How can flea bites cause itching and skin inflammation?

Flea bites cause itching and skin inflammation primarily due to the body's reaction to the insect's feeding habits and substances introduced during the bite. When fleas feed, they typically sample several adjacent spots on the skin, which results in a characteristic cluster of wheals (raised skin areas) and papules.1

The inflammation and intense itching are often linked to allergic reactions that individuals may develop after becoming sensitized to components in the flea's saliva or other excretory products introduced into the skin. While many animals may develop partial immunity to these attacks over time, humans can experience significant discomfort from these reactions. In the specific case of the jigger, or chigoe, flea, the female burrows into the host's skin, and the development of a cyst around the flea causes intense itching and potential secondary infections.12