The prevalence of Demodex folliculorum infection in patients attending a general ophthalmological consultation

Objectives: Determining Demodex folliculorum infection prevalence in patients attending general ophthalmological consultation and such infection's association with blepharitis.

Methods: This was a descriptive study of such prevalence. 128 subjects who attended the Virgilio Galvis Eye Centre were randomly selected and the presence of D. folliculorum was determined in 4 eyelashes taken from each of them.

Results: D. folliculorum infection prevalence was 42.1% (n=54); blepharitis was diagnosed in 38.3% of the patients (n=49) and 63.2% of them (n=31) were positive for D. folliculorum. Only 29.2% of the individuals in the group without blepharitis (n=79) had mites (n=23) (p=0.0003). A higher number of parasites was found in patients with blepharitis (12.7 parasitic load index cf 5.1; p=0.0001); 25% (n=32) of the participants had scaling in the form of cylinders and 96.9% of these had the mites (n=31), whereas the mite was only present in 24% (n=23) of subjects who had no cylinder-type scaling (n=96).

Conclusions: Demodex folliculorum is a parasite found in people without ocular lesions; however, it is more frequent and has a higher parasite burden in patients with blepharitis. Our results suggested the need for investigating the presence of D. folliculorum in all patients suffering from blepharitis, especially in cases where cylinder-type scaling has been observed in their eyelashes.