You are not contagious. If you've washed all items/tools/clothing/gardening gloves/etc you think came in contact with the oil, they should be fine.
With poison ivy (or poison oak or poison sumac), your body has an allergic reaction (contact dermatitis) to the Urushiol oil and as with any allergic reaction - you can blister anywhere - not just at the site of contact.
I've had it a few times, and my body won't quit reacting to it on it's own.
My personal record is 2 months of scratching. When I woke up from scratching my legs bloody in my sleep I gave up and went to the doctor. A prednisone steroid series finally shut the reaction down and my skin could finally heal up.
They say jewel weed salve is a natural treatment - acts as a topical steroid.
I only found out about it a short while ago, but it helped with one itchy spot I had (but I wasn't sure it was poison ivy that time).
A friend of mine's son got it bad in the middle of winter one year. It turned out the firewood he was carrying into the house had a dead, dried poison ivy vine that was attached to the piece of fire wood. The oil stays viable for YEARS after the plant has long since died away.