Fleas are blood-feeding parasites that can infest many species of birds and mammals. Although fleas on dogs and cats don’t infest people, fleas may bite people if an area is heavily infested. Flea infestation is one of the most common medical problems veterinarians see, and pets suffer greatly from this condition. Flea bites can trigger severe allergic reactions in some pets. The intense itching caused by flea infestation causes pets to scratch and bite themselves. This can lead to skin wounds, skin infections, and general misery for your pet. Even if your pet is not allergic to flea bites, fleas can transmit serious diseases, such as bartonellosis (the bacteria that causes “cat scratch disease” in people), and other parasites, like tapeworms.