Today I learned about another unusual mental illness: delusional parasitosis. Also known as “delusions of parasitosis,” this disorder involves a patient’s unshakable belief that their body is infested with bugs under the skin. Why did this come up? Well, a patient who had already had a dermatology consult, a CT scan of the head and a trial of various medications came in complaining of ongoing “bugs crawling all over my skin.” Turns out he’s had quite the workup, and the only remaining diagnosis is delusional parasitosis. Of course, when you’re convinced that your body is a breeding ground for subcutaneous bugs, it’s not very comforting to hear that you’re just delusional.
You might think that this would be a rare diagnosis, but this is the 3rd patient I’ve seen in a year and a half of practice. I can’t find any prevalence data, but it seems like a high rate for a primary care practice. Is it because we have such a high rate of mental illness in our clinic population? Or maybe delusional parasitosis is a hidden plague (or infestation, if you like bad jokes)? Whatever the case, it sure sucks if you’re the person who thinks–no, knows— you have bugs in your head.