Why do we feel itchy when we take a mosquito bite?

Are you going to say you never happened to, on a hot summer night, while you slept with the windows wide open, a hungry leggy partying and stuffing you with bites? But after all, why, besides sucking our blood, do these damn insects make us itchy?

According to the Today I Found Out website, what happens is that when female mosquitoes pierce our skin - using a structure called a proboscis - to suck blood, they also inject us with a tiny amount of saliva. This substance contains several anticoagulants and enzymes in its composition that help insects suck blood more easily.

Itch, itch

Image source: Reproduction / Wikipedia

However, once the mosquitoes are satisfied - or when they are frightened - and leave, our immune system reacts to the saliva left by the bite by producing antibodies that attack the antigens present in the substance. This response causes the release of histamine, which in turn triggers an inflammatory reaction.

The release of histamine also helps white blood cells and other proteins fight off the “invaders” in our body, making the capillaries of these structures become more permeable. Thus, histamine causes the blood vessels closest to the affected region to become swollen, giving rise to the irritated pink bite that kills us with itching.


Image source: Reproduction / Wikipedia

While it is virtually impossible to resist the urge to dig nails into the bite and scratch and scratch, it only makes matters worse. The act causes even more irritation and inflammation in the affected area, causing the immune system to "think" that more antibodies are needed to fight off enemy agents. Therefore, the more we scratch, the more swollen the region becomes, increasing the itching which, in turn, will also last longer.

The blood, by the way, is not just a banquet for the mosquitoes! Only females are “bloodthirsty” - males don't attack us - and they use this substance to produce eggs that, as you know, will give rise to more damn mosquitoes that will disrupt our nights sleep!

* Originally posted on 3/22/14