The Curse of Toxicodendron Bryan E. Bledsoe, DO, FACEP Midlothian, Texas

Toxicodendron  “ Leaves of three, let them be; berries white, run in fright.”

Toxicodendron  Name comes from the Greek: – Toxikos (poisonous) – Dendron (tree)

Toxicodendron  Poison ivy was one of the earliest plants noted by the first colonists.

Toxicodendron  In 1609, Captain John Smith is credited with naming the plant “poison ivy” because he thought it resembled English ivy or Boston ivy.  He also observed that the plant "caused itchynge, and lastly, blisters."

Toxicodendron  Kingdom: Plantae (Plants)  Division: Magnoliophyta (flowering plants)  Class: Magnoliopsida, (Dicotyledons)  Subclass: Rosidae (Roses)  Order: Sapindales  Family: Anacardiaceae (cashews, mangos, and pistachios)  Genus: Toxicodendron (poison ivies, oaks, and sumacs)

Toxicodendron  Relatives include: –Cashews –Mangos –Pistachios

Toxicodendron  Virtually every part of the United States, except desert regions, is home to members of the Toxicodendron family.

Toxicodendron  Highly variable species with multiple sub-types and regional variance.

Toxicodendron

Spring

Toxicodendron Summer

Toxicodendron Fall

Toxicodendron Winter

Toxicodendron All Seasons

Toxicodendron  Species found in North America: –Poison ivy (T. radicans) –Rydberg’s poison ivy (T. rydbergii) –Western poison oak (T. diversilobum) –Eastern poison oak (T. toxicarium) –Poison sumac (T. vernix)

Eastern Poison Ivy  Toxicodendron radicans.  Often called “climbing poison ivy.”  Found throughout the US and Canada.  Typically a climbing vine, although it can be found as an upright shrub.  Blooms in June

Eastern Poison Ivy  6 sub-species: –T. radicans divaricatum –T. radicans eximium –T. radicans negundo –T. radicans pubens –T. radicans radicans –T. radicans verrucosum

T. Radicans (all)

T. radicans divaricatum

 Fairly rare species.  Found in southeastern corner of Arizona and extends into Mexico.  Also called “Baja California Poison Ivy.”

T. radicans eximium

 Fairly rare species  Occurs in southwest Texas and Mexico

T. radicans negundo

 Fairly common species.  Found in south Ontario, great lakes states, central and mid-western states.

T. radicans pubens

 Fairly common species.  Found in south central US from lower Mississippi valley to east Texas.

T. radicans radicans

 Moderately common species  Found in eastern and southeastern US, Bermuda, the Bahamas, and Nova Scotia.

T. radicans verrucosum

 Moderately common species.  Found in Texas, Oklahoma, and southwestern Missouri.

Western Poison Ivy  Toxicodendron rydbergii  Also called: –Non-climbing poison ivy –Rydberg’s poison ivy  Grows as a bush up to 3 feet high.  Most northerly of Toxicodendron

T. Rydbergii

Western Poison Oak  Toxicdendron diversilobum  Grows as a thick bush or a climbing vine.

T. diversilobum

Western Poison Oak

Eastern Poison Oak  Toxicodendron toxicarium  Grows in sandy soil and areas devastated by fire.

T. toxicarium

Poison Sumac  Toxicodendron vernix  Least encountered member of Toxicodendrom family  Water-loving plant found in swamps and bogs.

T. vernix

Poison Sumac

Toxicodendron  Major problem in the United States and Canada.  Estimated that more than 50% of workmen’s compensation cases in California are due to contact dermatitis from Western Poison Oak.

Pathophysiology

 Poison ivy is not an “allergy” as interpreted by most people.  It is a cell-mediated reaction that does not involve antibodies.  Classified as Type IV Hypersensitivity reaction (Delayed Hypersensitivity)

Pathphysiology  Initial Exposure: –Patient comes into contact with the allergen. –Allergens are harmless to most people. –Some are born with or later develop a hypersensitivity to the allergen in question.

Toxicodendron  All species of Toxicodendron contain substances in their sap called urushiols (also called catechols).  Group of oils secreted onto the plant’s surface.

Pathophysiology  Urushiol resin remains stable for years, even in dead or dried plants, and is equally hazardous in the winter as in the summer.  The resin can be carried by smoke if the plant is burned and infect the lungs.  Ingesting any part of the plant can cause a reaction in the oral cavity and gastrointestinal tract.

Pathophysiology  Estimated that 50-70% of the U.S. population is sensitized to urushiol, and would acquire the rash on casual contact.  Prolonged or repeated exposure may induce an allergic response to urushiol.  The reaction ranges from mild to severe, and sensitivity can develop later in life.

Pathophysiology  When urushiols are exposed to the air, they quickly oxidize and turn a dark brown.  If a leaf is placed between two white sheets of paper and the leaf is crushed, the wet spots will turn brown in a matter of minutes.

Pathophysiology  When sensitized, exposure results in 3 stages of response: –Redness –Rash and Blisters –Rupture of Blisters

Pathophysiology 1. A day or two after contact the infected area begins to itch and becomes red from the dilation of blood vessels. Swelling (lymph leaking from the blood vessels) also occurs.

Pathophysiology 2. Two days later, blisters filled with clear fluid appear.

Pathophysiology 3. Lastly large blisters burst and begin to ooze for about four days.

Toxicodendron  If you are sensitized to poison ivy, you are also sensitized to poison oak and poison sumac, and may be sensitized to: –cashew nut shell oil –mango fruit peels –Japanese lacquer.  A person is not sensitized to poison ivy the first time they touch it, but can become sensitized as the skin processes the resin.

Toxicodendron  Treatment: –Prevention  Limiting Exposure  Barrier Creams and Lotions  Plant Removal –Localized Treatment –Generalized Treatment –Massive Exposures

Treatment Prevention is the Best Treatment!

Treatment  Limit Exposure: –Wear long sleeves and pants. –Wear gloves when working in areas where plants are common. –Wear a mask when mowing in areas where plants are common.

Treatment  Limit Exposure: –Pets can get resin on them and transfer it to you. –Resin will remain in clothing unless you wash it in hot water with a good soap.

Treatment  Limit Exposure: –If you are exposed, rinse affected area with cold water. –Hot water will open up the pores and increase exposure. –Clean under fingernails. –Use strong soap –DO NOT RETURN TO PLANT AREA AFTER USING SOAP.

Treatment  Limit Exposure: –Consider the use of poison ivy/oak solvents to break down the resin.

Treatment  Barrier Creams and Lotions –For the most part, barrier creams and lotions are ineffective because of sweating and movement. –Many brands are available on the market without a prescription.

Treatment  Barrier Creams and Lotions:

Treatment  Plant Removal: –Herbicides

Treatment  Plant Removal: –Physical Removal (best performed in Winter months). 1. Cover yourself with clothing, gloves, and mask (Ivy Block if you want). 2. Loosen the soil by moistening with water. 3. Remove and carefully bag plants. 4. DO NOT BURN PLANTS! 5. Shower immediately to remove any possible resin.

Treatment  Plant Removal: –Physical Removal

Treatment  Localized Treatment: 1.Minimize exposure with soaps or solvents. 2.Localized analgesic creams or ointments. 3.Antihistamines for itching. 4.OTC steroid creams (Cort-Aid) 5.Prescription steroid creams (Diprolene)

Treatment  Localized Treatment:

Treatment  Localized Treatment:

Treatment  Localized Treatment:

Treatment  Localized Treatment:

Treatment  Generalized Treatment: –If significant body area exposed, then localized treatment will be ineffective and expensive. –Genital exposure can be quite bothersome. –Use local remedies as needed. –Definitive treatment is high-dose corticosteroids.

Treatment  Generalized Treatment: –I typically prescribe the following steroid regimen:  Prednisone 60 mg a day for 3 days,  Then 40 mg a day for 3 days,  Then 20 mg a day for 3 days, then stop. –Hydroxyzine 50 mg QID prn itching.

Treatment  Massive Exposure: –High-dose steroids –Analgesics –Hospitalization –Potent antihistamines –Pity

Treatment

Myths 1. You can get poison ivy from the fluid in the blisters. 2. There is a shot that prevents poison ivy. 3. Injected steroids are better than oral steroids. 4. If I am “allergic” to poison ivy, then my kids must be “allergic.”

Myths 5. Medrol “Dose Packs” are satisfactory treatment for generalized rashes. 6. It is safe to burn the plants. 7. Removing the plants in Winter is safe as the resin is gone. 8. Homeopathic remedies will treat or prevent poison ivy.

Myths 9. I can get the rash from somebody who has it. 10. Benadryl cream or spray is an effective treatment.

Summary  “ Leaves of three, let them be; berries white, run in fright.”