What is usually in a mosquito bite

Inflamed mosquito bite - anything but harmless

The itchy wheals do not always remain inconspicuous: Mosquito bites can develop into extensive skin inflammations that require medical treatment. An expert says how this can happen.

They are small, their piercing tools can hardly be seen with the naked eye, but their sting can have fatal consequences. In tropical and subtropical regions, mosquitoes transmit pathogens that lead to serious diseases. There have also been isolated cases of malaria in Switzerland, as confirmed by the FOPH: In 1997 and 1999, one person each from the Zurich region was infected. Neither of them had previously visited an endemic area.

They were probably infected by mosquitoes that were brought in by plane. Potential vectors for pathogens such as the Asian tiger mosquito or the Asian bush mosquito are increasingly being sighted in our latitudes.

So far, the Federal Office of Public Health is not aware of any case according to which an immigrant or native mosquito in this country has transmitted exotic viral diseases such as dengue, zika, West Nile or Chikungunya fever from person to person. Experts cannot rule out that this will happen in the future.

Itchy wheals as a souvenir

The docking points of the tiny pests usually leave little more than a small, unpleasant bump on the skin. The body's own reaction to substances that are released into the wound by the mosquito during the biting process is responsible for the itching.

"They have an anesthetic effect, inhibit blood clotting and ensure that the blood vessels expand," says Dr. med. univ. Jan Eggen, specialist in dermatology from Central Swiss Derma in St. Anna in Meggen. The body reacts to this by releasing the messenger substance histamine, and an itchy wheal forms.

Not everyone reacts the same to a mosquito bite. In Central Europe there are increasing reports that those affected complain of strong local inflammatory reactions after contact with a bloodsucker. “Theoretically, the body can develop an allergy to all substances that are foreign to the body,” says Eggen when asked by “Bluewin”.

However, allergic reactions to mosquito bites are rather unlikely. On the other hand, more species of mosquitoes from other countries would be native to us. “When they prick, they secrete proteins that our immune system is not yet aware of. It is conceivable that this leads to an excessive local reaction to insect bites. "

The scratching provides temporary relief for the stab victim, but it does get bacteria that colonize our skin surface into the wound. The mosquito itself can smuggle in germs. In rural areas in particular, skin infections are due to the fact that the insects came into contact with liquid manure and the faecal bacteria it contains.

If there is inflammation, see a doctor

If there is an inflammation, one should be vigilant, "especially if the reddening spreads and becomes larger than a five-puffer," explains Jan Eggen. If the findings are very pronounced, the development of a wound rose is theoretically possible. The inflammation spreads around the mosquito bite like a tongue of flames, antibiotic therapy is necessary here. Extremely rarely, it leads to life-threatening blood poisoning (sepsis).



As soon as the reddening at the puncture site has spread massively and a strong swelling can be seen, the dermatologist advises to consult a doctor. Anyone who also observes symptoms such as fever or weakness in connection with such a skin inflammation must go to the hospital immediately.

If you don't want to be stung in the first place, you can use an anti-mosquito spray. And if you do get caught, a heat stick, which is pressed directly onto the bite, helps, as Eggen reveals: "Temperatures of around 50 degrees destroy the irritant proteins in the mosquito saliva and alleviate the symptoms."

If that is not enough, the specialist recommends antiallergic or anti-inflammatory creams with low-dose hydrocortisone or fusidic acid. And when you are out and about, a mosquito bite is very itchy and none of the mentioned remedies is at hand? "Don't scratch!", Eggen warns, "it's better to tap the puncture site with your finger."

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