Unilateral Demodicidosis of Face Mimicking Hansens Disease

The Effect of Volatile Oil from Chinese Mugwort Leaf on Human Demodecid Mites In Vitro

BACKGROUND

Human demodecid mites including Demodex folliculorum and Demodex brevis Akbulatova can cause acne, rosacea, epifolliculitis, blepharitis, seborrheic dermatitis, perioral dermatitis, acromastitis and such skin health problems. Artemisia (Composiate) are widely distributed in temperate regions in the northern hemisphere. It has been reported that 17 species of plants in Artemisia used to be mugwort in China. Mugwort volatile oil (MVO) has antibacterial and antiviral effects, can relieve cough and asthma, acts as an expectorant, choleretic and sedative, and promotes circulation and enhances immunity.

PURPOSE

This research was to observe the effect of MVO on two types of human demodecid mites in vitro.

METHODS

The MVO was obtained via the supercritical CO₂ extraction method, and the human demodecid mites were acquired with cellophane tape. MVO had a distinct killing effect on two types of human demodecid mites, Demodex folliculorum and Demodex brevis. The body of the demodecid mites has a classical temporal process, which consists of excitement, contractions, death and transparency. The killing time was lengthened with decreasing concentration, thus showing an evident dependence on concentration.

RESULTS

The experiment showed that 3.125% was the minimum effective concentration of MVO for killing D. brevis, and 6.25% was the minimum effective concentration for killing D. folliculorum; the killing effect of MVO on D. brevis was greater than on D. follilorum.

CONCLUSION

This result suggests that mugwort, which acts as a traditional Chinese herbal medicine, has a noticeable killing effect on human demodecid mites.

The Pathogenic Role of Demodex Mites in Rosacea: A Potential Therapeutic Target Already in Erythematotelangiectatic Rosacea?

Rosacea is a common facial dermatosis but its definition and classification are still unclear, especially in terms of its links with demodicosis. Triggers of rosacea (ultraviolet light, heat, spicy foods, alcohol, stress, microbes) are currently considered to induce a cascading innate and then adaptive immune response that gets out of control. Recent histological and biochemical studies support the concept that this inflammatory response is a continuum, already present from the onset of the disease, even when no clinical signs of inflammation are visible. The Demodex mite is beginning to be accepted as one of the triggers of this inflammatory cascade, and its proliferation as a marker of rosacea; moreover, the papulopustules of rosacea can be effectively treated with topical acaricidal agents. Demodex proliferation appears to be a continuum process in rosacea, and may not be clinically visible at the onset of the disease. Molecular studies suggest that Demodex may induce tolerogenic dendritic cells and collaborate with vascular endothelial growth factor (VEGF) to induce T cell exhaustion and favor its own proliferation. These interactions among VEGF, Demodex, and immunity need to be explored further and the nosology of rosacea adapted accordingly. However, treating early rosacea, with only clinically visible vascular symptoms, with an acaricide may decrease early inflammation, limit potential flare-ups following laser treatment, and prevent the ultimate development of the papulopustules of rosacea. The effectiveness of this approach needs to be confirmed by prospective controlled clinical trials with long-term follow-up. Currently, the evidence suggests that patients with only vascular symptoms of rosacea should be carefully examined for the presence of follicular scales as signs of Demodex overgrowth or pityriasis folliculorum so that these patients, at least, can be treated early with an acaricidal cream.