27 Jul

Map of the Week: Beware of Lyme Disease

According to the Centers for Disease Control and Prevention, black legged and deer ticks have invaded new areas across the United States, carrying Lyme Disease into places it has not existed before. Researcher Rebecca Eisen at the CDC said “even though you may live in an area that didn’t have ticks in the past or your parents don’t remember having ticks, the distribution is changing. More and more people are at risk.”

The expansion of the suburbs and the conservation of wooded areas has led to an increase in deer and mice populations. Ticks feed on deer and mice populations which in turn help spread ticks to new regions. For example, the lone star tick, originally from the southeast is now migrating north and can be found in 1300 counties throughout 39 states. A recent study found a 45% increase since 1998 in the number of counties with black legged ticks. Researchers at the Cary Institute of Ecosystem Studies found that the number of mice around the forest in the summer correlates to the cases of Lyme disease the following summer.  Mice are responsible for infecting the majority of ticks carrying Lyme in the Northeast and an individual mouse might carry up to 100 ticks covering its ears and face. 

As a result, Lyme disease cases in the United States have increased from about 12,000 in 1995 to nearly 40,000 in 2015 and is present in more than 260 counties. It is transmitted to humans through bacteria from the bite of an infected tick. The ticks cling to nearby plants and shrubs and attach themselves to people as they walk by. Once the bacteria enters the bloodstream, it can cause fever, headaches, fatigue, joint pain, and rashes. If not treated early, it can attack the circulatory and nervous system, causing severe muscle pain, irregular heartbeat, and cognitive problems.This week’s Map of the Week examines reported cases of Lyme disease in 2015. I analyzed data from the Centers for Disease Control and Prevention. Most of the reported cases of Lyme disease were in the northeastern United States while Connecticut contained the most reported cases of Lyme Disease in 2015. 95% of the confirmed cases of Lyme disease were reported in Maine, New Hampshire, Massachusetts, Rode Island, Connecticut, Vermont, New Jersey, New York, Delaware, Maryland, Pennsylvania, Virginia, Wisconsin, and Minnesota. 

According to the CDC, the number of Lyme disease cases has more than doubled between 2001 and 2015 due to the surge of mice and deer populations.

Dot density map of reported cases of Lyme disease in 2001 and 2015 from the CDC.


So how can Lyme disease be prevented? Add a daily tick check into your routine and make sure to check in the easy to hide places like behind your ears, the scalp, and the armpits. Be sure to remove the tick as soon as possible if found because the longer an infected tick stays on one’s body, the greater the chance of getting infected with Lyme bacteria. It generally takes 24 hours for the tick to infect someone with Lyme. Lastly, be on the lookout for Lyme disease symptoms, like a rash or a fever. The best chance for a full recovery from Lyme disease is to get treated as early as possible. 

Written by Danielle Bayer