Demodex - A louse specializing in parasites on ... human face skin

You do not need to feel itchy when reading this information. According to the researchers, Demodex lice do not seem to be harmful to the human body and perhaps anyone who lives also has them on their faces.

The lice are parasitic on . human face skin

The first thing is that you can't see them with your eyes, because then they will be able to live freely and freely on the " façade " of each person. But actually, if you " try" , with the help of a magnifying glass or microscope, you can see that the bug is shaped like a worm or worm that is crawling under its skin, like the following clip.

General description

There are two "like " living lice that are Demodex folliculorum (D. folliculorum) and D. brevis (also called Demodex). Although it looks deep, they are actually crustaceans, like insects or crustaceans. Their closest relatives are spiders and mites.

The first part of the Demodex folliculorum lice has 8 legs

The structure of Demodex consists of a head with 8 short and stubby legs that are divided into two sides , the body and tail are equal in size and extend into a large section that makes them look like worms. But due to the asymmetry so big, Demodex lice move very slowly. Under the microscope, Demodex looked like he was swimming in greasy " tanks" beneath human skin.

These two species of Demodex are distinguished primarily through their location.The species of D. folliculorum prefers to live near the skin surface, in pores or hair roots. And D. brevis lives in a deeper layer, beneath the epidermis of the skin, inside the sebaceous gland (oil) surrounding the human hairline.

D. brevis lives in sebaceious gland of humans

Compared to other parts of the body, pores on the face are wider and also have greasy glands. That is also the reason that Demodex louse prefers parasites here than other regions. However, for some "sensitive" reasons, Demodex is also found around the women's lap as well as the 18+ area.

Specific characteristics

In fact, the scientific community has known Demodex lice for a long time.In 1842, D. folliculorum was found in human ear wax in France . But they are not well studied until now. Until 2014, researchers from North Carolina State University (USA) learned about this species. Of all the people studied, up to 14% could find lice on their faces. All the rest of them had a trace of Demodex's DNA after they were dead!

Image of Demodex folliculorum species under scanning electron behavior glass (SEM)

Under each eyelash may be a Demomax louse

This led to the suspicion that any of us had Demodex lice , if not they had very large numbers on each body. Megan Thoemmes, head of the research team, said: " It's still quite difficult to determine the exact number but a small louse population can reach hundreds. A large population can reach the line. thousand children " . In other words, there may be a louse under each of your eyelashes.

Of course, there will be people who have more lice than others and vice versa. It may be on the same person but the left side will have more than the right or vice versa.

But the researchers have not answered the question - what does this louse search on our face? In fact, we have not yet determined what Demodex's ration is."Some people think that they eat bacteria that normally live on our skin. Others think they eat dead cells. Some people think that they eat oily substances from oily glands , " Thoemmes added. .

Photo of Demodex folliculorum species under optical microscope

Thoemmes and her colleagues are now analyzing the microbiological patterns in Demodex's gut. These creatures can help us imagine what this louse consumes on our faces.

The reproduction of this louse is also a concern. Although until now, Demodex is considered harmless, but certainly many people want to remove them. So how Demodex reproduces is also something to learn. Considering other lice, their reproductive methods are diverse, from "traditional" to incestuous and meat-eating relationships. But Demodex seems much more " benign" . " There are no records for them to eat other children. It seems that they only leave the team at night to find a partner and return later," Thoemmes commented.

However, the research team knows well about Demodex's spawn. The whole process was recorded in the clip below. Specifically, the Demodex females lay eggs right in the pores they are in.Demodex did not give birth much, almost only one egg for a single birth.

"Their eggs are really big, from 1/3 to 1/2 of their body size, which will require them to replenish their bodies a lot. Their eggs are so big that they can almost only give birth to one And at the same time, I could not imagine whether any more eggs could fit into their bodies with such size , " commented Thoemmes.

But this louse has a very strange point - they have no anus. So how do they " reincarnate cereals "? Of course, they still need to "get out ", but in a dramatic way - Demodex lice " explode" after death. It seems that this animal "stores" waste throughout its life, so they have long bodies and tails like worms. And after the metabolism of the body has stopped, Demodex's body is dry and all its waste is scattered around. The phrase " exploding" may be a bit exaggerated, but obviously at the time of death, this species is scattered on your face.

Good or bad?

There have been studies showing the relationship between Demodex lice and chronic rosacea (rosacea ). Specifically, some people initially become flushed, then switch to permanent status, appear darker red spots and become sensitive to changes in environmental temperature. These studies found that people with this condition often have more Demodex lice than normal people. For example, instead of only 1-2 children per centimeter square, in them up to 10-20.

The face of a person with Rosacea

But that does not mean that they are the cause of rosacea.Demodex lice may only be a consequence of the disease . Kevin Kavanagh, of Maynooth University (Ireland), said: " The lice are related to rosacea, but they are not the cause" . In his research in 2012, Kavanagh concluded that the cause of Demodex 's "population" increase came from the change of human skin.

Specifically, our skin changes over time, as well as living conditions and living environment. These effects make our sebaceous glands beneath the skin secrete more fatty substances, to keep our skin moisturized. And the Demodex can eat these mucus very much, so if the glands are more secreted, the more food they have, the more food they have. As a result, Demodex's "population" skyrocketed.

Kavanagh describes: " This phenomenon leads to swelling in our faces, because then there are too many lice born. When the lice die, they release substances in their bodies. Things like that. There are many bacteria and toxins that lead to itching and inflammation ".

The high secretion of mucus may cause the Demodex lice to thrive

But Demodex's death may be more related to our immune system . Thoemmes said that in patients with weakened immune systems such as people with AIDS or cancer, the number of Demodex lice became quite significant. " I think the lice explode because your body has an immune response to something on them. Rosacea is just such a reaction . " When the immune system weakened, such reactions were no longer available, so Demodex developed rapidly.

In fact, the relationship between us and Demodex lice has not yet been fully clarified. Parasitic or symbiotic is still an unanswered question. Although Demodex is related to rosacea, not everyone is sick and for people with AIDS or cancer, they are also more likely to suffer from other diseases that come from weakening of the immune system. It is worth mentioning that despite being present in most people, we hardly feel "uncomfortable" about them.

The image of human skin (purple) is proliferated by bacteria (oranges)

And if Demodex's hypothesis is that eating live bacteria on the skin or dead cells (apart from the fat "menu") is correct, then obviously they are useful for the human body. Imagine the sanitation workers who are "diligently" cleaning your office, Demodex louse is probably playing a role.

"Love" people

But many of you still want to remove the creature with 8 other legs out of the pores on your body? The answer is almost . impossible!

Although there are several methods to eliminate Demodex lice, they still reappear. The period lasts about 6 weeks. And the source of infection is, of course, the things around us, the people around us. "We get them from people we have contact with. We get them from blankets, pillows, towels. There is clear evidence that we 'exchange' them back and forth between people. ", Kavanagh said.

Demodex louse "like" human face

And Demodex louse "loves" the face of humans . No matter how infectious they are, they always find ways to crawl on our faces. It may also be a way for them to infect babies, when a mother breastfeeds her baby. Sex between people is also a good way for Demodex to infect.

Especially when we get older, Demodex lice are getting more and more . Thoemmes's research shows that Demodex's activity in people over 18 is much greater than that of teenagers. Most likely because the gland's activity or facial changes with age have stimulated them to grow.

But most of all, where does the louse come from? Of course they are not born on our faces but spread from others. So where is the root?

Source

There is still too little information to have an accurate answer, but Demodex seems to have gone along with the evolution of humanity. Thoemmes speculated that they may have appeared to humans " since we evolved from the Hominidae ancestors". Demodex has "co-operated" with humankind for at least 20,000 years.

Do they come from dogs?

But it is also possible that humans have been infected with D. brevis from a similar species living on dogs. When mankind assimilated wild dogs into domestic dogs, especially wolves, perhaps the exchange took place."Our ancestors lived close to them, for hunting and foraging and getting infected from there," Thoemmes commented.

But anyway, the relationship between humans and Demodex is very long . According to Thoemmes, Demodex can help understand the human migration process for thousands of years. When observing the DNA samples of the louse, Thoemmes found a group of lice collected in the Chinese community different from those of North and South America. This shows that the study of Demodex lice can provide more information about human history.

Photo of Demodex folliculorum lice crawling on human skin

"We can imagine relationships in the human community . Relationships that we never thought about before," Thoemmes commented. Take, for example, the colonization of Central and South America, the line of people who play the main role. " There are many different theories about which communities have colonized Brazil and bred with indigenous people."

Epilogue

And there are also many other things to study about Demodex, for example how they have changed when transmitted through people, or how people have changed since having them . Of course, not necessarily questions or Any hypothesis may be true. But after all, Demodex lice are just one of dozens of other parasitic species on the human body, such as ticks, fleas, bacteria, helminths . This tells another lesson about the human body. . We are not simply us - we are a moving body, part of our community and also a community with hundreds of species sharing that body.