“Over time, the number of counties identified as having high incidence of Lyme disease in the northeastern states increased more than 320 percent: from 43 (1993-1997) to 90 (1998-2002) to 130 (2003-2007) to 182 (2008-2012)”, said CDC’s Kiersten Kugeler. Scientists aren’t sure why high-risk areas are expanding, but it likely has something to do with development and other changes that cause the mice, deer and ticks that carry the bacteria to move, Kugeler said. Black-legged ticks, I. scapularis are known to transmit Lyme disease, Borrelia burgdorferi, to humans and animals during feeding, when they insert their mouth parts into the skin of a host, and slowly take in the nutrient-rich host blood. Now, high-risk zones encompass almost all of Massachusetts and New Hampshire and more than half of Maine and Vermont.

In the upper Midwest, Minnesota and Wisconsin have several high-risk counties, as do Iowa and Michigan.

A young pop singer who battled Lyme disease was recently on the cover of People magazine. These symptoms can include headaches, stiff neck, joint pain, muscle aches, chills, fever, swollen lymph nodes and fatigue. In the days to weeks after the tick bite, Lyme disease can cause more serious problems. But some reports have suggested it is far more common than that maybe as many as 300,000 cases.

The CDC found there was a steady march in all directions of the disease, from the places it was most densely reported, outward. Some counties have dropped off the high-risk list, including those in Virginia, Georgia, Missouri and North Carolina where significant clusters were reported in the 1990s. It is probable that those cases were a different tick-borne illness (southern tick-associated rash illness, also known as STARI) or that they were detected using tests for Lyme that are not as accurate as those used now.

The first symptom of Lyme disease is a rash that spreads from the site of the tick bite. GlaxoSmithKline eventually settled out of court, but an official follow-up study found nothing abnormal about the vaccine.

“Ticks are endemic in our area”, said PBMC rheumatologist Dr. Jenny Cabas-Vargas, adding that she sees an average of four patients a day at the new center. The center of infection has shifted from northern New Jersey to east-central Pennsylvania, and 15 other states now have at-risk counties, says a new CDC report.