Delusional parasitosis (DP) is the common medical term given to "mystery bites". Affected individuals have the mistaken but unshakable belief (delusion) that they are infected by “bugs”: parasites, mites, worms, bacteria, etc. They typically experience a sensation that they have been bitten by something. As with all delusions, this belief cannot be corrected by reasoning, persuasion or logical argument. Many affected individuals are quite functional; for others, the delusions may interfere with usual activity. DP is known by many different names and may be caused by different things. Determining the root cause requires the help of an experienced medical specialist. This is often difficult as the affected person is not always willing to cooperate. A general practitioner may be helpful in referring the patient to a psychiatrist, dermatologist or infectious disease specialist. Often the root cause is an internal chemical imbalance, an excess of extra-cellular dopamine within the striatum of the brain. This same condition is prevalent in individuals abusing illegal drugs; thus the nickname "cocaine bugs". Stress always aggravates DP symptoms. Fortunately, the condition is normally treatable.

Dry air increases static electricity and always aggravates itchy, dry skin.