Poison-ivy, poison sumac and Western poison oak (WSJ)

[Guest guest]

Least-Welcome Sign of Summer

By ANNE MARIE CHAKER and ANJALI ATHAVALEY, Wall Street Journal.

Carolyn collects and sells shade plants from her home in Bryn Mawr, Pa.

There's one plant she can't seem to get rid of this year—poison ivy. " I have

noticed a lot more little seedlings of it in my garden, " Ms. says. She

and her 19-year-old son have rashes on their arms. " I normally don't get it at

all, " she adds.

Poison-ivy season is upon us, and the scourge of summer is shaping up for one of

its most virulent and unpredictable seasons. Public gardening advisers in many

regions of the country say poison-ivy complaints this year are more plentiful

than in recent memory.

Campers, highway crews, kids chasing baseballs into the weeds—all are at risk

for an encounter with Toxicodendron radicans. " I think people are spending more

time landscaping, growing vegetables and just being in their yards more, " says

Bob Ary, an agent with the University of Tennessee extension in Sumner County,

who estimates poison-ivy queries from backyard gardeners are up about a third

over last year. " There are some plants that look pretty similar to poison ivy,

and inexperienced gardeners sometimes don't know how to tell the difference. "

Exact numbers on poison ivy's rise are hard to pin down, because so many cases

go unreported. More than 350,000 people each year suffer from poison ivy,

according to a 2006 study published in the Proceedings of the National Academy

of Sciences. Other estimates go higher, especially if taking poison ivy's toxic

cousins, poison sumac and Western poison oak, into account.

They all produce urushiol, a skin-irritating oil that combines with skin

proteins to trigger the tell-tale allergic reaction—an angry red rash that

itches badly enough to make a person miss a day or more of work or fun.

About 15% of the population is insensitive to urushiol and will never develop a

reaction. For everyone else, repeated exposure tends to make the rash worse.

" The dermatitis gets worse each subsequent time, " says Dawn , a

dermatologist at Mayo Clinic in Rochester, Minn. On the other hand, a person's

sensitivity tends to decline with age.

There's no shortage of theories on why poison ivy seems to be rising. Some

veteran gardeners think the particularly brutal winter in many regions killed

off many prized perennials and shrubs—leaving more room for weeds to flourish.

Another theory: more novice gardeners are zealously digging out weeds to plant

vegetable patches and making contact with poison ivy.

A study, published in the journal Weed Science in 2007, suggested that poison

ivy is getting bigger, spreading faster and producing more urushiol as the

result of increasing levels of carbon dioxide in the atmosphere. Ziska, a

plant physiologist at the U.S. Agriculture Department who led the study, exposed

poison ivy plants to different carbon dioxide concentrations—mirroring those

that actually existed in the atmosphere at various times over several decades.

The increased exposure levels produced bigger, hardier, and more irritating

plants.

Poison ivy makes for an unpredictable allergen that has no comfort zone. Geralyn

Caplan, an ville, Ind., biology teacher, says through many years of camping

as a child, she never caught poison ivy. But in each of the past three years,

she says, " I got nailed with it. " She has been spending more time out in the

yard clearing flower beds now that her kids are grown. She recently recovered

from her worst case ever, when rashes and welts spread on her arms and legs.

" You might not be sensitive to it your whole life, " says Dan Brown, a professor

of animal nutrition and toxicology at Cornell University. " And then, Bingo. "

After exposure, there is typically a 15- to 30-minute window in which you can

avoid a reaction, by washing the urushiol off the skin. Several over-the-counter

products can be used in this critical window and beyond, including Zanfel, a

soapy wash that sells in a one-ounce tube for $39.99. Sales so far this year are

running 10% to 12% ahead of the same period last year, says Steve Sisler, vice

president of sales at Zanfel Laboratories Inc., of Clive, Iowa. " The season this

year is moving appreciably faster than last year, " he says. Washing with regular

soap and warm water works, too, if done soon enough.

Prevention costs less than the cure: IvyBlock lotion, manufactured by Hyland's

Inc., Los Angeles, claims to work like sun block, with a patented ingredient

that absorbs urushiol before it can irritate the skin. The company says it has

Food and Drug Administration approval to help prevent poison ivy, oak and sumac

rashes; it retails for $12.99 for four ounces. Physicians stress the usefulness

of socks and long sleeves.

If a rash develops—in most cases 12 to 72 hours after exposure—dermatologists

say the first step is to try treating it at home (see " Itch Alternatives " on

home remedies). An over-the-counter topical cortisone ointment, like

Cortizone-10, can reduce the inflammation, and an antihistamine, like Benadryl,

can relieve the itch.

If that doesn't bring relief, a doctor may prescribe cortisone injections or

pills. " People can have extensive blistering in large areas of the body if they

have enough contact, " says ph Fowler, a clinical professor of dermatology at

the University of Louisville School of Medicine. " You can get blisters to the

point of being oozy and itchy. "

A very bad scenario would be to clear poison ivy from your yard and burn it in a

campfire, since it is possible to develop respiratory inflammation from

breathing urushiol-laced smoke.

Recognizing poison ivy isn't easy. It can grow as a ground cover, a vine or a

small bush. The leaves grow in clusters of three—hence the adage, " Leaves of

three, let it be " —but the leaves can be smooth or toothed, in which case

identification becomes more difficult. Western poison oak leaves are deeply cut

and resemble those of a true oak tree. Poison sumac's signature is its red

stems.

Poison sumac is typically found in swampy areas, especially in the South.

Western poison oak is common along the Pacific coast. Poison ivy typically grows

east of the Rockies, although recent reports suggest it may be spreading to

places where it didn't previously thrive.

One of poison ivy's quirks is that many animals can touch or even eat it with no

ill effects. " Animals not only eat it, they love it, " says Mohan, a

professor of ecology at the University of Georgia and co-author of the 2007 Weed

Science study.

Pets play an important role in the spread of poison ivy. A dog with urushiol on

its fur will pass it along to friendly humans who pat or rub those places.

The same sort of thing happens with camping equipment. Denis Sasseville,

director of the dermatology division at McGill University, in Montreal, recalls

a patient who came in every week with a new poison ivy reaction. He repeatedly

told the patient to stay out of the bushes and kept showing him photos so he

would know what poison ivy looked like. It didn't help. It turned out the

patient, who was camping, had a sleeping bag, chairs and a tent pole covered

with urushiol.

The lesson, Dr. Sasseville says: " Everything needs to be washed, because the sap

stays allergenic forever. "

In Junction, City, Kan., the Geary County Extension service, affiliated with

Kansas State University, says poison-ivy queries to its office were up by a

third last year and are running at about that same level this year. Poison-ivy

calls to the Cornell University ative Extension in Voorheesville, N.Y.,

have doubled in the past five years, says Pezzolla, community educator for

horticulture. " I think it's getting more prevalent, " says Randy Roloff, road

supervisor for Outagamie County in northeast Wisconsin. " It's spreading and

tough to kill. "

" Business is good, " says Umar Mycka, who started a landscaping company three

years ago devoted entirely to poison-ivy removal. Based in Philadelphia, he has

customers from land to New Jersey. " I call our method hand-to-vine combat, "

he says. " We get down on our hands and knees and find them, search them down to

the ground and dig them up. "

And then there are those people who actually like poison ivy. It's a native of

North America, and its berries are an important source of food for wildlife.

That explains why there are few concerted efforts to eradicate it. " We keep it

out of the garden beds but let it grow elsewhere, " says Eleanor Cone, a retired

photography teacher in Forest Hill, Md. " One reason we garden is to create and

maintain a habitat for wildlife. "

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http://en.wikipedia.org/wiki/Poison_ivy