From empiric anti-scabietic treatments to delusional infestation: A case report

Chronic pruritus accounts for approximately 1 % of all physician visits, and providers are often confronted with how to treat patients with pruritus. Scabies is oftentimes a concern by both patients and providers, and anti-scabietic treatments are generally considered safe and effective. However, the pruritus will continue if there is an alternate etiology. We present a case of a patient empirically treated for scabies with multiple courses of anti-scabietic therapy without diagnostic confirmation of scabies. Her pruritus failed to improve, and she ultimately developed delusions of infestation (DI), a debilitating and difficult-to-treat psychocutaneous condition characterized by a fixed, false belief that one is infested with parasites. While scabies is one cause of chronic pruritus, its misdiagnosis may increase the chance that at-risk individuals, often those with prior substance abuse or psychiatric disorders, develop a persistent concern for ongoing infestation. It is possible that, in treating chronic pruritus with repeated empiric anti-scabietic treatments, the prescribing physician may contribute to the development of DI. We review the approach to a patient with chronic pruritus and ways to avoid unnecessary repeated anti-scabietic treatments.