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Itch, scratch — poison ivy’s misery belied in display of autumn color

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It's one of the most colorful plants around right now, but one of the most potent. Only 1 nanogram (one billionth of a gram) of the urushiol oil irritant agent in poison ivy is needed to cause rash; a pinhead-size droplet could cause itching in 500 people, and one-fourth ounce could cause a rash on every person on earth.

Here in the Deep South we aren’t blessed with the groves of sugar maples, birches, and other trees that make the northern tier of states a riot of color this time of year.

But right now, while much of the landscape is still green, we do have an amazing palette of color in — would you believe? — poison ivy.

From subtle yellow to delicate pink to bright orange and red, this horrid vine (Toxicodendron radicans), which grows with great abandon in these parts, has a color range equaled only by sweetgum trees.

Still, I give it an extra wide berth, remembering too well the boyhood episodes of maddening itchy rashes that turned to blisters and sores that no amount of calamine lotion seemed to help. Even after I learned to identify it and steer clear, there were the accidental exposures and resultant misery.

The irritant agent in poison ivy, urushiol oil, is one of the most potent in nature. Only 1 nanogram (one billionth of a gram) of the oil is needed to cause rash, according to the Poison Ivy, Oak and Sumac Information Center; the average exposure is 100 times that amount. A pinhead-size droplet could cause itching in 500 people, the center says, and one-fourth ounce could cause a rash on every person on earth. It is the most common allergy in the U.S.

And it’s not necessary to even come in contact with the plant itself. Your dog might run through it, you pet the dog, and whammo!, you’re breaking out. Or taking off shoes and clothes from a walk through the woods. Even the smoke from a fire that contains poison ivy can cause a rash.

Seemingly uncaring about soil or environment, the stuff grows just about anywhere. Birds drop the seeds, rains wash them thither and yon, and soon there are thickets of the stuff.

It loves to grow up the sides of trees; I’ve seen stalks big enough for Tarzan to swing on  (he would certainly regret having done so). Not far from here, a farmer years ago planted a long row of Lombardy poplars as a windbreak on a field. Now 50 feet tall, the trees are covered in poison ivy from bottom to top.

Even in town, I drive around and see trees with trunks covered in poison ivy, or fences almost obscured by lush growths of it, and I can only wonder how the owners are so oblivious to the menace.

Off and on since the 1980s, Research Professor Mahmoud ElSohly and associates at the University of Mississippi School of Pharmacy’s National Center for Natural Products Research have been working to develop a pharmaceutical product to rein in the allergic reaction to the plant.

Earlier this year, they licensed a promising compound to a Memphis company, Hapten Sciences Inc., with clinical trials planned. “We’re enthusiastic about the significant potential health benefits of this product candidate,” said Raymond J. Hage, Jr., company president/CEO.

 

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