How to avoid the scourge of poison ivy/oak dermatitis

Abstract

Our society pursues diverse wilderness activities for excitement, exploration, science, and industry. One of the undesirable effects of an excursion in field or forest is a bout of poison ivy/oak dermatitis. Because half the population of the United States is clinically sensitive to these weeds [1], the number of cases reported annually is increasing apace with those answering the call of the wild. Physicians need to espouse a strategy to reduce or minimize the chance of acquiring the rash of urushiol (resin)-laden poison ivy/oak. In this issue of the Journal of Wilderness Medicine, Zink and colleagues put the lid on a common folk remedy, the application of jewel weed juice. Nearly a decade ago, the Forestry Service requested that we prepare a governmental report on the best ways to prevent and treat poison ivy dermatitis in the field, to help keep firefighters on the line when they fought forest fires. That document was translated into layman's language in a government bulletin, which has only recently been rereleased [2). Clearly, education about the weeds and their growth habits is essential if we are to avoid or diminish contact. Unfortunately, I cannot display a generic picture of poison oak or poison ivy. The fact is that the weeds, ubiquitous throughout North America, assume different forms in different regions. Poison ivy tends to grow east of the Rocky Mountains as a climbing vine on trees, poles, and houses, which allows it to ascend towards the sun. West of the Rockies, poison oak luxuriates mostly as small bushes or trees; yet, it too can become a climbing vine in dense forests. In Texas, the forms co-mingle. The important lesson is that we should find out what the weeds look like in the area where contact will be made, and avoid them if possible. The weeds are more fastidious than most people believe. For instance, they tend not to grow above 4000 ft elevation. The Rocky and Sierra Nevada mountain ranges are safe, and there is a large plateau in much of Nevada and parts of Idaho where the weeds are scarcely seen. They do not grow in hot, dry deserts, unless rain and water are bountiful. Thus, the plants are rarely seen in central Mexico. However, in Baja, California, where the climate is more temperate, poison oak abounds in the foothills. The weeds do not grow in rain forests; in northern Canada, they virtually disappear. It is said they do not grow in Alaska. In Hawaii, although poison oak or ivy is not found, plants with crossreacting allergens, such as mango rind and cashew nut shells, occur. Poison oak and ivy survive near the ocean, at the edge of sandy beaches, or in brushy woodlands along both US coasts. They flourish along streams and around lakes that are hot in the summer, with abundant rain or snow in the winter. Once the leaves have fallen, the weeds are recognizable only as stark sticks standing together in areas previously known to contain poison oak or ivy.