Delusions of parasitosis. A psychiatric disorder to be treated by dermatologists? An analysis of 33 patients.

Delusions of parasitosis is a rare disorder in which patients have the false and fixed belief that they are infested by parasites. It is a psychiatric disorder, but patients usually present to a dermatologist and referral to a psychiatrist is almost always rejected. Treating a patient with delusions of parasitosis requires patience and tact. The neuroleptic pimozide is the treatment of choice, but a significant problem is convincing the patient to take the drug. We report a study of 33 patients (13 men and 20 women) with delusions of parasitosis. The mean age at onset was 56.9 years and the mean duration of symptoms before attending the department of dermatology was 1.3 years. Pimozide (Orap) was prescribed for 24 patients, but only 18 patients took it. Follow-up information was available for 18 patients: five had full remission, four were less symptomatic, five were unchanged and four had died of unrelated causes.