Sunday, February 23, 2014

Poison Ivy

Leaves Of Three, Let It Be!    Berries White, Take Flight!
• by John David Fawcett
Humans are the only members of the animal kingdom afflicted by Rhus radicans, otherwise known as poison ivy. Although it's a nuisance to people, poison ivy is of considerable value for many animals such as deer and other small mammals which browse on the leaves, twigs and berries. A popular food for birds such as grouse, quail and turkey, especially during fall migration and in winter when other foods are scarce, the small waxy, yellowish-white berries of the poison ivy plant pass through these animals and are widely distributed throughout the forest. There is rarely enough sunlight for the plant to thrive deep in the forest, but in the damp, rich soil of clearings and the forest edge it may stand upright like a shrub, spread over the ground, or be a vine climbing up tree trunks attached with thousands of aerial rootlets. The young leaves are often reddish colored in the spring and green during the summer, while in autumn they turn red, orange or yellow depending on the amount of sunlight they receive.

Although you're more likely to contract rhus dermatitis in spring and summer when the plant leaves are soft and more easily bruised, the dermatitis can also occur in autumn and winter. Some people claim to be immune to poison ivy but medical research indicates that the severity of the rash depends on the condition of the plant and the circumstances under which the individual is exposed. Toxicodendrol, a phenolic oily resin, is present in the resinous juice of the plant and contains a chemical called urushiol which is absorbed by the skin cells. The itching skin lesions which result are the body's immune system responding to these contaminated cells. An allergic reaction will occur if the plant oil remains on the skin for several hours. After twelve to twenty-four hours a rash will develop and once the reaction has begun it will persist until all the contaminated cells have been shed, a process that generally takes up to two weeks. Once contact with poison ivy is made, your skin absorbs the urushiol within three to five minutes. Although all skin areas that come in contact with the urushiol may be affected, the most severe poisoning affects areas with thin skin. Symptoms are usually less severe or do not occur at all in areas with thick skin or heavy hair. There have been reports of males unknowingly transferring the urushiol from their hands to their genitalia and even to the genitals of their sex partners during intercourse. The rash usually begins as an area of blisters appearing in thin lines where the person has brushed against the plant and is accompanied by stinging or itching. The affected area is often hot and swollen, and oozes a clear yellow fluid before eventually drying. Crusting of the lesions occurs as the fluid dries. Once healed, the affected areas will often remain hypersensitive to further contact with urushiol for several years.

The best way to prevent catching poison ivy is to learn to recognize and avoid the plants, which are hazardous even in winter when they have dropped their leaves. If exposed, washing the oil from the affected area as soon as possible with a strong soap and cold water will usually prevent or minimize the reaction. Using hot water is not recommended, since it can cause the skin pores to open and allow the urushiol to penetrate. It's also extremely important that you wash everything that may have come into contact with the oil, since it is easily spread and can remain on clothing, pets and other contacted items for many months. In cool dry weather the urushiol retains its harmful effect for quit a long period of time. However, under hot and humid conditions the toxin is rendered inert in about a week. A thorough washing with an alkaline soap or organic solvents such as alcohol is necessary to prevent absorption of the urushiol. Originally designed to remove radioactive dust from the skin, Technu Poison Oak-n-Ivy Cleansing Treatment from Tec Laboratories has proven to be an effect skin cleanser. Barrier cream skin protectants that are applied prior to contact, such as IvyBlock manufactured by EnviroDerm Pharmaceuticals, Inc., have recently become popular and are reported to be effective against poison ivy, poison oak and poison sumac. I've used a bar laundry soap called Fels Naphtha with great success. While it is a bit harsh, it works great for getting the oil off your skin, as well as any other item that may be contaminated.

There are many myths told about poison ivy, such as "scratching the blisters will spread the rash". Scratching will not spread the rash on the infected person or to anyone else if all the oil has been washed off. Scratching the affected areas after the rash appears will not spread the infection, but different levels of exposure and secondary exposure can cause delayed reactions up to two or three days, which give the impression of spreading.

Centuries ago, Native Americans used the juice from crushed leaves of the jewel weed (impatiens capensis) often found growing near poison ivy, both to prevent the rash and to treat the rash after it developed. A more modern suggestion for relief is to apply hot water to the rash. The heat releases histamine, which is responsible for the intense itching. Once the cells are depleted of histamine, it is possible to obtain six to eight hours of relief. The various over-the-counter remedies usually contain alcohol which appears to provide temporary relief by cooling and drying the infected area. The alcohol, however, has been reported to cause dry and cracked skin resulting in even more itching. Hydrocortisone cream is effective at providing relief, but you may find that the 0.5% over-the-counter concentrations are too weak to be effective.

If you are unlucky enough to contract a serious rash, doctors can prescribe powerful steroids that apparently suppress the immune systems response to contaminated cells. These oral systemic gluco-cortico-steroids may cause behavioral changes, but are very effective and rapid with most symptoms disappearing within twenty-four hours. You should also be examined by a physician if you develop a severe rash, especially if the rash covers large areas or is accompanied by above-normal body temperatures.

Learning to recognize and avoid the poison ivy plant is an important outdoors skill. If you have never seen it lurking at the edge of the trail waiting for a careless step, you owe it to yourself to have someone point it out. Observe and search surrounding areas carefully when hiking and before choosing a campsite. It could save you from several weeks of misery.


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