If you are bitten by 15,000 mosquitoes, will you be sucked dry? (Be careful if you have trypophobia!)

What does it feel like to have 500 mosquitoes sucking your blood at the same time?

It's enough to make your scalp tingle, but for Perran Ross, it's just a normal, everyday activity.

Ross is a man who "feeds mosquitoes with his own body". With his own arms, he feeds thousands of hungry mosquitoes. On the highest day, he was sucked blood by 15,000 mosquitoes.

This isn't some crazy thrill-seeking exercise; it's part of serious scientific research.

Why would someone feed a mosquito with their arm? Image credit: Perran Ross

People who feed mosquitoes with their own bodies

Perrin Ross is a researcher at the University of Melbourne who studies how to control mosquito-borne diseases.

Specifically, he studies how to control the spread of dengue fever using Wolbachia. Wolbachia is a microorganism that can infect mosquitoes, which can control the reproduction of mosquitoes and reduce the ability of mosquitoes to spread dengue fever without causing any harm to humans. Scientists hope to spread this microorganism into wild mosquitoes, thereby reducing the threat of mosquito-borne diseases to humans.

Mosquito researcher Perrin Ross. Image source: School of BioSciences, University of Melbourne

To do this, they first needed to breed mosquitoes in the lab for testing. In order for female mosquitoes to lay eggs, they had to be provided with blood as a source of nutrition - Ross donated his arm for this.

Ross feeds mosquitoes with his arm. Image credit: Perran Ross

He would put his arm through the mesh sleeve on the side of the mosquito cage and let the female mosquito suck his blood. He always wears gloves when feeding, which can prevent his palms from being bitten by mosquitoes. There are about 500 mosquitoes in the cage in the picture. It takes about 2 minutes to feed a mosquito. In order to ensure that everyone can eat as much as possible, he will keep his arm in the cage for at least 10 minutes each time. The specific frequency of feeding mosquitoes is determined by the experimental requirements.

When the video of feeding mosquitoes became popular on social networks, netizens commented that what Ross did was "horrible self-abuse" and "the worst job in the world." However, Ross himself disagreed. He said in a Twitter comment: "I really feel that the process of feeding mosquitoes is very relaxing."

A mosquito cage with a mesh sleeve on the side. The sleeve is inserted into the arm to reduce the chance of mosquitoes escaping. Image credit: Ari Daniel/NPR

How itchy is this?

Ross started feeding mosquitoes when he was studying for his master's degree in 2012, and he has been doing it for more than 10 years. At the beginning, the large number of mosquito bites did make him itch badly, and he couldn't control the urge to scratch for several weeks, and had to rinse his arms with cold water to relieve the discomfort.

However, his body has now adapted to the frequent bites. Although he is not completely insensitive, he can completely ignore the mosquito bites, and the redness and swelling will disappear in just one day. Several other researchers who feed mosquitoes in person have had the same experience. According to the experience of Italian researcher Chiara Andolina, after two months of frequent mosquito feeding, the body will become accustomed and the reaction will be greatly reduced.

After a day of feeding mosquitoes, Perran Ross's arm is completely free of traces. Image source: Perran Ross

This is because the redness, swelling and itching of mosquito bites are largely due to allergic reactions, which are the result of the human immune system being activated by mosquito saliva proteins. Repeated exposure to allergens can lead to desensitization. After being bitten by mosquitoes enough times, the immune system of these people will no longer fuss about mosquitoes.

Will it be sucked dry?

Each mosquito can suck up about 3 microliters of blood at a time - although this is a surprisingly large amount compared to its own body weight, it is still very small for humans.

An Aedes aegypti mosquito sucking blood. Image source: Perran Ross

According to this number, if 5,000 mosquitoes suck blood at once, a person will lose 15 ml of blood, which is roughly equivalent to a blood test. Ross's record for feeding mosquitoes is to let 15,000 mosquitoes suck blood in one day, which will cause a loss of about 45 ml of blood, which is far from excessive blood loss.

Being bitten by 5,000 mosquitoes will result in a loss of blood equivalent to a physical examination.

Mosquitoes born in the laboratory do not carry pathogens, and feeding them will not cause diseases in humans. If mosquitoes need to be infected with pathogens in experiments, researchers will stop feeding them in person in accordance with ethical regulations and use other methods instead. In other words, apart from slight discomfort, feeding mosquitoes will not cause any obvious harm to health.

Does it have to be fed by humans?

In many cases, it is not necessary to feed the mosquitoes to humans. Instead, the mosquitoes can be fed the blood of anesthetized experimental animals, such as mice and rabbits.

Using anesthetized mice to feed mosquitoes, Image source: WIRED

If you don't want to use animals, researchers can also choose artificial blood feeders. When making this kind of feeder, they usually stretch the sealing film fully, then wrap the thinned film on the container, add anticoagulated animal blood to it, and let the mosquito pierce the film to absorb. In order to increase the attractiveness to mosquitoes, the feeder needs to be heated to 37°C in a water bath.

Experimental mosquitoes sucking blood from a film feeder. Image credit: Vosshall Lab

However, some mosquitoes are particularly picky eaters. They don't like animal blood or artificial feeding, and are only interested in biting living people. The researchers donated their arms to satisfy these picky mosquitoes so that the experiment can proceed smoothly.

At present, human volunteers are still indispensable in mosquito research, but scientists are also working hard to find better alternatives. For example, bioengineers at Rice University are developing an "artificial skin" made of gel that allows mosquitoes to suck blood from tiny channels in the gel.

An "artificial skin" device being tested, which is expected to replace human volunteers in mosquito experiments. Image source: Rice University

As technology develops, hopefully one day humans will no longer need to sacrifice their arms to kill mosquitoes.

References

[1] https://www.washingtonpost.com/health/mosquitoes-researchers-feeding-blood/2020/08/21/25f30252-c608-11ea-a99f-3bbdffb1af38_story.html

[2] https://twitter.com/MosWhisperer/status/940472111461789702

[3] https://www.nationalgeographic.com/science/article/the-worst-bit-about-feeding-mosquitoes-is-the-waiting

[4] https://www.npr.org/sections/health-shots/2013/01/02/167048030/mosquito-maven-takes-bites-for-malaria-research

[5] https://twitter.com/MosWhisperer/status/1258227471624757248

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