Feral cats normally have fleas, so if you come into contact with one or have one living near your house, you will probably be exposed to these parasites. Any cats or dogs you have will probably catch fleas, and you may be bitten. You won't be infested, however.
The cat flea has the scientific name of Ctenocephalides felis and is the most common flea in the United States. They also live on dogs, despite their name. They are small wingless insects about one-sixteenth to one-eighth of an inch long and have large back legs that allow them to jump onto passing hosts. They have flat reddish-brown bodies and mouthparts designed to pierce the skin and suck the blood of their host.
Cat Fleas and People
Fleas will not live on people because humans have no thick coat for them to hide in, but they will occasionally feed from humans. This is most likely to happen if you handle a flea-infested animal or if you walk through an area these animals frequent. A flea may take a bite of you and realize that you're not to its taste. Bites mostly occur around the ankles and lower legs on people, and can be recognized as itchy red bumps with red "halos."
Cat Flea Life Cycle
Female fleas lay eggs in the fur of the animal they live on. Some of these fall onto the ground wherever the cat spends time. Eggs hatch into larva that feed on dead skin, adult flea excrement and other organic material. Larva pupate and hatch out as adult fleas which jump onto any passing animal or human. They will use the passerby as a host or else just have a feed and drop to the ground until a better host passes by. So although you can't get a flea infestation yourself, a flea may hitch a ride on you and then make the switch to your dog or cat.
Controlling Fleas From Feral Cats
To eliminate fleas, both the host animal and the premises must be treated. If you have a feral cat living near your home you must either get rid of it or treat it for fleas. Your vet can give you medication to put in food to treat fleas, or you can borrow or buy a humane cat trap to catch, treat and release it. Areas where the cat spends time should be vacuumed or steam-cleaned every few days, and you can use a plant-safe flea-and-tick killer on lawns and gardens where the cat roams.