However, even though the plant may not have leaves and be actively growing in the winter, it can be a problem as all parts of the plant contain urushiol, the oil that causes the contact dermatitis or skin reaction. For sensitive people, even rubbing a pet that has brushed against a vine can result in blisters or handling boots or clothes that came into contact with poison ivy the previous year - the oil can stay active for up to one year.
Firewood should be inspected to make sure there are no vines attached since inhaling the smoke from burning poison ivy can be a serious health risk as the blisters may form inside the lungs.
It would have been nice if my early and severe introduction to poison ivy had imbued me with immunity for life but it did not and I had future doctor visits to address encounters - an expensive and time-consuming necessity. Some people (self included) swear by a natural homeopathic remedy called Rhus-Tox as both a treatment and a preventative for poison ivy; this is particularly good for those who work outside a lot and who frequently encounter the plant. Rhus-Tox can occasionally be found in local drugstores and apothecaries.
The oil is so potent that in 1748, Peter Kalm wrote that 'the letters and characters made upon linen with it cannot be removed, but grow blacker the more the cloth is washed'. (Source: Wildly Successful Plants, A Handbook of North American Weeds by Lawrence J. Crockett, Collier Books, NY, 1977, p. 61).
However, as difficult as poison ivy is for some humans to deal with (about 15% of the population are not sensitive to the oil), it is native to North American and therefore has numerous ecological benefits; deer and other mammals eat the foliage with impunity and many bird species relish the berries that form in mid to late summer.
There are a couple of look-alike plants which are also native to Virginia and which provide valuable habitat and food for wildlife : Virginia creeper and the boxelder tree. As with any control measure, making a positive id is crucial before treatment options are determined.
One suggestion: if you are allergic to poison ivy, mechanical control with bare hands is not advised.