Southern Ontario has its share of this plant. A responsible hiker will learn to recognize the plant and avoid contact with all parts of it (not just the leaves). Some people think that poison ivy is always a low lying plant, yet it isn't uncommon for it to become a woody climbing vine/shrub on trees and old fences. Pictured below is poison ivy climbing up a Shagbark Hickory on the east side of Haldimand Road 54 opposite Ruthven Park National Historic Site. This picture was taken by Jan Hember (2008MAY24 Saturday) during the building of a new portion of the Grand Valley Trail. An excellent resource is Poison Ivy (Toxicodendron radicans) - Ontario Trees and Shrubs by Walter Muma. Also read more about poison ivy at Wikipedia. Note that poison ivy is known as Rhus radicans (older scientific name) or Toxicodendron radicans.
"Poison-ivy is sometimes mistakenly called Poison-oak because some plants have very coarsely toothed or lobed leaflets. The true Poison-oak, Rhus toxicodendron L. (not illustrated) occurs in the southern United States, but not in Canada." > Quote is from: Ontario Ministry of Agriculture, Food and Rural Affairs
"Identifying poison ivy isn’t always easy to do" by Diane Brown, Michigan State University Extension (July 25, 2016) - Use this online web page that contains excellent pictures and other information. It will help you begin to recognize the various forms of poison ivy.
If you are new to hiking, it will take time and practice to learn the recognition of poison ivy in its various stages. Learn from other experienced hikers. In time you will be able to recognize these plants in its various stages of development. For example, in late fall and the leaves are gone, you might recognize the fruit and avoid it.