Exploring Demodex in Chronic Urticaria: Lack of Association but Evidence for Type-2 Immune Activation in Demodex

Chronic spontaneous urticaria (CSU) is a mast cell driven multifactorial disorder with complex pathogenesis. While the association between CSU and internal parasites has been investigated, the association of ectoparasites such as Demodex mites remains elusive. This study aims to compare Demodex prevalence in CSU patients with healthy controls and to evaluate selected immunologic parameters in Demodex patients. A prospective case-control study was conducted including 100 patients with CSU and 50 age- and sex-matched controls. Skin surface biopsy was performed using the cyanoacrylate method, and participants were classified as Demodex-positive if more than five mites were detected within a 1 cm² field. Serum levels of total IgE, eosinophil counts, thyroid-stimulating hormone (TSH), free thyroxine (T4), and anti-thyroid peroxidase (anti-TPO) antibodies were measured. Demodex positivity was observed in 26% of CSU patients and 26% of controls (p = 1.00). Median IgE (208.08 IU/mL, range 4.89-1207.00) and eosinophil counts (0.17 ± 0.07 × 10⁹/L) were significantly higher in Demodex-positive participants than in Demodex-negative ones (65.72 IU/mL, range 2.40-632.11, and 0.14 ± 0.09 × 10⁹/L, respectively; p < 0.05). Thyroid function parameters and antibody levels showed no significant differences between groups. Although Demodex prevalence did not significantly differ between CSU patients and controls, infestation was associated with elevated IgE and eosinophil levels, suggesting a possible association with type 2-skewed immune markers. Further studies with quantitative mite assessment and detailed immunologic profiling are needed to better understand this relationship.