berrios - delusional parasitosis and physical disease

Comprehensive Psychiatry (Official Journal of the American Psychopathological Association)

VOL. 26, NO. 5 SEPTEMBER/OCTOBER 1985

Delusional Parasitosis and Physical Disease

G.E. Berrios

An historical account is offered of the syndrome of delusional parasitosis. Two explanatory hy-

potheses developed at the turn of the century are identified and traced to current debates on the

etiology of the condition. The clinical and therapeutic aspects of delusional parasitosis are touched

upon and four cases with different etiological associations are reported. It is concluded that organic

factors must always be kept in mind as it is likely that in some cases pruritus and other tactile

disorders (particularly in the elderly) may be elaborated into delusions of infestation.

0 1985 by Grune & Stratton, Inc.

D ELUSIONAL parasitosis has been defined as a “persistent condition in which

the patient believes that small animals such as insects, lice, vermin, or maggots

are living and thriving on or within the skin. Despite all evidence to the contrary

the patient has a firm conviction that she is infested. This belief is unshakable and

best characterized as a primary delusion. It is an isolated phenomenon without

relation to other psychiatric symptoms.“’ It should be added that the symptom

often disrupts behavior and psychosocial competence. Affected individuals will

have their houses disinfected at regular intervals, complain to local authorities, and

refuse to see their doctor.

The aforementioned definition suggests that the central symptom is always a

“primary delusion.” This may not be so in a proportion of cases as there is some

evidence that the symptom may occur in patients suffering from physical disorders.

Delusions of infestation can be found in clinical situations which range from the

fleeting sensory delusions of the patient with delirium (see Case 4), to the more

persistant delusional elaborations of (e.g., carcinomatous) pruritus (see Case 1) to

the well-systematized delusions of the patient with late-onset monosymptomatic

psychosis (see Case 2).

It is the latter form of the disorder that is usually considered as the clinical

paradigm. In terms of classical nosology it meets four criteria: the symptoms are

persistant and enduring; are unaccompanied by other Schneiderian first rank symptoms; there is no cognitive impairment; and organic factors are absent. However,

the phenocopies caused by organic factors (Cases 1, 2, and 3) raise interesting

From the Department of Psychiatry, Aldenbrooke’s Hospital, Cambridge, England. Address reprint requests to G.E. Berries, MA (Oxon): MD; FRCPsych.: Consultant and University Lecturer

in Psychiatry Department of Psychiatry, Aldenbrooke’s Hospital (Level 4), Hills Road, Cambridge CB2 2QQ England.

@I 1985 by Grune & Stratton. Inc. 001@440x/85/2605-ooo1$03.00/0

Comprehensive Psychiatry, Vol. 26, No. 5, (September/October) 1985 395

396 G.E. BERRIOS

questions concerning the mechanisms involved in the origin and elaboration of the delusion. This paper reviews the historical, clinical, and therapeutic aspects of delusional parasitosis.

THE HISTORY OF THE CONCEPT

Various terms have been used in the literature to refer to delusional parasitosis (Table 1). Thibierge (1894)2 reported as “Acarophobes” patients who had developed a phobic fear of scabies after having suffered from it or having been in contact with an affected individual. Perrin (1896)3 coined the term “parasitophobic neu- rodermatitis” to refer to the intense fear of having parasites living under the skin. He reported three cases and made the important point that, although these subjects suffer from a psychiatric disorder, they are more often found attending dermatological services. Perrin suggested that pruritus and other skin symptoms play a role in the initiation of the symptoms and noticed that the “phobic” aspect of the illness was less important than its “obsessional” or “delusional” core. He concluded that the condition had a bad prognosis.

Perrin’s views contain in embryonic form the two current views on delusional parasitosis: one suggests that the central symptom is a primary delusion; the other that the delusion is an elaboration of a primary pathological experience such as a tactile hallucination, parasthesiae, or pruritus.

The secondary view was favoured early in the 20th century. For example, Dupre and Levy described the wider condition of “dClire de Zoopathie interne” which included the belief that one’s body was inhabited by all manner of animals. The French considered that in these cases the primary hallucinatory experience was the crucial phenomenon. Delusional parasitosis was included into this category.4

Analyses of the few cases reported during this early period, however, suggested a higher prevalence for the syndrome among the middle-aged or older. Likewise a possible affective etiology was recognized after the description by Schwartz5 of depressive illness among some of these patients.

In 1928 MacNamara, a Cambridge graduate working as a psychiatrist at the Charing Cross Hospital, reported five cases in the Lancet.6 He suggested that, apart from primary tactile hallucinations, the patients suffered from “little or no mental disorder”; they showed “normal affections, proper orientation, good powers of judgement.” All his cases were female, had a mean age of 55 (SD + 0.27) and complained of “black things, insects or microbes living under their skin.“”

Table 1. Delusional Parasitosis

Synonyms

Acarophobia Le dblire dermatozoaire L’hallucinose tactile chronique Parasitoses dblirantes Chronische Taktile Dermatozoenhallucinose Dermatozoenwahns (Ekbom) Neurodermies parasitophobiques Delusory Parasitosis Parasitophobia Dermatophobia

DELUSIONAL PARASITOSIS AND PHYSICAL DISEASE 397

In 1938 Ekbom’ published his classic paper on “Presenile Dermatozoenwahns”

and reported seven female cases with an average age of 58 (SD Z!Z 6.95). He included in his paper a list of most of the cases described until then (females with a mean

age of 54.4 f 10.02). He took an eclectic position regarding etiology and concluded

that the syndrome (which since has borne his name) may originate from either

primary parasthesiae (related to senile changes) or primary delusions.

A decade later Harbaue? reported four cases whose primary experience he

believed to be a parasthesiae; one of these was the first male patient ever described;

he also concluded that the syndrome was not always related to the higher age

brackets.

An important contribution in the English language appeared in 1946. Wilson

and Miller9 reviewed all cases (45) published until then and added six of their own,

two of which were also males (mean age 52 k 7.19). All six complained of infestation

by mites, lice, or insects. They proposed the term “delusion of parasitosis” and

concluded that the symptom complex occurred in relation to toxic psychosis,

dementia praecox (paranoid type), involutional melancholia and in “paranoia-par-

anoid” conditions. They considered the prognosis not to be very good. Six years

later Wilson’O reported 34 new cases and introduced a fifth etiological possibility:

“it may be found occasionally as a manifestation of a severe psychoneurosis . and the dermatological manifestations accompanying the disorder may be totally

unrelated to it; they may be the result of physical or chemical trauma inflicted by

the patient upon himself.”

In 1954 Bers and Conrad” put forward in a seminal paper the view that the

syndrome was the manifestation of a “chronic tactile hallucinosis”, itself based

upon a fundamental “sensory delusion”12 and reported four cases with a mean age

of 53 (SD + 4.1). In a well-known exchange, FleckI called into question this

suggestion and postulated that the mechanism involved was a secondary delusional

elaboration of a real tactile experience.

Psychodynamic interpretations have also been offered. For example Faure et alI4

reported two cases and suggested that the parasites involved in the delusion held

symbolic meaning for the patients. Verbeek15 emphasized in a single case study the

importance of family dynamics and Zeidens I6 studied the psychodynamics of self-

inflicted dermatoses.

CURRENT VIEWS

Interest in delusional parasitosis remains unabated but no agreement exists on

its clinical nature (Table 2) and elaborations of the early primary-secondary hy-

potheses are still entertained (see Table 3). The low incidence of the condition

precludes the collection of cohorts of adequate size. Likewise its predilection for higher age groups makes it difficult to assess the role of organic factors.

CLINICAL FEATURES

Patients attending skin clinics seem to exhibit encapsulated delusions, unimpaired

cognition and behavior, and little psychiatric pathology (e.g., affective disorder or late paraphrenia). Those seen by the psychiatrist, on the other hand, tend to suffer from a more severe form of the condition and show marked psychiatric pathology. It is unclear whether these constitute two different clinical populations or the same one, at different stage of their illness.

Tab

le

2.

Del

usi

on

al

Par

asit

osi

s S

ince

19

63

Wor

kers

Sex

N

o.

of

Mea

n A

ge

and

Pat

ient

s S

D

F

M

Clin

ical

V

iew

s C

ateg

ory

Sch

rut

& W

aldr

on

(196

3)”

rr:m

39

.3

+

1.6

3 (4

1

fam

ily)

Pau

lson

&

P

etru

s (1

969)

26

5 46

.8

+

3.1

3

Hop

kins

on

(1 9

73)2

7 8

45.4

f

13.1

6

Sim

on

(1 9

73)2

8 4

82

+

7.1

2

Gan

ner

8 Lo

renz

i (1

975)

29

10

66

+

9.9

5

Siz

aret

&

Sim

on

(197

6)3a

1

87

1

Gou

ld

&

Gra

gg

(197

6)31

2

62.5

2

Sko

tt (1

978)

’ 46

69

33

1 2 2 2 5 0 0 13

Nil

Ave

rage

in

telli

genc

e;

psyc

hone

uros

is;

som

atic

de

lusi

on

had

sexu

al

basi

s.

Cas

es

atte

ndin

g th

e de

rmat

olog

ist

have

le

ss

psyc

hiat

ric

diso

rder

th

an

thos

e at

tend

ing

psyc

hiat

rist.

The

ci

rcum

scrib

ed

delu

sion

m

ay

hera

ld

dem

entia

or

af

fect

ive

diso

rder

.

Cas

es

can

be

pure

bu

t al

so

asso

ciat

ed

with

de

pres

sion

, de

men

tia

or

be

indu

ced.

In

- vo

lutio

nal

stag

e im

port

ant.

No

evid

ence

of

co

gniti

ve

impa

irmen

t.

Der

mat

olog

ists

sh

ould

tr

eat

patie

nts

them

selv

es

if th

ere

is a

nxie

ty,

benz

o-

diaz

epin

es;

if de

lusi

on

Trif

luop

eraz

ine.

Sam

ple

from

de

rmat

olog

ical

cl

inic

. O

nly

half

com

plai

ned

of

prur

itus;

ha

lluci

natio

ns

rare

; ps

ychi

atric

di

agno

ses

wer

e:

anxi

ety,

ph

obic

ob

sess

iona

l st

ate,

de

pres

sive

an

d pa

rano

id

psyc

hose

s,

orga

nic

fact

ors

rele

vant

in

ab

out

half;

pr

ogno

sis

not

too

bad.

delu

sory

pa

rasi

tosi

s

delu

sion

s of

pa

rasi

tosi

s

psyc

hiat

ric

synd

rom

e of

in

fest

atio

n

Der

mat

ozoo

ses

delir

ante

s ou

sy

ndro

me

d’E

kbom

Der

mat

ozoe

nwah

n

delir

es

a ec

topa

rasi

tes

delu

sion

s of

pa

rasi

tosi

s

delu

sion

s of

in

fest

atio

n


Table 3. Delusion of Parasitosis

Psychopathological Mechanism Syndrome

Perceptual disorder with secondary delusions

Primary delusion

Chronic tactile hallucinations

Paranoid delusions

Affective Disorder with Depressive secondary delusions delusions

Organic damage with Cognitive secondary delusions impairment

Parasthesiae or other somatic pathological sensations with secondary delusions

Formication

Clinical Picture

Encapsulate psychosis

Paranoia or Schizophrenia

Affective Psychosis

Dementia; brain damage; brain tumor

Cocaine intoxication; alcoholism, vitamin B12 or nicotinamide deficiency

Authors

Bers and Conrad, 1954”

Huber, 195?

Schwarz, 1 92g5

Ekbom, 1938’

Magnan and Saury, 1889=

Likewise there is no data on the incidence or prevalence of delusional parasitosis

although there are grounds to believe that it may be less rare than published work indicates. For example Schrut and Waldron ” intimate that one of them had seen

over 100 cases in five years (although they only report three cases). Skott’ found

over 400 cases. Llyelll* has reported the results of a postal survey carried out among

dermatologists who between them had treated over 285 cases.

Age of highest prevalence is also unknown although there is a predominance of

middle-aged and elderly individuals. A tendency to chronicity, however, may lead

to accumulation of cases in the higher age brackets. Comparison of cases with early

and late onset suggests some differences. Younger patients tend to be obsessional

phobic and paranoid; elderly patients exhibit more organic involvement e.g., occult

neoplasm (see Cases 1 and 2); toxic state (see Case 4) and dementia.‘4m1L The mechanism involved in this association is however unclear and in some cases

the presence of organic factors may be coincidental. The possibility of an affective

disorder, particularly psychotic depression, must also be entertained.

Prognosis is uncertain. An editorial in the British Medical Journal concluded

not long ago that “whether treated by the dermatologist or psychiatrist, the prog-

nosis for recovery is poor.“23 This may be too pessimistic a view as it is based on

evidence pertaining to cases who have arrived at the psychiatrist’s door almost “in

extremis.” Skott’ in her magnificent monograph on dermatological patients sug-

gested that the prognosis is less somber. The same view has been taken by a Leader in the Lancet,24 on what it calls the syndrome of the “matchbox” sign. Earlier

detection of cases and adequate follow-up should provide a better idea of the

natural history of this condition.

TREATMENT

Treatment such as ECT, psychosurgery and psychotherapy have been tried with little success. These poor results may be explained by the fact that delusional parasitosis is probably a behavioral phenocopy, caused by a variety of etiologies. Patients whose primary condition is a psychiatric one (starting as primary delusions or hallucinations) as in cases of senile schizophrenia or late paraphrenia require

400 G.E. BERRIOS

energetic treatment with neuroleptics. Elderly subjects with partial sensory deaf- ferentation, early dementia, senile pruritus, or pruritus caused by occult Ca may need correction of their sensory handicaps, orientation therapy, and physical man- agement of the underlying pathology.

Psychotropic drugs should be tried according to whether there is evidence of primary paranoid psychosis or depression. ECT may be required in cases where depressive illness refractory to medication is suspected. Among the neuroleptic drugs there have been recent reports that Pimozide, in doses up to 10 mg daily in divided doses, may be of some value.25

Case 1

CASE REPORTS

A 77 year-old widow, childless, with no family or personal history of psychiatric illness. Referred

by general practitioner on account of “phobia to being infested with insects.” Her complaints had

started two years earlier when she found *‘a large beetle-like bug in her bed.” She proceeded to get rid

of the “progeny” but the bugs continued pestering her. They had bitten into her skin and deposited

eggs which caused soreness and itching. The size of the insects had ominously decreased to the point

that they had become invisible to the naked eye. She also intimated that people avoided her because

they knew “certain things about her.”

On mental examination she was an elderly, obese woman, articulate and with no cognitive impairment.

There was no evidence of depression nor were there other hallucinations or delusions apart from the

ones already mentioned. On physical examination she was slightly deaf and had bilateral ankle edema.

She was admitted to a psychiatric ward for further investigation. All tests were normal except the

EEG which showed changes compatible with cerebrovascular disease and chest X-ray which showed

a mass situated in the anterior mediastinum. She was referred to the chest physician and a diagnosis

of a mediastinal lymphoma was made. She was put on Pimozide 8 mg daily and transferred to a chest

hospital. She died ten months later. Her delusional parasitosis improved for the first five months but

worsened during the terminal stage of her life.

Case 2

A 68 year-old married woman with family history of psychiatric illness (her father had suffered from

depression and had been treated in the local mental hospital). She had no personal history of psychiatric

illness although she was described as obsessional and a worrier. Her illness had started two years earlier

when, according to her, there had been a potato blight which had infected her. She came to the clinic

carrying a bottle containing fluff, skin scales, and detritus as evidence that her body and new home

were infested (she had already moved twice since the onset of her illness). She could both see and feel

the bugs crawling under her skin. Items of furniture at home were also being eaten away and she had

tried to sue the Council for not rehousing her once again. Her husband was sympathetic towards her

but intimated (when seen separately) that he had not heard or seen anything. On mental examination

she was a thin woman, somewhat anxious but with no evidence of affective disorder. She was cognitively

all right and there were no other hallucinations or delusions apart from the ones already mentioned.

She was not suicidal, phobic, or obsessional. Her delusional system was well organized.

This patient was treated with Pimozide 8 mg and the case was followed up for about a year. The

intensity of her delusions decreased a great deal to the point that she decided to “put up with it” and

did not ask to be rehoused again. She refused to accept, however, that previous experiences had been

the result of an illness but believed that like the blight in Ireland, sooner or later, the insects had to

go.

Case 3

A 41 year-old man admitted at the request of his general practitioner on account of “strange behaviour, standing like a statue,” following women and “touching them.” He had no family or personal history of psychiatric illness and had come to the United Kingdom from Jamaica in 1962. He had two children


and his wife had died from a cancer of the cervix two years before his admission. His occupational

history had been unremarkable and he had always been seen as “strange.” During the last year he had

neglected himself and lived in squalor.

On admission he complained of feeling persecuted, of hearing voices and of flies crawling all over

his face. He would constantly rub his face with his hands to keep it free from the insects.

On examination he seemed of limited intelligence and this was confirmed by formal psychological

testing. He was not disorientated nor was there any evidence of delirium. He was a tall man, found to

have pitting edema of both legs, BP of 2301140, cardiomegaly, early papilloedema and constriction of

the visual fields. His CAT scan showed enlarged pituitary fossa with destruction of the inferior part

of the dorsum sella. It was thought that the onset of his psychotic features might have coincided with

an infarction of a pituitary tumor (of unknown histology). Repeated endocrinology assessments were

reported as normal. Since there was no evidence of suprasellar extension of the tumor, it was felt that

no surgery was indicated. A second opinion sought from the National Hospital for Nervous Diseases

concurred with this decision.

After some attempts to return him to the community, he was allowed to become a long-term patient. His belief concerning flies dwelling on his face remained although after treatment with Chlorpromazine

he never again volunteered information in this regard. His manneristic behavior and face-rubbing have

also continued to this day. He was not treated with Pimozide.

Case 4

A 92 year-old widow with personal history of depression and anxiety that required episodic treatment

with antidepressants. She was referred to the psychiatrist on account of seeing “ants all over” and on her own body. She started seeing these “little things” about four weeks before her referral and worried

lest she was ill. There was a degree of insight into her experiences. Around the same period she had

been found to have a malignant lump in her breast and had been started on therapy.

On mental examination she was alert, with a cognitive score of 29 in the Blessed scale. She complained

of feeling unhappy but not depressed and of hearing voices calling her name, mainly at night. She was

not phobic, obsessional, or suicidal.

Although this woman complained of parasites infesting her and others the diagnosis of “delusional

parasitosis” was not made. There was clinical evidence of episodic confusion and her symptoms were

worst at night. She was reassured but no medication prescribed for her visual hallucinations and

secondary delusional elaboration. She died seven months later.

SUMMARY AND CONCLUSIONS

A review is presented of the concept of delusional parasitosis and four cases

reported: three with the typical syndrome and, for comparison purposes, another

who showed visual hallucinations of parasites and secondary delusional elaboration

in the context of intermittent confusion and breast carcinoma.

The differences that emerge well illustrate the nature of delusional parasitosis.

It can be defined as a delusional syndrome, affecting middle-aged and elderly

subjects, mainly women, that consists in the belief that parasites plague the skin.

Cases 1 and 3 show how organic factors (neoplasm) may be related to secondary

delusional elaborations. Case 2 belongs to the category of a primary psychiatric disorder in an obsessional and hypochondriacal personality leading to the final

crystallization of a delusion; therapeutic result in this case was adequate.

It is concluded that patients presenting with delusional parasitosis and without past history of psychiatric illness must be investigated for occult neoplasm and other organic factors.

ACKNOWLEDGMENT

The author would like to express thanks to M. Coburn for typing the manuscript

402 G.E. BERRIOS

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