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Urushiol. Mechanisms of Transmission. Urushiol can be Transmitted. By contact with the plants that contain it. By contact with inanimate objects which have come in contact with it. By contact with other living things that have come in contact with it. Direct Contact with the Skin.
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Urushiol Mechanisms of Transmission
Urushiol can be Transmitted • By contact with the plants that contain it. • By contact with inanimate objects which have come in contact with it. • By contact with other living things that have come in contact with it.
Direct Contact with the Skin • The easiest, most common way to get dermatitis from urushiol is to physically contact any part of the plants that contain it. • Often this happens without notice – symptoms may not show up for several days, if at all.
Contact with Contaminated Objects • These can include clothing or shoes that have contacted urushiol. • A guy was wearing these pants when he encountered poison oak. His legs were covered in blisters. • Urushiol can stay on unwashed clothes for up to a year.
Contact with Contaminated Objects • Dead dry leaves still contain active urushiol for some time. • The same is true for gardening tools.
Contact with Contaminated Animals • Animals can get urushiol on their fur and have no reaction, but can transfer it to humans. • Once skin exposed to urushiol has been thoroughly washed, human-to-human transmission is nearly impossible.
How does it work? • Chemically, urushiol is harmless to humans. • However, when contacted, it bonds to deep skin proteins. • This initiates a T-cell mediated immune response towards the urushiol derivatives which are bound up in the skin proteins. • The result is an allergic reaction characterized by redness, swelling, and blisters.
Urushiol causes an allergic reaction (Rhus dermatitis) in about 85% of people exposed to it. This percentage decreases with age. Breathing burning urushiol can be extremely serious. In severe cases there is a risk of anaphylactic shock. As with many allergies, reactions become more pronounced with repeated exposures. Once a rash develops, it can linger for up to a month. What happens
Recurrence • Strangely, a rash may appear months – even years – later, despite there being no further exposures.
References • Poison Sumac http://www.poison-sumac.org/ • Aetna Intellihealth http://www.intelihealth.com/IH/ihtIH/WSIHW000/7945/7991/442902.html • The University of Iowa http://www.uihealthcare.com/topics/medicaldepartments/dermatology/poisonivy/index.html • Poison Ivy, Oak and Sumac Information Center http://poisonivy.aesir.com/view/comments.html?func=showMessage&mid=100590&wid=279 • Wikipedia http://en.wikipedia.org/wiki/Urushiol-induced_contact_dermatitis