STEVE INSKEEP, HOST:
The best way to keep poison ivy away is never to touch it. An old saying is meant to help. If it has leaves of three, let it be. But it's not that simple. Here's Blake Farmer of our member station WPLN in Nashville.
BLAKE FARMER, BYLINE: Every year since she bought her house in east Nashville, Sara Weedman ends up nursing a nasty poison ivy rash.
SARA WEEDMAN: This time, I actually had it on my neck and my face, which is a first.
FARMER: She's already been to get a steroid shot, and she's enduring scalding hot baths, though the relief is temporary and not recommended by doctors. Weedman blames her repeated rashes on her inability to spot poison ivy.
WEEDMAN: I've kind of become afraid of my own yard because it's a miserable feeling to have poison ivy. I mean, it's been two weeks, and my ankles still itch.
FARMER: Purely out of self-preservation, I developed an eagle eye when it comes to PI - what we called it in my landscaping days. We walked down Weedman's chain-link fence just a few steps and bingo.
You see this right here?
WEEDMAN: This? Yes.
FARMER: Now, that is some funky-looking poison ivy, but that is definitely poison ivy.
This plant has so many different looks, even occasionally on the same vine. And while the leaves do come in threes, some have smooth edges, others are saw-toothed. Still, others have angular lobes. They look almost like a mitten. They're shiny. They're dull. Virginia Tech microbiologist John Jelesko is one of the few researchers as fascinated as I am.
JOHN JELESKO: In fact, in general, we call this plant in the lab the familiar stranger.
FARMER: Even Jelesko, who specializes in plant-generated chemicals, realized he didn't know much about it until 2012 when he had his own run-in cutting up a tree with an electric chainsaw. When he coiled up the cable, it was covered in poison ivy, and the active ingredient, urushiol, got onto his arms. The next day - a red, streaky rash.
JELESKO: My response to this was, oh, this is kind of amusing. Let's - you know, let's see where this goes. How bad could it be?
FARMER: And so began a career-bending science experiment.
JELESKO: Well, this initiated about a 2 1/2 week odyssey of lots of itching and not very much sleep.
FARMER: During those long nights, he dug into the scientific literature and realized there wasn't a whole lot. So he started cataloguing the variety of leaf shapes as well as the varied plant forms. The weed is native to much of the U.S. A very close cousin, poison oak, is found in western states. It can grow in many shapes and sizes. It appears in big mats on the ground.
JELESKO: It can also grow as shrubs.
FARMER: Scariest of all is when poison ivy climbs. It can grow so large that the vine puts out branches that intermingle with the host tree. Jelesko says the best thing to do when you get snagged is wash with sudsy dishwashing soap, but do it quickly.
JELESKO: This chemical will actually chemically crosslink itself to your skin. Once that happens, there is no amount of washing with soap that is going to take that off.
FARMER: After the damage is done, there are many a home remedy, from cold compresses to Clorox. Steroids and anti-itch creams help but aren't totally effective. Researchers at Duke University have found an antibody that offers some relief but is not yet ready for humans. The only way, really, to avoid misery is prevention, but don't stay inside. Just study up. For NPR News, I'm Blake Farmer in Nashville.
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