Column: Creepy Crawlies, Part II

Any scientist who works with parasites knows about the “matchbox sign.”

The scientist is contacted by a stranger, given a small container – like a matchbox – and asked to identify the organism inside.

But the matchbox is empty.

The “matchbox sign” is a clue that a person suffers from a mental illness called delusional parasitosis (DP). This means that a person imagines having a parasite infestation, but the parasites are not real.

Alcohol and drug abuse can trigger DP, but the cause of DP is often unknown. DP can be a symptom of a secondary mental illness like schizophrenia. It can also stand-alone in the mind of an otherwise rational person.

According to a paper published by the Society of Vector Ecology, a sad or stressful event can result in an episode of DP.

“One case involved the death of a pet dog, and another case involved a mother-in-law’s visit,” wrote the researchers.

Anyone who has seen Arachnophobia knows that creepy-crawly skin sensation, but the mind of a person with DP turns a normal phenomenon into a complicated delusion. People will DP will blame respiratory and intestinal pain on parasites. Skin lesions are common in DP patients who use needles or knives to try to dig out the parasites.

The cure

About once a month, Dr. Steve Nadler, chair of the Nematology Department at UC Davis, gets a call or e-mail from a person with DP who wants him to analyze parasite specimens.

This exchange puts Nadler in an awkward position – he wishes he could help the person, but he legally can’t.

“I always tell them that a professor at UC Davis cannot accept a specimen from a patient and make a diagnosis,” Nadler said.

Yet they keep coming to him.

DP sufferers often complain that physicians are ignorant of parasites – physicians don’t know enough to take parasite infestations seriously, they say. This frustration leads DP patients to contact parasite experts like Nadler.

While physicians do investigate parasites, the accusation by DP patients is partly true. Nadler said that when he worked in parasitology courses at the Louisiana State University Medical Center, the class spent several months on parasites. Many programs today spend only weeks. Contemporary physicians know less about parasites, and this can result in two problems: either they mistake DP for a true parasite infestation or they dismiss a real infestation for DP.

According to the report from the Society of Vector Ecology, “One entomologist reported a case where a client was told by her physician that she was mentally imbalanced only to discover that she was actually infested with scabies.”

Anecdotes like this show why DP sufferers are suspicious of traditional medicine. Unfortunately, the “alternative medicine” scene is often a source of paranoia, not help.

A “holistic and alternative medicine” journal called The Secrets of Robust Health published a six-page article on parasites, headlined “Silent Killers.” The article is riddled with enough scientific language to make false information sound true.

“As amazing as this seems, according to statistics eight to nine out of 10 of us are infected with parasites,” writes the journal editor.

There is no source for these statistics, but the writer is quick to describe how his friends all discovered worms in their poop.

While humans can be infested by parasites like tapeworms or scabies, infection rates in the U.S. are low.

There are real cures for DP, but getting patients to cooperate is difficult.

The delusion seems so real that a patient sees no need for mental help. In a review of DP cases, tropical medicine expert Randolph Wykoff described a woman who visited 103 physicians and one veterinarian because she thought she had parasites. All she really needed was a psychologist.

According to research by psychotherapist Wolfgang Trabert, if a doctor manages to get a DP patient to a psychologist, there is about a 60 percent rate of recovery.

The delusional biologist

A few years ago, Nadler was contacted by a retired invertebrate biologist from Santa Rosa who believed he had discovered a new microscopic lungworm. The biologist had taken hundreds of photos of the lungworms with a specially modified microscope. Nadler looked at the photos and thought the “worms” looked like small fibers, not animals.

The biologist had been diagnosed with chronic fatigue syndrome (CFS). He thought the lungworm was connected to the condition. A parasite infestation would be a comforting delusion to help explain a mysterious illness like CFS.

Nadler hoped to use science to help the biologist see reason. Nadler ran DNA tests on the supposed worms and found nothing. Still, the biologist was convinced he had discovered a new species.

I talked to the delusional biologist to hear his side. He explained that the lungworm is not easily identified as a worm because it’s unique anatomy and outer cuticle makes it hard to extract DNA. The biologist was excited that his photos showed worm anatomy.

“The thing that stands out, that looks most like nematodes [worms], are the male reproductive structures,” he said.

Nadler said the photos are too blurry to show anatomy. The worm photos are like UFO photos: just blurry enough that the shapes could be anything. You could see a worm or a carpet fiber, depending on what you’re looking for. Unfortunately for the biologist, the scientific evidence does not point toward worms.

The biologist is a friendly, highly educated man, but his delusion isolates him from the scientific world he loves. He recently gave a talk at the University of Texas about his worm research, but his fellow scientists dismissed the microscope pictures and told him to come back with DNA evidence. The biologist couldn’t believe that they didn’t recognize the worm that he knew so well.

“Even my wife could see it,” he said, “and she’s not a trained biologist.”

MADELINE McCURRY-SCHMIDT had a dream once that caterpillars were crawling on her face. Freaky. E-mail her column ideas at memschmidt@ucdavis.edu.

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