Delusional infestation: Clinical presentation in 147 patients seen at Mayo Clinic

Background: Delusional infestation is the conviction that one's skin is infested with foreign organisms or materials despite contradictory objective evidence. Objective: To delineate clinical characteristics of patients presenting with delusional infestation. Methods: We performed a retrospective study of patients meeting delusional infestation criteria who were seen for diagnosis and treatment in our tertiary care academic medical center (2001-2007). Medical records were reviewed to abstract demographic, historical, and physical findings and treatment. Results: Over 7 years, 147 patients presented with delusional infestation; 87% (123/142) for another opinion. Mean age was 57 years; female-to-male ratio was 2.89 to 1; 82 (56%) were married. Mean duration of symptoms was 31 months. Employment data were available for 145 patients: 48 (33%) were self-described as disabled, 16 of whom cited delusions as their disability; 41 (28%) were retired; and 38 (26%) were employed. Reported infestations included multiple materials (45% [64/143]), not limited to insects (79% [113/143]), worms (27% [39/143]), and fibers (20% [29/143]). Most patients presented initially to dermatology or other specialties; only 3 presented to psychiatry. A high proportion (81%) had prior psychiatric conditions. Thirty-eight (26%) of the 147 patients had a shared psychotic disorder. Limitations: The retrospective nature of the study and the incompleteness of some data because not all the characteristics that were analyzed were documented for every patient. Conclusion: Patients were predominantly female, had a long history of symptoms, and had been seen previously at many medical centers. A large proportion were disabled or retired. Patients reported skin infestation with both animate and inanimate objects.