Approach Considerations
After medication has cleared the delusions of parasitosis, the agent should be continued for several months and then discontinued. Often, patients come to think that the medication has killed the bugs, and many (but not all) have a remission of their delusions.
Medical Care
In 2014, an article on delusions of parasitosis stressed the need of the physician to establish a therapeutic alliance with patients suffering from the condition. Without this alliance it is difficult to convince patients to take the necessary medications. The first meeting with a patient with DP can set the tone for all subsequent encounters. [40]
Another article states that the patient's autonomy must be respected in all encounters.
The physician must provide provide full information regarding the treatment plan and seek consent before starting treatment or asking the patient to seek a psychiatric referral. [41]
There has been an increase in combined psychiatric/dermatologic approaches to treating delusions of parasitosis, using a multidisciplinary approach with dermatologists working with psychiatrists and others. One clinic in Singapore used this approach and noted that delusions of parasitosis was the most common psychophysiologic disorder. The study noted that 20% of patients had psychiatric disorders underlying their skin problems and that trichotillomania and dermatitis artefacta were also observed. [12]
The only clear method to clear the delusion that underlies delusions of parasitosis is the administration of psychotropic medications. However, the condition can remit on its own. If the sensation of itch is related to some actual disease or substance use rather than a monosymptomatic hypochondriacal psychosis, the disease can be treated, or the substance inducing the sensation can be eliminated.
It is vitally important that the practitioner does not "use the delusion" to encourage the patient to accept certain treatments. While getting the patient to take a medication, such as risperidone, may help the condition, telling them that it is a medication that "kills the parasites" reinforces and validates the delusion. Even giving the patient a course of topical permethrin "just in case" may strengthen the delusion and make it that much more difficult later on. Every delusions of parasitosis patient can recount the visit on which his or her suspicions of infestation were "confirmed."
Serotonergic antidepressants may have a role in the treatment of these patients. [42, 43]
Reichenberg et al [44] reported on a patient whose delusions of parasitosis was cured overnight by having him stop taking cetirizine and doxepin (25 mg), as well as any over-the-counter medications.
Rocha and Hara [45] reported that aripiprazole at 15 mg for 8 weeks and then 7.5 mg/d was effective for delusions of parasitosis treatment. They stated:
Aripiprazole has a unique pharmacologic profile that is different from other atypical antipsychotic drugs. It is considered a partial dopaminergic agonist acting on both postsynaptic dopamine D2 receptors and presynaptic autoreceptors. It acts as a weak stimulator (so-called “partial” agonist) at dopamine D2 receptors, with the potential for exerting either antagonistic (inhibitory) or agonistic (stimulating) effects, depending on the sensitivity of the receptors and availability of dopamine, its natural agonist in the brain. In addition, aripiprazole displays partial agonism at serotonin (1A) receptors and antagonism at serotonin (2A) receptors.
Secondary delusional parasitosis was treated successfully with the combination of citalopram and clozapine. What relevance this has for treating primary delusions of parasitosis is unclear. A middle-aged woman treated with extended-release mixed amphetamine salts developed secondary delusions of parasitosis, which resolved with stopping the medication, underlying the need to assess medication usage before making a diagnosis of delusions of parasitosis.
Ladizinski et al also report that aripiprazole may be a useful treatment for delusions of parasitosis. [46]
Szepietowski et al [47] sent out 172 specially designed questionnaires to dermatologists regarding delusions of parasitosis patients; 118 responded. The questions and resulting percentages are as follows:
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Had seen at least one patient with delusions of parasitosis - 84.7%
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Had 1-2 cases of delusions of parasitosis over the preceding 5 years - 33%
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Had seen 3-5 such patients over the preceding 5 years - 28%
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Had diagnosed no cases of delusions of parasitosis during the past 5 years - 23%
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Had more than 10 patients with delusions of parasitosis over the past 5 years - 7%
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Were currently treating a patient with delusions of parasitosis - 20%
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Always request a psychiatric opinion about their patients with delusions of parasitosis - 40.75%
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Often ask for a psychiatric opinion about their patients with delusions of parasitosis - 28.8%
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Use their own pharmacological treatment, mostly sedatives and anxiety-relieving drugs - 15.3%.
Consultations
A psychiatrist should be consulted if the dermatologist cannot or will not prescribe the necessary medications. Most patients with delusions of parasitosis are reluctant to see a psychiatrist, and the dermatologist may be more successful in giving the referral if they have gained the patient's trust after several clinic visits instead of immediately after meeting the patient.
