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Infested with worms, but are they really there?
CASE Detoxification and preoccupation with parasites
Mr. H, age 51, has an extensive history of alcohol and methamphetamine use. He presents to the emergency department (ED) requesting inpatient detoxification. He says he had been drinking alcohol but is unable to say how much. His blood ethanol level is 61 mg/dL (unintoxicated level: <50 mg/dL), and a urine drug screen is positive for methamphetamine; Mr. H also admits to using fentanyl. The ED team treats Mr. H’s electrolyte abnormalities, initiates thiamine supplementation, and transfers him to a unit for inpatient withdrawal management.
On the detoxification unit, Mr. H receives a total of 1,950 mg of phenobarbital for alcohol withdrawal and stabilizes on a buprenorphine/naloxone maintenance dose of 8 mg/2 mg twice daily for methamphetamine and fentanyl use. Though he was not taking any psychiatric medications prior to his arrival at the ED, Mr. H agrees to restart quetiapine
During Mr. H’s 3-day detoxification, the psychiatry team evaluates him. Mr. H says he believes he is infested with worms. He describes a prior sensation of “meth mites,” or the feeling of bugs crawling under his skin, while using methamphetamines. However, Mr. H says his current infestation feels distinctively different, and he had continued to experience these
The psychiatry team expresses concern over his preoccupation with infestations, disheveled appearance, poor hygiene, and healed scars from excoriation. Mr. H also reports poor sleep and appetite and was observed writing an incomprehensible “experiment” on a paper towel. Due to his bizarre behavior, delusional thoughts, and concerns about his inability to care for himself, the team admits Mr. H to the acute inpatient psychiatric unit on a voluntary commitment.
HISTORY Long-standing drug use and repeated hospital visits
Mr. H reports a history of drug use. His first documented ED visit was >5 years before his current admission. He has a family history of substance abuse and reports previously using methamphetamine, heroin, and alcohol. Mr. H was never diagnosed with a psychiatric illness, but when he was younger, there were suspicions of bipolar depression, with no contributing family psychiatric history. Though he took quetiapine at an unspecified younger age, Mr. H did not follow through with any outpatient mental health services or medications.
Mr. H first reported infestation
In the 6 months prior to his current admission, Mr. H came to the hospital >20 times for various reasons, including methamphetamine abuse, alcohol withdrawal, opiate overdose, cellulitis, wound checks, and 3 visits for hallucinations for which he requested physical evaluation and medical care. His substance use was the suspected cause of his tactile and visual hallucinations of infestation because formication
Continue to: The authors' observations
The authors’ observations
Delusional parasitosis (DP), also known as delusional infestation or Ekbom Syndrome, is a condition characterized by the fixed, false belief of an infestation without any objective evidence. This condition was previously defined in DSM-IV, but was removed from DSM-5-TR. In DSM-5-TR, DP is most closely associated with delusional disorder
DP is rare, affecting approximately 1.9 per 100,000 people. There has not been consistent data supporting differences in prevalence between sexes, but there is evidence for increasing incidence with age, with a mean age of diagnosis of 61.4.2,3 DP can be divided into 2 types based on the history and etiology of the symptoms: primary DP and secondary DP. Primary DP occurs when there is a failure to identify an organic cause for the occurrence of the symptoms. Therefore, primary DP requires an extensive investigation by a multidisciplinary team that commonly includes medical specialists for a nonpsychiatric workup. Secondary DP occurs when the patient has delusional symptoms associated with a primary diagnosis of schizophrenia, depression, stroke, diabetes, vitamin B12 deficiency, or substance use.4
Though Mr. H initially presented to the ED, patients with DP commonly present to a primary care physician or dermatologist with the complaint of itching or feelings of insects, worms, or unclear organisms inside them. Patients with DP may often develop poor working relationships with physicians while obtaining multiple negative results. They may seek opinions from multiple specialists; however, patients typically do not consider psychiatrists as a source of help. When patients seek psychiatric care, often after a recommendation from a primary care physician or dermatologist, mental health clinicians should listen to and evaluate the patient holistically, continuing to rule out other possible etiologies.
[polldaddy:12570072]
TREATMENT Finding the right antipsychotic
In the psychiatric unit, Mr. H says he believes worms are exiting his ears, mouth, toenail, and self-inflicted scratch wounds. He believes he has been dealing with the parasites for >1 year and they are slowly draining his energy. Mr. H insists he contracted the “infection” from his home carpet, which was wet due to a flood in his house, and after he had fallen asleep following drug use. He also believes he acquired the parasites while walking barefoot along the beach and collecting rocks, and that there are multiple species living inside him, all intelligent enough to hide, making it difficult to prove their existence. He notes they vary in size, and some have red eyes.
During admission, Mr. H voices his frustration that clinicians had not found the worms he has been seeing. He continuously requests to review imaging performed during his visit and wants a multidisciplinary team to evaluate his case. He demands to test a cup with spit-up “samples,” believing the parasites would be visible under a microscope. Throughout his admission, Mr. H continues to take buprenorphine/naloxone and does not experience withdrawal symptoms. The treatment team titrates his quetiapine to 400 mg/d. Due to the lack of improvement, the team initiates olanzapine 5 mg/d at bedtime. However, Mr. H reports significant tinnitus and requests a medication change. He is started on haloperidol 5 mg twice daily.
Continue to: Mr. H begins to see improvements...
Mr. H begins to see improvements on Day 7 of taking haloperidol. He no longer brings up infestation but still acknowledges having worms inside him when directly asked. He says the worms cause him less distress than before and he is hopeful to live without discomfort. He also demonstrates an ability to conduct activities of daily living. Because Mr. H is being monitored on an acute inpatient psychiatric basis, he is deemed appropriate for discharge even though his symptoms have not yet fully resolved. After a 19-day hospital stay, Mr. H is discharged on haloperidol 15 mg/d and quetiapine 200 mg/d.
[polldaddy:12570074]
The authors’ observations
Mr. H asked to have his sputum examined. The “specimen sign,” also called “matchbox sign” or “Ziploc bag sign,” in which patients collect what they believe to be infected tissue or organisms in a container, is a well-studied part of DP.5 Such samples should be considered during initial encounters and can be examined for formal evaluation, but cautiously. Overtesting may incur a financial burden or reinforce deleterious beliefs and behaviors.
It can be difficult to identify triggers of DP. Research shows DP may arise from nonorganic and stressful life events, home floods, or contact with people infected with parasites.6,7 Organic causes have also been found, such as patients taking multiple medications for Parkinson disease who developed delusional symptoms.8 Buscarino et al9 reported the case of a woman who started to develop symptoms of delusions and hallucinations after being on high-dose amphetamines for attention-deficit/hyperactivity disorder. Research shows that stopping the suspected medication commonly improves such symptoms.9,10 Although methamphetamine can remain detectable in urine for up to 4 days after use and potentially a few days longer for chronic users due to circulating levels,11 Mr. H’s symptoms continued for weeks after all substances of abuse should have been cleared from his system. This suggests he was experiencing a psychiatric illness and was accurate in distinguishing methamphetamine-induced from psychiatric-induced sensations. Regardless, polysubstance use has been shown to potentially increase the risk and play a role in the onset and progression of delusional illness, as seen in prior cases as well as in this case.9
It has been hypothesized that the pathophysiology of DP is associated with the deterioration of the striatal dopaminergic pathway, leading to an increase in extracellular dopamine levels. The striatum is responsible for most dopamine reuptake in the brain; therefore, certain drugs such as cocaine, methamphetamine, and methylphenidate may precipitate symptoms of DP due to their blockade of presynaptic dopamine reuptake.12 Additionally, conditions that decrease the functioning of striatal dopamine transporters, such as schizophrenia or depression, may be underlying causes of DP.13
Treatment of DP remains a topic of debate. Most current recommendations appear to be based on a small, nonrandomized placebo-controlled trial.14 The first-generation antipsychotic pimozide had been a first-line treatment for DP, but its adverse effect profile, which includes QTc prolongation and extrapyramidal symptoms, led to the exploration of second-generation antipsychotics such as olanzapine and risperidone.15,16 There is a dearth of literature about the use of haloperidol, quetiapine, or a combination of both as treatment options for DP, though the combination of these 2 medications proved effective for Mr. H. Further research is necessary to justify changes to current treatment standards, but this finding highlights a successful symptom reduction achieved with this combination.
Continue to: Patients may experience genuine symptoms...
Patients may experience genuine symptoms despite the delusional nature of DP, and it is important for clinicians to recognize the potential burden and anxiety these individuals face. Patients may present with self-inflicted bruises, cuts, and erosions to gain access to infected areas, which may be confused with skin picking disorder. Excessive cleansing or use of irritant products can also cause skin damage, leading to other dermatological conditions that reinforce the patient’s belief that something is medically wrong. During treatment, consider medications for relief of pruritus or pain. Focus on offering patients the opportunity to express their concerns, treat them with empathy, avoid stigmatizing language such as “delusions” or “psychosis,” and refrain from contradicting them until a strong rapport has been established (Table 217).
Symptoms of DP can persist for months to years. Patients who fully recovered experienced a median duration of 0.5 years until symptom resolution, compared to incompletely recovered patients, who took approximately 1 year.18 Primary DP has slower improvement rates compared to secondary DP, with the median onset of effects occurring at Week 1.5 and peak improvements occurring at Week 6.16
OUTCOME Continued ED visits
Unfortunately, Mr. H does not follow through with his outpatient psychiatry appointments. In the 7 months following discharge, he visits the ED 8 times for alcohol intoxication, alcohol withdrawal, and methamphetamine abuse, in addition to 2 admissions for inpatient detoxification, during which he was still receiving the same scheduled medications (haloperidol 15 mg/d and quetiapine 200 mg/d). At each of his ED visits, there was no documentation of DP symptoms, which suggests his symptoms may have resolved.
Bottom Line
Because delusional parasitosis symptoms feel real to patients, it is crucial to build rapport to recommend and successfully initiate treatment. After ruling out nonpsychiatric etiologies, consider traditional treatment with antipsychotics, and consider medications for relief of pruritus or pain.
Related Resources
- Sellman D, Phan SV, Inyang M. Bugs on her skin—but nobody else sees them. Current Psychiatry. 2018;17(8):48,50-53.
- Campbell EH, Elston DM, Hawthorne JD, et al. Diagnosis and management of delusional parasitosis. J Am Acad Dermatol. 2019;80(5):1428-1434. doi:10.1016/j.jaad.2018.12.012
Drug Brand Names
Buprenorphine/naloxone • Suboxone
Haloperidol • Haldol
Hydroxyzine • Vistaril
Lithium • Eskalith, Lithobid
Methylphenidate • Concerta
Olanzapine • Zyprexa
Permethrin • Elimite
Phenobarbital • Solfoton, Tedral, Luminal
Pimozide • Orap
Quetiapine • Seroquel
Risperidone • Risperdal
Sertraline • Zoloft
Valproic acid • Depakote
1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed, text revision. American Psychiatric Association; 2013.
2. Bailey CH, Andersen LK, Lowe GC, et al. A population-based study of the incidence of delusional infestation in Olmsted County, Minnesota, 1976-2010. Br J Dermatol. 2014;170(5):1130-1135. doi:10.1111/bjd.12848
3. Kohorst JJ, Bailey CH, Andersen LK, et al. Prevalence of delusional infestation-a population-based study. JAMA Dermatol. 2018;154(5):615-617. doi:10.1001/jamadermatol.2018.0004
4. Freinhar JP. Delusions of parasitosis. Psychosomatics. 1984;25(1):47-53. doi:10.1016/S0033-3182(84)73096-9
5. Reich A, Kwiatkowska D, Pacan P. Delusions of parasitosis: an update. Dermatol Ther (Heidelb). 2019;9(4):631-638. doi:10.1007/s13555-019-00324-3
6. Berrios GE. Delusional parasitosis and physical disease. Compr Psychiatry. 1985;26(5):395-403. doi:10.1016/0010-440x(85)90077-x
7. Aizenberg D, Schwartz B, Zemishlany Z. Delusional parasitosis associated with phenelzine. Br J Psychiatry. 1991;159:716-717. doi:10.1192/bjp.159.5.716
8. Flann S, Shotbolt J, Kessel B, et al. Three cases of delusional parasitosis caused by dopamine agonists. Clin Exp Dermatol. 2010;35(7):740-742. doi:10.1111/j.1365-2230.2010.03810.x
9. Buscarino M, Saal J, Young JL. Delusional parasitosis in a female treated with mixed amphetamine salts: a case report and literature review. Case Rep Psychiatry. 2012;2012:624235. doi:10.1155/2012/624235
10. Elpern DJ. Cocaine abuse and delusions of parasitosis. Cutis. 1988;42(4):273-274.
11. Richards JR, Laurin EG. Methamphetamine toxicity. StatPearls Publishing; 2023. Updated January 8, 2023. Accessed May 25, 2023. https://www.ncbi.nlm.nih.gov/books/NBK430895/
12. Huber M, Kirchler E, Karner M, et al. Delusional parasitosis and the dopamine transporter. A new insight of etiology? Med Hypotheses. 2007;68(6):1351-1358. doi:10.1016/j.mehy.2006.07.061
13. Lipman ZM, Yosipovitch G. Substance use disorders and chronic itch. J Am Acad Dermatol. 2021;84(1):148-155. doi:10.1016/j.jaad.2020.08.117
14. Kenchaiah BK, Kumar S, Tharyan P. Atypical anti-psychotics in delusional parasitosis: a retrospective case series of 20 patients. Int J Dermatol. 2010;49(1):95-100. doi:10.1111/j.1365-4632.2009.04312.x
15. Laidler N. Delusions of parasitosis: a brief review of the literature and pathway for diagnosis and treatment. Dermatol Online J. 2018;24(1):13030/qt1fh739nx.
16. Freudenmann RW, Lepping P. Second-generation antipsychotics in primary and secondary delusional parasitosis: outcome and efficacy. J Clin Psychopharmacol. 2008;28(5):500-508. doi:10.1097/JCP.0b013e318185e774
17. Mumcuoglu KY, Leibovici V, Reuveni I, et al. Delusional parasitosis: diagnosis and treatment. Isr Med Assoc J. 2018;20(7):456-460.
18. Trabert W. 100 years of delusional parasitosis. Meta-analysis of 1,223 case reports. Psychopathology. 1995;28(5):238-246. doi:10.1159/000284934
CASE Detoxification and preoccupation with parasites
Mr. H, age 51, has an extensive history of alcohol and methamphetamine use. He presents to the emergency department (ED) requesting inpatient detoxification. He says he had been drinking alcohol but is unable to say how much. His blood ethanol level is 61 mg/dL (unintoxicated level: <50 mg/dL), and a urine drug screen is positive for methamphetamine; Mr. H also admits to using fentanyl. The ED team treats Mr. H’s electrolyte abnormalities, initiates thiamine supplementation, and transfers him to a unit for inpatient withdrawal management.
On the detoxification unit, Mr. H receives a total of 1,950 mg of phenobarbital for alcohol withdrawal and stabilizes on a buprenorphine/naloxone maintenance dose of 8 mg/2 mg twice daily for methamphetamine and fentanyl use. Though he was not taking any psychiatric medications prior to his arrival at the ED, Mr. H agrees to restart quetiapine
During Mr. H’s 3-day detoxification, the psychiatry team evaluates him. Mr. H says he believes he is infested with worms. He describes a prior sensation of “meth mites,” or the feeling of bugs crawling under his skin, while using methamphetamines. However, Mr. H says his current infestation feels distinctively different, and he had continued to experience these
The psychiatry team expresses concern over his preoccupation with infestations, disheveled appearance, poor hygiene, and healed scars from excoriation. Mr. H also reports poor sleep and appetite and was observed writing an incomprehensible “experiment” on a paper towel. Due to his bizarre behavior, delusional thoughts, and concerns about his inability to care for himself, the team admits Mr. H to the acute inpatient psychiatric unit on a voluntary commitment.
HISTORY Long-standing drug use and repeated hospital visits
Mr. H reports a history of drug use. His first documented ED visit was >5 years before his current admission. He has a family history of substance abuse and reports previously using methamphetamine, heroin, and alcohol. Mr. H was never diagnosed with a psychiatric illness, but when he was younger, there were suspicions of bipolar depression, with no contributing family psychiatric history. Though he took quetiapine at an unspecified younger age, Mr. H did not follow through with any outpatient mental health services or medications.
Mr. H first reported infestation
In the 6 months prior to his current admission, Mr. H came to the hospital >20 times for various reasons, including methamphetamine abuse, alcohol withdrawal, opiate overdose, cellulitis, wound checks, and 3 visits for hallucinations for which he requested physical evaluation and medical care. His substance use was the suspected cause of his tactile and visual hallucinations of infestation because formication
Continue to: The authors' observations
The authors’ observations
Delusional parasitosis (DP), also known as delusional infestation or Ekbom Syndrome, is a condition characterized by the fixed, false belief of an infestation without any objective evidence. This condition was previously defined in DSM-IV, but was removed from DSM-5-TR. In DSM-5-TR, DP is most closely associated with delusional disorder
DP is rare, affecting approximately 1.9 per 100,000 people. There has not been consistent data supporting differences in prevalence between sexes, but there is evidence for increasing incidence with age, with a mean age of diagnosis of 61.4.2,3 DP can be divided into 2 types based on the history and etiology of the symptoms: primary DP and secondary DP. Primary DP occurs when there is a failure to identify an organic cause for the occurrence of the symptoms. Therefore, primary DP requires an extensive investigation by a multidisciplinary team that commonly includes medical specialists for a nonpsychiatric workup. Secondary DP occurs when the patient has delusional symptoms associated with a primary diagnosis of schizophrenia, depression, stroke, diabetes, vitamin B12 deficiency, or substance use.4
Though Mr. H initially presented to the ED, patients with DP commonly present to a primary care physician or dermatologist with the complaint of itching or feelings of insects, worms, or unclear organisms inside them. Patients with DP may often develop poor working relationships with physicians while obtaining multiple negative results. They may seek opinions from multiple specialists; however, patients typically do not consider psychiatrists as a source of help. When patients seek psychiatric care, often after a recommendation from a primary care physician or dermatologist, mental health clinicians should listen to and evaluate the patient holistically, continuing to rule out other possible etiologies.
[polldaddy:12570072]
TREATMENT Finding the right antipsychotic
In the psychiatric unit, Mr. H says he believes worms are exiting his ears, mouth, toenail, and self-inflicted scratch wounds. He believes he has been dealing with the parasites for >1 year and they are slowly draining his energy. Mr. H insists he contracted the “infection” from his home carpet, which was wet due to a flood in his house, and after he had fallen asleep following drug use. He also believes he acquired the parasites while walking barefoot along the beach and collecting rocks, and that there are multiple species living inside him, all intelligent enough to hide, making it difficult to prove their existence. He notes they vary in size, and some have red eyes.
During admission, Mr. H voices his frustration that clinicians had not found the worms he has been seeing. He continuously requests to review imaging performed during his visit and wants a multidisciplinary team to evaluate his case. He demands to test a cup with spit-up “samples,” believing the parasites would be visible under a microscope. Throughout his admission, Mr. H continues to take buprenorphine/naloxone and does not experience withdrawal symptoms. The treatment team titrates his quetiapine to 400 mg/d. Due to the lack of improvement, the team initiates olanzapine 5 mg/d at bedtime. However, Mr. H reports significant tinnitus and requests a medication change. He is started on haloperidol 5 mg twice daily.
Continue to: Mr. H begins to see improvements...
Mr. H begins to see improvements on Day 7 of taking haloperidol. He no longer brings up infestation but still acknowledges having worms inside him when directly asked. He says the worms cause him less distress than before and he is hopeful to live without discomfort. He also demonstrates an ability to conduct activities of daily living. Because Mr. H is being monitored on an acute inpatient psychiatric basis, he is deemed appropriate for discharge even though his symptoms have not yet fully resolved. After a 19-day hospital stay, Mr. H is discharged on haloperidol 15 mg/d and quetiapine 200 mg/d.
[polldaddy:12570074]
The authors’ observations
Mr. H asked to have his sputum examined. The “specimen sign,” also called “matchbox sign” or “Ziploc bag sign,” in which patients collect what they believe to be infected tissue or organisms in a container, is a well-studied part of DP.5 Such samples should be considered during initial encounters and can be examined for formal evaluation, but cautiously. Overtesting may incur a financial burden or reinforce deleterious beliefs and behaviors.
It can be difficult to identify triggers of DP. Research shows DP may arise from nonorganic and stressful life events, home floods, or contact with people infected with parasites.6,7 Organic causes have also been found, such as patients taking multiple medications for Parkinson disease who developed delusional symptoms.8 Buscarino et al9 reported the case of a woman who started to develop symptoms of delusions and hallucinations after being on high-dose amphetamines for attention-deficit/hyperactivity disorder. Research shows that stopping the suspected medication commonly improves such symptoms.9,10 Although methamphetamine can remain detectable in urine for up to 4 days after use and potentially a few days longer for chronic users due to circulating levels,11 Mr. H’s symptoms continued for weeks after all substances of abuse should have been cleared from his system. This suggests he was experiencing a psychiatric illness and was accurate in distinguishing methamphetamine-induced from psychiatric-induced sensations. Regardless, polysubstance use has been shown to potentially increase the risk and play a role in the onset and progression of delusional illness, as seen in prior cases as well as in this case.9
It has been hypothesized that the pathophysiology of DP is associated with the deterioration of the striatal dopaminergic pathway, leading to an increase in extracellular dopamine levels. The striatum is responsible for most dopamine reuptake in the brain; therefore, certain drugs such as cocaine, methamphetamine, and methylphenidate may precipitate symptoms of DP due to their blockade of presynaptic dopamine reuptake.12 Additionally, conditions that decrease the functioning of striatal dopamine transporters, such as schizophrenia or depression, may be underlying causes of DP.13
Treatment of DP remains a topic of debate. Most current recommendations appear to be based on a small, nonrandomized placebo-controlled trial.14 The first-generation antipsychotic pimozide had been a first-line treatment for DP, but its adverse effect profile, which includes QTc prolongation and extrapyramidal symptoms, led to the exploration of second-generation antipsychotics such as olanzapine and risperidone.15,16 There is a dearth of literature about the use of haloperidol, quetiapine, or a combination of both as treatment options for DP, though the combination of these 2 medications proved effective for Mr. H. Further research is necessary to justify changes to current treatment standards, but this finding highlights a successful symptom reduction achieved with this combination.
Continue to: Patients may experience genuine symptoms...
Patients may experience genuine symptoms despite the delusional nature of DP, and it is important for clinicians to recognize the potential burden and anxiety these individuals face. Patients may present with self-inflicted bruises, cuts, and erosions to gain access to infected areas, which may be confused with skin picking disorder. Excessive cleansing or use of irritant products can also cause skin damage, leading to other dermatological conditions that reinforce the patient’s belief that something is medically wrong. During treatment, consider medications for relief of pruritus or pain. Focus on offering patients the opportunity to express their concerns, treat them with empathy, avoid stigmatizing language such as “delusions” or “psychosis,” and refrain from contradicting them until a strong rapport has been established (Table 217).
Symptoms of DP can persist for months to years. Patients who fully recovered experienced a median duration of 0.5 years until symptom resolution, compared to incompletely recovered patients, who took approximately 1 year.18 Primary DP has slower improvement rates compared to secondary DP, with the median onset of effects occurring at Week 1.5 and peak improvements occurring at Week 6.16
OUTCOME Continued ED visits
Unfortunately, Mr. H does not follow through with his outpatient psychiatry appointments. In the 7 months following discharge, he visits the ED 8 times for alcohol intoxication, alcohol withdrawal, and methamphetamine abuse, in addition to 2 admissions for inpatient detoxification, during which he was still receiving the same scheduled medications (haloperidol 15 mg/d and quetiapine 200 mg/d). At each of his ED visits, there was no documentation of DP symptoms, which suggests his symptoms may have resolved.
Bottom Line
Because delusional parasitosis symptoms feel real to patients, it is crucial to build rapport to recommend and successfully initiate treatment. After ruling out nonpsychiatric etiologies, consider traditional treatment with antipsychotics, and consider medications for relief of pruritus or pain.
Related Resources
- Sellman D, Phan SV, Inyang M. Bugs on her skin—but nobody else sees them. Current Psychiatry. 2018;17(8):48,50-53.
- Campbell EH, Elston DM, Hawthorne JD, et al. Diagnosis and management of delusional parasitosis. J Am Acad Dermatol. 2019;80(5):1428-1434. doi:10.1016/j.jaad.2018.12.012
Drug Brand Names
Buprenorphine/naloxone • Suboxone
Haloperidol • Haldol
Hydroxyzine • Vistaril
Lithium • Eskalith, Lithobid
Methylphenidate • Concerta
Olanzapine • Zyprexa
Permethrin • Elimite
Phenobarbital • Solfoton, Tedral, Luminal
Pimozide • Orap
Quetiapine • Seroquel
Risperidone • Risperdal
Sertraline • Zoloft
Valproic acid • Depakote
CASE Detoxification and preoccupation with parasites
Mr. H, age 51, has an extensive history of alcohol and methamphetamine use. He presents to the emergency department (ED) requesting inpatient detoxification. He says he had been drinking alcohol but is unable to say how much. His blood ethanol level is 61 mg/dL (unintoxicated level: <50 mg/dL), and a urine drug screen is positive for methamphetamine; Mr. H also admits to using fentanyl. The ED team treats Mr. H’s electrolyte abnormalities, initiates thiamine supplementation, and transfers him to a unit for inpatient withdrawal management.
On the detoxification unit, Mr. H receives a total of 1,950 mg of phenobarbital for alcohol withdrawal and stabilizes on a buprenorphine/naloxone maintenance dose of 8 mg/2 mg twice daily for methamphetamine and fentanyl use. Though he was not taking any psychiatric medications prior to his arrival at the ED, Mr. H agrees to restart quetiapine
During Mr. H’s 3-day detoxification, the psychiatry team evaluates him. Mr. H says he believes he is infested with worms. He describes a prior sensation of “meth mites,” or the feeling of bugs crawling under his skin, while using methamphetamines. However, Mr. H says his current infestation feels distinctively different, and he had continued to experience these
The psychiatry team expresses concern over his preoccupation with infestations, disheveled appearance, poor hygiene, and healed scars from excoriation. Mr. H also reports poor sleep and appetite and was observed writing an incomprehensible “experiment” on a paper towel. Due to his bizarre behavior, delusional thoughts, and concerns about his inability to care for himself, the team admits Mr. H to the acute inpatient psychiatric unit on a voluntary commitment.
HISTORY Long-standing drug use and repeated hospital visits
Mr. H reports a history of drug use. His first documented ED visit was >5 years before his current admission. He has a family history of substance abuse and reports previously using methamphetamine, heroin, and alcohol. Mr. H was never diagnosed with a psychiatric illness, but when he was younger, there were suspicions of bipolar depression, with no contributing family psychiatric history. Though he took quetiapine at an unspecified younger age, Mr. H did not follow through with any outpatient mental health services or medications.
Mr. H first reported infestation
In the 6 months prior to his current admission, Mr. H came to the hospital >20 times for various reasons, including methamphetamine abuse, alcohol withdrawal, opiate overdose, cellulitis, wound checks, and 3 visits for hallucinations for which he requested physical evaluation and medical care. His substance use was the suspected cause of his tactile and visual hallucinations of infestation because formication
Continue to: The authors' observations
The authors’ observations
Delusional parasitosis (DP), also known as delusional infestation or Ekbom Syndrome, is a condition characterized by the fixed, false belief of an infestation without any objective evidence. This condition was previously defined in DSM-IV, but was removed from DSM-5-TR. In DSM-5-TR, DP is most closely associated with delusional disorder
DP is rare, affecting approximately 1.9 per 100,000 people. There has not been consistent data supporting differences in prevalence between sexes, but there is evidence for increasing incidence with age, with a mean age of diagnosis of 61.4.2,3 DP can be divided into 2 types based on the history and etiology of the symptoms: primary DP and secondary DP. Primary DP occurs when there is a failure to identify an organic cause for the occurrence of the symptoms. Therefore, primary DP requires an extensive investigation by a multidisciplinary team that commonly includes medical specialists for a nonpsychiatric workup. Secondary DP occurs when the patient has delusional symptoms associated with a primary diagnosis of schizophrenia, depression, stroke, diabetes, vitamin B12 deficiency, or substance use.4
Though Mr. H initially presented to the ED, patients with DP commonly present to a primary care physician or dermatologist with the complaint of itching or feelings of insects, worms, or unclear organisms inside them. Patients with DP may often develop poor working relationships with physicians while obtaining multiple negative results. They may seek opinions from multiple specialists; however, patients typically do not consider psychiatrists as a source of help. When patients seek psychiatric care, often after a recommendation from a primary care physician or dermatologist, mental health clinicians should listen to and evaluate the patient holistically, continuing to rule out other possible etiologies.
[polldaddy:12570072]
TREATMENT Finding the right antipsychotic
In the psychiatric unit, Mr. H says he believes worms are exiting his ears, mouth, toenail, and self-inflicted scratch wounds. He believes he has been dealing with the parasites for >1 year and they are slowly draining his energy. Mr. H insists he contracted the “infection” from his home carpet, which was wet due to a flood in his house, and after he had fallen asleep following drug use. He also believes he acquired the parasites while walking barefoot along the beach and collecting rocks, and that there are multiple species living inside him, all intelligent enough to hide, making it difficult to prove their existence. He notes they vary in size, and some have red eyes.
During admission, Mr. H voices his frustration that clinicians had not found the worms he has been seeing. He continuously requests to review imaging performed during his visit and wants a multidisciplinary team to evaluate his case. He demands to test a cup with spit-up “samples,” believing the parasites would be visible under a microscope. Throughout his admission, Mr. H continues to take buprenorphine/naloxone and does not experience withdrawal symptoms. The treatment team titrates his quetiapine to 400 mg/d. Due to the lack of improvement, the team initiates olanzapine 5 mg/d at bedtime. However, Mr. H reports significant tinnitus and requests a medication change. He is started on haloperidol 5 mg twice daily.
Continue to: Mr. H begins to see improvements...
Mr. H begins to see improvements on Day 7 of taking haloperidol. He no longer brings up infestation but still acknowledges having worms inside him when directly asked. He says the worms cause him less distress than before and he is hopeful to live without discomfort. He also demonstrates an ability to conduct activities of daily living. Because Mr. H is being monitored on an acute inpatient psychiatric basis, he is deemed appropriate for discharge even though his symptoms have not yet fully resolved. After a 19-day hospital stay, Mr. H is discharged on haloperidol 15 mg/d and quetiapine 200 mg/d.
[polldaddy:12570074]
The authors’ observations
Mr. H asked to have his sputum examined. The “specimen sign,” also called “matchbox sign” or “Ziploc bag sign,” in which patients collect what they believe to be infected tissue or organisms in a container, is a well-studied part of DP.5 Such samples should be considered during initial encounters and can be examined for formal evaluation, but cautiously. Overtesting may incur a financial burden or reinforce deleterious beliefs and behaviors.
It can be difficult to identify triggers of DP. Research shows DP may arise from nonorganic and stressful life events, home floods, or contact with people infected with parasites.6,7 Organic causes have also been found, such as patients taking multiple medications for Parkinson disease who developed delusional symptoms.8 Buscarino et al9 reported the case of a woman who started to develop symptoms of delusions and hallucinations after being on high-dose amphetamines for attention-deficit/hyperactivity disorder. Research shows that stopping the suspected medication commonly improves such symptoms.9,10 Although methamphetamine can remain detectable in urine for up to 4 days after use and potentially a few days longer for chronic users due to circulating levels,11 Mr. H’s symptoms continued for weeks after all substances of abuse should have been cleared from his system. This suggests he was experiencing a psychiatric illness and was accurate in distinguishing methamphetamine-induced from psychiatric-induced sensations. Regardless, polysubstance use has been shown to potentially increase the risk and play a role in the onset and progression of delusional illness, as seen in prior cases as well as in this case.9
It has been hypothesized that the pathophysiology of DP is associated with the deterioration of the striatal dopaminergic pathway, leading to an increase in extracellular dopamine levels. The striatum is responsible for most dopamine reuptake in the brain; therefore, certain drugs such as cocaine, methamphetamine, and methylphenidate may precipitate symptoms of DP due to their blockade of presynaptic dopamine reuptake.12 Additionally, conditions that decrease the functioning of striatal dopamine transporters, such as schizophrenia or depression, may be underlying causes of DP.13
Treatment of DP remains a topic of debate. Most current recommendations appear to be based on a small, nonrandomized placebo-controlled trial.14 The first-generation antipsychotic pimozide had been a first-line treatment for DP, but its adverse effect profile, which includes QTc prolongation and extrapyramidal symptoms, led to the exploration of second-generation antipsychotics such as olanzapine and risperidone.15,16 There is a dearth of literature about the use of haloperidol, quetiapine, or a combination of both as treatment options for DP, though the combination of these 2 medications proved effective for Mr. H. Further research is necessary to justify changes to current treatment standards, but this finding highlights a successful symptom reduction achieved with this combination.
Continue to: Patients may experience genuine symptoms...
Patients may experience genuine symptoms despite the delusional nature of DP, and it is important for clinicians to recognize the potential burden and anxiety these individuals face. Patients may present with self-inflicted bruises, cuts, and erosions to gain access to infected areas, which may be confused with skin picking disorder. Excessive cleansing or use of irritant products can also cause skin damage, leading to other dermatological conditions that reinforce the patient’s belief that something is medically wrong. During treatment, consider medications for relief of pruritus or pain. Focus on offering patients the opportunity to express their concerns, treat them with empathy, avoid stigmatizing language such as “delusions” or “psychosis,” and refrain from contradicting them until a strong rapport has been established (Table 217).
Symptoms of DP can persist for months to years. Patients who fully recovered experienced a median duration of 0.5 years until symptom resolution, compared to incompletely recovered patients, who took approximately 1 year.18 Primary DP has slower improvement rates compared to secondary DP, with the median onset of effects occurring at Week 1.5 and peak improvements occurring at Week 6.16
OUTCOME Continued ED visits
Unfortunately, Mr. H does not follow through with his outpatient psychiatry appointments. In the 7 months following discharge, he visits the ED 8 times for alcohol intoxication, alcohol withdrawal, and methamphetamine abuse, in addition to 2 admissions for inpatient detoxification, during which he was still receiving the same scheduled medications (haloperidol 15 mg/d and quetiapine 200 mg/d). At each of his ED visits, there was no documentation of DP symptoms, which suggests his symptoms may have resolved.
Bottom Line
Because delusional parasitosis symptoms feel real to patients, it is crucial to build rapport to recommend and successfully initiate treatment. After ruling out nonpsychiatric etiologies, consider traditional treatment with antipsychotics, and consider medications for relief of pruritus or pain.
Related Resources
- Sellman D, Phan SV, Inyang M. Bugs on her skin—but nobody else sees them. Current Psychiatry. 2018;17(8):48,50-53.
- Campbell EH, Elston DM, Hawthorne JD, et al. Diagnosis and management of delusional parasitosis. J Am Acad Dermatol. 2019;80(5):1428-1434. doi:10.1016/j.jaad.2018.12.012
Drug Brand Names
Buprenorphine/naloxone • Suboxone
Haloperidol • Haldol
Hydroxyzine • Vistaril
Lithium • Eskalith, Lithobid
Methylphenidate • Concerta
Olanzapine • Zyprexa
Permethrin • Elimite
Phenobarbital • Solfoton, Tedral, Luminal
Pimozide • Orap
Quetiapine • Seroquel
Risperidone • Risperdal
Sertraline • Zoloft
Valproic acid • Depakote
1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed, text revision. American Psychiatric Association; 2013.
2. Bailey CH, Andersen LK, Lowe GC, et al. A population-based study of the incidence of delusional infestation in Olmsted County, Minnesota, 1976-2010. Br J Dermatol. 2014;170(5):1130-1135. doi:10.1111/bjd.12848
3. Kohorst JJ, Bailey CH, Andersen LK, et al. Prevalence of delusional infestation-a population-based study. JAMA Dermatol. 2018;154(5):615-617. doi:10.1001/jamadermatol.2018.0004
4. Freinhar JP. Delusions of parasitosis. Psychosomatics. 1984;25(1):47-53. doi:10.1016/S0033-3182(84)73096-9
5. Reich A, Kwiatkowska D, Pacan P. Delusions of parasitosis: an update. Dermatol Ther (Heidelb). 2019;9(4):631-638. doi:10.1007/s13555-019-00324-3
6. Berrios GE. Delusional parasitosis and physical disease. Compr Psychiatry. 1985;26(5):395-403. doi:10.1016/0010-440x(85)90077-x
7. Aizenberg D, Schwartz B, Zemishlany Z. Delusional parasitosis associated with phenelzine. Br J Psychiatry. 1991;159:716-717. doi:10.1192/bjp.159.5.716
8. Flann S, Shotbolt J, Kessel B, et al. Three cases of delusional parasitosis caused by dopamine agonists. Clin Exp Dermatol. 2010;35(7):740-742. doi:10.1111/j.1365-2230.2010.03810.x
9. Buscarino M, Saal J, Young JL. Delusional parasitosis in a female treated with mixed amphetamine salts: a case report and literature review. Case Rep Psychiatry. 2012;2012:624235. doi:10.1155/2012/624235
10. Elpern DJ. Cocaine abuse and delusions of parasitosis. Cutis. 1988;42(4):273-274.
11. Richards JR, Laurin EG. Methamphetamine toxicity. StatPearls Publishing; 2023. Updated January 8, 2023. Accessed May 25, 2023. https://www.ncbi.nlm.nih.gov/books/NBK430895/
12. Huber M, Kirchler E, Karner M, et al. Delusional parasitosis and the dopamine transporter. A new insight of etiology? Med Hypotheses. 2007;68(6):1351-1358. doi:10.1016/j.mehy.2006.07.061
13. Lipman ZM, Yosipovitch G. Substance use disorders and chronic itch. J Am Acad Dermatol. 2021;84(1):148-155. doi:10.1016/j.jaad.2020.08.117
14. Kenchaiah BK, Kumar S, Tharyan P. Atypical anti-psychotics in delusional parasitosis: a retrospective case series of 20 patients. Int J Dermatol. 2010;49(1):95-100. doi:10.1111/j.1365-4632.2009.04312.x
15. Laidler N. Delusions of parasitosis: a brief review of the literature and pathway for diagnosis and treatment. Dermatol Online J. 2018;24(1):13030/qt1fh739nx.
16. Freudenmann RW, Lepping P. Second-generation antipsychotics in primary and secondary delusional parasitosis: outcome and efficacy. J Clin Psychopharmacol. 2008;28(5):500-508. doi:10.1097/JCP.0b013e318185e774
17. Mumcuoglu KY, Leibovici V, Reuveni I, et al. Delusional parasitosis: diagnosis and treatment. Isr Med Assoc J. 2018;20(7):456-460.
18. Trabert W. 100 years of delusional parasitosis. Meta-analysis of 1,223 case reports. Psychopathology. 1995;28(5):238-246. doi:10.1159/000284934
1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed, text revision. American Psychiatric Association; 2013.
2. Bailey CH, Andersen LK, Lowe GC, et al. A population-based study of the incidence of delusional infestation in Olmsted County, Minnesota, 1976-2010. Br J Dermatol. 2014;170(5):1130-1135. doi:10.1111/bjd.12848
3. Kohorst JJ, Bailey CH, Andersen LK, et al. Prevalence of delusional infestation-a population-based study. JAMA Dermatol. 2018;154(5):615-617. doi:10.1001/jamadermatol.2018.0004
4. Freinhar JP. Delusions of parasitosis. Psychosomatics. 1984;25(1):47-53. doi:10.1016/S0033-3182(84)73096-9
5. Reich A, Kwiatkowska D, Pacan P. Delusions of parasitosis: an update. Dermatol Ther (Heidelb). 2019;9(4):631-638. doi:10.1007/s13555-019-00324-3
6. Berrios GE. Delusional parasitosis and physical disease. Compr Psychiatry. 1985;26(5):395-403. doi:10.1016/0010-440x(85)90077-x
7. Aizenberg D, Schwartz B, Zemishlany Z. Delusional parasitosis associated with phenelzine. Br J Psychiatry. 1991;159:716-717. doi:10.1192/bjp.159.5.716
8. Flann S, Shotbolt J, Kessel B, et al. Three cases of delusional parasitosis caused by dopamine agonists. Clin Exp Dermatol. 2010;35(7):740-742. doi:10.1111/j.1365-2230.2010.03810.x
9. Buscarino M, Saal J, Young JL. Delusional parasitosis in a female treated with mixed amphetamine salts: a case report and literature review. Case Rep Psychiatry. 2012;2012:624235. doi:10.1155/2012/624235
10. Elpern DJ. Cocaine abuse and delusions of parasitosis. Cutis. 1988;42(4):273-274.
11. Richards JR, Laurin EG. Methamphetamine toxicity. StatPearls Publishing; 2023. Updated January 8, 2023. Accessed May 25, 2023. https://www.ncbi.nlm.nih.gov/books/NBK430895/
12. Huber M, Kirchler E, Karner M, et al. Delusional parasitosis and the dopamine transporter. A new insight of etiology? Med Hypotheses. 2007;68(6):1351-1358. doi:10.1016/j.mehy.2006.07.061
13. Lipman ZM, Yosipovitch G. Substance use disorders and chronic itch. J Am Acad Dermatol. 2021;84(1):148-155. doi:10.1016/j.jaad.2020.08.117
14. Kenchaiah BK, Kumar S, Tharyan P. Atypical anti-psychotics in delusional parasitosis: a retrospective case series of 20 patients. Int J Dermatol. 2010;49(1):95-100. doi:10.1111/j.1365-4632.2009.04312.x
15. Laidler N. Delusions of parasitosis: a brief review of the literature and pathway for diagnosis and treatment. Dermatol Online J. 2018;24(1):13030/qt1fh739nx.
16. Freudenmann RW, Lepping P. Second-generation antipsychotics in primary and secondary delusional parasitosis: outcome and efficacy. J Clin Psychopharmacol. 2008;28(5):500-508. doi:10.1097/JCP.0b013e318185e774
17. Mumcuoglu KY, Leibovici V, Reuveni I, et al. Delusional parasitosis: diagnosis and treatment. Isr Med Assoc J. 2018;20(7):456-460.
18. Trabert W. 100 years of delusional parasitosis. Meta-analysis of 1,223 case reports. Psychopathology. 1995;28(5):238-246. doi:10.1159/000284934
