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Demodex: Exploring
Its Role in Rosacea
Although the relationship is not fully understood, targeting the mites often improves skin
symptoms of rosacea.
WITH DR. FRANK POWELL
Image Courtesy of NRS
With increased understanding of the
microbic organisms that live on Demodex
human microbiome, physicians and espemites may also be involved in rosacea. A recent
cially dermatologists are considering its
study found a diversity of such microorganaffects on health. In particular, there has
isms, including a total of 92 species, 36 of which
been increased focus on the potential role
were never before recorded on humans.
of Demodex mites in rosacea. The National
Rosacea Society recently convened a
Do you discuss Demodex with
roundtable discussion, with support from
patients? If so, what do you say?
Galderma, to bring together experts to dis“I do discuss Demodex with patients,” Dr.
cuss the role of Demodex in rosacea.
Powell says. They should understand that rosaAlthough Demodex mites are a norcea is not caused by an infection. “I tell them
Figure. The microscopic skin
mal part of the human microbiome,
that we all have these mites but that patients with
mite Demodex folliculorum.
they have been found in more than four
rosacea have more than average,” he says.
times greater numbers on the facial skin
of rosacea sufferers, according to Dr. Frank Powell, conIn the roundtable, you mentioned a Super Glue
sultant dermatologist at Mater Misericordiae Hospital in
test for Demodex. Is this a potential clinical tool?
Dublin and former president of the European Academy of
“The glue is put on a glass slide that is placed on the
Dermatology and Venereology. Ahead, Dr. Powell answers
skin. The glue dries and when the slide is removed it
questions about Demodex and rosacea.
extracts the contents of the follicles in which the Demodex
lives,” Dr. Powell, explains.“It is mainly used for researchers
As new research is emerging, how would you best or by dermatologists who feel a particular case is abnormal,”
describe the role of Demodex in rosacea?
he adds.
“The role of Demodex in rosacea is unclear. It is not solely
the cause,” Dr. Powell says. But he adds, “It probably is a factor Now that a topical ivermectin formulation that
in some patients.”
targets Demodex is available in the US for rosaDemodex folliculorum and D. brevis have long been
cea, where do you think it fits in the treatment
known to live in the hair follicles and sebaceous glands of
regimen?
the facial skin. D. folliculorum is also found in the meiboIvermectin is a known anti-vermicidal and antiparasitic
mian glands of ocular rosacea patients.
recently shown to have anti-inflammatory actions, as well. In
Dr. Powell has suggested that a genetic predisposition for
a large study on the action of topical ivermectin in patients
rosacea may be reflected in a different skin type with specific
with moderate to severe rosacea, 38.4 to 40.1 percent of
lipid qualities that allows Demodex to flourish in greater num- subjects received physician assessments of clear or almost
bers. The finding that individuals who had significant acne
clear. At 12 weeks, there were 64.9 to 65.7 percent mean
when younger often are observed to have rosacea later may
reductions of inflammatory lesions of test subjects.
supports a possible genetic component in patients with skin
“Topical ivermectin is establishing itself as an alternative
that reacts to either Propionibacterium acnes or Demodex.
mainstream treatment to more established treatments of
During the roundtable, discussion touched on the fact that
metronidazole and azelaic acid,” per Dr. Powell. n
30 PRACTICAL DERMATOLOGY
OCTOBER 2015