Editor's note: This article was updated on March 28, 2018.
Cases of Lyme diease have been trending upward, more than doubling nationwide between 1995 and 2015.
It's the most common vector-borne illness reported in the U.S. Although most cases are still reported in the Northeast, the black-legged tick -- also known as the deer or bear tick -- has been found as far south as Florida and as far north as Canada, data from the CDC show. There is currently no vaccine to prevent the disease. For most people, the disease causes flu-like symptoms. About 80% of people who get it fully recover by taking antibiotics, the CDC says.
What is Lyme disease?
Lyme disease is caused by a bacteria, Borrelia burgdorferi, that’s transmitted to humans through a bite from an infected black-legged or deer tick. Symptoms can occur anywhere from 3 to 30 days after the bite, and symptoms can be wide-ranging, depending on the stage of the infection.
The chances you might get Lyme disease from a tick bite depend on the kind of tick, where you were when the bite occurred, and how long the tick was attached to you, according to the CDC. Black-legged ticks must be attached to you for at least 24 hours to transmit Lyme disease.
What are the symptoms of Lyme disease?
In about 70% to 80% of infections, a rash is seen. About 30% of those rashes have a “bull's-eye” appearance, but most do not, says John Aucott, M.D., director, Johns Hopkins Lyme Disease Clinical Research Center. “It’s uniformly round and red” or bluish-red, he says.
The rash expands gradually over a period of days and can grow to about 12 inches across, according to the CDC. It may feel warm to the touch, but rarely itches or is painful, and it can appear on any part of the body.
As infection progresses, symptoms can include:
- Severe headache or neck stiffness
- Additional rashes on other areas of the body
- Arthritis with severe joint pain and swelling, particularly in the knees
- Loss of muscle tone or “drooping” on one or both sides of the face.
- Heart palpitation or an irregular heartbeat
- Inflammation of the brain and spinal cord
- Shooting pains, numbness, or tingling in the hands or feet
How is Lyme disease diagnosed?
Doctors diagnose Lyme disease based on symptoms and a history of tick exposure. Two-step blood tests are helpful, the CDC says, if used correctly. However, the accuracy of the test depends on the disease stage; in the first few weeks of infection, the test may be negative, as antibodies take a few weeks to develop. Tests aren’t recommended for patients who don’t have Lyme disease symptoms.
How is Lyme disease treated?
If you're treated early in the infection stage, a full recovery is likely.
How prevalent is Lyme disease?
About 30,000 cases of Lyme disease are reported to the CDC each year, the agency says, but that doesn’t reflect every case that’s diagnosed. The CDC estimates about 329,000 cases of Lyme disease occur each year.
Infection is more common in males up to age 15 and between the ages of 40 and 60, says Alan Taege, MD, of Cleveland Clinic’s Department of Infectious Disease. “These are people who are likelier to play outside, and go camping, hunting, and hiking,” he says.
What areas are more likely to have it?
Mainly New England, the Mid-Atlantic states, and part of the upper Midwest. According to the CDC, 95% of confirmed cases in 2015 were in 14 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and Wisconsin.
Black-legged ticks have been found in 43 states, as of last year. However, they behave differently, depending on climate.
In the South, which is more prone to hot weather, ticks tend to stay under leaf litter and don’t come up higher to feed much, Aucott says -- “ticks don’t like to dry out.” This means Southern ticks don’t transmit Lyme as frequently because they don’t tend to feed on humans.
What’s driving up Lyme numbers?
While a worldwide warming trend has made more northern areas like Canada, Maine, and Minnesota hospitable to ticks, the population of deer carrying the ticks probably plays a bigger role.
Development led to record low numbers of deer early in the last century, Mead says. But the deer population has rebounded as reforestation took place over several decades, meaning the tick population has increased and expanded as well.
“Ticks have a pretty long life cycle, lasting 2-3 years, and typically don’t move very far within their lifetime, so it takes a while to see large changes,” he says.
Deer and white-footed mice, which also transmit Lyme disease to ticks that bite them, also are moving closer to humans as their habitat disappears, says Taege.
In some areas, an increase in the mouse population may lead to more cases of Lyme disease, Aucott says, but that may vary in different regions.
Another reason: Warmer weather and mild winters may bring more people outside, raising their chances of being bitten, particularly in Lyme-prone areas, Taege says.
“With more of a warming trend … we’ll see an increase in cases during the winter months. If you look at comparative numbers from 15 years ago, you can say it’s true now.”
That doesn’t mean you should be afraid of outdoor activities, as long as you take precautions to avoid tick bites, Aucott says.
How do you know if you’ve been bitten?
Given that the ticks are the size of a poppy seed, you’ve got to have pretty good eyes. The CDC recommends that if you’ve been walking in the woods, in tall grass, or working in the garden, check your skin afterward, ideally in the shower or bath. That way, you’ve removed your clothes, which may carry ticks, too.
What do you do if there’s a tick under your skin?
Remove it with a pair of fine-tipped tweezers as soon as possible, pulling upward with steady pressure. If parts of the tick remain in the skin, also try to remove them with the tweezers. After everything is out, clean the bite area with rubbing alcohol or soap and water.
Mead says you’re not likely to get infected if you remove the tick within 36 to 48 hours.
Some people have an allergic reaction to ticks, so they’ll notice a bite right away.
How do you dispose of a tick?
Place it in soapy water or alcohol, stick it to a piece of tape, or flush it down the toilet.
When should you see a doctor if you suspect you have Lyme?
The rash is a pretty good indication that you may have been bitten. At this stage of the illness, treatment with antibiotics will probably be successful, Aucott says.
What’s the best way to prevent a tick bite?
Ticks can’t fly or jump, but instead live in shrubs and bushes, and grab onto someone when they pass by. To avoid getting bitten:
- Wear pants and socks in the woods, areas with lots of trees, and while handling fallen leaves
- Wear a tick repellent on your skin and clothing that has DEET, lemon oil, or eucalyptus.
- For even more protection, use the chemical permethrin on clothing and camping gear.
- Shower within 2 hours after coming inside, if possible.
- Look at your skin and wash ticks out of your hair.
- Put your clothing and any exposed gear into a hot dryer to kill whatever pests might remain.
Is there any progress on a vaccine for Lyme disease?
The FDA last July gave "fast-track" approval to test potential Lyme disease vaccine VLA15 on adults in the U.S. and Europe. The designation helps speed drugs and vaccines to market more quickly.
What if a tick bites my dog?
It’s pretty likely your furry pal has been bitten by a black-legged tick, especially if you live in the Northeast. In fact, dogs are a barometer of where ticks live, Mead says.
“The fact that dogs are good at picking up ticks means that where humans are getting Lyme, dogs are getting it very often. Where they aren’t infected a lot is a good indicator where Lyme is not,” he says.
And they can get sick. About 10% of dogs with Lyme disease will become ill. Common symptoms are lameness, a fever, lethargy, and enlarged lymph nodes. Dogs also receive antibiotics for treatment.
What if my dog brings ticks into the home?
Practice prevention habits and use a tick control product on your pet.