Delusional parasitosis
Delusional parasitosis (DP) or delusional infestation is a mental disorder in which individuals have a persistent delusion that their body is infested with living or nonliving agents, such as parasites, insects, or bacteria, when no such infestation is present. People with this condition may have skin symptoms such as the urge to pick at one's skin (excoriation) or a sensation resembling insects crawling on or under the skin (formication), associated with tactile hallucinations.