A Longitudinal Case of Shared Delusional Infestation

Delusional infestation disorders are characterized by fixed but false beliefs about infection by a parasite, insect, or other living organism. Shared psychotic disorders are characterized by a single delusion instigated by a “primary” index patient and then induced in one or more “secondary” persons. We describe a case report of shared delusional infestation among an index patient and two family members that generated many healthcare encounters over the course of 12-15 months. This case report highlights the challenges in diagnosing and treating these conditions in the Emergency Department setting and their disproportionate utilization of healthcare resources. We discuss risk factors and characteristics of delusional infestations and shared psychotic disorders, as well as best practices to approach diagnosis, treatment, and disposition in the Emergency Department.