Delusional infestations: case series, differential diagnoses, and management strategies

Physicians are not infrequently consulted by distraught patients with delusions of infestation who believe that they are infested with external or internal parasites and describe a crawling sensation of bugs or worms on or under their skin. Internet search engines were queried with the keywords as search terms to examine the latest articles on delusional infestations in order to describe presenting manifestations, differential diagnoses, and effective management strategies. The demographic and behavioral features of delusional infestations have remained constant and include: (1) onset in well-educated, middle-aged adults who are pet owners; (2) production of purported specimens of causative parasites; (3) pesticide overtreatment of themselves, their households, and pets; (4) excessive cleaning or vacuuming of households; (5) intense anger and resentment directed at physicians failing to confirm their self-diagnoses; and (6) sharing delusional symptoms with spouses or relatives. Although some reports have suggested that cases of delusional infestation are increasing today in the tropics, most studies have confirmed a stable incidence over time and similar disorder demographics worldwide. However, management strategies for delusional infestations have changed significantly over time with second generation, atypical antipsychotics offering safer adverse effect profiles and better prognoses than earlier therapies with first generation, typical antipsychotics. The most effective management strategies for delusional infestations include empathetic history-taking and active listening to the patient, careful exclusion of true parasitoses, and a therapeutic regimen that includes a second generation neuroleptic agent.