engleski

Demodicosis and rosacea

SIR, -Although mites of the genus Demodex were described as parasites of hair follicles and sebaceous glands in man more than 150 years ago and the first reports suggesting a connection with skin lesions were recorded at the very beginning of this century, their pathogenicity/innocuity remains controversial. One reason for this uncertainty has been that uncomfortable, invasive diagnostic methods (scarification, biopsy) have limited epidemiological inquiry. Since 1976 scotch-tape swabs of suspected areas have been used increasingly2.3 but this non-invasive technique has yet to be tested against classical methods on a large scale. We have tested the tape method on 177 patients with facial demodicosis proved by scarification. The tape test was positive in 165 (932%). We then extended the investigation to 87 dermatologically healthy individuals and found the mites in 11 of them (13%). In mite-infested individuals D folliculorum alone was identified in 703%, D brevis in 24-1 %, and both species in 5-6%. Since facial demodicosis has most often been associated with facial skin disease we also included in our observations 57 patients with acne vulgaris and 79 with rosacea. In the acne vulgaris group the prevalence of demodicosis was 12% (as in the group with healthy skin) but of the patients with rosacea 64 (81%) had demodicosis. In no group was there any influence from age. Nor did sex influence the infestation rate in rosacea group and controls. All the patients have been clinically verified and followed up at the clinic for skin and venereal diseases, Zagreb Medical School. We are not suggesting a straight cause-and-effect relation between demodicosis and rosacea. There are other factors to be analysed, such as immune status and current therapy, before firm conclusions are drawn. Nevertheless, our findings may be of interest to dermatologists and parasitologists.

mites ; Demodex ; scarification ; biopsy ; scotch-tape swabs

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