Delusional parasitosis

Delusional parasitosis is a condition in which a person has a fixed, false belief that they are infected by an organism despite evaluation not showing an infection to be present. This is also called delusional infestation. Morgellons disease is a form of delusional parasitosis.

By Mayo Clinic Staff

Delusional parasitosis is a condition in which people firmly believe that they're infested by parasites, mites, worms or other organisms even though a physical examination by a healthcare professional doesn't support this idea. The condition also is called delusional infestation.

One form of delusional parasitosis is Morgellons disease. Symptoms of Morgellons disease include the feeling that fibers are emerging from the skin. People with this condition often report feeling as if something is crawling on or stinging their skin. The intense itching and sores that come with delusional infestation can severely interfere with quality of life.


People who have delusional infestation report the following symptoms:

  • Skin rashes or sores that can cause intense itching.
  • Crawling sensations on and under the skin, often compared with insects moving, stinging or biting.
  • A belief that fibers, threads or black stringy material is in and on the skin.
  • Difficulty concentrating.
  • Depressed mood.

What about Morgellons disease?

One of the largest studies of Morgellons disease was done by the Centers for Disease Control and Prevention (CDC) in 2012. It found that the condition isn't caused by an infection or parasites.

This CDC study involved 115 people with Morgellons, which the CDC refers to as an unexplained dermatopathy. The study showed that most of the fibers in the skin sores could be explained by repeated itching and contamination by fabric fibers rather than fibers emerging from the skin. The study also noted that the condition is most often seen in middle-aged white women. The study found that the symptoms of Morgellons disease are very similar to those of a mental illness involving false beliefs about infestation by parasites. This condition is called delusional infestation. A 2012 European study of delusional infestation came to a similar conclusion. The study included a subset of people with Morgellons disease.

Small research studies have tried to determine the cause of and effective treatment for Morgellons disease. But there is still no proven guidance on diagnosis and treatment. Further study is needed.

The mainstream scientific consensus is that Morgellons disease is a form of delusional infestation. Some studies have suggested using the term Morgellons disease as it carries less stigma and may help forge a better patient-doctor relationship. Treatment may involve mental health therapy and medicine for delusions, anxiety or depression.

Coping with delusional parasitosis

The symptoms linked to delusional parasitosis can be distressing. People with this condition deserve compassionate treatment, even though healthcare professionals and patients may disagree about the nature of the condition. To manage the symptoms of the condition:

  • Establish a relationship with a caring healthcare professional. Find someone who acknowledges your concerns, does a thorough examination and talks through treatment options. It helps if your healthcare professional is part of a team of specialists from various fields.
  • Be patient. Your healthcare professional will likely look for known conditions that point to evidence-based treatments before considering a diagnosis of Morgellons disease.
  • Keep an open mind. Consider various causes for your symptoms and discuss your healthcare professional's recommendations for treatment — which may include long-term mental health therapy.
  • Seek treatment for other conditions. Get treatment for anxiety, depression or any other condition that affects your thinking, mood or behavior.

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April 09, 2024