Having to do a talk to local GPs about rosacea does focus the mind somewhat on this pretty prevalent skin condition. It was also helpful to see that the October 2019 issue of the British Journal of Dermatology had a study from Belgium on the condition.
What is rosacea?
Rosacea is typically characterised by easy facial flushing which can then lead onto persistent facial redness of the central parts of the face. As the disease progresses, red spots and pustules can develop and there may be a textural change to the skin with skin thickening and a sensation of fullness or lumpiness. Some people can go on to get eye involvement and changes to the shape of their nose which can get quite bulbous.
It typically occurs between the ages of 30 and 40 years but can occur in individuals much younger or older than this.
What causes rosacea?
Traditionally, it was thought that rosacea was a result of dilatation of the vessels in the face. Affected individuals would report worsening of facial flushes after certain things such as alcohol, drinking hot drinks, hot spicy foods, moving from a cold to a hot room. However, we’re not sure how this vessel dilatation in the face leads on to rosacea. It has been suggested that minute amounts of plasma leak out of vessels every time the face flushes. These minute amounts of plasma then induce an inflammatory response and hence the cycle repeats every time the face flushes.
{Wilkin JK. Oral thermal-induced flushing in erythematotelangiectatic rosacea. J Invest Dermatol. 1981;76:15-8.]
However, for quite some time now, we have known that the mite Demodex folliculorum might be implicated in the pathogenesis of rosacea.
There is a mite in my skin!
The mite Demodex folliculorum lives in the grease gland unit (sebaceous follicles) on the head, predominantly in the centre of the face, where rosacea is more prevalent. We are not born with Demodex in our skin, we acquire it by direct contact with the skin of other humans. The mites are present at low levels as part of the normal human microbiota. However, more Demodex mites are seen in rosacea patients than in non-affected individuals.
[Bonnar E, Eustace P, Powell FC. The Demodex mite population in rosacea. J Am Acad Dermatol 1994;28:443-8.]
However, it was and is still not known if this increased prevalence of Demodex is because there is rosacea present or whether they are the cause of rosacea.
How could a mite cause rosacea?
It is thought that the mites feed on the sebum or grease in the grease gland unit and eventually burst. This results in the release of toxins and bacteria which activates the immune response. It has also been suggested that they penetrate the deeper layers of the skin (the dermis) and trigger an exaggerated immune response that way.
[Thyssen JP. Are demodex mites the best target for rosacea treatments? Br J Dermatol 2019;181:652-653.
Forton F and De Maertelaer V. Erythematotelangiectatic rosacea may be associated with a subclinical stage of demodicosis: a case- control study. Br J Dermatol 2019;181:818-825.]
How do we treat rosacea?
Rosacea is traditionally treated with long term, low dose antibiotics of the tetracycline class of antibiotics. Isotretinoin, a treatment usually reserved for resistant or nodulocystic acne, can also be used in the most severe forms. However, for the rosacea patient that has no spots or textural change and only redness (so called erythematotelangiectatic rosacea or ETR) treatment can be a little difficult. Laser treatment is usually the only effective treatment.
In recent years, a topical agent, ivermectin, that kills Demodex has been in use for the treatment of rosacea with associated spots (so called papulopustular rosacea or PPR) and has been shown to be effective.
[Stein L, Kirik L, Fowler J et al. Efficacy and safety of invermectin 1% cream in treatment of papulopustular rosacea: results of two randomized, double-blind, vehicle-controlled pivotal studies. J Drugs Dermatol 2014;13:316-23.]
So what did the study from Belgium show?
This study looked at Demodex densities in the skin of patients with ETR, PPR, normal skin of healthy control patients, and other skin conditions caused by Demodex (demodicosis).
Twenty-three patients with ETR were biopsied and compared with biopsies from the study group’s previous studies in 254 PPR patients, 20 healthy controls and 590 with demodicosis.
They found that the patients with ETR did have higher Demodex densities than normal healthy controls. Patients with PPR and demodicosis had the highest densities of Demodex, which is not surprising.
What does this mean for the rosacea patient?
It might mean that it might be worth trying a topical agent that kills Demodex such as topical ivermectin for those patient with ETR. The study group say that such treatment has led to improvement and disappearance of the redness and other sensations such as burning of the skin so that sometimes laser treatment has not been necessary.
So it’s good news for what has been a challenging condition to treat for many patients for many years…
Kind regards,
Sandy
Dr Sandy Flann, Consultant dermatologist
