What is Lyme disease? Experts explain

For many people, one of the least appealing parts of hiking, camping or even taking the dog on a trail isn’t the steep climb or sleeping on the ground, it’s the thought of finding a tick afterward. Social media has only amplified those fears.
The truth is that Lyme disease is a serious illness that deserves attention, but it’s also widely misunderstood. The vast majority of cases can be treated successfully when diagnosed early, while delayed treatment increases the risk of more serious complications.
Here’s what Lyme disease is, how it spreads and when to seek medical care.
What is Lyme disease?
Lyme disease is a bacterial infection caused primarily by Borrelia burgdorferi – and less commonly in the United States by Borrelia mayonii – that spreads to humans through the bite of infected blacklegged ticks, commonly called deer ticks, explains Dr. Jake Scott, an infectious disease physician at Stanford University School of Medicine.
It is the most common tick-borne disease in the United States, with the U.S. Centers for Disease Control and Prevention estimating that roughly 476,000 Americans are diagnosed with and treated for Lyme disease each year. Official surveillance “captures only part of the burden,” says Scott, because many people are treated based on clinical suspicion and never appear in official case counts.
People are most likely to encounter infected ticks in “suburban, exurban and rural areas where shrubs, brush and tall grasses provide a suitable habitat,” says Dr. John Halperin, a member of the department of neuroscience at Atlantic Health Overlook Medical Center. As a result, anyone who spends time hiking, camping, gardening, hunting, landscaping or maintaining a yard bordering wooded areas faces an increased risk. “Children who play outdoors in such areas are also more commonly exposed,” he adds.
Symptoms usually develop three to 30 days after an infected tick bite. Early signs often resemble the flu and include “fatigue, fever, chills, headache, muscle and joint aches and swollen lymph nodes,” says Scott.
Many people also develop an expanding skin rash called erythema migrans, which often forms a bull’s-eye or other circular pattern. It’s a hallmark symptom that occurs in “up to 90% of infected individuals,” says Halperin, but Scott notes that “in many cases the rash is uniformly red rather than always being ring-shaped.”
Without treatment, the bacterial infection can spread to the joints, nervous system and heart. Scott says this can lead to facial paralysis, nerve inflammation, severe arthritis and heart rhythm abnormalities. Halperin adds that some patients also develop dizziness, double vision or heart block severe enough “to cause lightheadedness or fainting.”
What causes Lyme disease? How to spot a tick
Nearly all U.S. cases result from the bite of an infected blacklegged tick, says Scott. Ticks acquire the bacteria by feeding on infected small mammals – particularly mice – before passing it to humans during a later feeding. Contrary to common myths, Lyme disease cannot be spread through kissing, coughing, sharing food or casual contact, nor is it transmitted by mosquitoes or other common insects.
Transmission usually isn’t immediate. Halperin says infection generally requires the tick to remain attached for “at least 24 hours,” making thorough tick checks after spending time outdoors one of the best preventive measures. “One can judge how long it’s been attached by how plump or blood filled the tick is,” he explains.
Scott similarly notes that removing an attached tick within the first 24 hours “essentially prevents Lyme disease.” Even if a high-risk tick has been attached longer, the overall risk of infection from a single bite remains relatively low. However, “a single dose of doxycycline at the time will lower the risk further,” Halperin says.
After spending time outdoors in wooded areas, he says it’s best to perform a head-to-toe tick check, paying close attention to the scalp, behind the ears, under the arms, around the waist, behind the knees, between the legs and anywhere clothing fits tightly. A tick may appear as a tiny black dot about the size of a freckle.
If you find one, Halperin says to “place fine-tipped tweezers between the skin and the tick” and pull upward with steady, even pressure before cleaning the bite area with soap and water or rubbing alcohol. “Avoid folklore remedies such as burning the tick or coating it with petroleum jelly, which can delay proper removal,” Scott adds.
He also recommends prevention by using EPA-registered repellents containing 20% to 30% DEET, picaridin, IR3535 or oil of lemon eucalyptus, along with permethrin-treated clothing for extended outdoor activities. Showering within two hours of coming indoors and drying outdoor clothing on high heat for an hour can also help eliminate ticks that may have gone unnoticed.
How is Lyme disease treated?
Even if you miss finding a tick, Lyme disease is “curable in virtually all patients,” says Halperin, because the bacteria respond well to commonly prescribed antibiotics. Still, “the earlier it’s caught, the easier the cure,” adds Scott.
Doctors typically prescribe doxycycline, amoxicillin or cefuroxime for 10 to 14 days. More advanced infections involving the nervous system or heart may require longer treatment or intravenous antibiotics. Along with antibiotics, supportive care like rest, hydration and physician-approved pain relievers can help ease symptoms during recovery.
A small percentage of patients continue to experience fatigue, pain or cognitive difficulties after treatment, a condition known as Post-Treatment Lyme Disease Syndrome. Scott emphasizes that these symptoms “can be very real and disabling,” but says research shows they are not caused by an ongoing active infection. As a result, prolonged antibiotic therapy has not been shown to improve outcomes and instead carries meaningful risks.
Rather than pursuing repeated courses of antibiotics, it’s best to work with a health care provider to manage lingering symptoms while evaluating other possible causes.