Delusions of Ocular Parasitosis

MARK D. SHERMAN, MD, GARY N. HOLLAND, MD, DOUGLAS S. HOLSCLAW, MD,JAMES M. WEISZ, MD, OSAMA H. M. OMAR, MD, AND RONALD A. SHERMAN, MD

● PURPOSE: To describe four cases of delusions ofparasitosis in which self-inflicted ocular traumaoccurred. Delusions of parasitosis is a somaticdelusional disorder in which patients have theirrational belief that their bodies are infested byparasites or other infectious organisms. Self-in-flicted trauma can result from attempts to elimi-nate the supposed infestation.● METHODS: We reviewed the case histories offour patients (one male, three females, 35 to 45years of age) who presented with complaints ofocular infestation but had no evidence of infec-tious ocular disease. The characteristics of thesecases were compared with the features of delusionsof parasitosis.● RESULTS: All patients maintained their beliefsregarding infestation, despite extensive clinical andlaboratory investigations that found no evidence ofinfectious diseases. Self-inflicted eye injury, asso-ciated with attempts to eliminate the infestation,occurred in each case.● CONCLUSIONS: The cases presented in this re-port are consistent with a diagnosis of delusions ofparasitosis. The eye can be a principal focus ofattention in this disorder, which may lead to visionloss caused by self-inflicted injury. (Am J Oph-

thalmol 1998;125:852–856. © 1998 by ElsevierScience Inc. All rights reserved.)

D ELUSIONS OF PARASITOSIS IS DEFINED AS AN

erroneous but unshakable belief that thebody is infested by parasites or other infec-

tious organisms.1–3 It is a well-characterized disorderseen most commonly by dermatologists and infec-tious disease specialists.4–7 Delusions of parasitosishas been described as “the most difficult problem ofmanagement in dermatology.”1 We present fourpatients with delusions of parasitosis in which theprincipal focus of attention was their eyes.

CASE REPORTS

● CASE 1: A 40-year-old woman presented to theemergency room for evaluation of periorbital ery-thema. She reported that her home was infestedwith insects and that her eyes were infested as well.She demonstrated how she would remove the insectparticles from her eyes with a cotton-tip swab.There was no known history of psychiatric disor-ders. There was no history of recent substanceabuse. Visual acuity (contact lens correction in theright eye only) was RE, 20/30 and LE, countingfingers. Intraocular pressure was normal in botheyes. External examination demonstrated moderateleft eyelid erythema. The left bulbar conjunctivahad marked chemosis and the left cornea demon-strated punctate epithelial keratopathy. There wereno other signs of local or systemic infestation. Eyelidcultures demonstrated rare colonies of coagulase-negative Staphylococcus species. The patient wastreated with topical erythromycin ointment andfollow-up at the outpatient ophthalmology clinicwas arranged. An emergency room psychiatry con-

Accepted for publication Oct 22, 1997.From the Southern California Permanente Medical Group, Cornea/

External Disease Service (Dr Sherman) and UCLA Ocular Inflamma-tory Disease Center, The Jules Stein Eye Institute, and Department ofOphthalmology, UCLA School of Medicine, and OphthalmologySection, Surgical Service, West Los Angeles Department of VeteransAffairs Medical Center (Drs Holland, Weisz, and Omar), Los Angeles,California; University of California, San Francisco, School of Medicine,Department of Ophthalmology and The Francis I. Proctor Foundation,San Francisco, California (Dr Holsclaw); and University of California,Irvine, School of Medicine, Division of Infectious Disease, Departmentof Medicine, Irvine, California (Dr Sherman).

Reprint requests to Mark D. Sherman, MD, Department of Ophthal-mology, 411 N Lakeview Ave, Anaheim, CA 92807-3028; fax: (714)279-6204; e-mail: mark.d.sherman@kp.org

© 1998 BY ELSEVIER SCIENCE INC. ALL RIGHTS RESERVED.852 0002-9394/98/$19.00PII S0002-9394(98)00048-8

sultant determined that she was “not holdable” andarranged an outpatient psychiatric evaluation. Shedid not keep her follow-up appointments. Sixmonths later, she returned complaining of fungalinfestation of both eyes. She described removingmaterial from her left eye with a cotton-tip swaband brought samples of objects she had removedfrom her eyes, ears, mouth, and rectum. Examina-tion did not reveal a substantial change from herprevious emergency room visit. The patient did notreturn for further follow-up.

● CASE 2: A 45-year-old woman was seen with achief complaint of “tiny white worms and yellowtube-bugs shooting out of my skin into my eyes.”She denied any history of ocular, medical, or psy-chiatric disorders. There was no history of previoussubstance abuse. The patient had given away onedog and two cats because of her belief that theycarried worms. She terminated her friendship with aneighbor, believing the neighbor to be a source ofworms. The patient reported a 14-month history ofitching, scratching, and a “wiggling sensation” be-neath her skin, scalp, eyebrows, and ears. She hadbeen evaluated by more than 10 dermatologists, allof whom she described as being “completely incom-petent.” She had been previously referred for psy-chiatric evaluation but did not keep her appoint-ments. On examination, visual acuity withoutcorrection was measured at BE, 20/20. Externalexamination was notable for three discrete patchesof alopecia on her scalp. There was mild inspissationof the meibomian glands in the eyelids of both eyes.The tarsal conjunctiva showed a mild papillaryreaction in both eyes. The corneas were clear, andthe remainder of the anterior and posterior segmentexamination was unremarkable in both eyes. Eyelidcultures grew coagulase-negative staphylococci.Conjunctival cultures were negative. The patientwas treated for blepharitis with eyelid hygiene andpreservative-free artificial tears. She returned forfollow-up with her eyebrows shaved off, which sheexplained as an attempt to get rid of the worms. Onthree subsequent visits, she brought “specimens”which she had removed with her fingernails andtaped onto a piece of wax paper. On one occasion,the patient presented with a 3-mm conjunctival

laceration in the right eye, which she had causedwhile trying to “dig out worms” with tweezers.

● CASE 3: A 35-year-old home health care nursewas seen with a nonresolving corneal ulcer in herleft eye. She had been using an assortment ofprescribed, as well as over-the-counter, topical med-ications. Her ocular, medical, and family historieswere unremarkable. There was no known history ofpsychiatric disorders. The patient complained that“little crawlies” had infested her left eye. On exam-ination, her visual acuity without spectacle correc-tion was RE, 20/20 and LE, hand motions. Externalexamination was unremarkable. The right eye wasnormal. On the left, there was a mild papillaryreaction of the lower tarsal conjunctiva. The corneashowed a dense midstromal focal infiltrate in theupper nasal quadrant and multiple small satelliteinfiltrates in the midperiphery. A 6-mm epithelialdefect was present. The anterior chamber was quietand posterior pole was normal. Cultures were ob-tained and she was started on topical fortifiedantibiotics. The cultures showed no growth andsmears showed inflammatory cells but no organisms.There was no other sign of local or systemic infes-tation. After 2 weeks without improvement, acorneal biopsy was performed and demonstratedCandida albicans. She was started on topical ampho-tericin B 0.15% every hour and oral ketoconazole(200 mg twice a day). The cornea became progres-sively necrotic and a therapeutic penetrating kera-toplasty was performed. The patient did well for 6weeks, obtaining 20/80 vision in that eye. Despite asuccessful graft, she was not convinced that theinfection had been eradicated. Eight weeks aftersurgery, she presented to the office complaining ofbugs crawling out of her eye, nostrils, and rectum.She said they were on her furniture, in her cat’s eye,and was concerned that her children may carrythem as well. As evidence, she brought a culturettewith which she cultured her cat’s eye and collected“specimens” that she taped to a sheet of paper. Onexamination, she was found to have a dense cornealinfiltrate that involved the donor cornea as well asthe recipient bed and sclera. She underwent urgentlimbus-to-limbus penetrating keratoplasty. Culturesobtained in the office and intraoperatively grewLactobacillus species. Her postoperative course was

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complicated by repeated episodes of epithelialbreakdown that healed with patching. Ultimatelythe graft failed and a conjunctival flap was per-formed. She was treated during this period withfluoxetine (Prozac) on the recommendation of theinpatient psychiatry consultant, who felt she suf-fered from an obsessive-compulsive disorder. Shewas referred for continued outpatient psychiatrycare but did not keep her appointments because shefelt that hers was not a psychiatric disorder. Oncethe conjunctival flap was performed, the patient wasconvinced that the infestation was gone and she hasdone well, despite her decreased vision.

● CASE 4: A 40-year-old man presented to the emer-gency room complaining of 3 weeks of severe burning,tearing, and light sensitivity of both eyes. The patientreported that he was “infested with lice” and had beenbathing in, and applying to both eyes, antilice medi-cation. He was homeless. There was no history ofrecent substance abuse. Visual acuity without correc-tion was BE, counting fingers at 10 feet. Externalexamination revealed multiple periocular superficialexcoriations. The eyelids were moderately erythema-tous. The bulbar conjunctiva was injected and mildlychemotic bilaterally. No signs of lice were visible inthe periocular region or along the eyelids. Both cor-neas had epithelial defects involving over 90% of thecorneal surface, moderate stromal haze, and mildedema without infiltrate. He was treated with eryth-romycin ointment and unilateral patching, which thepatient promptly removed in order to “get at the lice.”Dermatologic evaluation revealed no objective signs oflocal or systemic parasitic infection. Psychiatric con-sultation resulted in a diagnosis of bipolar disorder, andthe patient was admitted for inpatient psychiatricstabilization. The patient was followed for approxi-mately 13 days, during which time there was nore-epithelialization of the corneas, and he persistentlyclaimed his eyes were infested with lice. After 2 weeksof hospitalization, the patient left the hospital againstmedical advice and was lost to follow-up.

RESULTS

FOUR CASES OF DELUSIONS OF PARASITOSIS WITH

ocular involvement are described. The patients

included three women and one man. The averageage was 40 years (range, 35 to 45 years). Eachpatient maintained the belief that his or her eyeswere infested despite exhaustive clinical and labo-ratory evidence to the contrary. Three patientssubmitted “specimens” of their supposed infectiousagents. Patients attributed their conditions to avariety of organisms, including fungi (Case 1),worms (Case 2), parasites (Case 3), and lice (Case4). Three patients presented to the ophthalmologistwith a complaint of concomitant nonocular infes-tation. One patient, who initially presented with anisolated ocular complaint, later developed systemiccomplaints. Three patients underwent at least aninitial psychiatric evaluation. One of these patientswas diagnosed with bipolar affective disorder, andanother was diagnosed with obsessive-compulsivedisorder. None of the patients continued with theirformal psychiatric evaluation.

Self-inflicted eye injury occurred in each case.Three patients sustained bilateral ocular injury, andthe other had unilateral injury. Injuries were me-chanical in two patients, chemical in one patient,and combined chemical and mechanical in onepatient. Visual acuity ranged from 20/20 to handmotions in the involved eyes. The spectrum of tissuedamage included periocular excoriation, papillaryconjunctivitis and chemosis, conjunctival lacera-tion, corneal epithelial toxicity, and corneal stromalulceration. One patient required surgical interven-tion.

DISCUSSION

DELUSIONS OF PARASITOSIS WAS FIRST DESCRIBED BY

the French dermatologist Thibierge in 1894.8 Before1946, the condition was known by a variety ofnames, including acarophobia, dermatophobia, andparasitophobia. Wilson and Miller coined the name“delusions of parasitosis” to distinguish the unshak-able conviction that the skin is infested from thefear of infestation.9,10 Patients with delusions ofparasitosis characteristically come to the physiciancomplaining of itching, biting, and crawling sensa-tions. They may point to “tracks” on their skin anddescribe the “life-cycle” of the parasite. Frequentlythey have had multiple encounters with physicians

AMERICAN JOURNAL OF OPHTHALMOLOGY854 JUNE 1998

and may describe with hostility the ineptitude of thephysicians at recognizing or curing the disease.6 Thepatients may report multiple changes in domicile,extensive use of pesticides at home, and evenelimination of family pets thought to be possibleintermediate hosts for the parasites.4,6,7 Consulta-tion with a psychiatrist is unusual because thepatients are not easily convinced that psychiatricevaluation is indicated and they are resistant tothorough psychiatric evaluation.11–13

The most extensive survey of patients with delu-sions of parasitosis was reported by Lyell.1 In hisseries of cases, he found a 1:1 male to female ratiofor patients under 50 years of age and 3:1 ratio forpatients over 50 years of age. Lyell described pa-tients with a variety of personality types, includingthose with paranoid and aggressive personalities.Two theories have been proposed to explain thebehavior manifested in patients with delusions ofparasitosis.6,14–17 The first theory suggests that themajor problem is a primary somatic delusional stateknown as formication, in which the patient displaysmonosymptomatic hypochondriacal psychosis. Thesecond theory suggests that the delusion is anelaboration of another pathologic state, such astactile hallucinations, pruritus, or paresthesias. Pa-tients may remain functional in other areas of theirlives.6

The skin lesions manifested in patients withdelusions of parasitosis can be classified into thefollowing categories: psychosomatic dermatoses(neurodermatitis); physical trauma resulting fromattempts to remove the “parasites” with fingernailsor other instruments; and chemical trauma causedby solvents and soaps used to kill or remove the“parasites.” In some cases, however, no abnormalityof the skin may be discernible. Patients frequentlybring “samples” of the parasites wrapped in tissue,enclosed in small containers (the “matchbox sign”),or sealed in envelopes.1,3 Careful examination ofthese specimens is imperative. In cases of delusionsof parasitosis, these specimens generally turn out tobe bits of dirt, mucus, or keratotic skin debris.

The differential diagnosis of self-inflicted skininjury includes factitial dermatitis, Munchausensyndrome, neurotic excoriation, trichotillomania,and various organic disorders.18 Factitial dermatitisis a condition in which patients produce skin lesions

through their own purposeful actions, in order todraw attention to themselves. They generally denyany role in the production of these lesions. Mun-chausen syndrome refers to patients that repeatedlyfeign disease to obtain secondary gain. These pa-tients typically appear in emergency departmentsdemanding pain relief and, when confronted withthe suspicion of self-induced disease, leave and seektheir desired care elsewhere. Patients with neuroticexcoriation readily admit to manipulation of theskin in order to reduce an uncontrollable urge toscratch or pick at the area involved. Trichotilloma-nia refers to repetitive plucking of hair from theeyebrows, eyelashes, scalp, and body.

Delusions of parasitosis has been described inpatients with various organic disorders, includingvitamin B12 deficiency, renal failure, Hodgkin dis-ease, hypothyroidism, diabetes mellitus, and hepa-tobiliary dysfunction.6,9,19 It has also been reportedin association with alcohol, cocaine, amphetamine,and certain monoamine oxidase inhibitor use.1,6,13

Ophthalmologists considering the diagnosis of delu-sions of parasitosis must rule out the possibility ofany unusual ocular infection and exclude the possi-bility of organic disease.3,6,11,20

Various treatments for delusions of parasitosishave been described.11,21 Psychotherapy has a re-ported efficacy rate close to the spontaneous curerate.6,9,15,22 Nonpharmacologic treatments, such aselectroconvulsive therapy and frontal lobotomy,have also been tried without notable success.2 Phar-macologic treatment has included neuroleptics, pla-cebo medications, benzodiazepines, and monoamineoxidase inhibitors.6,17 Pimozide, a neuroleptic drug,has shown some benefit.21,23 Unfortunately, pimo-zide is associated with substantial adverse side ef-fects, and its dose must be carefully titrated.

We have described four cases of delusions ofparasitosis in which a principal focus of attentionwas the eyes. Epidemiologic studies have shown thatthe prevalence of delusions of parasitosis is fargreater than suggested by the medical literature.3

This condition is probably more common in thegeneral ophthalmology practice than currently rec-ognized as well. We refer to this variant of thecondition as “delusions of ocular parasitosis” toaccentuate sight-threatening features, as seen in ourpatients, from the more typical syndrome. We hope

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that by drawing the attention of ophthalmologiststo this condition, earlier diagnosis and successfultreatment will be possible. Earlier consultation witha psychiatrist or psychiatric liaison, emphasizing therisk of vision loss, may improve the possibility of asuccessful outcome.

REFERENCES

1. Lyell A. Delusions of parasitosis. Br J Dermatol 1983;108:485–499.

2. Cotterill JA. Dermatological non-disease: a common andpotentially fatal disturbance of cutaneous body image. Br JDermatol 1981;104:611–619.

3. Delusions of parasitosis [editorial]. Br Med J 1977;1:790–791.4. Webb JP. Case histories of individuals with delusions of

parasitosis in Southern California and a proposed protocolfor initiating effective medical assistance. Bulletin of theSociety for Vector Ecology 1993;18:16–25.

5. Koblenzer CS. The clinical presentation, diagnosis andtreatment of delusions of parasitosis: a dermatologic per-spective. Bulletin of the Society for Vector Ecology 1993;18:6–10.

6. Wykoff RF. Delusions of parasitosis: a review. Rev Inf Dis1987;9:433–437.

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8. Thibierge G. Les acarophobes. Rev Gen Clin Therap1894;32:373–376.

9. Wilson JW, Miller HE. Delusion of parasitosis. Arch DermSyphilol 1946;54:39–56.

10. Wilson JW. Delusions of parasitosis (acarophobia): furtherobservations in clinical practice. Arch Dermatol Syphilol1952;66:577–585.

11. Gould WM, Gragg TM. Delusions of parasitosis: an ap-proach to the problem. Arch Dermatol 1976;112:1745–1748.

12. Munro A. Delusions of parasitosis [letter]. Br Med J1977;1:1219.

13. Tullett GL. Delusions of parasitosis. Br J Derm 1965;77:448–454.

14. Munro A. Monosymptomatic hypochondriacal psychosismanifesting as delusions of parasitosis. Arch Dermatol1978;114:940–943.

15. Kushon DJ, Helz JW, Williams JM, et al. Delusions ofparasitosis: a survey of entomologists from a psychiatricperspective. Bulletin of the Society for Vector Ecology1993;18:11–15.

16. Berrios GE. Delusions of parasitosis and physical disease.Compr Psychiatry 1985;26:395–403.

17. Monk BE, Rao YJ. Delusions of parasitosis with fataloutcome. Clin Exp Dermatol 1994;19:341–342.

18. Fabisch, W. Psychiatric aspects of dermatitis artefacta. Br JDerm 1980;102:29–34.

19. Pope FM. Parasitophobia as the presenting symptom ofvitamin B12 deficiency. Practitioner 1970;204:421–459.

20. Soylu M, Ozcan K, Yalaz M, et al. Dirofilariasis: anuncommon parasitosis of the eye. Br J Ophthalmol 1993;77:602–603.

21. Reilly TM, Jopling WH, Beard AW. Successful treatmentwith pimozide of delusional parasitosis. Br J Dermatol1978;98:457–459.

22. Torch EM, Bishop ER. Delusions of parasitosis: psychother-apeutic engagement. Am J Psychother 1981;35:101–106.

23. Johnson GC, Anton RF. Pimozide in delusions of parasi-tosis [letter]. J Clin Psychiatry 1983;44:233.

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AMERICAN JOURNAL OF OPHTHALMOLOGY856 JUNE 1998