Review of types of Human Allergy Tests for Exposure or Sensitivity to Mold or Pet Allergens
InspectAPedia® -
Types of allergy tests for humans
Allergy tests for humans: a clear summary of allergy testing options
Accuracy of human allergy exposure or allergy sensitivity tests
Questions & answers about allergy tests and building allergen contamination
This article describes human testing for allergic sensitivity to animal, food, mold, insect, trees, grasses, and other possible environmental allergens and irritants. People who have tested as sensitive to allergens, others who have tested as "not sensitive" but who have building related complaints, and others often ask us how to test a building or home for mold, or for cat, dog, or other animal allergens. At ALLERGY TEST ACCURACY we discuss the accuracy and limitations of these tests.
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Human Tests for Allergy Sensitivity or Tests for Exposure to Allergens
Skin Testing for Allergic Response, Allergies, and Allergic Exposure in Humans
The most common allergy test type performed on humans are skin tests to determine whether or not a person has or will have an allergic response to certain common allergens. Skin tests are quick, reliable, and less costly than blood tests and immunoassay tests discussed at ELISA and RAST. The doctor places a small amount of an allergen on or below the person's skin, using a needle prick, a small round scratch or scarifier, a tiny injection of substance below the skin, or a skin patch - a pad containing the allergen is taped to the skin for 24 hours or longer.
The physician (typically an allergist who specializes in allergies) "reads" the results of the skin test by noting the varying severity of skin reaction (swelling, reddening, itching) at each test site. When the author's cousin, Dr. Edward Friedman, a diplomate allergist, performed these tests on the website author (DJF), he used a round scarifier to make a field of about 12 test sites on the patient's arm, then placing a different test solution on each scratch spot. In less than an hour the variation in reaction among allergens was visibly obvious.
Accuracy of Skin Tests for Allergies, Including Mold Sensitivity or Mold Exposure Testing
Accuracy of skin testing for allergens is reasonably good, certainly sufficient for an allergist to decide on treatment (or environmental steps such as cleaning and avoidance of exposure to certain allergens). But here are some allergy skin test accuracy considerations readers should keep in mind:
False positive allergy test results: the intradermal (injection) test for allergies can produce false positive results, indicating an allergic response in an individual who has not previously reacted to that allergen in the environment.
False negative allergy test results: we have experience with these conditions that allergy sufferers or anyone who experiences respiratory or apparent indoor air quality complaints associated with spending time in a building:
Limited number of FDA-approved substances for allergy testing: according to Dr. Friedman, at the time of our allergy test experiments, the actual number of substances that are US FDA approved for use in preparation of allergy testing serums was quite small. For example, although there are about 1.5 million mold species, less than ten molds have been approved for use by physicians or drug companies for the preparation of mold testing serums.
While there are likely to be common chemical characteristics among many mold genera and species, making selected very common molds (an individual Cladosporium species, for example) useful in gauging reaction to a wider number of molds from the same mold genera or even among several genera of molds, a negative mold test result, having combined perhaps seven molds to make up the test, can hardly be taken as a guarantee that the individual is really not mold sensitive to any of the remaining 1,399,993 mold genera/species in the world.
Immunoassay Allergy Testing: ELISA and RAST Allergy Tests Humans for Allergen Exposure - The Basics
Here is some basic information about ELISA and RAST tests used on humans to look for exposure to animal allergens. These allergen tests are allergy blood tests designed to be performed on humans (or on animals themselves with even more inaccurate results), not on indoor building samples of dust or debris. Blood tests for allergies look for antibodies in the blood that are formed in response to the individual's exposure to allergens. According to WebMD and some other sources, blood tests for allergies are less sensitive than skin prick or scratch tests, but are used for people who must avoid skin tests for allergies.
ELISA "enzyme-linked immunosorbent assay" (also referred to as ELISA, EIA) is a rapid immunochemical test procedure that involves an enzyme (a protein that catalyzes a biochemical reaction) that tests for hormones, bacterial antigens, and antibodies. ELISA testing also involves an antibody or antigen (immunologic molecules).
The assay procedure is widely used, not just for allergens - even for drug use. MedicineNet provides a detailed definition of ELISA testing. ELISA are popular over RAST (below) probably because they don't require radioisotopes or a radiation-counting apparatus. ELISA tests are indeed quite sensitive and ELISA testing is specific to the particular allergens (or other exposures) under study. In accuracy, ELISA testing is similar in accuracy to radioimmune assay (RIA) tests.
RAST (radioallergoabsorbent testing) is an older allergen test (exposure detection) in popular use for testing humans, radioallergosorbent test, an IgE test: In this test, a sample of blood is taken, mixed with the suspected allergen, and the level of immunoglobulin E (IgE) is measured. IgE is an antibody produced by the immune system that indicates an allergic reaction.
Immunoassay capture testing (ImmunoCAP, UniCAP, or Pharmacia CAP) are other allergy tests used on humans to obtain additional allergy exposure and allergy sensitivity data.
The ELISA and RAST allergen exposure tests are performed on the individual, not on the environment that the individual has occupied.
If we're trying to determine which environment is more likely to be contributing to allergen exposure (dander and hair), a dust screen from that environment tells us what we need to know; testing the person who is suffering is pertinent to the physician and the treatment plan, but it does not identify the problem source - the location.
Example: we inspected and tested in an office where an employee complained of severe allergic responses - suspecting that there were animal allergens in the workplace. We collected dust from the workplace, and from her desk, chair, and clothing - nearly all of the animal dander (cats in this case) was on the employee's clothing - the employee was picking up the allergens somewhere other than in the workplace.
Accuracy of ELISA and RAST testing
Sheryl B. Miller and others have raised questions about the actual accuracy of ELISA test results and about the absence of a comparative standard.
Check With Your Doctor About Allergens and About Whether or Not Building Tests for Allergens or Mold are Recommended
Of course since individual sensitivity to allergens varies, we suggest that anyone suffering from allergies and considering steps to further clean their home should also consult with their allergist and their general physician.
Safety Warning: if indoor air quality complaints include respiratory distress, headaches, nausea, and similar symptoms, it is important to immediately rule out unsafe heating equipment, chimneys, flues, or carbon monoxide hazards. See
CARBON MONOXIDE - CO
The types, accuracy, and variability of human tests for allergy sensitivity and allergy or mold exposure are discussed further at ALLERGY TESTS.
The combination of allergy testing limitations and occupant complaints that may in some cases justify a building survey for physical particles or other evidence of significant levels of problem allergens, molds, or other conditions is discussed at ALLERGY TEST LIMITATIONS.
See MOLD EXPERT, WHEN TO HIRE for advice on determining when it is appropriate and justified to order inspections and tests of a building for mold or allergens.
See BIOLOGICAL POLLUTANTS for information about recognizing and removing these indoor contaminants.
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Additional technical contributors & reference sources for this article are listed below.
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MedicineNet.com provides a detailed definition of ELISA at www.medterms.com/script/main/art.asp?articlekey=9099
"IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Allergies, Allergens, Allergy Testing in buildings - References & Products
Allergen Tests in buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
"IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
Allergens: Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
Allergens: WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
Rodent control issues, including dander, fecal, and urine contamination of buildings and Building insulation are discussed at our
Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
Atlas of Indoor Mold, Online Clinical Mold Atlas, Toxins, Pathogens, Allergens and Other Indoor Particles - Medical Health Effects of Mold (separate online document)
Black Mold that is Harmless Photos of recognizable, usually harmless black mold on wood, bluestain, ceratocystis, ophistoma
Building Floods: quick steps after a building flood or plumbing leak can prevent costly mold contamination
Classes of Mold: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention Program for Certain Vegetable Crops," David B. Langston, Jr., Extension Plant Pathologist - Vegetables, University of Georgia (PDF document) original source: www.reeis.usda.gov/web/crisprojectpages/209797.html
"Disease Prevention in Home Vegetable Gardens,"
Patricia Donald,
Department of Plant Microbiology and Pathology,
Lewis Jett
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
US EPA: Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold
cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.
Ozone Warnings - Use of Ozone as a "mold"
remedy is ineffective and may be dangerous.
Pet control - if you can't say goodbye to your bird, cat, dog, guinea pig, hamster, tropical fish, then limit the
areas they occupy and limit the airflow from that area to sleeping or other areas of the building, use allergenic
bedding, eliminate wall-to-wall carpeting, improve housecleaning including use of a HEPA-rated vacuum cleaner. For more details
see our article Dog, Cat, and Other Animal Dander - Information for Asthmatics and Indoor Air Quality
Rodents, Mice, Squirrel Control - I find high levels of mouse and rodent dander, fecal dust, and urine-contaminated dust in some buildings,
and high levels of these materials in building insulation in those locations. If you have a mouse problem, particularly if mice and their waste (fecals or urine) are contaminating
the building HVAC or building insulation, may need both steps to clean up or remove infected materials and steps to stop an ongoing
rodent problem. If squirrels are a problem, the cleanup needs to include closing off entry openings into the building. Get some
help from a licensed pest control expert.
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