Presence of Demodex in Seborrheic Dermatitis Lesions and its Relationship with Disease Severity: A Case Control Study

Abstract

Objective: Seborrheic dermatitis (SD) is a common, chronic, recurring, inflammatory skin disorder. The cause of the disease is still completely unknown. Recent studies suggest that Demodex parasites may play a role in the etiopathogenesis of SD. The purpose of this study was, to investigate the presence of Demodex in SD and its association with disease severity. Material and Methods: A total of 40 patients over the age of 18 years, who were clinically diagnosed with SD, and 40 healthy control subjects were included in the study. The skin surface biopsy method was used to detect Demodex parasites on lesional and non-lesional skin of the patients and healthy skin of the control group. The Seborrheic Dermatitis Area Severity Index was used to calculate disease severity. The presence of 5 or more Demodex parasites per square centimeter was considered positive. Results: While Demodex parasites were found in 50% of the lesional skin and in 2.6% of the non-lesional skin of the patients, 12.5% of the control group (p<0.001) had Demodex parasites. No relationship was found between the presence of Demodex parasites in the lesional skin and the severity index of the SD area. Conclusion: In this study, we found that the presence of Demodex was more prevalent in SD lesions than in control skin and lesion-free skin. A member of the microbiota, Demodex may be a predisposing factor in the development of SD.