Diagnosis
Delusional parasitosis 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 delusional parasitosis, the delusions are the only manifestation of a psychiatric disorder. Secondary delusional parasitosis 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 DP 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.
Society and culture
Jay Traver (1894–1974), a University of Massachusetts entomologist, was known for "one of the most remarkable mistakes ever published in a scientific entomological journal", after publishing a 1951 account of what she called a mite infestation which was later shown to be incorrect, and that has been described by others as a classic case of delusional parasitosis as evidenced by her own detailed description. Matan Shelomi argues that the historical paper should be retracted because it has misled people about their delusion. He says the paper has done "permanent and lasting damage" to people with delusional parasitosis, "who widely circulate and cite articles such as Travers and other pseudoscientific or false reports" via the internet, making treatment and cure more difficult.Shelomi published another study in 2013 of what he called scientific misconduct when a 2004 article in the Journal of the New York Entomological Society included what he says is photo manipulation of a matchbox specimen to support the claim that individuals with DP are infested with collembola. See also
Stimulant psychosis
Formication

References
Further reading
Halvorson CR (October 2012). "An approach to the evaluation of delusional infestation". Cutis (Review). 90 (4): E1–E4. PMID 24005827. Simpson L, Baier M (August 2009). "Disorder or delusion? Living with Morgellons disease". Journal of Psychosocial Nursing and Mental Health Services (Case report and review). 47 (8): 36–41. doi:10.3928/02793695-20090706-03. PMID 19681520.