You get Lyme disease from the bite of an infected blacklegged tick. There is no other established route of transmission. The tick must typically be attached to your skin for more than 24 hours before the bacteria pass into your body, which means finding and removing ticks quickly is one of the most effective ways to prevent infection.
How the Tick Transmits the Bacteria
Lyme disease is caused by a spiral-shaped bacterium that lives in the gut of certain ticks. When an infected tick latches onto your skin and begins feeding, it doesn’t transmit the bacterium right away. The organism needs time to migrate from the tick’s gut to its salivary glands before it can enter your bloodstream. In most cases, this process takes more than 24 hours of continuous attachment.
This delay is important because it creates a window for prevention. If you check your body thoroughly after spending time outdoors and remove any attached tick within that first day, your risk of infection drops significantly. The longer a tick stays attached, the higher the chance of transmission. By 48 to 72 hours, the risk climbs substantially.
Which Ticks Carry Lyme Disease
Only blacklegged ticks transmit Lyme disease in the United States. In the eastern and central states, the deer tick is the primary carrier. Along the Pacific coast, particularly in northern California, its close relative the western blacklegged tick fills the same role. Other common ticks, like the American dog tick or the lone star tick, do not transmit the Lyme bacterium.
Not every blacklegged tick is infected. Infection rates vary by region and by the tick’s life stage, but in high-risk areas of the Northeast and upper Midwest, a significant percentage of nymphal and adult ticks carry the bacterium. A secondary species of Lyme-causing bacteria has also been identified in the upper Midwest, though it accounts for a small number of cases.
Why Nymphal Ticks Are the Biggest Threat
Most people who develop Lyme disease are bitten by nymphal ticks, the juvenile stage between larva and adult. Nymphs are about the size of a poppy seed, making them extremely difficult to spot on your skin. They’re small enough to feed in places you might not think to check, like behind the knee, in the groin, along the hairline, or in the armpit.
Nymphs are most active from mid-May through June, which is why late spring and early summer are peak season for Lyme transmission. Adult blacklegged ticks can also transmit the disease and are active in the fall and even into winter on milder days, but their larger size (closer to a sesame seed) makes them easier to find and remove before the 24-hour window closes.
Where You’re Most Likely to Pick Up a Tick
Ticks don’t jump, fly, or drop from trees. They wait on the tips of grasses, shrubs, and leaf litter with their front legs outstretched, a behavior called questing. When you brush past, they grab on and crawl upward looking for a place to feed.
The environments that support questing ticks share a few features: moisture, shade, and access to animal hosts. Woodlands and forests are the most reliable habitat because the canopy and leaf litter maintain the humidity ticks need to survive. They dehydrate quickly in dry, sun-exposed areas and retreat to ground level to reabsorb moisture, which reduces the time they spend seeking hosts. Forest edges are particularly high-risk zones because they combine vegetative cover with high populations of white-tailed deer, one of the tick’s primary hosts.
You don’t need to be deep in the woods to encounter ticks. Suburban yards that border wooded areas, overgrown gardens, stone walls with leaf litter buildup, and shaded paths through tall grass are all common pickup sites. Even a short walk through the right patch of vegetation is enough.
How Pets Factor In
Your dog or cat cannot give you Lyme disease directly. But pets that spend time outdoors can carry unattached ticks into your home on their fur. Those ticks may then crawl off and attach to you. This is one reason Lyme cases sometimes occur in people who don’t recall spending time in wooded areas. Checking your pets after they come inside, and using tick-prevention products recommended by your veterinarian, reduces this risk.
Ways You Cannot Get Lyme Disease
Lyme disease does not spread from person to person. You cannot catch it through touching, kissing, or sexual contact with someone who has it. It is not transmitted through breast milk, blood transfusions, or airborne droplets. The only established route is through the bite of an infected blacklegged tick. Mosquitoes, fleas, and other biting insects do not carry or transmit the Lyme bacterium.
How Common Lyme Disease Is
Lyme disease is the most common vector-borne illness in the United States. Over 89,000 cases were reported to the CDC in 2023, but that number captures only a fraction of actual infections. The CDC estimates that roughly 476,000 people may be diagnosed and treated for Lyme disease each year, though this figure likely includes some patients treated based on clinical suspicion who may not have actually had the disease.
Cases are heavily concentrated in the Northeast, mid-Atlantic, and upper Midwest, with a smaller pocket along the northern Pacific coast. If you live in or travel to these regions, your risk is meaningfully higher than the national average. States like Connecticut, Pennsylvania, New York, New Jersey, Wisconsin, and Minnesota consistently report the highest numbers.
Reducing Your Risk
Prevention comes down to two strategies: avoiding tick contact and finding ticks before they’ve been attached long enough to transmit infection. When you’re in tick habitat, wearing long pants tucked into socks and treating clothing with permethrin (a repellent that kills ticks on contact) both reduce the chance of a tick reaching your skin. Applying insect repellent containing DEET to exposed skin adds another layer of protection.
The more reliable strategy is a thorough tick check after you come indoors. Shower within two hours of being outside, which helps wash off unattached ticks and gives you a chance to inspect your body. Pay close attention to hidden areas: the scalp, behind the ears, under the arms, around the waist, behind the knees, and between the legs. Running clothes through a hot dryer for 10 minutes kills any ticks hitching a ride on fabric, even if the clothes are dry.
If you find an attached tick, remove it by grasping it as close to the skin as possible with fine-tipped tweezers and pulling straight up with steady pressure. Don’t twist, crush, or apply nail polish or heat. Clean the bite area with rubbing alcohol or soap and water, and note the date. If a rash develops, particularly a circular or expanding rash at the bite site, or if you develop fever, fatigue, or joint pain in the following weeks, that’s a signal to seek evaluation promptly.