A new national map shows the places where people are most at risk to contract Lyme disease and several other diseases ticks carry. It's the largest study of its kind. In 2010, there were 135 cases of Lyme disease reported in Illinois. The study involved dragging cloths tied to sticks through forests to see if they picked up disease-carrying ticks. Researchers found certain areas in the Midwest have concentrated areas of the insects. The northern border of Illinois was most abundant, but insects were also concentrated going down from Wisconsin, about halfway into Illinois. One reason for the increase is increasing populations of deer. Ticks are dependent upon deer. The study was funded by the Centers for Disease Control.