Delusional Parasitosis: The Delusion of Infestation

Delusional Parasitosis: The Delusion of Infestation

Delusional parasitosis is an uncommon psychotic disorder. A person who has delusional parasitosis erroneously believes that he or she has a parasitic infection. But this is not the case – they’re not infected by any kind of parasite.

Another name for delusional parasitosis is the delusion of parasitosis or Ekbom syndrome. A parasite does no good to its host. It depends on the host for survival. Examples of parasites are fleas, worms, mites, spiders, and lice.

A person who has delusional parasitosis has a hard time controlling or stopping these thoughts. It is not their fault that they believe they have a parasitic infection.

What are the types of delusional parasitosis?

There are three major types:

Primary delusional parasitosis

The affected individual has a single delusional thought. It is a one-symptom or monosymptomatic illness.

Secondary delusional parasitosis

The affected individual has other mental disorders such as dementia, depression, bipolar disorder, schizophrenia, and post-traumatic stress disorder.

Organic delusional parasitosis

This can manifest in people with underlying illnesses or conditions, like diabetes, hypothyroidism, heart disease, cocaine addiction, vitamin B-12 deficiency, and menopause.

Symptoms of delusional parasitosis

A person who is experiencing delusion of infestation would always consult a dermatologist or doctor for treatment, convinced that they have a parasitic infection on their skin or body.

No symptoms exist apart from the delusion that you are infected with. Some patients may also think that they have this parasite in their furniture, surroundings, or home.

Another symptom that usually presents in people with the delusion of infestation is formication. Formication is a medical term that describes a crawling feeling on the skin.

Others may have symptoms such as:

  • Feeling of numbness
  • Itchiness or a burning feeling
  • A prickling or crawling feeling under the skin
  • Picking at the skin
  • Scratching at the skin
  • Scrubbing the skin with chemicals
  • Excessive scratching resulting in ulcers or skin lesions
  • Self-mutilation in extreme cases

What causes delusion of infestation?

Scientists do not know the cause of this disorder. The delusion of infestation is most common in middle-aged or old women. Nevertheless, it can affect both women and men of any race and age.

Sometimes, this condition may occur due to a chemical imbalance in the brain. Most cases of chemical imbalance are associated with attributed to addiction or drug use.

Where this condition precisely occurs is not known. Studies suggest that dopamine has a role in psychosis. Chronic stress can also trigger the excessive secretion of dopamine in the brain.


If you think that you’re affected by this condition, then see your doctor. They will most likely do a physical examination. They may also order blood tests. The goal is to rule out other factors that may cause crawling, skin itching, numbness, and other similar symptoms.

Other conditions that may contribute to delusional parasitosis include:

  • Thyroid disease
  • Anemia
  • Lymphoma
  • Kidney disease
  • HIV infection
  • Louse infection
  • Nerve disorders
  • Alcohol misuse
  • Medications (methylphenidate, amphetamines)
  • Fibromyalgia
  • Parkinson’s disease
  • Dermatitis herpetiformis
  • Drug misuse

Treatment for the delusion of infestation

Treatment for this condition includes treating any underlying condition. If there is a health trigger, then it is important to treat that trigger. Doing so can ease or completely stop the parasitosis.

Your doctor may prescribe some antipsychotic medications for you. However, it is most likely that the patient will refuse this medication because they erroneously believe that they have a parasitic infection instead of a mental health problem.

It is also important that you talk with a trusted psychiatrist. The reason is that many dermatologists and doctors are not familiar with the medications for such conditions.

A psychiatrist may recommend medications such as:

  • Aripiprazole
  • Pimozide
  • Olanzapine
  • Risperidone

Note that it is very difficult to talk to people with this condition out of the condition. The best that you can do is refer them to a psychiatrist.

Outlook for delusional parasitosis

Treatment may take time considering that it is a mental condition. The patient will also need to make many visits to doctors and psychiatrists. Also, the doctor may need to combine several treatments as one kind of treatment may not be effective for everyone with this condition.

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