You may want to be a bit more wary when walking in the woods this summer. The mild winter may mean more of the tiny ticks that carry Lyme disease. But don’t allow the terror of ticks keep you from the great outdoors.

Lyme disease — so named because it was first reported in the United States in the town of Old Lyme, Connecticut, in 1975 — is caused by the bacterium Borrelia burgdorferi. It is spread by the bite of infected blacklegged ticks (also known as deer ticks) in New England, Mid-Atlantic and Great Lakes regions. It can also be spread by the western blacklegged tick in the Pacific Northwest.

While the number of Lyme disease cases is growing, it remains a largely regional concern. According to the Centers for Disease Control and Prevention, 94 percent of Lyme disease cases were reported from 12 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Jersey, New Hampshire, New York, Pennsylvania, Virginia and Wisconsin. (You can see reported cases of Lyme disease over the years mapped out here.)

"Typically, Lyme disease is not acquired in the southeastern United States and central Texas," says Dr. Paul Auwaerter, an associate professor of medicine at the Johns Hopkins University School of Medicine who also serves as the clinical director for the Division of Infectious Diseases.

Lyme disease is more common in northern states because of large numbers of the deer tick's preferred hosts: white-footed mice and deer, according to the American Lyme Disease Foundation. White-footed mice are the principal "reservoirs of infection" on which many larval and ticks feed, according to the group's website.

While they may transmit other diseases, ticks common in other parts of the country — such as the Lone Star tick (Amblyomma americanum), the American dog tick (Dermacentor variabilis), the Rocky Mountain wood tick (Dermacentor andersoni) and the brown dog tick (Rhipicephalus sanguineus) — are not known to transmit Lyme disease, according to the CDC.

But even finding the right tick — or wrong tick, depending on your point of view — latched onto your skin doesn't mean you're going to get Lyme disease.

"If you get the tick off within 24 to 36 hours, you're not going to get Lyme disease," says Dr. Michael Zimring, co-author of "Healthy Travel" and director of the Center for Wilderness and Travel Medicine at Mercy Medical Center in Baltimore.

A close-up of a deer tick, Ixodes scapularisOnly certain ticks, like the deer tick pictured here, will transmit Lyme disease to humans. (Photo: Steven Ellingson/Shutterstock)

How can you tell how long the tick has been there? Is it full of blood?

"If the tick is flat — chances are you didn't get Lyme disease," says Auwaerter.

The telltale symptom of Lyme disease is a red, circular "bulls-eye" rash that appears five to 14 days after infection. About 70 to 80 percent of people infected develop the rash, but Dr. Steven Soloway, a board-certified rheumatologist in Vineland, New Jersey, says the numbers may be higher and many people simply don't notice the rash. Other symptoms in this first stage of Lyme disease include fatigue, chills, fever, headache, muscle and joint aches and swollen lymph nodes.

The symptoms will fade, even if untreated. Symptoms of stage 2 Lyme disease, also known as early disseminated Lyme disease, include swollen joints, particularly the knees. The symptoms are similar to rheumatoid arthritis. The difference, Soloway says, is that rheumatoid arthritis typically affects knuckles first.

Other symptoms include Bell's palsy and heart palpitations and dizziness due to changes in heartbeat.

Lyme disease is treated with antibiotics for two to four weeks. The vast majority of patients recover quickly, experts say. A very few people treated for Lyme disease will continue to have some symptoms. The cause of post-Lyme disease syndrome isn't known. But treatment, experts say, should target the specific symptoms, say joint swelling. Long-term use of IV antibiotics is not appropriate, experts say.

You can take steps to prevent Lyme disease by taking steps to avoid a tick bite. Avoid bushy and grassy areas when walking in the woods, especially in the areas with deer ticks. Wear long pants and long-sleeved shirts and wear insect repellent containing DEET on exposed skin. After walking in wooded areas, thoroughly check the skin for the poppy seed-sized ticks.

Want more info on Lyme disease? The CDC has produced a thorough guide to the disease and this video from the Infectious Disease Society of America walks you through one man's experience with Lyme disease.