Role of Demodex folliculorum in the pathogenesis of blepharitis

Abstract

Editor, T he ectoparasite Demodex folliculorum (Simon 1843) is most common parasite of humans. In the eye, D. folliculorum is found in the eyelash follicle. The aim of this study was to examine the prevalence of D. folliculorum in the eyelashes in patients with haematologic disorders. Eyelashes were collected from 95 patients of the Clinic of Haematology Pomeranian Medical University, Szczecin, Poland, and from 1091 healthy controls. There were 47 (49%) women and 48 (51%) men in the patients group (age range: 58.6 ± 13.1) and 759 (69.6%) women and 332 (30.4%) men in the control group (age range: 58.6 ± 13.0). From each patient, we aseptically collected two lashes from the upper right eyelid and two lashes from the upper left eyelid. The collected material was used in preparations examined using light microscopy (magnified 100 times). Infection of the examined subjects was confirmed by the detection of adult and larval forms of D. folliculorum. Demodex folliculorum is found in 21.8% of healthy controls and 18.9% of haematologic patients (Fig. 1; Table 1). In the control group, D. folliculorum occurred in 22.3% of women and in 20.8% of men. In patients with haematologic disorders, D. folliculorum occurred in 17.5% of women and in 25% of men. A much lower rate of infestation of D. folliculorum (12%) was found in immunosuppressed patients with rheumatoid arthritis (Ciftci et al. 2006). On the other hand, in patients with final-stage renal failure (ESRF) on dialysis treatment, D. folliculorum found in 44.4% of patients (Karincaoglu et al. 2005). In our study, the percentage of D. folliculorum infestation in haematologic patients ranged from 16% of patients with acute leukaemia, MPS and other haematologic diseases, and 21.7% with multiple myeloma, to about 24.1% in patients with nonHodgkin’s lymphoma and CLL. Seyhan et al. (2004) found D. folliculorum in the skin of patients with acute lymphocytic leukaemia (12%), acute myelocytic leukaemia (32%), chronic lymphocytic leukaemia (4%), chronic myelocytic leukaemia (10%), Hodgkin’s lymphoma (4%) and nonHodgkin’s lymphoma (38%). Demodex folliculorum seem to be a mediator of chronic blepharitis; some recommend that mites be sought in cilia of chronic blepharitis patients (Czepita et al. 2007). Elevated subjective symptoms of the ocular surface were caused by increased levels of D. folliculorum. Itching, burning, foreign body sensation, crusting and redness of the lid margin, and blurry vision are the main symptoms. Signs include disorders of eyelashes, lid margin inflammation, meibomian gland dysfunction, blepharoconjunctivitis and blepharokeratitis (Czepita et al. 2007). In the control group, the most common symptoms related to D. folliculorum infestation included sensitivity to light, dacryorrhea and itching of the eyelids; loss of eyelashes was the least common. In the group of haematology patients, dacryorrhea was most frequent, without any reports of sensitivity to smoke, light, foreign body sensation under the eyelids or loss of eyelashes. A 61.7% of D. folliculorum-infected patients in the ophthalmology clinic reported itching, and 59.1% reported red eyes (Inceboz et al. 2009). In our study, we found that D. folliculorum infestation was correlated with cylindrical dandruff in the lash roots, both in the control group and in haematologic patients. In patients with D. folliculorum infestation in eyelashes, we found trichiasis, meibomian gland dysfunction with lipid tear deficiency and conjunctival inflammation (Czepita et al. 2007). The prevalence of D. folliculorum in patients with haematologic diseases was similar to that of the control group. Demodicosis may cause itchiness in the eyelids and cylindrical dandruff in the lash roots.