Abstract

BACKGROUND:

Delusional infestation (DI) is an uncommon psychiatric disorder in which patients present with the false and fixed belief of infestation. Numerous studies have demonstrated improvement with pharmacological treatment; however, recurrence rates on cessation of treatment remain unknown.

OBJECTIVES:

To assess the clinical response and recurrence rates following treatment for DI.

METHODS:

All patients with DI seen in our combined dermatology/psychiatry clinic to date (n=73) were offered pharmacological therapy. Patients were contacted to complete a telephone questionnaire to assess clinical outcomes, including remission and recurrence rates following treatment.

RESULTS:

Fifty-nine of 73 (81%) patients with DI received treatment, of whom 40/59 (68%) reported improvement or resolution of symptoms, and the remaining 19/59 (32%) failed to respond. Fifteen of 40 patients with DI completed a course of treatment, 12/40 patients are still undergoing treatment, and outcomes are unknown for 13/40. Of those who completed treatment, 11/15 (73%) reported total remission for at least 9months after discontinuing treatment (range 9months-2·5years). Recurrence of symptoms occurred in 4/15 (27%) within 4months of stopping treatment.

CONCLUSIONS:

Pharmacological treatment of DI can be effective, particularly in a combined dermatology/psychiatry clinic. Most treated patients have a good prognosis, and a remission period can be expected. However, more than 25% of patients may relapse on stopping treatment, with the greatest risk being within the first few months of discontinuation. These patients may require longer treatment courses, or long-term maintenance therapy for symptom control, although further studies are needed to provide recommended guidelines on drug and dosing regimen.

© 2011 The Authors. BJD © 2011 British Association of Dermatologists.