Why do mosquito bites welt?
When a mosquito bites you, it secretes a liquid which keeps the blood from clotting. Almost everyone is somewhat allergic to this liquid, so our body tries to fight it off. Blood flow to the area is increased, white blood cells are mobilized, and the ensuing battle causes the area to itch. The swelling is due to the increased blood flow.
When a mosquito bites you she injects some saliva before she starts sucking blood. The saliva contains proteins that act as an anticoagulant and keeps the blood flowing. Your body reacts to these foreign proteins by trying to isolate and destroy them by producing various substances of its own. Lymph collects around the bite site, skin cells swell slowing blood flow to keep the proteins from spreading that’s what causes the bump. Histamines attack the proteins and that’s what itches, it’s a localized allergic reaction to the proteins. Scratching causes damage to the skin, spreads the protein and the histamine and that just causes more itching. You’d be surprized how fast a bite can stop itching if you can just leave it alone. Grit your teeth for 15 minutes or scratch it and then scratch for hours. BTW That saliva can carry viruses and other parasites and that’s how mosquitos transmit diseases like West Nile Virus and malaria.
When the female mosquito pierces the skin with her mouthparts, she injects a tiny amount of saliva into the wound before drawing blood. The welt that appears after a mosquito bite is not a reaction to the wound, but an allergic reaction to the saliva injected during the bite. In most cases, itching and swelling subsides within several hours. In some highly sensitive people, they may persist for several days. Scratching mosquito bites can result in infection if bacteria under fingernails are transferred to the wounds.
