Delusional parasitosis

Overview

Delusional parasitosis, also known as Ekbom’s syndrome, is a rare psychiatric disorder in which a person has the false, unshakable belief that they are infested with parasites, insects, or bugs, despite no medical evidence supporting the claim. Individuals with this condition often report sensations of crawling, biting, or stinging on or under the skin (formication) and may go to great lengths to eliminate the perceived infestation. It is classified as a delusional disorder, somatic type, and can significantly impair a person’s daily functioning and quality of life.

Causes

The exact cause of delusional parasitosis is unknown, but it is believed to result from a combination of psychiatric, neurological, and possibly dermatological factors. Common causes and contributing factors include:

• Primary psychiatric illness: Schizophrenia, delusional disorder, or severe depression.

• Neurological conditions: Dementia, Parkinson’s disease, stroke, or brain injuries.

• Substance use: Chronic use of cocaine, amphetamines, or alcohol withdrawal can trigger similar symptoms.

• Medical illnesses: Diabetes, vitamin B12 deficiency, or thyroid dysfunction may cause sensations misinterpreted as infestation.

• Social isolation or stress: Loneliness, anxiety, or major life changes can contribute to or worsen the condition.

Symptoms

People with delusional parasitosis firmly believe they are infested with living organisms, often accompanied by physical sensations. Key symptoms include:

• Persistent belief in infestation: Despite clear medical evidence to the contrary.

• Formication: Sensations of crawling, biting, or stinging under the skin.

• Self-inflicted skin damage: Scratching, picking, or using chemicals to “remove” parasites, often leading to wounds or infections.

• Presentation of “evidence”: Patients may bring samples of skin, hair, or debris (known as the “matchbox sign”) to prove infestation.

• Anxiety and obsessive behaviors: Constant checking, cleaning, or disinfecting of the skin and environment.

• Social withdrawal: Fear of infecting others or being judged.

Diagnosis

Diagnosis of delusional parasitosis is challenging, as affected individuals often seek help from dermatologists or pest control professionals rather than mental health providers. Key steps in diagnosis include:

• Clinical evaluation: Detailed history of symptoms, medical background, and mental status examination.

• Physical examination: Typically reveals excoriated skin lesions, but no signs of true parasitic infection.

• Laboratory tests: To rule out actual parasitic infestations, nutritional deficiencies, or systemic illnesses.

• Psychiatric assessment: Helps identify underlying mental health conditions and confirms the presence of somatic delusions.

• Differential diagnosis: Important to distinguish from actual infestations (e.g., scabies), tactile hallucinations due to substance use, or dermatologic conditions.

Treatment

Treating delusional parasitosis requires a delicate, multidisciplinary approach, often involving dermatologists, psychiatrists, and primary care physicians. Key treatment strategies include:

• Antipsychotic medications: Atypical antipsychotics such as risperidone, olanzapine, or aripiprazole are commonly used and often effective in reducing delusional thinking.

• Cognitive Behavioral Therapy (CBT): May help address false beliefs and improve coping strategies, especially in motivated patients.

• Treatment of underlying conditions: Managing comorbid psychiatric or neurological disorders, or discontinuing causative substances if applicable.

• Supportive care: Establishing a therapeutic alliance, validating the patient's distress, and gradually introducing psychiatric referral without confrontation.

• Wound care: Treating secondary skin infections or damage caused by self-manipulation.

Prognosis

The prognosis for delusional parasitosis varies. Some patients respond well to antipsychotic treatment and psychotherapy, particularly if they are willing to engage with psychiatric care. However, many individuals lack insight into their condition, making treatment adherence difficult. Without treatment, the disorder may become chronic and lead to ongoing distress, social isolation, or physical harm due to persistent skin damage. Early intervention, patient trust, and a nonjudgmental, multidisciplinary approach are key to improving long-term outcomes.