| Cause: | Rhus
anacardiaceae. - Evergreen or deciduous shrubs or trees. Hardy
anywhere and thrive in poor soil. Can cause sever dermatitis
on contact; even breathing in smoke from a burning plant is harmful.
Poison oak (Rhus diversiloba) is common in California, western Oregon and western Washington. In open or filtered sun it grows as a dense, leafy shrub. Where shaded it becomes a tall-climbing vine. Its leaves are divided into 3 leaflets, edges of which are scalloped, toothed or lobed. Poison ivy (Rhus radicans) grows in eastern Oregon, eastern Washington (and eastward). It is more sprawling and rarely climbs. Plant has dark brown to black oily substance that is excreted in the woody trunk like sap and on the leaves. Contact with sensitive people can produce sever skin reaction and long-term discomfort. Avoid at all cost. If Rhus is growing on your property, use a full strength chemical brush killer. Then carefully remove the dead growth while remaining completely covered (hat gloves, long sleeve shirt, long pants, mask goggles.) Dispose of or wash clothes in hot water with strong detergent. Wash tools with solvent to remove oil. Secondary contact with oil may cause re-infection of poison oak/ivy. |
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| Pathogenesis: | The skin
reaction from poison ivy/poison oak is a delayed contact hypersensitivity
reaction to an oleoresin (uroshiol) which the active sensitizing
ingredient is pentadecylcatedhol. Typical skin reactions include
itching, redness, papules, vesicles, and bullae. Depending on type
of contact with the resin, the reaction may be localized or diffuse.
Resin can be contacted from pet fur. Typical reaction can occur as
soon as 8 hours after contact and as late as 8 days after contact with the
resin. When the reaction shows itself will depend on the degree of
exposure, how sensitive the skin is, and where the contact is on the
individual. Skin reaction can persist from one to three weeks.
Sensitization to poison oak/poison ivy may cause cross reactions from related plants. Furniture lacquer form Japanese lacquer tree, oil from the shell of the cashew nut, fruit pulp from a ginkgo tree, and the rind of a mango. Care must be taken when exposed to plants from Anacardiaceae. |
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| Management: | Prevention
is the best course of action. Learn to identify and avoid contact
with the plant. If it is located on your property or near where
children play, use a chemical exfoliate and physically remove the remains.
If you recognize that you may have come in contact with the resin, wash immediately and aggressively with warm water and soap. If the resin is not removed, the resin may be transmitted from the exposure site to the hands, face, forearms, and genitalia. Contrary to popular belief, you cannot get poison ivy/poison oak from the fluid filled vesicles of another individual. However, contamination may occur with contact from the resin. Completely remove all clothing and wash in warm water and detergent. Harsh soaps and vigorous scrubbing of the skin is no advantage. Simply soaking in a cool bath with mild hand soap is sufficient to remove the resin and help prevent the spread of the dermatitis. This will not prevent the typical skin reaction in a highly sensitive person. |
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| Treatment: | Anti-itch
medication is helpful in relieving the symptoms. Calamine lotion, and cool
compresses will help relieve the itch. A cool bath with baking soda
or oatmeal preparations will help buffer the skin’s pH and relieve
symptoms. Avoid topical anesthetic agents like antihistamines,
benzocaine, and zirconium. Topical steroids like Cortaid are helpful
to relieve the itching. Oral antihistamines like Benadryl are
helpful in relieving the itch but may cause drowsiness. Do not
"pop" the large lesions. These may become infected
if not drained aseptically. Infected lesions may lead to secondary
cellulitis.
Severe, incapacitating cases of poison oak/poison ivy can be treated with short-term oral corticosteroid use. Typically prescribed as a daily or twice daily regimen in a decreasing or tapering dose for one to two weeks. Premature termination of steroid therapy can result in rapid rebound of the symptoms. The use of injectable steroids is discouraged. Avoid exposure to the sun. Sun exposure may cause scaring in healing tissue. |
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| Bibliography: |
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