The name delusional parasitosis has been the most common name since 2015, but the condition has also been called delusional infestation, delusory parasitosis, delusional ectoparasitosis, psychogenic parasitosis, Ekbom syndrome, dermatophobia, parasitophobia, formication and "cocaine bugs".Morgellons is a form of delusional parasitosis in which people have painful skin sensations that they believe contain fibers of various kinds; its presentation is very similar to other delusional infestations, but people with this self-diagnosed condition also believe that strings or fibers are present in their skin lesions.Delusory cleptoparasitosis is a form of delusion of parasitosis where the person believes the infestation is in their dwelling, rather than on or in their body. Signs and symptoms
People with delusional parasitosis believe that "parasites, worms, mites, bacteria, fungus" or some other living organism has infected them, and reasoning or logic will not dissuade them from this belief. Details vary among those who have the condition, though it typically manifests as a crawling and pin-pricking sensation that is most commonly described as involving perceived parasites crawling upon or burrowing into the skin, sometimes accompanied by an actual physical sensation (known as formication).
Merrem may refer to:

Meropenem, an antibiotic initially marketed under the trade name Merrem
Blasius Merrem (1761–1824), German naturalist, zoologist, ornithologist, mathematician, and herpetologist