Friday, September 11, 2009

Delusions of Parasitosis

Imagine, for a moment, that you have a crawling sensation on your arm. You scratch at the itch, and it seems to go away. A short time later it returns, and you find yourself scratching at it again. You examine your arm for the cause and find what look like small insect bites.
The next day, your arm is itching again. This time you cannot find relief, and your back begins itching as well. The itch distracts you throughout your day, and towards the end of the evening you ask a friend to look at your back. She says it is a bit red, but otherwise she doesn’t see anything. That night as you try to sleep, you feel something crawling across your skin. You turn on the light, but find nothing.

In the morning you find that you have scratched so much that whelps have scabbed over. Bits of white debris are on the spot where your arm itches. When you examine the debris closely, you see that it looks like tiny insects. You realize with a touch of horror that you are infested with some sort of bug. You place the carcasses into a small plastic container and make an appointment with your doctor.

You explain the situation to your doctor. He sees you scratching, sees the discomfort you are in. He examines you, and examines the bugs in the container. Unbelievably he tells you there is nothing wrong with you. “Those are not bugs at all,” he says. “It is bits of your skin.” He claims it is all in your mind.

Delusional Parasitosis (DP), also known as Ekbom’s Syndrome, was first described in the medical literature in the 1800s. Patients complained of parasitic infestation, however, no physical evidence of that infestation could be found. The infestation was, in fact, all in their minds. A delusion. A hallucination.

Patients with DP most often describe that insects are crawling, biting, and/or burrowing in their skin, although there have been reports of delusional intestinal parasitosis and DP of the oral cavity. In their delusion, many patients will actually “see” the parasite, and can describe, and even draw, the insect in great detail. Many will bring their physicians containers of matter they say is from the bugs. This behavior is so common that it is known as the “matchbox sign,” i.e. debris is carried to the doctor in a matchbox. Upon evaluation, however, the matter is often small bits of human skin or hair, or other fibers.

To rid themselves of the insects, patients will often impart in elaborate purification rituals, which often lead to self-mutilation. They may apply pesticides or disinfectants to the skin, and will often scratch themselves to bleeding. They may cut into the skin in an attempt to remove the parasites. One study describes a patient who tried to remove the parasites using a blowtorch. Changes in the skin, such as excoriation or lichenification, are typically observable, particularly on the scalp, face, and hands. Occasionally the condition leads to suicide.

Two variants of DP are described in the literature. Primary DP occurs in the absence of any underlying disorder. There is nothing wrong with the patient -- aside from the delusion. DP may also be secondary to other conditions, including schizophrenia, depression, and dementia, as well as other physical disorders, such as diabetes mellitus, renal insufficiency, hepatitis, vitaminB12 deficiency, multiple sclerosis, or leprosy. DP may also be induced via use of drugs, for example amantadine, anticholinergic agents, levodopa, and occasionally by some antibiotics, as well as recreational drugs, such as crystal methamphetamine and amphetamines. DP is so common among cocaine users that it is referred to as “cocaine bugs” by cocaine users.

Most DP patients share the following characteristics: (1) They are likely to exhibit slightly paranoid or obsessive-compulsive behaviors, (2) have difficulty expressing anger or hurt feelings, (3) have difficulties forming close relationships, and have limited social networks, (4) they may be predisposed to skin conditions which cause varied sensation responses, (5) they are likely to live in impoverished conditions, and (6) they may have underlying sexual impulses or thoughts which them deem to be “filthy” or “unclean.” Overall however, their mental status is stable.

Onset of DP has been reported following traumatic events (such as death of a loved one), after flooding of one’s home, travel, injury, and after contact with persons with an actual insect infestation (i.e., lice, scabies); however, DP does not necessarily include a recognizable precursory event.

DP takes a significant toll on the patient’s life. Patients will express significant concern about infecting others, and will take steps they feel will prevent this from occurring. Shared delusions, known as folie á deux or folie á famille, have been reported. Some studies suggest this phenomenon occurs in as many as 25% of DP cases. In this case, one or more household members of the DP patient reports infestation. Typically, the initial patient is the mother – who is often a dominating family force. They will often consult a number of different healthcare providers of many different specialties, as well as pest control professionals and entomologists. Ultimately, much time, money, and effort are expended in an attempt to get rid of the bugs. Frustration will mount, and feed into a perception that no one wants to help them. Despite the quest for assistance, however, DP patients generally refuse psychiatric intervention. The suggestion that the problem is one of the mind reinforces the aforementioned feelings of abandonment by the medical community.

A key issue in terms of treatment is the general refusal of DP patients to seek psychiatric help. The delusion is real to them – they truly believe they are infested with parasites – therefore to refer them for psychiatric evaluation is to further reinforce their belief that the healthcare practitioner does not care about their suffering.

The incidence of delusional parasitosis is difficult to determine due to lack of reporting and the variety of health care practitioners consulted. One study estimated seven in 10,000 psychiatric admissions were related to DP. A 2007 study of dermatologists found that 85% of the doctors in the study had observed patients at some point in their practice with DP.

In cases associated with substance abuse, patients are more likely to be young adults of marginalized socio-economic status. In contrast, DP patients without history of substance abuse are more likely to be over age 50. DP seems to affect older women at a higher rate than older men. A 1978 study of 57 DP patients described a mean age of onset at 64 years of age and a predilection for women (74%). Other characteristics included a history of mental retardation, folie á deux, underlying chronic disorder (such as dementia and diabetes) and additional underlying psychiatric disorders. Two of the patients in this study reported history of suicide attempt.

A 1983 survey of dermatologists also found that women were more likely to exhibit DP, particularly when over age 50. This survey also noted underlying chronic conditions such as diabetes and hepatitis, as well as psychological disorders, including depression and schizophrenia. A similar survey of dermatologists in 1986 found older women more likely to present with DP. This was supported yet again in a 1990 study in which 82% of the patients were women.

Seasonality has been described in the literature. One researcher conducted a long-term survey of telephone consultations of persons suspected of having DP with the Mississippi health department and cooperative extension offices. Over an eight year period, he found DP to be more prevalent during the late summer and early fall. Interestingly, most of the calls I have taken like this occur in the spring. The weather warms up and the DP cases increase.

It is important to rule out actual insect infestation or allergens before beginning other treatments, as well as to explore co-morbidities or behaviors (i.e. drug abuse) which may be causing the delusion (as in secondary DP). While a physical cause for the patient’s symptoms may not be found upon examination, the suffering of DP patients is intense, real, and clearly visible. Interviewing techniques that include empathy and relationship-building are repeatedly emphasized in the literature.

It has been suggested that many health care professionals who treat DP patients may not have the specific expertise to effectively manage the patient’s psychological needs, and dermatological training that covers psychodermatoses may be beneficial. For dermatologists and others who encounter DP patients in their offices, it is helpful to have an established relationship with a psychiatrist for referrals of patients willing to see one. In some instances, it may be possible for the psychiatrist to evaluate the patient in the dermatologist’s office. A liaison that can smoothly transition the patient between dermatological care and psychiatric care can also be beneficial.

Due to the negative side effects of neuroleptic DP treatments, health professionals may find it useful to determine which patients could develop insight into their condition over time. There is some discussion in the literature of patients presenting with “shakable” as opposed to “fixed” (true delusion) beliefs about the parasites. This is an important distinction in terms of treatment. Studies have demonstrated that some DP patients hold shakable beliefs, and will agree that they perhaps are not infested when presented with ample evidence to the contrary. For these patients, talk therapy, as well as treatment of any underlying disorder, is indicated. The therapist should empathize with the patient’s condition and accept that the patient truly is in distress; however, to agree that the patient is actually infested only furthers the delusion.
Material brought by the patient (the matchbox sign) should be examined. The therapist should explain what the specimen actually is (fibers, bits of skin, etc). The therapist should review the negative laboratory studies with the patient and explain their meaning, and remind the patient that no medical professional has been able to validate their claim. Patients with shakable beliefs, may, when confronted with enough evidence, accept that they are not infested. Some patients will continue with their delusion regardless of evidence presented.

DP is a condition which a variety of healthcare workers, public health professionals, veterinarians, and etymologists may encounter in their practice. The condition has significant impact on the lives of those who suffer from it. When confronted with a DP patient, a compassionate response is indicated. One should empathize with the patient without feeding in to the delusion, and demonstrate scientifically (when feasible) that there is no rational basis for their claim. Preexisting relationships with mental health providers may facilitate getting patients proper treatment and alleviating much suffering.


  1. My brother has been to several doctors, including an infectious disease doctor in Jackson, MS. He has the symptoms of Morgallon's and even brought research to this last doctor, who said it was internet "mumbo-jumbo". He is 40yrs old and the symptoms have been ongoing for several months. He believes he has an internal single cell parasite that moves around in his body, along with headaches, muscle cramps, swollen knees, ankles, a feeling of warm water running down the side of his face and tightness of the chest. He is on high blood pressure meds along with a beta blocker. How can we find someone to see him without discouraging him (even if this is mental, which I am unsure about)? I am also reseaching the effects of mold since some of his symptoms match this, too. Thank you for all of your information.

  2. Has he tried contacting the Morgellon's Research Center? They might be able to refer him to a physician in his area who could help. I agree with you that this is a difficult situation, especially when you don't know if there is a physical cause or not.