Delusional parasitosis in the elderly: a review and report of six cases from northern Finland.

A patient with delusional parasitosis has a strong conviction of being infested with parasites: for example, lice or worms. Such a patient is not satisfied with assurances or test results that no parasites are present, but is so convinced that he or she will go as far as to bring the parasites in "matchboxes" to a physician. Subjectively worried, the patient may try to pick the parasites out of the skin, causing cutaneous lesions and even ulcerations. The condition is classified as a delusional/paranoid disorder, somatic type according to DSM-III-R. Not much is known epidemiologically of this rare disorder, which usually affects older women who often are isolated socially. Therapy is regarded as difficult, and a wide variety of treatment methods have been attempted. In this article six female cases are presented, showing that a typical patient is an elderly woman who has suffered losses or is socially isolated. These patients lack deeper psychiatric insight into their problem, so they are mostly in the care of nonpsychiatric physicians. Treatment with a low dose of high-potency neuroleptics combined sometimes with antidepressants appears to be effective. Reducing social isolation is also important.