DAVIS--Those who chronically complain about bugs biting them and burrowing beneath their skin, may have what is known as “delusional infestation,” a syndrome caused by a medical condition, prescription drugs, or the use of such illicit drugs as methamphetamine, heroin or cocaine, says Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at the University of California, Davis.

Delusional infestation is linked to a wide variety of conditions, ranging from AIDS, alcoholism, diabetes, cancer and Parkinson's disease to medications and drug abuse, said Kimsey, author of a newly published paper in Acta Dermato-Venereologica, an international peer-reviewed journal for clinical and experimental research in the field of dermatology and venereology. 

 “Delusional infestation, delusional parasitosis, Morgellon's or Ekbom's syndrome are all names for a disorder where sufferers feel itching, crawling and pinching sensations (paresthesia) that may become chronic,” she wrote. “These individuals believe they are infested with parasites, yet no parasites can be found.”

 “Delusional infestation is a symptom,” she said, “not a disease.”

 Kimsey, who has been researching delusional infestation for more than two decades, described chronic pruritus or chronic itching as “an itch that persists for six weeks or longer. It is a major symptom in a diversity of diseases and health issues.”

Some blame the itching on “no-see-ums,” or tiny valley black gnats that feed on blood. “But no-see-ums are very regional,” Kimsey said, “and really seasonal in most places, and they most decidedly don't go indoors.”

In her review article, Kimsey lists medical conditions reported to cause chronic itching, pinching sensations and delusional infestations. They include AIDS/HIV, alcoholism, autoimmune disease, cancer, cholestasis, diabetes mellitus, hepatitis, hyperthyroidism, Lupus erythematosus, renal failure, stress, and stroke, as well as meth, heroin and cocaine use.

She said that some of the most commonly prescribed U.S. drugs and side effects that can cause skin sensations, but no physical changes, include antibiotics, analgesics, antidepressants, and medications for hypertension, angina, gastric ulcers, and diabetes.

Kimsey defines “delusional infestation” as the “mistaken belief that the skin and often other parts of the body are infested by parasites. The reported identification of these parasites ranges from insect groups, usually flies or Strepsiptera (commonly called twisted-wing parasites), to mites, nematodes, ‘worms' or even new and unknown types of organisms.”

They have usually suffered for months or longer, she said, “and have seen numerous specialists ranging from dermatologists to entomologists. They come from a variety of occupational and socioeconomic backgrounds, generally possess average or above average intelligence, and generally lack a fear of insects…They often engage in self-mutilation, which can range from scratches to deep ulcerations, in their attempt to dig out the parasites. Unfortunately, the delusion may also result in the use of home remedies, a distrust of prescription drugs and doctors, and exposure to potentially dangerous levels of pesticides and cleaning products, such as bleach.”

In one study, the Centers for Disease Control found the syndrome in 3.7 Kaiser Permanente health care patients per 100,000 in central California. Using that statistic, Kimsey calculated that some 9300 residents of the United States may have delusional infestation. But it is likely much higher, she said, due in part to the growing use of illegal drugs.

The United Nations Office on Drugs and Crime estimated the worldwide production of amphetamine-type stimulants, which includes methamphetamine, at nearly 500 metric tons a year, with 24.7 million abusers. Latest U.S. statistics (2008) indicate that 13 million people over the age of 12 have used meth and 529,000 are regular users.

Meth addicts commonly report bugs crawling under their skin, or what the medical and scientific communities label as “meth mites.”

In reality, only a few groups of insects “live entirely in or on human skin in some life stage, including lice, tunga fleas and maggots,” the UC Davis entomologist said. “Then there are the free-living blood-feeders, including adult flies (mosquitoes, blackflies, sandflies and horseflies), kissing bugs, bedbugs and fleas.” Most of these bugs just simply feed and leave, she said.

Some of the sufferers blame the medical and scientific communities for failing to research a new bug or causal organism. “Anything new would be a tremendous discovery, but despite decades of searching, no one has found an actual organism associate with the syndrome,” said Kimsey, whose research included studying samples brought into the Bohart Museum. 

The delusional infestation may arise from an underlying physiological or physical cause that triggers an itch pathway, she said, and that itch pathway can also be “triggered by exogenous causes, such as drug use or abuse.” Underlying psychiatric conditions may also be linked to this pathway.

Treatment, Kimsey said, is “largely based on the patient's interpretation of the cause and the physician's response to that interpretation.”

“The bottom line is that it is a symptom, not a disease,” she reiterated.

 Related Links:

Delusional Parasitosis: What's Attacking Me? UC Statewide Integrated Pest Management Program (UC IPM)

Delusional Parsitosis Bohart Museum of Entomology