Why do fleas bite humans?
Fleas often bite more than once, testing different areas before selecting a site for feeding, explains the Illinois Department of Public Health. This often results in a line or cluster of itchy red marks on the skin around 30 minutes after the bites occur. Sensitive individuals may also experience raised bumps within 24 hours after the bites occur. Cat and dog fleas do not transmit diseases to humans through these bites, but rat fleas sometimes do; rat fleas can transmit bubonic plague and murine typhus to humans.