While the ticks may use deer for part of their life cycle, its rodents, small mammals, and pets - dogs and cats - that are largely responsible for spreading the ticks, and bringing the ticks in contact with humans.
Additionally, letting your dog out in deer tick infested areas will likely infect your dog with lyme disease.
Deer ticks will hitch a ride and feed on any mammal.
Michigan DNR:
"Other species of ticks such as the dog tick or wood tick, the lone-star tick and the rabbit tick, and biting insects such as mosquitoes, deer flies and horse flies have been shown to carry the Lyme disease bacterium. However, their ability to transmit the disease is not known at this time.
In the spring, the eggs hatch into larvae. During the summer, the larvae feed on mice, squirrel, raccoon, rabbit and other animals. In the fall, the larvae mature into nymphs, which then hibernate over winter. In the spring and summer these nymphs become active again, preferring to feed on mice. It is during the time the tick is in the nymphal stage that it is most likely to infect humans. At the end of its life cycle the female tick lays eggs and dies."
And this:
In the first 15 years after Lyme disease was discovered in coastal New England, several studies showed that many adult ticks feed on deer, and researchers surmised that deer were critical to the tick life cycle. When researchers eradicated deer from New England islands, tick populations crashed.
Unfortunately, nature has a way of being more complex than first thought.
The key to the Lyme disease problem seemed at hand. Unfortunately, nature has a way of being more complex than first thought. One complication is that adult black-legged ticks feed on raccoons, skunks, opossums, and other medium-sized mammals. When deer are scarce, ticks don?t necessarily become scarce, because they have alternative hosts. Indeed, several recent studies (e.g., Jordan and Schulze, 2005; Ostfeld et al., 2006; Jordan et al., 2007 ? see citations below) on mainland sites in New York and New Jersey found no correlation between deer and ticks.
Second, ticks and Lyme disease are rare or absent in parts of the United States (the Southeast, most of the Midwest) where deer are abundant.
Third, ticks are only dangerous if they are infected, and deer play no role in infecting ticks. Ticks become infected with the Lyme disease bacterium by feeding on small mammals such as white-footed mice, chipmunks, and shrews. And mice play the additional role of increasing tick survival ? they are at the opposite extreme from opossums, which kill the vast majority of ticks they encounter. When our group compared the importance of deer, mice, and climate in determining the number of infected ticks over 13 years in southeastern New York State, mice were the winners hands down.
http://roomfordebate.blogs.nytimes.com/2009/07/29/are-deer-the-culprit-in-lyme-disease/
