While certain species of fleas will prefer a particular type of host, such as Ctenocephalides canis on dogs and Ctenocephalides felis on cats, many fleas will attack and feed on any type of animal they encounter. Moreover, cat fleas are usually more common in both cats and dogs, and these, as well as the dog flea, would not mind sucking human blood.
This is why it is important to treat infected animals as well as the environment, as many flea species carry diseases that could easily be transmitted to humans. Always try to combine dog flea treatment with house and yard spray to eliminate the infestation as soon as possible and prevent fleas from attacking your family members or yourself.