Infection usually begins with a red rash that spreads like a bulls-eye around the bite site.
In advanced cases, infections can cause disabling symptoms in the heart and brain. Most cases of Lyme disease in the U.S. are clustered in New England and the mid-Atlantic states and in the upper reaches of the Mississippi River. Deer ticks tend to favor wooded areas, high grasses, marshes, and beaches. But even in areas where the disease is common, the overall risk of infection following a deer tick bite is still 1 in 50, researchers estimate. A different type of repellent designed for application on clothing only and containing the chemical permethrin has also been shown to be highly effective.