Fleas are medically important because of their irritating bites, abundance, worldwide distribution and ability to transmit diseases. Flea bites Different people have differing reactions to flea bites. Some people are either immune to the bites, unattractive to fleas, or both. Others seem to be highly attractive to fleas. In a flea-infested household, one or two individuals may show severe irritation from the bites, while others may not even realize fleas are present.
Fleas prefer the blood of pets.
Thus, people may coexist with the pet and the pet's flea population while being bitten only occasionally. When the pet is removed from the environment, such as during a family vacation, a large population of hungry adult fleas may accumulate. A small red spot with a light-colored center appears where the mouthparts entered the skin. Irritation, itching and rash are caused by salivary secretions that the flea injects during feeding. The typical human reaction to a flea bite is a small, hard, red, slightly raised, itching spot.