<unk>  is diagnosed when the delusion is the only symptom of psychosis, the delusion has lasted a month or longer, behavior is otherwise not markedly odd or impaired, mood disorders—if present at any time—have been comparatively brief, and the delusion cannot be better explained by another medical condition, mental disorder, or the effects of a substance. For diagnosis, the individual must attribute abnormal skin sensations to the belief that they have an infestation, and be convinced that they have an infestation even when evidence shows they do not. The condition is recognized in two forms: primary and secondary. In primary<unk> , the delusions are the only manifestation of a psychiatric disorder. Secondary<unk>  occurs when another psychiatric condition, medical illness or substance (medical or recreational) use causes the symptoms; in these cases, the delusion is a symptom of another condition rather than the disorder itself. Secondary forms of<unk>  can be functional (due to mainly psychiatric disorders) or organic (due to other medical illness or organic disease. The secondary organic form may be related to vitamin B12 deficiency, hypothyroidism, anemia, hepatitis, diabetes, HIV/AIDS, syphilis, or abuse of cocaine. Examination to rule out other causes is key to diagnosis. Parasitic infestations are ruled out via skin examination and laboratory analyses. Bacterial infections may be present as a result of the individual constantly manipulating their skin. Other conditions that can cause itching skin are also ruled out; this includes a review of medications that may lead to similar symptoms. Testing to rule out other conditions helps build a trusting relationship with the physician; this can include laboratory analysis such as a complete blood count, comprehensive metabolic panel, erythrocyte sedimentation rate, C-reactive protein, urinalysis for toxicology and thyroid-stimulating hormone, in addition to skin biopsies and dermatological tests to detect or rule out parasitic infestations. Depending on symptoms, tests may be done for "human immunodeficiency virus, syphilis, viral hepatitis, B12 or folate deficiency," and allergies. Differential<unk>  must be distinguished from scabies, mites, and other psychiatric conditions that may occur along with the delusion; these include schizophrenia, dementia, anxiety disorders, obsessive–compulsive disorder, and affective or substance-induced psychoses or other conditions such as anemia that may cause psychosis. Pruritus and other skin conditions are most commonly caused by mites, but may also be caused by "grocer's itch" from agricultural products, pet-induced dermatitis, caterpillar/moth dermatitis, or exposure to fiberglass. Several drugs, legal or illegal, such as amphetamines, dopamine agonists, opioids, and cocaine may also cause the skin sensations reported. Diseases that must be ruled out in differential diagnosis include hypothyroidism, and kidney or liver disease. Many of these physiological factors, as well as environmental factors such as airborne irritants, are capable of inducing a "crawling" sensation in otherwise healthy individuals; some people become fixated on the sensation and its possible meaning, and this fixation may then develop into<unk> .
Delusional parasitosis
Helminthiasis
Acariasis
Soil-transmitted helminthiasis
Schistosomiasis
Toxocariasis
Cyclosporiasis
Isosporiasis