You don’t need to feel squeamish reading this information. According to researchers, the Demodex mite seems to be harmless to the human body, and it is likely that anyone living has them on their face.
The Mite That “Uses the Bathroom” on… Human Skin
Firstly, you cannot see them with the naked eye, which allows them to live comfortably and freely on the “facade” of every person. However, if you “try” with the help of a magnifying glass or microscope, you may see these mites, shaped like worms or larvae, crawling under your skin, as shown in the following clip.
General Description
Demodex was first discovered by Gustav Simon, a German dermatologist, in 1842. Nearly 200 years later, scientists are still not entirely sure why these mysterious mites exist and live on mammals. According to Michelle Trautwein, an entomologist at the California Academy of Sciences, “Demodex exists not only on human skin but on all mammals. They evolved alongside primitive mammals and continue to coexist.”
Demodex is the name of a type of parasite (also known as mites) and is among the billions of parasites, with Demodex being the smallest type, making them very difficult to see with the naked eye. This parasite prefers to inhabit areas around hair follicles and sebaceous glands, such as the face, nose, forehead, chin, and eyes.
There are two species of mites that “prefer” to live on human faces: Demodex folliculorum (D. folliculorum) and D. brevis (also called Demodex). Although they resemble larvae, they are actually crustaceans, similar to insects or crabs. Their closest relatives are spiders and ticks.
The head of the Demodex folliculorum mite has 8 short and stout legs
The structure of Demodex consists of a head with 8 short, stout legs evenly distributed on either side, and its body and tail are of equal size, extending into a longer segment, making them appear like worms. However, due to such great asymmetry, Demodex mites move very slowly. Under a microscope, Demodex appears to swim in the “pools” of oil beneath the human skin.
These two species of Demodex are primarily distinguished by their living locations. The D. folliculorum species prefers to reside near the skin’s surface, in pores or hair follicles. Meanwhile, D. brevis lives deeper, beneath the skin’s epidermis, inside the sebaceous glands that surround human hair follicles.
D. brevis lives in the sebaceous glands of humans
Compared to other parts of the body, the pores on the human face are larger and have more sebaceous glands. This is also why Demodex mites prefer to parasitize here rather than in other areas. However, for some “sensitive” reasons, Demodex has also been found around women’s breasts and in the 18+ area.
Unique Characteristics
In fact, the scientific community has known about Demodex mites for quite some time. In 1842, the D. folliculorum species was discovered in human earwax in France. However, they were not studied in depth until now. It wasn’t until 2014 that researchers from North Carolina State University (USA) began studying this species. Among all the people studied, up to 14% could find the mite living on their face. The rest all had traces of Demodex DNA after they had died!
Image of Demodex folliculorum under a Scanning Electron Microscope (SEM)
Under every eyelash could be a Demodex mite
This raises the question that any of us may have Demodex mites, if not, they exist in large numbers on each person’s body. Megan Thoemmes, the lead researcher, stated: “It is still a bit difficult to determine the exact number, but a small population of mites can reach hundreds. A large population can reach thousands.” In other words, there could be a mite swimming under each of your eyelashes.
Of course, some people will have more mites than others, and vice versa. It is also possible that on the same person, one side of the face has more than the other.
However, researchers have yet to answer the question – what do these mites seek on our faces? In fact, we have not clearly identified what Demodex’s diet is. “Some people believe they eat the bacteria that usually live on our skin. Others think they consume dead skin cells. Some believe they feed on the oils produced by sebaceous glands,” Thoemmes added.
Image of Demodex folliculorum under a Light Microscope
Currently, Thoemmes and her colleagues are analyzing the microbial samples found in the guts of Demodex. These organisms may help us understand what these mites consume on our faces.
The reproduction of these mites is also a topic of interest. Although Demodex is considered harmless so far, surely many people want to eliminate them. Therefore, understanding how Demodex reproduces is also necessary. Considering other mite species, their reproductive methods are very diverse, ranging from “traditional” mating to incest and cannibalism. However, Demodex seems to be “more benign.” “There have been no reports of them cannibalizing other mites. They seem to only leave their nests at night to find mates and return afterward,” Thoemmes noted.
However, the research group is well aware of Demodex’s egg-laying behavior. The entire process has been recorded in the clip below. Specifically, female Demodex lay eggs right in the pore they are residing in. Demodex does not lay many eggs, almost only one egg per time.
“Their eggs are really large, from 1/3 to 1/2 the size of their body, which requires them to replenish their bodies significantly. Their eggs are so large that they almost can only lay one egg at a time. And I cannot imagine if there is another egg that can fit into their body at such a size,” Thoemmes commented.
But this species of mite has a very strange feature – they do not have an anus. So how do they “recycle“? Of course, they still need to “release” waste, but in a very dramatic way – Demodex mites “explode” after they die. Apparently, these creatures “store” waste throughout their lives, which is why they have a long body and tail like a worm. After their metabolic process stops, the Demodex body dries up, and all of their waste scatters around. The term “explode” may be somewhat exaggerated, but clearly at death, the feces of this species are scattered on your face.
Benefits or Harms?
Face mites (Demodex folliculorum) do not have an anus. They also do not excrete waste through their mouths like some other organisms. All the waste produced after consuming skin cells and sebum on human faces is compacted into their intestines.
With this peculiar digestion process, face mites only live up to 16 days. After they die and decompose, their waste remains on the human face, combining with bacteria that cause skin diseases (such as erythema).
There have been studies showing the relationship between Demodex mites and chronic rosacea. Specifically, some individuals initially experience facial redness, which then progresses to a permanent condition characterized by more intense red spots and increased sensitivity to environmental temperature changes. These studies found that those with this condition often have more Demodex mites than normal individuals. For instance, instead of just 1-2 mites per square centimeter, they can have up to 10-20.
A face affected by Rosacea
However, this does not mean that they are the causative agents of rosacea. The number of Demodex mites may simply be a consequence of the condition. Kevin Kavanagh from Maynooth University (Ireland) states: “The mites are associated with rosacea, but they are not the cause.” In his research in 2012, Kavanagh concluded that the increase in the “population” of Demodex is due to changes in the human skin.
Specifically, our skin changes over time, as well as due to living conditions and environmental factors. These influences cause the sebaceous glands beneath our skin to secrete a greater amount of oily sebum to keep our skin moisturized. It is likely that Demodex mites feed on this sebum, so if the sebaceous glands produce more, they have more food. As a result, the “population” of Demodex increases dramatically.
Kavanagh describes: “This phenomenon leads to inflammation on our faces, as too many mites are produced. When the mites die, they release substances present in their bodies. These include many bacteria and toxins that cause itching and inflammation.“
Excess sebum secretion may be the cause for increased Demodex growth
However, the death of Demodex mites is likely more related to our immune system. Thoemmes indicates that in patients with weakened immune systems, such as those with AIDS or cancer, the number of Demodex mites becomes quite significant. “I believe the mites explode because your body has an immune reaction to something present on them. Rosacea is just one such reaction.” When the immune system weakens, such reactions are not as frequent, allowing Demodex to proliferate rapidly.
In fact, the relationship between us and Demodex mites is still not fully understood. Whether they are parasitic or symbiotic remains an unanswered question. Although Demodex is linked to rosacea, not everyone suffers from this condition, and those with AIDS or cancer are also susceptible to other diseases due to their weakened immune systems. Remarkably, despite being present in almost everyone, we generally do not feel “bothered” by them.
Image of human skin (purple) affected by bacteria (orange) proliferating
If the hypothesis that Demodex mites feed on bacteria living on the skin or dead skin cells (in addition to their “fatty menu”) is true, then they are clearly beneficial to the human body. Imagine sanitation workers diligently cleaning your office; Demodex mites could very well be performing a similar role.
“Loving” Humans
However, many of you might want to eliminate these eight-legged creatures from your pores, right? The answer is almost… impossible!
Although there are some methods to remove Demodex mites, they tend to reappear. The duration is about 6 weeks. And the source of infection is naturally from objects around us and the people we live with. “We catch them from those we come into contact with. We catch them from bedding, pillows, and towels. There is clear evidence that we ‘exchange’ them back and forth between individuals,” Kavanagh explains.
Demodex mites “like” human faces
And Demodex mites “love” human faces. Regardless of how they are transmitted, they always find a way to crawl onto our faces. The presence of these mites in women’s breast areas may also be a means for them to infect newborns during breastfeeding. Sexual intercourse is also a good pathway for Demodex transmission.
Especially, as we age, the number of Demodex mites increases. Thoemmes’ research shows that Demodex activity in those over 18 years old is significantly higher than in teenagers. This is likely due to the activity of the sebaceous glands or changes in facial skin with age stimulating their growth.
But above all, where do these mites originate? Naturally, they do not spontaneously generate on our faces but are transmitted from others. So what is the root cause?
Origins
There is still too little information to provide a precise answer, but it seems that Demodex has evolved alongside humanity. Thoemmes speculates that they may have appeared with humans “since we evolved from our Hominidae ancestors.” This means that Demodex mites have “accompanied” humanity for at least the past 20,000 years.
Could they have come from dogs?
However, it is also possible that humans contracted D. brevis from a similar species found in dogs. When humanity domesticated wild dogs, particularly wolves, this exchange likely occurred. “Our ancestors lived closely with them, to hunt and forage, and became infected from there,” Thoemmes remarks.
Regardless of how it happened, the relationship between humans and Demodex is very ancient. According to Thoemmes, Demodex can help understand the migration processes of humanity over thousands of years. When examining the DNA samples of these mites, Thoemmes found that the mites obtained from Chinese communities differ significantly from those in North and South American communities. This detail suggests that studying Demodex mites could provide additional insights into human history.
Image of Demodex folliculorum crawling on human skin
“We can imagine the relationships within human communities… Relationships that we have never considered before,” Thoemmes comments. For instance, during the colonization of Central and South America, which groups played key roles. “There are many different hypotheses about which communities colonized Brazil and interbred with the indigenous people.“
Conclusion
And there are still many more things to study about Demodex, such as how they have evolved when transmitted between humans or how humans have changed since acquiring them… Of course, not every question or hypothesis can be correct. But ultimately, Demodex mites are just one of many parasitic species found on the human body, such as ticks, fleas, bacteria, and worms… This highlights another lesson about the human body. We are not simply ourselves – we are a moving organism, a part of the human community, and also an ecosystem shared with hundreds of species inhabiting that body.
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