Treatments for Primary Delusional Infestation: Systematic Review

BACKGROUND: Delusional infestation, also known as Ekbom syndrome, is a rare delusional disorder characterized by the fixed belief that one is infested with parasites, worms, insects, or other organisms. Although delusional infestation is a psychiatric condition, patients often consult dermatologists with skin findings, and it is currently unclear what treatments are recommended for this disorder. OBJECTIVE: We aimed to systematically review and describe the treatment and management of patients presenting with primary delusional infestation. METHODS: A systematic search was conducted using Ovid on MEDLINE, Embase, PsycINFO, and the Cochrane Register of Clinical Trials. Relevant data, including treatment, dosage, response, adherence, and side effects, were extracted and analyzed. RESULTS: A total of 15 case series were included, comprising 280 patients (mean age 53.3 years, 65.4% female) with delusional infestation. Overall, aripiprazole had the highest complete remission rate at 79% (11/14), although this was limited to 14 patients. Among drug classes, selective serotonin reuptake inhibitors were the most effective with a 79% (11/14) complete remission rate and 43% (9/21) partial remission rate in patients with comorbid depression, anxiety, or trichotillomania. First-generation antipsychotics and second-generation antipsychotics had similar complete remission rates (56/103, 54.4% vs 56/117, 47.9%, respectively) and partial remission rates (36/103, 35% vs 41/117, 35%, respectively). CONCLUSIONS: Due to the rarity of delusional infestation, we only found 15 case series. However, we found that first-generation antipsychotics appear to be similar in effectiveness to second-generation antipsychotics for the treatment of primary delusional infestation. Larger studies and randomized controlled trials are needed to evaluate the efficacy of pharmacological therapy for delusional infestation. TRIAL REGISTRATION: PROSPERO CRD42020198161; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=198161