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.

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THERAPEUTIC HOTLINE: SHORT PAPER
A patient with delusional infestation by proxy: Issues for
vulnerable adults
Khawar Hussain | Maria-Angeliki Gkini | Ruth Taylor | Satwinder Shinhmar |
Anthony Bewley
Royal London Hospital, Barts Health Trust,
London, United Kingdom
Correspondence
Anthony Bewley, Royal London. Hospital,
Barts Health Trust, London, United Kingdom.
Email: anthony.bewley@bartshealth.nhs.uk
Abstract
A 57-year-old Caucasian female presented to our clinic with her 23-year-old son, who was pro-
foundly 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 traf-
fic 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.
KEYWORDS
delusional infestation, delusional infestation by proxy, patient safety, psychodermatology
1|INTRODUCTION
We describe an interesting case of delusional infestation (DI) by proxy
to highlight the importance of patient safety and safeguarding when
there are issues surrounding mental capacity.
Delusional infestation is a complex rare condition whereby
patients describe being infested by a range of different organisms or
even fibers.
In 1946, Wilson and Miller proposed the term “delusions of
parasitosis,”which is a more appropriate name as the condition is a
true delusion, a fixed, false belief, rather than a phobia, an abnormal
fear response to a stimulus (Wilson & Miller, 1946). It can occur as a
delusional disorder, meeting the ICD–10 criteria for persistent
delusional disorder (World Health Organisation, 1993) and the DSM-
V criteria for delusional disorder of the somatic type (American Psy-
chiatric Association, 2013).
Delusional infestation has become the preferred term for this dis-
ease as some patients describe infestations with microorganisms or
even fibers and inanimate material (Misery, 2013; Mohandas, Bew-
ley, & Taylor, 2018). Sometimes patients make a diagnosis following
their own research from social media (Misery, 2013).
The diagnosis of primary delusional parasitosis can be made
only after real infection or other underlying medical or psychiatric
conditions have been excluded, because delusional parasitosis can
be associated with several physical illnesses, psychiatric disorders,
or intoxications (Magnan, 1889, Ekbom, 1938, Huber, 1957, Berrios,
1985, Freyne & Wrigley, 1994, Freudenmann, 2002). Treatment
options are based mostly on the use of anti-psychotic medications
and have a high treatment response rate (Freudenmann &
Lepping, 2009).
We describe an interesting case of delusional infestation by proxy to highlight
the importance of patient safety and safeguarding when there are issues sur-
rounding mental capacity. We also believe that this is the first case to be
described where a patient presents with delusional infestation by proxy, where
the proxy individual is a vulnerable adult with limited capacity.
Received: 16 March 2018 Revised: 21 August 2018 Accepted: 22 August 2018
DOI: 10.1111/dth.12724
Dermatologic Therapy. 2018;31:e12724. wileyonlinelibrary.com/journal/dth © 2018 Wiley Periodicals, Inc. 1of3
https://doi.org/10.1111/dth.12724

The pathogenesis of DI is unknown. Despite limitations to current
knowledge, pathogenesis is likely to be multifactorial. Possible factors,
such as genetics, organic factors, premorbid traits, acute triggers, and
social vulnerability, are known from other psychotic disorders
(Freudenmann & Lepping, 2009).
There is also evidence of functional distortions in related net-
works of the brain that may be responsible for the symptoms, with
the neurotransmitter dopamine playing a key role (Huber, Kirchler,
Karner, & Pycha, 2007).
DI is more common in women with the mean age of onset being
61 years (Bailey, Andersen, & JM, 2014).
There does not appear to be a link with socioeconomic status.
2|CASE REPORT
A 57-year-old Caucasian female presented to our clinic with her
23-year-old son, who was profoundly autistic and was convinced that
he had an infestation with fibers. She believed that her son had devel-
oped the condition as a young child and she described the symptoms
of the infestation in her son's skin on his behalf, as he was not able to
talk and communicate. She had also identified dietary factors as a
causative factor and wanted them removed from her son's diet. Her
son had seborrhoeic dermatitis on clinical examination, with no evi-
dence of any infestation. In addition, the son (an only child of divorced
parents) had severe learning disabilities and was in state care for many
years (although the mother supervised care in the “home”and was
very “hands-on”). She later identified that fibers were coming out of
her skin as well. Her only medical history included a road traffic acci-
dent resulting in chronic back pain. There was no previous psychiatric
history in the son or the mother. Blood, urine, and microbiological
investigations were normal. She was diagnosed with delusional infes-
tation by proxy (DI by proxy), and was started on risperidone. Her son
was always accompanied by his caretakers and he lived in a care
home. The care given by his caretakers was subject to many com-
plaints from his mother. Our patient's son did not have capacity due
to his severe learning difficulties, so his next of kin, his mother was at
this stage making his best interests decisions. We started risperidone
in very low doses, according to our already reported practice
(Ahmed & Bewley, 2013). Our patient engaged with that treatment
initially without hesitation, but subsequently challenged the use of ris-
peridone. At that stage, however, both son and mother were well
enough to function without further systemic medication.
However, as she had DI by proxy, she did not have capacity to
make appropriate health decisions about the care of her son. Our
management plan was as follows:
•Manage the son's well-being via a multidisciplinary team involving
the “vulnerable adult protection team”(social workers, key care-
takers, primary care, dermatology team).
•Manage the seborrhoeic dermatitis of the son.
•Manage the DI of the mother (with antipsychotics and topical
preparations for the skin).
•Manage the risk to the son (i.e., stop inappropriate labeling of the
son as having “an infestation”; support the caretakers in their
management of the son; ensure that the son is not subject to
inappropriate “cleansing”and delousing of the skin).
3|DISCUSSION
DI is a condition that is best managed by a psychodermatology mul-
tidisciplinary team. It carries a high level of psychosocial morbidity
and may even result in the patient's suicide. Such is the conviction
of belief and potential plausibility of the delusion, that in up to 25%
of cases another individual may share the psychosis, giving rise to
the term folie à deux (Skott, 1978). There have even been cases
where DI has presented as a folie à trois (Friedmann, Ekeowa-
Anderson, Taylor, & Bewley, 2006). Interestingly, folie a deux/
famille has also been shown to occur in children of a mother who
has been affected with DI (Ahmed, Blakeway, Taylor, & Bew-
ley, 2015).
From previous reports of DI by proxy, patients project the delusion
onto a third party who usually cannot share the delusion (e.g., a pet, a
young child, or a mentally disabled person) (Freudenmann, 2002).
The problem here is that the proxy individual does not appear to
have capacity and the next of kin or person with legal representation
has a monosymptomatic delusional hypochondriasis. This raises issues
about the safety and safeguarding of a vulnerable individual. In British
law, one of the mandates about making a best interest's decision on
behalf of someone who does not have capacity is to consult with their
next of kin, but in this case the next of kin also does not have capacity
to make that decision. In this case, the Court of Protection may need
to be involved to help appoint deputies who can also take decisions
on health and welfare on behalf of the patient. We believe that DI by
proxy in a vulnerable adult population is rare, but may be under-
recognized.
4|CONCLUSION
After several months of being on risperidone and topical therapies,
the mother reported that her condition had improved and that of her
son had resolved. Her son was treated for his seborrhoeic dermatitis
which improved, and the caretakers were less consulted about any
dermatological issues. The son was therefore discharged from our
care while the mother remained under psychodermatology
supervision.
5|LEARNING POINTS
•DI is a complex rare condition whereby patients describe being
infested by a range of different organisms or even fibers.
•DI by proxy is where a patient presents another individual (often
a child or a pet) as being infested (when the other individual has
no evidence of infestation).
•We believe that this is the first case to be described where a
patient presents with DI by proxy where the proxy individual is a
vulnerable adult with limited capacity.
2of3 HUSSAIN ET AL.

•Safeguarding concerns are raised when the vulnerable individual
is part of the delusion and its consequences.
•DI is a condition that is best managed by a psychodermatology
multidisciplinary team.
CONFLICT OF INTEREST
None declared.
ORCID
Khawar Hussain https://orcid.org/0000-0003-2116-7718
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How to cite this article: Hussain K, Gkini M-A, Taylor R,
Shinhmar S, Bewley A. A patient with delusional infestation by
proxy: Issues for vulnerable adults. Dermatologic Therapy.
2018;31:e12724. https://doi.org/10.1111/dth.12724
HUSSAIN ET AL.3of3