When an insect bites and pierces the skin, it introduces an unknown protein into it, says Dr. Walter M. Ryan III, an osteopathic and allergy specialist at the Florida Center for Allergy & Asthma Care in Boca Raton and Coral Springs. Our immune cells do not recognize these unusual proteins which trigger an inflammatory process in the form of an allergic reaction.
The body then seeks to destroy and eliminate these unknown proteins.
Usually, this inflammatory process results from the release of a chemical, histamine, which comes from immune cells called mast cells.
“When histamine is released following the insect bite, the skin becomes reddened, itchy, and raised bumps called papules often form,” says Chicago Skin Clinic dermatologist Dr. Danilo Del Campo.
Most people have temporary minor itching, redness and some swelling.
But in people with papular urticaria, a trivial sting can trigger an exaggerated immune response with more severe and longer-lasting symptoms.
Researchers describe papular urticaria as an extreme or increased sensitivity to insect bites, or an allergic reaction to them, he explains.
Urticaria is one of reactions that indicate a possible allergy to mosquito bites.