Evaluation of Demodex folliculorum as a Risk Factor for the Diagnosis of Rosacea In Skin Biopsies. Mexico's General Hospital (1975-2010)

CONTEXT: Rosacea significantly affects the quality of life and its pathophysiology is not well understood. It has been suggested that the presence of Demodex folliculorum in the affected skin could be related to the development of rosacea. AIMS: To study the risk for association between the presence of D. folliculorum in skin biopsies and the diagnosis of rosacea. SETTINGS AND DESIGN: Analytical, observational, retrospective, case–control study. MATERIALS AND METHODS: Skin biopsies of patients diagnosed clinically as rosacea and the same number of controls were studied. The controls were selected among the facial skin biopsies that were not diagnosed as rosacea. All the slides were analyzed for the presence of D. folliculorum and the density of the infestation was assessed. STATISTICAL ANALYSIS USED: Absolute/relative frequencies, mean, standard deviation, odds ratio (OR), Chi square and Independent Student t-test with Epi Info v. 3.4.3(®). RESULTS: D. folliculorum was present in 80% of the skin biopsies of rosacea patients and in 30% of the controls. The risk of suffering rosacea was increased among persons infested with the mite (OR = 9.33 [95% confidence interval: 2.85-30.60]; P = 0.0001). The mean infestation density among the cases was 1.908 for every 10 high-power fields while it was 0.718 among the controls (P < 0.005). There were no statistically significant differences among the groups with regard to sex and age. CONCLUSIONS: The presence of D. folliculorum in skin biopsies is associated with the diagnosis of rosacea. The infestation density was increased among the patients with rosacea.