Most adults have no need to fear the virus. It's primarily the elderly, infants and people with immune problems that are at risk for developing encephalitis. From what I understand, the virus itself is NOT encephalitis. So most of you are perfectly safe hiking. It's the same population that is vulnerable, mostly the elderly.
Ticks are a much bigger problem.
When hiking during tick season, spray your shoes and socks completely with good bug spray, and stay on the trail. If you do this, it is very unlikely that you will pick up any ticks. Adult deer ticks are active ALL YEAR, including warm winter days, but adults are easy to see. The nymphs are active May-July. Most people get Lyme Disease from the nymphs because they are harder to see.