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

Delusional infestation is the conviction that one's skin is infested with foreign organisms or materials despite contradictory objective evidence.

To delineate clinical characteristics of patients presenting with delusional infestation.

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.

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.

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.

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.