Demodex may prolong, intensify rosacea
Demodex mites and rosacea have an unusual pathogen–disease relationship, one that is still being explored. According to Edward J. Wladis, MD, FACS, the association between Demodex and rosacea is not all that well-known.
“Demodex is both under-recognized and highly treatable. The problem is that we often fail to recognize the presence of Demodex until it’s pretty late in the game and patients are already suffering. However, with the proper treatment protocols, we can usually get the rosacea to quiet down and get patients feeling better,” Wladis told Primary Care Optometry News.
A variety of skin diseases can be caused by an imbalance in the immune mechanism, triggered by a high Demodex infestation, he said.
Toll-like receptors, inflammation
“The theory is that Demodex can stimulate a class of immunologic proteins called toll-like receptors,” Wladis said. “Our research has shown that patients with ocular rosacea have increased concentrations of these receptors in eyelid skin, and that these receptors seem to drive the inflammation that is associated with ocular rosacea.
“So, the presence of Demodex really adds gasoline to the fire,” he continued. “These patients have a tendency to develop an exuberant immune reaction, due to the prevalence of these receptors and the fact that the mite that can stimulate them is present in increased quantities. Taken together, it’s the perfect storm to induce a lot of inflammation, and these patients really suffer. Ultimately, the longstanding inflammation can scar the meibomian glands, leading to a loss of the normal egress of their contents and instability of the tear film.”
Mites can multiply rapidly, leading to different pathogenic conditions, with a common prevalence, found in 23% to 100% of healthy adults, according to Rather and colleagues.
“Demodex can occur in asymptomatic patients, but it seems to really trigger the effects that we all associate with ocular rosacea,” Wladis continued, “Specifically, because Demodex stimulates a particular immune receptor (toll-like receptors), inflammation can really go haywire after Demodex infestation. Once that receptor starts the inflammatory process, the itching, burning and ocular surface irregularities that we associate with ocular rosacea can really flare.”
Demodex may influence the type and severity of visible manifestations of rosacea in different individuals, and “the classic ‘subtypes’ of rosacea appear to reflect variations in inflammatory and immunologic responses, which, in some cases, may be induced by Demodex mites,” James Del Rosso, MD, said in a press release from the National Rosacea Society.
In those with compromised immune systems, increased Demodex numbers resulting in inflammation may be the culprit.
The number of Demodex mites present in the hair follicle or sebaceous glands also increases with age. Due to low sebum production, children and infants lack significant Demodex colonization, according to Rather’s research.
Mario Gutierrez, OD, FAAO, added that older patients tend to have higher rates of mites, which may be attributed to drier eyes as people age, changes in lid morphology, decline in hygiene and reduced resistance to disease.
Demodex brevis is also thought to be associated with meibomian gland dysfunction (MGD), chalazion/internal hordeolum and evaporative dry eye, he said.
What to look for
Wladis offered tips on identifying Demodex.
“A patient with cylindrical dandruff, clogged meibomian glands and the classic appearance of periocular inflammation likely has an infestation,” he said. “That presence needs to be addressed when developing a treatment strategy for the patient.”
Scott Schachter, OD, FAAO, suggested looking for cylindrical dandruff, missing lashes, weak, brittle lashes, a scalloped lid margin, lid telangiectasias and conjunctival injection in patients with possible Demodex.
“Cylindrical dandruff is pathognomonic for Demodex. It represents the colony waste from the follicle,” he told PCON. “If you want to confirm their presence, epilate lashes and place them under a microscope.”
Gutierrez said, and Schachter agrees, that it is not necessary to have a microscope to diagnose Demodex infestation. Gutierrez detailed a technique from Katherine Mastrota, OD, MS, FAAO, of lash rotation at the base of the lash with forceps to see the mites’ cream-colored tails poking out of the follicle under high magnification. Demodexfolliculorum can also be viewed with high slit lamp magnification on the patient’s facial pores.
Most people are carriers of Demodex mites and do not develop clinical symptoms, Wladis said, and primary or secondary immunodepression can transition a clinically unapparent colonization of mites to dermatoses.
The pathogenesis of demodicosis and immune response to mite invasion are poorly understood, he noted.
Demodex-type rosacea is characterized by dryness, follicular scaling, superficial vesicles and pustules, as opposed to common rosacea, which is characterized by oily skin, absent follicular scaling and being more seated, Wladis said.
“The etiological role of this versatile mite should be kept in mind, as human demodicosis can present as a variety of clinical manifestations mimicking many other dermatoses,” according to a study from Parvaiz Anwar Rather, MD, in the Indian Journal of Dermatology.
In a study in the British Journal of Dermatology, 98% of 45 controls without rosacea had less than five Demodex/cm2. In 49 patients with rosacea, Demodex density was significantly higher at 10.8/cm2. Demodex density was statistically significantly higher than in controls only in the papulopustular rosacea (PPR) group at a mean of 12.8/cm2. The researchers Forton and Seys suggest that standardized surface biopsy could be a useful diagnostic tool for PPR, with a 98% specificity when Demodex density is higher than 5/cm2.
Schachter discussed his own research where 28 out of 100 consecutive patients at his office had Demodex blepharitis.
Results from a poll on Healio.com/Optometry show that 80% of respondents see Demodex in 20% or less of their patients, and 40% saw concomitant rosacea in 20% or less of patients with Demodex.
“There is a strong comorbidity with blepharitis and rosacea. It is believed that hypersensitivity to a bacteria that lives in the gut of the mite is the culprit, Bacillus oleronius,” Schachter said.
“Blepharitis, in general, often goes undiagnosed, as it is a chronic condition rather than acute,” he added. “Patients adapt to the growing discomfort and seem to consider it normal. Many doctors don’t bother with chronic conditions unless patients are complaining.”
Dermatologist Erin B. Lesesky, MD, also believes the link between Demodex and blepharitis is essential for optometrists to understand.
“Demodicosis can be rosacea or rosacea-like, perioral dermatitis-like or blepharitis-like,” she told PCON. “That is probably the most important thing for optometry: discussing the blepharitis that can be associated with Demodex.”
Lesesky suggests considering Demodex when patients are not responding to typical treatments.
“We all have those patients who aren’t responding to what other patients are responding to,” she said. “Maybe there is something else that is contributing to this that we aren’t targeting. That’s the time to consider Demodex. If things aren’t working, consider treating Demodex.”
Schachter recommends proper hygiene for the long term. As for treatment, tea tree oil therapy is toxic to the mites.
“I refer to products that simply clean the lid margin as the janitor,” he said. “Tea tree oil is the terminator.”
Tea tree oil is antibacterial, antifungal and anti-inflammatory and has acaricidal effects, he said.
Gutierrez offered further treatment pearls.
“It is important that we properly instruct our patients on our prescribed treatment,” he said. “Have them clean their lashes, eyelids, eyebrows and skin around the orbit and nose, not just the eyelashes. Also remember, baby shampoo lid hygiene is ineffective in treating Demodex.”
He believes that any blepharitis or MGD patients deserve treatment whether they are symptomatic or not.
“Clinically, I have noticed that any Demodex treatment is significantly enhanced with aggressive warm compress therapy. I feel D. brevis does not get enough notoriety. In fact, some clinicians, including myself, feel that suspected D. brevis infestation may be more pathological than D. folliculorum,” Gutierrez said. – by Abigail Sutton
- Forton F, et al. Br J Dermatol. 1993;128:650-659.
- Rather PA, et al. Indian J Dermatol. 2014;59(1):60-66.
- National Rosacea Society. New studies discuss significance of Demodex in care of rosacea. www.rosacea.org. Posted July 30, 2015. Accessed October 1, 2015.
- For more information:
- Mario Gutierrez, OD, FAAO, is in private practice in San Antonio, Texas. He can be reached at email@example.com
- Erin B. Lesesky, MD, practices at Duke Dermatology in Durham, N.C. She can be reached at firstname.lastname@example.org.
- Scott Schachter, OD, is in private practice in Pismo Beach, Calif. He can be reached at email@example.com.
- Edward J. Wladis, MD, FACS, is an oculoplastic surgeon with the Lions Eye Institute in Slingerlands, N.Y. He can be reached at firstname.lastname@example.org.
Disclosures: Gutierrez is the designer of the Gutierrez Blephbrush, and Inventor of MG Expressor and MG Lid Plate Plus. Lesesky reports no relevant financial disclosures. Schachter is a consultant for Allergan and Bio-Tissue. Wladis reports no relevant financial disclosures.