Introduction
If you have been bitten by a mosquito, you will usually only realize this some time after the mosquito has struck. Mostly a slightly reddened and swollen spot is noticeable, which also itches. This is caused by the fact that the mosquito not only sucks blood when biting, but also gives some of its saliva under the skin. This dilutes the blood, which makes it easier for the mosquito to suck the blood. The body then starts a defensive reaction, which causes the swelling to form.
Why does swelling occur after a mosquito bite?
Immediately after a mosquito bite, a small wheal can be noticeable. This is caused by the saliva that the mosquito injects under the skin to thin the blood. A short time later, the body begins to attack this foreign substance.
To do this, immune cells are first brought to the bite, which locate, recognize and attack the foreign substance. Once the body has recognized the substance, more specific cells can be sent to the sting. These are better “trained” to the saliva of the mosquito and can thus get it out of the way as quickly as possible.
Fluid is needed to transport the defense cells to the bite. The cells first swim in the blood vessels and then emerge from the vessels into the tissue in the liquid. The swelling is usually caused by this additional fluid, which is needed to transport the cells.
This also leads to a local defense reaction that attracts further defense cells. To neutralize the substances contained in the saliva, the sting heats up. Typically, this also leads to itching, and the swelling also expands due to the inflammation. A particularly strong swelling occurs with a mosquito bite when the immune system reacts excessively, as in an allergic reaction. This is when there is a regular influx of cells together with fluid.
What does an extremely strong swelling after a mosquito bite indicate?
An extremely strong swelling after a mosquito bite can have two causes:
- A possible cause is an allergic reaction to mosquito saliva. In this case, the immune system releases other substances in addition to its normal defence cells. These in turn attract additional cells to the area of the bite, which causes the extremely strong swelling.
This is caused, for example, by the fact that the mosquito itself is colonized by bacteria. During the bite, the bacteria get under the skin together with the saliva. The body then has to defend itself not only against the foreign substances in the saliva, but also against potentially dangerous bacteria and therefore increases the number of cells that are washed up for defence. In addition, a bacterial infection usually leads to inflammation around the sting. This is accompanied by redness and swelling.
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