Transcript Poison Ivy
Toxicodendron: A painful summer institution Jacobi Ambulatory Care Service A Latin Refresher: • • • • Toxicodendron means Poisonous Tree Toxicodendron radicans is Poison Ivy Toxicodendron toxicarium is Poison Oak Toxicodendron vernix is Poison Sumac Jacobi Ambulatory Care Service Leaves are primarily trifolate Jacobi Ambulatory Care Service Urushiol is the allergenic component. It is a kind of oil found in the leaves, stems, and roots. Jacobi Ambulatory Care Service It is found in other foodstuffs: Jacobi Ambulatory Care Service Urushiol penetrates the epidermis and binds to Langerhans cells. In sensitized patients, previously stimulated helper T cells recognize the urushiol and initiate an immune response. Jacobi Ambulatory Care Service Time Course • Symptoms develop in 4 to 96 hours. • Symptoms can peak up to 2 weeks after exposure. • The fluid in the blisters is NOT antigenic. The rash doesn’t spread. Continued infection is due to re-exposure. • Allergic responsiveness wanes with age, particularly in those with milder reactions. Jacobi Ambulatory Care Service More information about urushiol: • It binds to cell membranes. After an hour or so, it won’t wash off. • It is stable at high temperatures. So, burning poison ivy or poison oak disperses through the air with it’s allergenic potential intact. It can cause inflammation and irritation of respiratory tissues. • It is stable in general, and can remain on fomites for a long time. Some say up to 5 years! • It can waft on a summer breeze and cause a reaction in the very very allergic. • Some native American tribes use it to remove warts. • Only homo sapiens react to it. Jacobi Ambulatory Care Service Looks like: Jacobi Ambulatory Care Service Jacobi Ambulatory Care Service Jacobi Ambulatory Care Service Jacobi Ambulatory Care Service Not… Jacobi Ambulatory Care Service Complications • Edema, especially when the face or genitals are affected. • Respiratory difficulties. • Bacterial super-infection, primarily with gram positive organisms. Jacobi Ambulatory Care Service Treatment • Calamine lotion and oatmeal baths. • Sedating anti-histamines. • High potency topical corticosteroids. (But not on mucous membranes or in skin folds.) • Systemic glucocorticoids if: face or genitals are affected; more than 10% of the body is involved; reaction is severe. Start with 1 mg/kg of prednisone, give it for a week, and then taper over the next two weeks. • NB: Avoid topical benadryl, which causes a reaction all it’s own. Jacobi Ambulatory Care Service