What is Ekbom’s syndrome?

Ekbom’s syndrome, also known as delusional parasitosis, is a rare psychiatric disorder in which individuals have a persistent delusional belief that they are infested with parasites, insects, or other organisms. Despite lack of medical evidence, they believe bugs are crawling in or on their skin. Ekbom’s syndrome is challenging to treat, as patients firmly hold to their delusional beliefs. However, with psychiatric help and medication, remission is possible.

What are the symptoms?

The main symptom is a firmly-held delusional belief of parasitic infestation, despite lack of medical evidence. Additional symptoms may include:

  • Pruritus – severe itching, often focused on one area such as the scalp
  • Excoriations – skin lesions from repetitive scratching
  • Dermatitis – inflammation of the skin from rubbing or scratching
  • insomnia and anxiety due to discomfort
  • “Matchbox sign” – collecting debris or fibers from skin as “proof” of infestation
  • Social isolation out of fear of spreading “bugs” to others

Patients may insist they feel crawling, stinging, or movement under their skin. They may report seeing the parasites, often describing them as insects, worms, fibers, sand, or other organisms. Patients will go to extreme lengths to eradicate the perceived infestation, causing skin damage.

What are common delusions?

Ekbom’s patients often have very detailed delusional descriptions. Common delusions include:

  • Bugs, ants, worms, or parasites are crawling under, on top of, or out of the skin
  • Fibers or filaments are emerging from skin lesions
  • Insects are breeding in the skin and body
  • The infestation was transmitted by bugs jumping from furniture or carpets onto the skin
  • The infestation came from contaminated food or exposure to insects
  • Government entities have implanted devices under the skin which attract the bugs
  • Pharmaceutical companies or doctors are responsible for the bugs
  • Romantic partners or family members are intentionally infesting them with parasites

Patients often bring in samples of “bugs” such as skin flakes, scabs, lint, or household debris. No matter how diligently doctors examine samples, patients remain adamant that bugs exist.

How does Ekbom’s syndrome start?

Onset is usually gradual and takes place in stages:

  1. Sensory stage – burning, stinging, itching, tingling, or crawling sensations under the skin. Medical exam is normal.
  2. Somatic stage – picking at the skin in response to pruritus. Patients believe something is in the skin. Lesions start appearing.
  3. Delusional stage – firmly fixed belief that bugs are present despite lack of evidence. Patients may collect debris as proof of infestation.

During this progression, patients become convinced they are infested, despite reassurance from doctors. The tactile hallucinations become a delusional belief that cannot be altered.

Who is at risk for Ekbom’s syndrome?

While rare, certain factors increase risk:

  • Age – Most common after age 40, average onset is 62.
  • Sex – Slightly more common in women.
  • Drug use – Chronic stimulant or hallucinogen use can trigger symptoms.
  • Mental illness – A pre-existing psychiatric disorder is present in up to 75% of cases.
  • Physical illness – Diseases causing itching can precede delusions.
  • Isolation – Social isolation tends to exacerbate symptoms.
  • Genetics – Family history of delusional disorders increases risk.

Up to 25% of patients have no underlying psychiatric illness, indicating Ekbom’s can arise on its own. However, a personal or family psychiatric history increases vulnerability.

How is Ekbom’s syndrome diagnosed?

Ekbom’s syndrome presents a diagnostic challenge. Doctors must rule out any medical condition which could genuinely explain sensations. A thorough workup may include:

  • Physical exam to identify skin lesions or parasites
  • Skin scrapings to analyze for scabies, fungi
  • Blood tests to check for medical causes of itching
  • Neurological exam to identify any nerve damage
  • MRI or CT scan of the brain if neurological causes suspected
  • Evaluation of living environment to identify any parasite exposures
  • Psychiatric evaluation and patient history to identify any mental illness

Once medical causes are definitively ruled out, Ekbom’s syndrome becomes the diagnosis of exclusion. The hallmark is an intractable delusional belief despite lack of evidence and medical reassurance.

How is Ekbom’s syndrome treated?

Treatment is challenging, as patients deny mental health factors. A combination approach is optimal:

  • Antipsychotics – Medications like pimozide or risperidone to reduce delusions.
  • Antidepressants – SSRIs may provide relief from depression and anxiety.
  • Psychotherapy – Talk therapy aimed at reducing patient isolation and challenging delusions.
  • Environmental changes – Reducing infestation triggers by removing carpets, repainting walls, applying pesticides.
  • Family therapy – Including loved ones in treatment to interrupt dysfunctional behaviors.

With ongoing treatment, 30-50% of patients experience remission of symptoms. Support groups can also provide community and validation. However, without treatment Ekbom’s tends to persist and may worsen over time.

What is the history behind Ekbom’s syndrome?

  • 1686 – Dry itch mite delusions reported in Germany
  • 1867 – French neurologist Thibierge describes acarophobia – irrational fear of mites
  • 1894 – Term delusions of parasitosis coined by Italian entomologist Canestrini
  • 1938 – Swedish neurologist Karl Axel Ekbom publishes seminal paper formally describing delusional parasitosis
  • 1946 – Syndrome named Ekbom’s syndrome
  • 2001 – Name updated to delusional parasitosis in DSM-IV psychiatric manual

Ekbom extensively documented patients’ delusional symptoms in his 1938 paper. He noted the strikingly vivid nature of their sensory hallucinations. His name became eponymous with the disorder.

How does Ekbom’s differ from actual parasitosis?

Ekbom’s syndrome is often confused with diagnosable parasitosis, where real parasites infect the skin:

Ekbom’s Syndrome Actual Parasitosis
No medical evidence of parasites Detectable parasites present
Symptoms are delusional beliefs Symptoms are caused by infection
Lack of insight into delusions Insight into real medical issue
Typically does not improve without treatment Resolves with anti-parasitic treatment

Doctors can distinguish Ekbom’s once they definitively rule out any parasitosis or dermatological condition. The key differentiator is a fixed, false belief of infestation.

What conditions are associated with Ekbom’s?

Ekbom’s overlaps with numerous psychiatric and medical conditions:

  • Delusional disorder – Ekbom’s is classified as a delusional disorder in DSM-5. Other forms involve delusions of persecution, jealousy, erotomania.
  • Schizophrenia – Tactile hallucinations and delusions may occur in schizophrenic patients.
  • Obsessive compulsive disorder – Obsessions about contamination may resemble Ekbom’s fears.
  • Major depressive disorder – Depression can create sensations of numbness, tingling, or burning.
  • Generalized anxiety disorder – Anxiety commonly produces tingling, crawling feelings.
  • Parkinson’s disease – Tingling and crawling sensations are common Parkinson’s symptoms.
  • Diabetes mellitus – Itching is a frequent effect of diabetes.
  • Kidney disease – Renal failure often causes severe uremic pruritus.
  • Liver disease – Hepatic conditions like cholestasis can result in itching.
  • Thyroid disorders – Diseases like hyperthyroidism create crawling skin.
  • Iron deficiency anemia – Low iron is linked to sensations of ants crawling over skin.

Doctors must investigate and eliminate possible underlying physical contributors before assigning an Ekbom’s diagnosis.

What is the prognosis for Ekbom’s syndrome?

Delusional disorders like Ekbom’s tend to run a chronic course with periods of remission:

  • Symptoms persist long-term without treatment in over 70% of patients.
  • Approximately 20-25% experience a spontaneous remission of symptoms.
  • With antipsychotics and psychotherapy, 30-50% go into remission.
  • 50% suffer a relapse after initial remission.
  • Higher premorbid functioning and family/social support improve outcomes.
  • Substance abuse and poor insight predicts lower remission rates.

While difficult to treat, with a combination of pharmacotherapy and psychosocial interventions, recovery is possible for a subset of patients. Early intervention offers the best prognosis before beliefs become entrenched.


Ekbom’s syndrome is a challenging condition characterised by an unrelenting delusional belief in parasitic infestation, despite lack of objective evidence. Caused by changes in brain circuitry, it is classified as a subtype of delusional disorder. With antipsychotics and therapy, the delusions can be reduced in some patients. However, Ekbom’s often runs a chronic course and requires persistence and understanding from doctors and family members. While remission can occur, the severity and bizarre nature of the delusions means recovery is difficult without thorough psychiatric treatment.

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