A patient with delusional infestation by proxy: Issues for vulnerable adults

Abstract

A 57‐year‐old Caucasian female presented to our clinic with her 23‐year‐old son, who was profoundly autistic. Our patient was convinced that her son had an infestation with fibers and believed that he had developed the condition as a young child. She described the symptoms of the infestation in her son's skin on his behalf, as he was not able to communicate. She identified dietary factors as a causative factor and wanted them removed from his diet. Her son had seborrhoeic dermatitis on examination, with no evidence of an infestation. Our patient later identified that fibers were coming out of her skin also. Her medical history included a road traffic accident resulting in back pain. Blood, urine, and microbiological investigations were normal. She was diagnosed with delusional infestation (DI) by proxy, and was started on risperidone. We present an interesting case of a patient with DI by proxy, in which the delusional beliefs of the mother have been projected onto her son. Issues of safeguarding vulnerable adults are raised in such cases, suggesting the crucial role of the physician in ensuring patient safety. DI by proxy has been reported in patients with children and animals, but we believe this is the first report of DI by proxy involving a vulnerable adult.

Delusions of parasitosis and delusions of parasitosis by proxy in a mother and her children

“…Individuals often report an inciting incident that caused infestation, such as travel or sharing clothing, and the delusions usually involve insects and persist despite numerous negative clinical, laboratory, and pathology workups by multiple health care providers 2,3 . A rare form of this disease is known as delusions of parasitosis by proxy, which encompasses a delusional belief projected onto another person that lacks capacity to hold the same belief 4,5 . Delusions can be projected onto vulnerable individuals, such as children, those with cognitive disabilities, and persons in vegetative states 5–7 .…”

“…4,5 Delusions can be projected onto vulnerable individuals, such as children, those with cognitive disabilities, and persons in vegetative states. [5][6][7] These susceptible populations are subject to their caretakers' delusional system of beliefs, making it particularly important to handle such cases with extreme care.…”

“…2,3 A rare form of this disease is known as delusions of parasitosis by proxy, which encompasses a delusional belief projected onto another person that lacks capacity to hold the same belief. 4,5 Delusions can be projected onto vulnerable individuals, such as children, those with cognitive disabilities, and persons in vegetative states. [5][6][7] These susceptible populations are subject to their caretakers' delusional system of beliefs, making it particularly important to handle such cases with extreme care.…”

British Association of Dermatologists guidelines for the management of adults with delusional infestation 2022

“…12,48 Importantly, this may lead clinicians to have safety concerns about the wellbeing of children or vulnerable adults associated with people with DI. 49,50 Where there are concerns identified, a referral to appropriate safeguarding services may be necessary.…”

“…family or work colleagues), or present with shared fear of infestation with another close contact, such as a spouse (folie a deux), a child or even a pet (DI by proxy) 12,48 . Importantly, this may lead clinicians to have safety concerns about the wellbeing of children or vulnerable adults associated with people with DI 49,50 . Where there are concerns identified, a referral to appropriate safeguarding services may be necessary.…”