Demodex mites among solid organ transplant recipients: a cross-sectional study

Introduction:
Demodex mites (DM) are pathogenic parasites that in some people cause demodicosis. It is widely discussed which groups of patients are more prone to develop the disease.

Aim:
To evaluate the prevalence of DM in a population of solid organ transplant recipients (SOTRs) in comparison to immunocompetent controls.

Material and methods:
A total of 225 SOTRs were tested for DM by 2 methods: microscopic evaluation of scrapings of the face and by dermoscopic examination of the face. Additionally, a group of 95 patients, who do not have any immunosuppression history, were asked to volunteer as controls. Every patient in study group was examined for face symptoms and had his medical history reviewed.

Results:
The prevalence of positive Demodex test was not significantly different among SOTRs comparing to controls (21 positive results among SOTRs (9.3%) vs. 6 positive controls (6.3%), (p = 0.38)), but there was a numerically higher rate in SOTRs population. Patients treated with tacrolimus had a higher odds ratio of a positive Demodex test when compared to those treated with cyclosporine A (p = 0.046). Skin symptoms were characterized by relatively high negative predictive values (91.0–93.7%). Itch had the best balance between sensitivity and specificity, whereas exfoliation had the highest diagnostic accuracy.

Conclusions:
In our study, demodicosis does not occur more often among SOTRs than in the general population. Notably, itch and exfoliation are symptoms of the greatest diagnostic value in demodicosis diagnosis. Patients receiving tacrolimus had a higher prevalence of a positive Demodex test when compared to those treated with cyclosporine A.