The most serious contagious cat diseases are transmitted from a mother cat to her kittens or from one cat to another cat. There are a few diseases that are contagious between cats and other animals, such as humans and dogs. Those that are contagious to other species are generally easily treated.
Mother to Kitten
Feline leukemia virus is one of the most serious contagious cat diseases. There is no treatment and, while contagious from cat to cat, this disease can be spread from a mother cat to her kittens in the womb and during nursing. This disease isn't contagious to humans or other animals. A less serious disease spread from the mother cat to her kittens is roundworm infection. Roundworms are transmitted when kittens nurse. The infection is easily treated with standard kitten de-worming medications. While not directly contagious to humans and dogs, both species can be infected by coming in contact with contaminated soil.
Cat to Cat
There are many diseases that are contagious between cats. Most of these, such as various parasitic infections, are relatively easy to treat and not serious medical issues. Two of the most common contagious cat diseases that are most often fatal are feline immunodeficiency virus and feline panleukopenia, also known as feline distemper. Much less serious but highly contagious is respiratory infection. This is often seen in young cats who will show symptoms such as runny eyes and nose. Most kittens and cats recover from respiratory infection with antibiotic treatment. These diseases aren't contagious to other species.
Cat to Dog
The diseases most commonly spread between cats and dogs are parasitic infections. Most common are fleas, ticks and some types of intestinal parasites. Most mite infections cannot be transmitted from cats to dog. The mites that cause mange in cats are not the same type of mite that causes mange in dogs. The mites are species-specific. Likewise, the type of ear mites that infect cats is different from the type of ear mites that infect dogs.
Cat to Human
Aside from rabies, which any infected mammal can transmit to any other mammal, the most serious disease you could catch from your cat is bartonellosis, more commonly known as cat scratch fever. Bartonellosis is a bacterial infection transmitted by the bite or scratch of an infected cat. Less serious, more common and contagious is ringworm, a fungal infection that can be transmitted between cats, dogs, humans and other mammals.
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