|
Illusory
and Delusory Parasitosis
by
Barb Ogg, Ph.D., Extension Educator
Some
people encounter "bites," itching, or skin irritations thought
to be caused by insects but for which no insects can be identified.
Illusory parasitosis is one name used to describe bite-like
symptoms caused by non-animal environmental factors. Names that
people have invented for the nonexistent arthropods assumed
to be the cause of the bites are "paper mites," "sand fleas,"
and "cable mites." There are no such insects. There is
an arthropod named the "house dust mite," but these very small
mites do not bite people, but feed on sloughed skin cells and
other organic debris. When dust mites die, their bodies disintegrate
into very small particles. Persons who have allergic sensitivities
may experience an allergic reaction to the fine particles; the
most typical reaction is asthma rather than skin irritations.
There
are only a few biting insects that produce skin reactions, and
these are large enough to be seen and readily identified. Biting
pests most commonly encountered include fleas, head lice, ticks,
bat bugs, and mosquitoes. Bed bugs and body lice are relatively
uncommon in the U.S. In Nebraska, there were only three documented
cases of bedbug bites in 1992; no cases of body lice have occurred
in recent memory.
Occasionally,
people claim that they are being bitten by microscopic bugs.
These claims prove to be mites carried by pet cats or pesty
rodents or birds (usually pigeons) that live in or near the
homes of these unfortunate people. Because humans are not the
usual host animal, the problem is controlled by removing the
rodent or bird infestation or having the cats treated by a veterinarian.
The
only mites that infest humans are called scabies mites which
cause dermatitis. Dermatitis from scabies mites is almost exclusively
found on the hands, wrists, feet, ankles, and elbows and is
most likely a problem with older sedentary persons. Nursing
homes sometimes may have to deal with infestations of scabies
mites. Scabies mites are identified and treated by a dermatologist
who prescribes medicated ointment and lotion.
There
is a long list of potential causes for "biting" sensations or
skin irritation not caused by insects. The cause may be physical,
physiological, psychological or combinations of these factors.
Physical
factors may include dry air; static electricity; household or
personal products like disinfectants, detergents, cosmetics,
or jewelry. Environmental pollutants also may cause skin irritation.
These pollutants include microscopic fibers like fiberglass
or paper splinters. In addition, indoor air pollution can cause
"sick or tight-building syndrome."
Physiological
factors include sensitivity (i.e., allergies) to any of the
above physical factors. One should be aware that skin sensitivities
and allergies may change as we get older and our skin changes.
There also may be diseases and disorders such as diabetes or
neurological disorders such as shingles that may result in skin
problems.
Some
individuals may experience a heightened psychological state
related to stress in their lives from increased anxiety, anger,
and nervousness. Occasionally these persons may believe skin
irritations are caused by insect bites, but the biting insects
cannot be found. If environmental factors are not the cause
of the dermatitis, the person may be suffering from delusory
parasitosis. Delusory parasitosis is "an erroneous, unshakable
belief that the skin is infested with some parasite." When asked
to describe the so-called parasite (i.e., insect), persons suffering
from this malady often give similar descriptions of these "imaginary"
parasites. They are usually "microscopic"; they often "change
color" so they cannot be seen or caught easily. Sometimes they
"disappear" when a person tries to catch them. Some persons
may think the imaginary insect "lives in their skin pores" ;
others may see "maggots coming out of their skin." Persons suffering
from delusory parasitosis have a serious psychological disorder
and might benefit greatly from counseling with a capable psychotherapist.
These individuals may seem to be normal in other respects.
Obviously,
entomologists are not the appropriate specialists for diagnosis
of causes of dermatitis other than those caused by insects.
Persons suffering from skin irritation of unknown cause should
work closely with a dermatologist or allergist. If there is
a history of psychological stress, consultation with a psychologist
or psychiatrist may be helpful.
Repeated
application of pesticides or disinfectants to the premises or
body does not cure illusory or delusory parasitosis but may
be a cause of further skin irritation and allergies.
updated
May 29, 2002
 Return
for more information on Miscellaneous
Insects and Animals
|
