The bigger the mosquito bite, the more poisonous the mosquito is?

It is the golden season of "being sucked blood by mosquitoes" again. With a helpless and humorous attitude, everyone has started the state of being bitten and making fun of it again. How wonderful other aspects of summer are, the existence of mosquitoes is so annoying! In fact, we are not reluctant to give up their blood, but the arrogance of these "robbers" who are buzzing and noisy while sucking blood is too infuriating! The unbearable itching after being bitten is the most unbearable! If you are unlucky and encounter a "poisonous" mosquito, it will swell up so much that your mother won't recognize it!

There is a theory about mosquito bites that sounds reasonable: the bigger the bite, the more toxic it is. Wait, does the size of the bite have anything to do with the toxicity of the mosquito? Do different blood types have different attraction to mosquitoes? In fact, the consequence of being sucked by a mosquito is not just itchy for a few days, but also the risk of contracting infectious diseases! We need to know more about mosquito bites.

01

Mosquito bag model

It depends on the person

We often say "Oh, I got bit by a mosquito." Strictly speaking, the word "bite" is not accurate, because mosquitoes have no teeth and cannot complete the action of "biting." The specific process of mosquitoes sucking blood is: the piercing and sucking mouthparts penetrate the human skin to cause damage, and while sucking blood, they also secrete saliva into the human body to prevent blood from clogging the mosquito's mouthparts. Their saliva contains a variety of chemicals that can inhibit vasoconstriction, blood coagulation, and platelet aggregation. These "mosquito saliva" injected into the human body will cause local allergic reactions, causing immune cells to aggregate and release histamine and a variety of cytokines. These histamines and cytokines will dilate blood vessels, increase vascular permeability, local tissue edema, and cause itching and local inflammatory reactions.

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Because everyone's immune system reacts differently, the reaction to mosquito bites is also different. Some people may not react at all; most people will develop erythema, papules, wheals and itching after being bitten by mosquitoes; and some people with allergies will release a large amount of histamine and cytokines around the skin after being bitten by mosquitoes, causing extraordinary reactions such as blisters, plaques, ecchymosis, swelling and pain, which will last for a long time to subside. In addition, scratching will also cause excessive release of local histamine, and increased histamine will cause more severe reactions, which is why the more you scratch, the more itchy it becomes, the bigger it gets, and the slower it heals.

02

Mosquitoes also bully strangers?

Immunity to bugs has yet to take effect

Some people go out to the wild or travel to other cities, and after being bitten, they will have bigger, itchier, and more lumps than local mosquitoes. Over time, there is a saying that mosquitoes in the wild are more poisonous! Some northerners even found that being bitten by mosquitoes at home was not a big deal, but after going to a southern city, their arms and legs were covered with lumps as big as steamed buns? Are mosquitoes that grow in the hot and humid environment of the south more poisonous?

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In fact, these bumps are not necessarily caused by the bites of local mosquitoes. Because many arthropods (such as sandflies, midges, etc.) will cause similar reactions on our skin by sucking blood, and residents who have lived there for a long time have developed immunity and desensitization due to repeated bites, and will no longer have any reaction after being bitten. For people who enter these areas for the first time, they have not yet developed immunity to these insects, and after being bitten, they will experience symptoms that are more itchy, more severe, and last longer than previous mosquito bumps.

03

Is O-type blood the most attractive to mosquitoes?

Other blood types disagree!

There are many theories about what kind of blood mosquitoes prefer, and one of them is the "blood type theory" which holds that type O blood is the most attractive to mosquitoes, while type A blood is the least popular. But in fact, this theory has no scientific basis at all.

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The famous scientific magazine Nature once reported that mosquitoes bite humans because they like the smell of humans. The antennae of mosquitoes contain odor receptor proteins, which can recognize the different odors emitted by people's bodies. The odor of each of us is controlled by genes, which is why some people attract mosquitoes and some people are not easily bitten by mosquitoes. This difference has nothing to do with blood type. Since whether or not to attract mosquitoes is related to genes, people who attract mosquitoes cannot reduce their attractiveness to mosquitoes, and can only use physical protection and chemical mosquito repellent methods.

04

Drive away first and then take revenge

Leaving behind a "straw" will cause endless trouble

If you happen to find a mosquito sucking blood from your skin, should you kill it immediately to avenge yourself, or should you "expel" it and then make further plans?

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The New England Journal of Medicine once reported that after an American woman slapped a mosquito that was biting her, the pathogenic fungi carried by the mosquito entered her body through the tiny wounds left on her skin, infected the deep muscles, and eventually died. Of course, this is just an individual case. Generally speaking, if a mosquito is suddenly slapped to death while sucking blood and its mouthparts are not pulled out in time, the mouthparts left in the skin as foreign bodies are most likely to aggravate the local immune response, making the itching and rash more severe. Therefore, for safety reasons, if you find a mosquito that is sucking blood, it is best to gently drive it away first, and then track and kill it after the safety alert is lifted, rather than slapping it to death directly.

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05

The itch can be endured temporarily

Infectious diseases are more dangerous

When a mosquito bites you, besides losing a drop of blood, there are greater dangers: while the mosquito bites your skin and sucks blood, it also spreads a variety of diseases. There are more than 3,000 known mosquito species in the world, and there are more than 300 species of mosquitoes in my country. Among them, the main ones that spread diseases are Anopheles, Aedes and Culex.

In my country, the more common infectious diseases caused by mosquito bites include dengue fever, malaria, epidemic encephalitis B, filariasis, etc. The pathogens of these diseases can survive and multiply in the mosquito's body. The mouthparts that pierce the skin when the mosquito sucks blood and the saliva injected into the human body during the bite are all ways for humans to be infected with viruses. These diseases will have serious symptoms, such as fever, headache, impaired consciousness, gastrointestinal discomfort, rash, lymphangitis, etc. Therefore, avoiding mosquito bites is our compulsory course in summer.

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Author | Chen Xue, attending physician at Beijing Tongren Hospital, Capital Medical University

Review | Feng Jun, Deputy Chief Physician, Dermatology Department, General Hospital of Datong Coal Mine Group Co., Ltd.

This article is produced by the "Science Rumor Refutation Platform" (ID: Science_Facts). Please indicate the source when reprinting.

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