Delusions of parasitosis (DOP) is a disorder in which patients erroneously insist that they are infested with parasites. These patients have an unshakable belief that their problems are medical. They rarely present to a psychiatrist and are almost always resistant to psychiatric referral. Thus, this disorder proves to be difficult to treat. The classic patient with DOP is a middle-aged woman frustrated by unsuccessful attempts to discover the cause of her ailment that has been affecting her for months or years.1 She may complain of a crawling, biting, burrowing sensation (formication) on or under her skin. She may claim her symptoms originate from insects or other creatures that infest her, her home, or her work. She may actually see the crawling culprits and be able to describe them in detail. This delusion may impinge on her activities of daily living, but she is otherwise a functional well-adjusted person. Oftentimes she will bring in proof of infestation that, under close examination, are pieces of lint or other nonparasitic materials.1 Despite thorough examination and reassurance, the patient relentlessly believes she is infested. She will most likely refuse referral to a psychiatrist, the one clinician with the most experience treating delusional disorders. Thus, it is important for the general practitioner and other nonpsychiatric clinicians to be familiar with DOP and its management.
Medical Management
Medical or psychiatric treatment aimed at eliminating the delusion should be attempted only after rapport with the patient has been established. Koo and Pham2 stated: "The greatest challenge in the treatment of delusional patients is in obtaining their agreement to start treatment with an antipsychotic medication." Numerous case reports have been published in which the clinician was unable to successfully treat DOP because of a lack of patient confidence.3-5 We modified a suggested management strategy first described by Gould and Gragg6 and incorporated strategies from a lecture on promoting a trusting relationship with delusional patients presented by Koo7 at the University of Southern California Dermatology Grand Rounds to create the following management strategy for clinicians:
- Listen to the patient's story. Give the patient a few minutes to narrate and then proceed with a battery of direct questions. Do not dwell on the patient's psychiatric history, which will encourage trust and allow you to control the dialogue.
- Thoroughly examine the patient's skin and any evidence of infestation that they bring. This task may seem dishonest when you are convinced the patient is delusional; however, it is possible there is a true infestation. Even if he/she is not infested, developing a bond with the patient will allow you to suggest treatments that the patient may otherwise not accept.2
- Perform a biopsy if the patient insists, which will show that you genuinely care about his/her problem. Allow the patient to pick the skin area he/she believes is the most involved, but insist that if the biopsy is negative, he/she should entertain the possibility that the ailment may not be due to a living organism.
- Show concern for how the condition has affected the patient's life. This technique has been shown to have a positive effect on the establishment of a good physician-patient relationship. Furthermore, it can help you individualize a therapeutic strategy for the patient in a way that does not reinforce the delusion. For example, you may say, "We will work diligently to relieve the stress this problem has caused you."
- Be empathetic, not sympathetic. Let the patient know that you understand how the condition has left him/her feeling isolated.
Be aware that rapport with the patient will not always develop immediately. It may take a few visits before the patient is comfortable enough to accept treatment suggestions. Clinicians are most concerned with discussions with the patient relating to the diagnosis and treatment. Most patients will not accept a psychiatric diagnosis for a condition that they are sure is somatic. The following statements made by clinicians have been used with success:
- "You have a very difficult problem, but I will study the specimens you have brought and will try to help you in any way that I can."6
- "I did not find any parasites today, but I am willing to examine any evidence that you bring me in the future."2
- "I noticed that you have been suffering with this problem and this is really bothering you day and night. Maybe I can offer you a medication that can help relieve some of this distress."2
- "This medication has been known to help others with the same problem."8
- "I would like to refer you to a specialist for this disorder."9 (The patient is not immediately told that the specialist is a psychiatrist, but this fact is not denied if asked.)
- "You may very well have had an infestation initially that was adequately treated, and the only sign now is the residual sensation you feel in your skin. Given the experience you have had, I can understand how you feel that parasites are still there. This is a situation that I have seen before, and the medication that I am going to prescribe is usually very helpful in getting rid of this last remaining discomfort."10