Demodex mite infestation high in patients with rosacea
The prevalence and degrees of Demodex mite infestation are higher in patients with rosacea than in control patients, a recent study has found.
Systematic literature review and meta-analysis were conducted to determine the prevalence and degrees of Demodex mite infestation in patients with rosacea. A total of 23 case-control studies were included, which involved 1,513 patients with rosacea.
Researchers pooled odds ratios (ORs) for prevalence of infestation and standardized mean difference (SMD) for Demodex density in patients. They also performed subgroup analysis for type of rosacea, control group, and sampling and examination methods.
Patients with rosacea had significantly higher prevalence of Demodex mite infestation (OR, 9.039; 95 percent CI, 4.827 to 16.925) and significantly greater Demodex density (SMD, 1.617; 1.090 to 2.145) compared with the control patients. Furthermore, both erythematotelangiectatic rosacea (SMD, 2.686; 1.256 to 4.116) and papulopustular rosacea (SMD, 2.804; 1.464 to 4.145) had significantly higher Demodex density than did healthy control patients.
These findings suggest that “Demodex mites may play a role in both erythematotelangiectatic rosacea and papulopustular rosacea,” according to researchers, adding that their systematic review and meta-analysis were limited by a high interstudy variability and the failure to establish causal relationship due to the design of the included studies.
In an earlier study, the investigators concluded that although Demodex mites did not appear to cause rosacea, they might represent an important cofactor, especially in papulopustular rosacea. Immunohistochemical findings suggested that a delayed hypersensitivity reaction, possibly related to D. folliculorum, might occur, stimulating progression of the affection to the papulopustular stage. [J Eur Acad Dermatol Venereol 2001 Sep;15(5):441-4]