Are Demodex Mites a Cause of Rosacea?

ishonest: What do you think is the cause of rosacea? Do you think Demodex mites play a role in rosacea development?

Jessica Wu, MD (

There's no general consensus on the exact cause of rosacea, but I think an abnormal immune system may be the common pathway that produces the familiar symptoms we see. Some studies have shown an increased number of Demodex folliculorum mites in patients with rosacea, and it's thought that either the mites or bacteria living on the mites could trigger rosacea, but the overgrowth could be a result of inflammation and increased oil production, rather than the underlying cause.

Recent research shows that those with rosacea have an altered immune response in their skin. This makes them more sensitive than others to a variety of factors, including heat, UV rays, bacteria, skin care products, and certain foods. Studies have shown that those with rosacea have abnormally high levels of a peptide (protein fragment) called cathelicidin in their bloodstream. In addition, this peptide is different in people with rosacea. These peptides trigger the formation of new blood vessels (leading to redness and spider veins) as well as inflammation (leading to pimples, bumps, and breakouts). Once we figure out how to normalize this altered immune response, we'll have better therapies for rosacea.

Nicholas Perricone, MD (

Rosacea is a chronic skin disorder that appears to be more common in women than in men. It usually appears in middle age or later, and people who blush easily and/or have fair skin appear to be most at risk. Many skin conditions, including acne and rosacea, are systemic inflammatory diseases, which tend to run in families. Rosacea is characterized by dilated capillaries (tiny blood vessels connecting arteries to veins that carry oxygen and nutrients to individual cells) on the skin's surface. Other rosacea symptoms include skin thickening, pimples, bumps, and persistent redness, primarily on the forehead, nose, cheekbones, and chin. Rosacea can also cause discomfort and burning in the eyes and on the eyelids. Although rosacea symptoms will come and go, unfortunately rosacea is a lifetime problem. The Demodex mites are one of the factors quoted in the dermatologic research literature as causative; however, this disease is multi-factorial and the final common pathway is inflammation.

Elizabeth Tanzi, MD (

Yes, Demodex mites do have a role in the development of rosacea, but they are not the only cause. Rosacea is a chronic skin condition that is defined by a chronic state of inflammation which subsequently leads to facial redness, capillaries, acne-like bumps, and coarse skin texture.

Howard Murad, MD (

Although the exact cause of rosacea is unknown, various theories about the disorder's origin have evolved over the years. Rosacea is an inflammatory condition when facial blood vessels dilate too easily, and the increased blood near the skin surface makes the skin appear red and flushed. Various things — called trigger factors — can increase this redness response and additionally cause acne-like bumps to appear, often in the redder area of the central face. This may be due to factors related to blood flow, skin bacteria, microscopic skin mites (Demodex), irritation of follicles, sun, damage of the connective tissue under the skin, an abnormal immune or inflammatory response, or psychological factors. None of these possibilities have been proven; although potential inflammatory pathways have been identified in recent ongoing research — including an immune response triggered by a type of antimicrobial protein known as cathelicidin. A recent study also found that certain bacteria present on otherwise harmless Demodex mites could prompt an inflammatory response in Rosacea patients.

Macrene Alexiades-Armenakas, MD (

First and foremost, vascular reactivity — the tendency to flush — is the main cause [of rosacea]. Over time, this evolves into hive-like pimples and eventually scarring to the skin. It has been suggested that the mites take hold after the rosacea is fairly progressed. However, it would not be surprising if the mites actually induce the disease or its worsening in a subset of individuals.

Dennis Gross, MD (

Rosacea's exact cause has been an endless source of debate in the medical community, but it is known to have both a bacterial and inflammatory component. People with fair skin are more prone and it does run in families. Its symptoms include diffuse redness (flushing), broken capillaries and inflamed bumps or pimples, which is why it is often confused with acne.

Jeannette Graf, MD (

Rosacea is an inflammatory process that has no specific etiology; more likely multiple factors are involved such as sun exposure, genetics, hormones, and medical history to name a few. Demodex mites are found much more frequently in rosacea patients than non-rosacea control groups. Demodex mites probably multiply in the environment of increased blood vessels and connective tissue changes in rosacea.

Neil Sadick, MD (

The cause of rosacea is rather unclear. It can be a genetic predisposition. Demodex mites are a secondary symbiotic bystander rather than a pathogenetic causation factor.

Marta Rendon, MD (

The definitive cause of rosacea is still unknown; however, there are many factors that can aggravate or trigger it. Examples of triggers are stress, physical exertion, sun exposure, and certain foods such as spicy foods and alcohol. Demodex mites have also been implicated as a possible trigger is some patients with rosacea.

H.L. Greenberg, MD (

There are many possible causes of rosacea, from blood vessels being closer to the surface in people with rosacea to an inflammation to even Demodex mites. Although many people are colonized with Demodex, people who have reactions to the mites may manifest that reaction as rosacea.

Sarah Swanson (

Rosacea is a result of vascular dilatation resulting in an acne-type red rash. It is most common in patients between 30 to 60-years-old with fair skin and light eye and hair color. The exact cause and trigger of the vascular dilatation in rosacea is unknown, although factors that trigger the innate immune responses are linked to increased symptoms. The hair follicle mites, Demodex folliculorum and Demodex brevis, have been postulated to play a causative role in the inflammatory lesions. Studies have found increased numbers of mites in the skin of patients with rosacea compared with unaffected people. However a study of patients with rosacea treated with tetracycline improved rosacea symptoms despite no change in mite counts. Thus the increased number of mites may be effect rather than cause, and the contributors to the cause of rosacea remains elusive.

Eric Schweiger, MD (

Rosacea is a chronic condition characterized by central facial redness, and occasionally pimples. The etiology of rosacea appears to be multifactorial with some people having a genetic predisposition. Environmental triggers can contribute, and flares can occur after emotional distress, drinking alcohol, or eating certain foods. In addition, some studies have indicated that people with rosacea have an increased number of Demodex mites on their skin and overgrowth of bacteria in their gut.

Nelson Lee Novick, MD (

Genetics are the cause of rosacea. That being said, certain things may be aggravating factors, including the Demodex mites. While these mites are common and harmless inhabitants of the skin, in certain rosacea patients — perhaps not all — their presence or the metabolic byproducts may trigger rosacea flares. This may explain why certain patients with redness from rosacea benefit from the application of crotamiton lotion (Eurax), a scabicide.

Darrell W. Gonzales, MD (

Rosacea is a common problem that can affect any skin type. There are several different variants including vascular rosacea, papulopustular rosacea, and ocular rosacea. What makes rosacea so frustrating is that there is no one single cause of it and therefore no one simple cure to fix it. The one universal finding that we understand about rosacea is that it is related to skin vascular hyper-reactivity and inflammation. Although Demodex mites have been found on the faces of people with rosacea, there is no scientific evidence that the mite plays any primary role in its causation.

Jeffrey Ellis, MD, and Amy Slear, MD (

Though rosacea is a very common condition, there is still much that we need to learn about it. For example, the precise cause is unknown. We believe genetic, environmental, vascular and inflammatory factors all play a role. The role of Demodex (hair follicle mites) or Helicobacter pylori in the stomach is uncertain.

William Ting, MD (

Rosacea is a multifactorial skin condition with a strong familial predilection that affects the central third of the facial profile. Demodex mites can occasionally play a role as they can kick-start a cascade of inflammatory skin processes leading to red bumps. One of the treatment goals of topical metronidazole is to minimize Demodex mite skin colonization.

Dina Strachan, MD (

Much like acne vulgaris, I think that the cause of rosacea is multi-factorial. There are different clinical presentations of rosacea. Some people have broken blood vessels. Others have acne, skin thickening or even eye symptoms. Vascular hyperactivity seems to be an important feature. Although Demodex mites have been shown to be increased in the sebaceous follicles of people with rosacea, it is not clear whether this is a cause or a consequence. It is possible that the environment of the sebaceous gland in a person with rosacea is more hospitable to the mite. Rosacea does not respond to antimite treatments. On the other hand, immunocompromised people with excessive mites in their follicles who develop a rosacea-like condition do tend to respond to anitmite treatments. These are probably two different diseases.

Brad Abrams, DO (

Rosacea is a common inflammatory disorder of the skin. The causes of rosacea include factors like genetic predisposition, inflammatory process and heredity. Rosacea tends to affect more people with fair skin or who blush easily. Demodex mites possibly play a role in rosacea. They are much more frequent in rosacea patients. The change in the vascular and connective tissue might create a more favorable environment for the proliferation of Demodex mites.

Eric Huang, MD (

Rosacea, while quite common and fairly easy to diagnose, is a complex skin condition with variable clinical manifestations whose causes are poorly understood. At the most basic level, rosacea is vasodilation and inflammation in response to various stimuli. Each individual suffering from rosacea may have her own set of factors that lead to its development and affect the severity of the disease. These include a genetic predisposition, abnormal vascular reactivity due to neurologic stimuli, defective skin barrier function and skin irritability. Why some patients develop vascular, inflammatory, phymatous or ocular rosacea variants isn't clear. The link between Demodex mites and rosacea has been suggested by a couple studies, but a true cause-effect relationship has not been established. In addition, treatment with permethrin, which kills Demodex, is not an effective treatment for rosacea. At most, I believe the Demodex mite may lead to exacerbation of the disease in select individuals with ocular rosacea.

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