What You Need to Know About Lyme Disease

The best ways to protect yourself this tick season

tick crawling on jean Photo: Getty Images

An estimated 476,000 cases of Lyme disease occur in the U.S. every year, according to a recent Centers for Disease Control and Prevention study, making it far and away the most common bug-borne illness in the U.S.

But while Lyme is widespread and the number of cases is rising, many aspects of the disease—such as the best ways to diagnose and treat it, and the extent to which it can become a chronic condition—remain unclear.

“There is definitely some confusion and also some misinformation out there,” says Amy Schwartz, an epidemiologist at the CDC. “And it’s important to correct that, because without proper treatment, the condition can be devastating.”

Here’s a breakdown of what scientists do and don’t know about this dangerous and increasingly common illness.

How Lyme Disease Spreads

Lyme disease is spread primarily by bacteria known as Borrelia burgdorferi, which is transmitted to humans, household pets, and forest critters (including mice and deer) by the blacklegged tick, sometimes referred to as the deer tick, and the Western blacklegged tick. Rarely, Lyme can also be caused by recently discovered bacteria, Borrelia mayonii, also transmitted by blacklegged ticks.

More on tick-borne diseases

The CDC and the Infectious Diseases Society of America (IDSA) agree that the tick has to remain attached for 24 to 48 hours in order to transmit Lyme-causing bacteria. (Other diseases spread by these ticks, such as the Powassan virus, can be transmitted more quickly.)

The disease is most common in late spring and summer, when young, poppy-seed-sized ticks are active and when people tend to spend more time outdoors.

Both the blacklegged tick and the diseases it carries are most common in the Northeast, Middle Atlantic, and North Central U.S. The states with the highest rates of confirmed cases of Lyme disease include Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, West Virginia, and Wisconsin, plus the District of Columbia. The blacklegged tick can be found most anywhere East of the Mississippi River, while the Western blacklegged tick—which can also spread Lyme—is found in California, Oregon, and Washington, and parts of Arizona and Utah.

Despite what you might read online, a vast majority of scientists agree that getting bitten by a blacklegged tick is essentially the only way to contract Lyme disease. You can’t catch it from sex, from eating deer meat, or from any other type of tick. You also can’t catch it directly from pets or other animals; only ticks can transmit the disease to humans. In rare cases, the CDC says Lyme can be transmitted to a fetus in utero from an infected pregnant person. 

How to Protect Yourself

The good news is that you can take several steps to reduce your risk of being bitten by an infected tick in the first place. Here’s how: 

  • If you can, avoid areas with ticks, particularly during peak tick season (late spring to early fall). These include wooded and brushy areas with high grasses and leaf litter.
  • When spending time in a tick-infested area, dress carefully. Wear long sleeves, long pants, and long socks. Light colors are best because you can spot ticks more easily. To keep ticks from crawling up inside your clothes, tuck your pants into your socks and your shirt into your pants.
  • Apply an effective insect repellent to your clothes and exposed skin. You can also try clothing treated with the insecticide permethrin, but don’t spray this chemical on your skin.
  • After being outdoors, take a shower to wash off any ticks that may be crawling on your skin but not yet attached. While you’re there, check your body for attached ticks, especially in skin folds such as in the armpits and groin, and behind the ears. Remember that young ticks are tiny—about the size of a poppy seed—so they can be difficult to spot. (See these tips for removing any ticks you do find.) 
  • Another useful measure: Pop your clothes in the dryer for 15 minutes on high to kill any ticks that may be hiding.

How to Tell If You've Been Infected With Lyme Disease

The most obvious way to tell if you’ve been infected with Lyme disease is to check for the telltale bull’s-eye rash (called erythema migrans), which develops in 70 to 80 percent of cases. If you know you’ve been bitten by a blacklegged tick, you’ll want to keep a close eye out for this rash around the site of the bite. These images from the CDC can help you get an idea of how the rash might look if it appears on your skin.

If no such rash emerges—or if you never even found a tick on your body—but you develop symptoms of Lyme disease (fever, chills, joint pain) after being in a tick-infected area during tick season, you should ask your doctor whether Lyme disease might be possible.

Blood testing for Lyme has two tiers (or components) to it, and it’s important to make sure your doctor does both. “It’s a common misconception among doctors that you can skip the first part,” says Paul Auwaerter, MD, a past president at the IDSA. “A lot of doctors do that, and they end up misinterpreting the results and misdiagnosing people.”

The timing of the tests is also important, he says. It can take weeks for the body to mount an immune response to Lyme-causing bacteria and to produce the antibodies that the blood tests are designed to measure. So if you test negative in the first month after being bitten (or after symptoms emerge), you may want to get retested a few weeks later. “The test really can’t pick up infection reliably in the first few weeks,” Auwaerter says. “But if people have had symptoms for longer than that, it’s highly accurate.”

Treatment for Lyme Disease

If your doctor thinks you have Lyme, based on a positive test or the presence of symptoms (such as a telltale rash) and recent possible exposure to ticks, your doctor will most likely prescribe the antibiotic doxycycline. A one- to four-week course of the drug (depending on how you respond) will almost always wipe out the infection.

But you don’t necessarily have to wait for symptoms or a blood test to get treated for possible Lyme infection. According to the CDC and the IDSA, a single dose of doxycycline taken within 72 hours of a tick bite can prevent the disease from emerging altogether. This preventative treatment is recommended only if you received your tick bite in an area where Lyme is common. Your doctor must also be able to identify the tick that bit you as a blacklegged tick and be able to tell from how large it has swelled that it’s been attached to you for at least 36 hours. (If you find an attached tick while in an area where Lyme is common and you want to pursue this preventive treatment, then after you remove the tick, place it in a plastic bag and store it in the freezer. You’ll then need to see a doctor within 72 hours.)

Doxycycline does cause side effects. It can make your skin more sensitive to sunlight, and it causes nausea or vomiting in about 20 percent of people taking it.

Some doctors may prescribe a different antibiotic, such as amoxicillin. But that approach hasn’t been scientifically tested, and it’s unclear if or how well it works to combat Lyme.

What Is Chronic Lyme?

According to the CDC and the IDSA, most people who test positive for Lyme respond well to antibiotics. But some patients continue to suffer long after the standard antibiotic course.

Researchers have some ideas about the causes of this more difficult condition. It’s possible that the bacteria or some of the toxins they produce are sometimes able to survive the treatment. It’s also possible that the body suffers some sort of autoimmune response to the bacteria or the treatment itself. Or it could be that these illnesses are the result of multiple simultaneous infections—not just with Borrelia burgdorferi but with several other pathogens that the blacklegged tick is known to transmit.

But ultimately, doctors are divided over several basic questions: How common is this condition? Can it be treated with antibiotics? And what should it be called?

The CDC and the IDSA refer to this as post-treatment-Lyme-disease syndrome, a condition for which no proven cause or treatment options exist. According to both organizations, there’s no evidence that prolonged antibiotic therapy works against Lyme disease.

But other groups, including the International Lyme and Associated Diseases Society, call it chronic Lyme disease. They say it may stem from a failure to diagnose Lyme disease early on (often because the telltale rash doesn’t emerge and the person isn’t aware of being bitten by a tick). They also say that long-term antibiotic therapy can work, though they say relapses are common and the road to recovery is bumpy.

Most doctors still reject the term chronic Lyme, in part because many people who say they have this condition haven’t been infected with Borrelia bacteria. “We don’t use the term chronic Lyme because it can be confusing,” says Schwartz at the CDC. “Sometimes it is used to describe people who have tested positive for Borrelia and who have clearly had Lyme disease. But sometimes it refers to people with no such history.”

One thing everyone agrees on is that it will take time and much more research to sort out the mystery. And now some experts hope that research may be forthcoming because of the growing number of people experiencing another long-term post-infectious syndrome following infection with COVID-19, known as “long COVID.”

Some researchers have drawn comparisons between long COVID and post-treatment Lyme because of their diverse array of symptoms, such as fatigue, brain fog, and joint and muscle pain—complaints that can “appear vague, difficult to explain, multifactorial, or unexpected” and that can lead doctors to dismiss or minimize patients’ concerns, according to John Aucott, MD, director of the Johns Hopkins Lyme Disease Clinical Research Center, writing in The Lancet. He says that post-infectious syndromes of any kind “present the opportunity for novel, scientifically rigorous, inclusive, open-minded research with the aim of helping patients with these poorly understood conditions recover their health.”