I have become quite familiar with this rhyme over the past week. Last Saturday, I was overly aggressive when doing yard work at my sister's house. I pulled vines and ivy from a stone wall and around a tree. Unfortunately, I did not pay close enough attention. Some of that ivy was of the poisonous variety. I discovered this later that night when a red blotch appeared on my arm. The next day, more red blotches and blisters appeared. By Tuesday, my forearms and right hand were covered, and I had blisters on my fingers, legs, and feet. (I did wear gloves, so go figure!) I've been itchy and uncomfortable and wrapped in gauze, so I'm writing a public service announcement to warn you about this plant.

I am not alone. Poison ivy is one of three plants that causes an allergic reaction in 60-85% (statistics vary) of the population. The Boston Globe featured an article about this pesky plant in the Northwest section of yesterday's paper. It appears that poison ivy plants are more potent and larger now than they were 50 years ago. You can read an article in today's Globe on Boston.com about Jon Sachs, the creator of poison-ivy.org. On this website, you can look at pictures of plants, order identification posters, read stories from the afflicted, and even see some nasty poison ivy rashes.

The first key to avoidance is recognizing poison ivy, oak, and sumac. Poison ivy may grow as a bush, plant or vine, and will often wrap itself around trees. Poison oak, which is especially common in the west, can grow as a low plant or bush, and its leaves resemble oak leaves. Both poison ivy and poison oak typically grow three leaflets to a stem. Poison sumac grows as a bush or a tree looks different than the other two. It has two rows of 7-13 smooth leaflets on each stem and a leaflet at the tip. All three plants contain urushiol, which causes the reaction. If you are exposed to poison ivy or its kin, wash immediately. If you are quick enough, you may prevent the oil from penetrating your skin. However, it may only take minutes to do its damage. The rash may appear 12 to 48 hours after exposure and last from one to three weeks.

It is important to remember a few things:
-You must have direct contact with the urushiol to contract the rash. This includes touching the plant itself or any objects and clothing that touched the plant. These objects likely have the oil on them. For example, if you walk through poison ivy, you can spread the rash by touching your shoes. The oil can stay active on objects for years, so it is important to wash them, as well as your skin.

-The rash is not contagious. As mentioned above, it can only be spread through contact with the oil. Of course, if someone touches an exposed item before it is washed, that person may be affected.

-Contrary to popular belief, the rash does not spread when the blisters break becuase the blisters do not contain urushiol. It may appear that the poison ivy is spreading because the rash and blisters may not appear all at once.

-Scratching is not advised because dirty fingernails can cause infection; however, doing so will not spread the rash for the same reasons as above.

-If the rash is serious, see a doctor.

For more information about poison ivy, its causes, symptoms, and treatment, take a look at the FDA website or MedlinePlus.gov. Type poison ivy in the search box at the top of the page, and click on "Poison ivy, oak, and sumac." The site will will list information from various reliable sources such as the National Library of Medicine, The American Academy of Family Physicians, and the Mayo Clinic.

Have you been afflicted? Do you have a particularly helpful relief method? Leave a comment below.