The Problems with Delusional Parasitosis

It has been estimated that a dermatologist will see one patient with true delusional parasitosis in every seven years of practice (A. Lyell, The Michelson Lecture, Delusions of parasitosis, Br. J. Dermatol. 1983; 108:485).

The following definition is from Wikipedia:

Delusional parasitosis (also known as "Ekbom syndrome," and delusions of parasitosis) is a form of psychosis whose victims acquire a strong delusional belief that they are infested with parasites, whereas in reality no such parasites are present. Very often the imaginary parasites are reported as being "bugs" or insects crawling on or under the skin; in these cases the experience of the sensation known as formication may provide the basis for this belief.

The condition was first described by a Swedish neurologist named Karl Axel Ekbom in 1938. He also was first to describe a condition called “Restless Leg Syndrome,” also confusingly named “Ekbom Syndrome,” in 1945. And that’s all you can find out about his life and career on the web – unless you’re a medical professional. Try googling him. Or Wikipedia.

Ekbom described the typical sufferer as usually a middle-aged woman (who insists she can feel insects crawling around in her anus) or as a drug addict. This despite the fact that scabies mites will readily infest the anus.

More than anything else, the thing that dermatologists and psychiatrists look out for is called the “matchbox sign.” This is where a patient with unexplained symptoms will gather bits of lint, dirt, hairs, skin detritus, and anything that looks strange in a matchbox and present them to the doctor to check out. This, by itself, is taken as proof of delusional parasitosis. The contents of a typical “matchbox” are shown immediately below:

Delusory Parasitosis Ryan Davis Utah State University-50%
Typical “matchbox” sample submitted by a DP sufferer. Image from Utah State University.

Lint 1 (flea pupae)Lint 2 (flea pupae)-24%
Lint? Dirt? No, cocoons containing flea pupae. Image left from
Image right by Prof
Marcelo de Campos Pereira, University of São Paulo.

Another proof you have delusional parasitosis is if you insist that you don’t.

I believe that no sane human being would ever say “Yes, doctor, you’re right – I am delusional” on receiving this diagnosis. If they did, you know you’re dealing with someone who is mentally ill.

I always thought science was based on keen observation, logic, and insight.

But this is straight out of Kafka.

It demonstrates no logic whatsoever and a profound lack of understanding of human nature.

Most people, at some stage in their lives, will have, or know others who have or had, problems with fleas. Likewise with bedbugs and scabies. If they contract a problem with some unknown entity biting or making them itchy, they’ll look for fleas, bedbugs, or scabies signs. Not finding any, it is entirely natural and normal to go looking for odd things that might be unusual insect larval forms, exuviae, or egg-cases to present to the doctor treating them, both to help him and to help themselves.

According to Ekbom, performing this simple and meant-to-be-helpful act makes you a psychotic. I’ve been unable to find out whether he took account of the possibility of secondary hosting (where a pest cannot locate its primary host but must settle for a different species instead – in this case, me).

The other “proof” is so ludicrous it simply defies comment.

There’s more: if a relative of the sufferer, usually the spouse, also contracts the problem, this, too, is taken as a variant called delusional parasitosis folie á deux. Which basically means “You’re both nuts.” And it’s even been extended to the doctor-patient relationship.

What’s in a name?

In this case, labelled as “physician-patient folie á deux,” a patient was “incorrectly diagnosed first with parasitic infestation and then with primary delusional parasitosis (DP). Neither diagnosis was correct. As she traveled from doctor to doctor, however, the primary DP label gained credibility via repetition, with her ongoing symptoms seen as proof of its truth.”

The International Journal of Dermatology reported a case in March, 2006 in which a patient was diagnosed with delusional parasitotis. Further investigation revealed that the unfortunate woman was actually infested with Limothrips cerealium, (an insect that mainly lives around grain growing and storage areas). It is labelled as “pseudo-delusory syndrome.” That is, infestation by an uncommon insect.

But do you see what they labelled these cases? Why not call them what they really are: wrong diagnosis.

In 2000, some 20 individuals diagnosed with delusional parasitosis were selected from hundreds who applied for a study by the National Pediculosis Association and the Oklahoma State Department of Health. Repeated and exhaustive examination of their skin specimens revealed the presence of Collembola (Springtails) in18 of the 20.

And up until fairly recently, many doctors believed the Human Botfly was a mythical creature.

The times they are a-changin’

The only difference between swine ‘flu virus and an exotic insect pest is one of scale. Irish hospitals and nursing homes employ many wonderful staff from countries all over the world, countries whose insect pests and perils are very different to those native to Ireland. And since holidays today are taken in more exotic locations, patients and visitors can also bring in unwelcome and virtually invisible guests.

Dermatologists today have an awful lot more to consider than they used to. They now have to think about more than just fleas, bedbugs, lice, and scabies, the primary human skin parasites.

But thanks to the “roadblock” of this ludicrous delusional parasitosis diagnosis, most dermatologists rarely even consider the possibility of secondary hosting or exotic insect pests. Not to mention the scientific fact that changes in human body chemistry can cause an insect like demodex to change its lifestyle from commensal to parasitic.

They’re still stuck back in 1938.

And that suits them just fine. Because insects just don’t make for sexy medicine.

How Delusional Parasitosis Should be Diagnosed

Quoted from the Bohart Museum of Entomology, here’s how the diagnosis should be made, with my own experience in italics:

Diagnosis and treatment of delusional parasitosis is challenging and requires great patience. Early on in the diagnosis, it is essential that a trained entomologist or parasitologist be consulted to rule out the presence of actual parasites.
Not done by either dermatologist.

1. Take careful and tactful case histories.
Done by both dermatologists.

2. Run appropriate diagnostic tests to rule out other medical conditions. (In the case of secondary organic delusional parasitosis the delusion often disappears when the underlying organic illness is treated.)
Dermatologist A had access to my prior medical records. Apart from that, this was not done by either doctor.

3. Do a complete physical examination and laboratory evaluation, including: skin scrapings and biopsies, complete blood count, chemistry profile, thyroid function tests, and vitamin B12 levels.
I received a biopsy of an old flea bite from Dermatologist A; none of the rest of this list was done.

4. Rule out true infestations.
I don’t consider that this was done by either doctor since high magnification is required to see the plugs and filaments (as you’ll see in the galleries).

5. Rule out other organic causes such as allergies or contact dermatitis.
Contact dermatitis may have been ruled out without informing me but neither doctor tested me for allergies.

6. Determine whether there is a history of drug abuse.
I volunteered that I had smoked cannabis in my teens and early twenties and also researched a proposed reference book in 1977 that involved testing the effects of various drugs. Since then, in light of my earlier experience with iatrogenic Valium addiction, I have been drug-free (including, where possible, prescription drugs). In my desperation I did, however, try cannabis again recently to see if it would help my sleep problem. It did for a few nights, then stopped working. So, no point continuing with that.

Irish dermatologists obviously do things differently.
Read on to continue the story...