The Curse of Toxicodendron

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The CurseofToxicodendron

• Bryan E. Bledsoe, DO, FACEP
• Midlothian, Texas

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Toxicodendron

• Leaves of three, let them be berries white, run
  in fright.

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Toxicodendron

• Name comes from the Greek
• Toxikos (poisonous)
• Dendron (tree)

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Toxicodendron

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

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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."

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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)

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Toxicodendron

• Relatives include
• Cashews
• Mangos
• Pistachios

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Toxicodendron

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

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Toxicodendron

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

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Toxicodendron
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Toxicodendron
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Toxicodendron
Spring
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Toxicodendron
Summer
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Toxicodendron
Fall
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Toxicodendron
Winter
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Toxicodendron
All Seasons
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Toxicodendron

• Species found in North America
• Poison ivy (T. radicans)
• Rydbergs poison ivy (T. rydbergii)
• Western poison oak (T. diversilobum)
• Eastern poison oak (T. toxicarium)
• Poison sumac (T. vernix)

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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

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Eastern Poison Ivy

• 6 sub-species
• T. radicans divaricatum
• T. radicans eximium
• T. radicans negundo
• T. radicans pubens
• T. radicans radicans
• T. radicans verrucosum

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T. Radicans (all)
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T. radicans divaricatum
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T. radicans divaricatum

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

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T. radicans eximium
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T. radicans eximium

• Fairly rare species
• Occurs in southwest Texas and Mexico

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T. radicans negundo
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T. radicans negundo

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

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T. radicans pubens
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T. radicans pubens

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

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T. radicans radicans
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T. radicans radicans

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

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T. radicans verrucosum
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T. radicans verrucosum

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

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Western Poison Ivy

• Toxicodendron rydbergii
• Also called
• Non-climbing poison ivy
• Rydbergs poison ivy
• Grows as a bush up to 3 feet high.
• Most northerly of Toxicodendron

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T. Rydbergii
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Western Poison Oak

• Toxicdendron diversilobum
• Grows as a thick bush or a climbing vine.

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T. diversilobum
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Western Poison Oak
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Eastern Poison Oak

• Toxicodendron toxicarium
• Grows in sandy soil and areas devastated by fire.

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T. toxicarium
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Poison Sumac

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

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T. vernix
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Poison Sumac
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Toxicodendron

• Major problem in the United States and Canada.
• Estimated that more than 50 of workmens
  compensation cases in California are due to
  contact dermatitis from Western Poison Oak.

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Pathophysiology
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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)

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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.

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Toxicodendron

• All species of Toxicodendron contain substances
  in their sap called urushiols (also called
  catechols).
• Group of oils secreted onto the plants surface.

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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.

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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.

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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.

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Pathophysiology

• When sensitized, exposure results in 3 stages of
  response
• Redness
• Rash and Blisters
• Rupture of Blisters

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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.

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Pathophysiology

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

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Pathophysiology

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

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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.

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Toxicodendron

• Treatment
• Prevention
• Limiting Exposure
• Barrier Creams and Lotions
• Plant Removal
• Localized Treatment
• Generalized Treatment
• Massive Exposures

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Treatment

• Prevention is the Best Treatment!

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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.

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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.

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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.

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Treatment

• Limit Exposure
• Consider the use of poison ivy/oak solvents to
  break down the resin.

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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.

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Treatment

• Barrier Creams and Lotions

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Treatment

• Plant Removal
• Herbicides

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Treatment

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

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Treatment

• Plant Removal
• Physical Removal

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Treatment

• Localized Treatment
• Minimize exposure with soaps or solvents.
• Localized analgesic creams or ointments.
• Antihistamines for itching.
• OTC steroid creams (Cort-Aid)
• Prescription steroid creams (Diprolene)

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Treatment

• Localized Treatment

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Treatment

• Localized Treatment

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Treatment

• Localized Treatment

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Treatment

• Localized Treatment

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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.

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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.

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Treatment

• Massive Exposure
• High-dose steroids
• Analgesics
• Hospitalization
• Potent antihistamines
• Pity

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Treatment
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Myths

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

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Myths

• Medrol Dose Packs are satisfactory treatment
  for generalized rashes.
• It is safe to burn the plants.
• Removing the plants in Winter is safe as the
  resin is gone.
• Homeopathic remedies will treat or prevent poison
  ivy.

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Myths

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

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Summary

• Leaves of three, let them be berries white, run
  in fright.

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