What is delusional parasitosis?

Intense suffering: Delusional parasitosis is a psychiatric condition where a person believes s/he is infested or parasitized by bugs, worms, or other creatures. Most patients describe the infestation as being on or just under the skin, in or around body openings, or internal (particularly in the stomach or intestines). It can lead to severe scratching or mutilation, or using poisons to cleanse themselves.

False belief: From the online medical textbook UpToDate®: "Delusional parasitosis is a rare disorder in which affected individuals have the fixed, false belief (delusion) that they are infected by 'bugs': parasites, worms, bacteria, mites, or other living organisms. As with all delusions, this belief cannot be corrected by reasoning, persuasion, or logical argument."