Because the internet and the media contribute to furthering shared delusions, DP has also been called folie à Internet; when affected people are separated, their symptoms typically subside, but most still require treatment.Approximately eight out of ten individuals with DP have co-occurring conditions—mainly depression, followed by substance abuse and anxiety; their personal and professional lives are frequently disrupted as they are extremely distressed about their symptoms.A 2011 Mayo Clinic study of 108 patients failed to find evidence of skin infestation in skin biopsies and patient-provided specimens; the study concluded that the feeling of skin infestation was DP. Cause
The cause of delusional parasitosis is unknown. It may be related to excess dopamine in the brains striatum, resulting from diminished dopamine transporter (DAT) function, which regulates dopamine reuptake in the brain. Evidence supporting the dopamine theory is that medications that inhibit dopamine reuptake (for example cocaine and amphetamines) are known to induce symptoms such as formication. Other conditions that also demonstrate reduced DAT functioning are known to cause secondary DP; these conditions include "schizophrenia, depression, traumatic brain injury, alcoholism, Parkinsons and Huntingtons diseases, human immunodeficiency virus infection, and iron deficiency". Further evidence is that antipsychotics improve DP symptoms, which may be because they affect dopamine transmission.
Transmission via the secretions of carriers can result from direct interpersonal contact or contact with a contaminated surface. Bacteria on contaminated surfaces can be easily cultured. In conditions with sufficient nutrients, pneumococci can survive for 24 hours and avoid desiccation for multiple days. Reduced transmission has been observed amongst children with Pneumococcal conjugate vaccine (PCV) immunization as acquisition of a new strain of S. pneumoniae is inhibited by pre-existing colonization. Immunoglobulin G (IgG) immunization with high antibody concentration can also inhibit acquisition. These antibodies require the agglutinating function of the Fc fragment. For successful acquisition in a new host, pneumococcus must successfully adhere to the mucous membrane of the new host’s nasopharynx. Pneumococcus is able to evade detection by the mucous membrane when there is a higher proportion of negatively charged capsules. This clearance is mediated by Immunoglobulin A1 (IgA1) which is abundant on the URT mucosal surfaces. Colonization
Transparent and opaque colony morphology has been observed for pneumococci. Airway colonization is observed in transparent phenotypes of serotypes, while survival in bloodstreams is observed for opaque phenotypes. Colonizable strains exhibit resistance against neutrophilic immune response. Successful colonization requires S. pnuemoniae to evade detection by the nasal mucus and attach to epithelial surface receptors. Asymptomatic colonization occurs when S. pneumoniae bind to N-acetyl-glucosamine on epithelium without inflammation. However, co-infection with a pre-existing inflammatory URT infection results in an over-expression of the epithelial receptors utilized by S. pneumoniae, thus increasing the likelihood of colonization.