Erythematotelangiectatic rosacea and subclinical demodicosis

Abstract

Demodex mites are small parasites that live in the skin pores of all adult humans, mainly on the face, and feed on human cells. Demodicosis is a facial skin condition that occurs when the mites proliferate (multiply) abnormally. Demodicosis shows as scales on the skin surface and, when the mites cause inflammation, by redness and/or red or weeping spots. Rosacea is another frequent skin condition affecting more than 10% of the population and characterised by facial redness. Sometimes spots develop and the condition is then called papulopustular rosacea (PPR). The cause of rosacea is still controversial, but it has been suggested that Demodex mites may be involved, because patients with PPR have a high density of mites on the facial skin, similar to patients with demodicosis. In this study, from Belgium, the density of Demodex mites was measured by two successive skin biopsies in patients in the early stage of a condition called erythematotelangiectatic rosacea (ETR), where patients have only redness without spots. The mean densities were lower than the densities in patients with PPR and patients with demodicosis but higher than in patients with healthy skin and patients with other skin conditions. The authors suggest that ETR may favour Demodex proliferation and may represent an early phase of demodicosis, with mites beginning to proliferate but not yet clinically visible. As such, dermatologists should look for Demodex mites in patients with ETR, so that appropriate treatment can be offered if densities are high.