in cats. FeLV-positive cats are more susceptible to contracting other diseases, so good hygiene is always a must for infected cats and their owners.
Parvo Virus
Even though there are many human versions of the parvo virus, these are not the same as that which causes parvo virus infections in dogs. So if your dog does become infected with the parvo virus, you and your household are not at risk. However, good hygiene is necessary for the entire household, because dogs infected with parvo can also have other diseases that they can spread to you, such as worms.
Kennel Cough
Kennel cough is caused by bacteria and viral components. The viral portion is a very species-specific virus to dogs. While there are viruses very similar to kennel cough that can make humans sick, the kennel cough virus your dog has will not be spread to you.
It's important to remember that, even if your pet has one of these diseases which are not known to cause problems in people, your pet may also have other infections that are known to cause problems in humans. I always recommend good hygienic habits when handling any affected animals to lessen the possibility of secondary or co-infections.
Have any of your pets been affected by these diseases? If so, what did you do to protect your pet from secondary infections?