Lyme disease comes from a tick bite, not from another person

You contract Lyme disease when an infected tick bites you and stays attached long enough to transmit the bacteria Borrelia burgdorferi into your bloodstream. The tick must be feeding on you for roughly 24 to 48 hours for transmission to occur in most cases. You cannot catch Lyme disease from another person, from pets, from food, or from the air.

The ticks that carry Lyme disease are deer ticks (also called black-legged ticks), which are much smaller than the common wood tick or dog tick. An adult deer tick is about the size of a sesame seed; a nymph (immature tick) is smaller still, roughly the size of a poppy seed. Because they are so small, many people do not notice them and do not realize they have been bitten.

Deer ticks live in wooded areas, tall grass, and leaf litter across much of the United States, particularly in the Northeast, Mid-Atlantic, and upper Midwest. They are active in spring, summer, and fall, though they can bite year-round in milder climates. The ticks become infected when they feed on infected animals—particularly white-tailed deer and small rodents like mice—and then pass the bacteria to humans during a later bite.

Key Takeaways

  • Lyme disease is transmitted only through the bite of an infected deer tick that has been attached for at least 24 hours.
  • Deer ticks are very small—nymphs are poppy-seed sized—which is why many people do not notice the bite.
  • The bacteria spreads from the tick's saliva into your bloodstream during feeding, not through the tick's bite wound itself.
  • Removing a tick within 24 hours of attachment significantly reduces the risk of infection.
  • You cannot contract Lyme disease from another person, from pets, or from any source other than an infected tick bite.

Why the 24-hour window matters

The bacteria Borrelia burgdorferi lives in the tick's gut, not in its mouthparts. When the tick feeds, it takes a blood meal over hours or days. As the tick's gut fills and pressure increases, the bacteria migrate from the gut into the tick's salivary glands. This migration typically takes 24 to 48 hours. Once the bacteria reach the salivary glands, they flow into your bloodstream along with the tick's saliva during feeding.

This timeline is why early removal matters. If you find and remove a tick within 24 hours of attachment, the bacteria likely have not yet migrated to the salivary glands, and transmission is unlikely. After 48 hours, the risk of transmission increases substantially. This does not mean infection is certain after 48 hours—some infected ticks do not transmit the bacteria even with longer attachment—but the longer a tick feeds, the higher your risk.

The challenge is that most people do not know they have been bitten. Deer ticks are so small that you may not see them on your skin, and their saliva contains a numbing agent, so the bite itself causes no pain or immediate irritation.

Where ticks hide on your body

Ticks do not drop from trees or fly onto you. They climb onto your skin when you brush against vegetation where they are waiting. Once on your body, they crawl to warm, moist areas where they are less likely to be noticed or brushed off. Common attachment sites include the groin, armpits, behind the knees, between the toes, the navel, and the hairline or scalp.

Because ticks seek out these hidden areas, a tick may feed for days without you noticing it. This is especially true for nymphs, which are so small that even if you see one, you might mistake it for a freckle or a speck of dirt. Adult ticks are larger and somewhat easier to spot, but they still often attach in places you do not regularly inspect.

Checking your body for ticks after time outdoors—particularly in wooded areas or tall grass during warm months—is one of the most effective ways to catch a tick before it has fed long enough to transmit the bacteria.

How the bacteria spreads once inside your body

After the bacteria enter your bloodstream through the tick's saliva, they begin to spread. In the early stage of infection, the bacteria often cause a characteristic rash called erythema migrans, which expands outward from the bite site in a bull's-eye or target pattern. This rash appears in roughly 70 to 80 percent of infected people, though some people never develop one.

The bacteria can spread to your joints, heart, and nervous system if the infection is not treated. This is why early recognition and treatment matter. If you notice a rash that expands over days, or if you develop fever, fatigue, or joint pain after a tick bite or time in tick-prone areas, medical evaluation is important. A blood test can confirm whether you have been infected.

The bacteria do not spread through your saliva, blood, or other body fluids to other people. You cannot transmit Lyme disease to a family member, partner, or healthcare worker through contact, sharing food, or any other means.

Tick behavior and seasonal risk

Deer ticks are most active when temperatures are above freezing, but their peak activity occurs in spring and early summer when nymphs are feeding, and again in fall when adult ticks seek hosts before winter. Nymphs are responsible for most human infections because they are abundant, small enough to go unnoticed, and actively feeding during the warm months when people spend time outdoors.

Risk is highest in areas where deer ticks are established and where infected animals are common. The Northeast and Mid-Atlantic states, particularly areas with mixed forest and open land, have the highest rates of Lyme disease. However, infected ticks have been found in many states, and the range continues to expand. Even in high-risk areas, not all ticks carry the bacteria—estimates vary by region, but typically 10 to 50 percent of deer ticks in endemic areas are infected.

This means that a tick bite does not automatically mean you will develop Lyme disease. Many tick bites do not result in infection, either because the tick was not infected or because it was removed before transmission could occur.

Preventing tick bites and transmission

Because transmission requires a tick to remain attached for at least 24 hours, prevention focuses on two goals: avoiding tick bites in the first place, and finding and removing any ticks that do attach before they have fed long enough to transmit the bacteria.

To reduce tick bites, wear light-colored clothing in wooded or grassy areas so ticks are easier to spot. Tuck your pants into your socks and your shirt into your pants if you are walking through tall vegetation. Use an insect repellent containing DEET or permethrin on exposed skin and clothing. Permethrin is particularly effective on clothing and gear—it kills ticks on contact—but should not be applied directly to skin.

After time outdoors, shower within a few hours and check your entire body for ticks, paying special attention to warm, moist areas. Wash your clothes in hot water. If you find a tick, remove it promptly by grasping it as close to the skin as possible with tweezers and pulling straight out with steady pressure. Do not twist, squeeze, or use heat or petroleum jelly, as these methods may cause the tick to regurgitate infected material into the bite wound.

When a tick bite leads to infection

Even with precautions, some people are bitten by infected ticks and develop Lyme disease. The infection is treatable with antibiotics, particularly if caught early. Doxycycline, amoxicillin, or cefuroxime are commonly prescribed, depending on your age and other factors. Early treatment typically prevents the infection from spreading to joints, the heart, or the nervous system.

If you develop a rash, fever, or joint pain after a tick bite or time in a tick-prone area, contact your doctor. Bring any information you have about the tick—when you were bitten, where, and whether you removed it yourself. A doctor can order a blood test to confirm infection and start treatment if needed.

Post-exposure prevention is also an option in some cases. If you have been bitten by a tick in a high-risk area and can see a doctor within 72 hours, a single dose of doxycycline may prevent infection. This is not routine practice, but your doctor can discuss whether it is appropriate for your situation.

Frequently Asked Questions

Can you get Lyme disease from a tick that is not attached to your skin?

No. A tick must bite you and feed on your blood to transmit the bacteria. A tick crawling on your skin or clothing cannot transmit Lyme disease. Once you remove the tick, even if it is still alive, it cannot infect you.

If a tick is attached for less than 24 hours, is infection impossible?

Infection is unlikely but not impossible. Most transmission occurs after 24 to 48 hours of attachment, but rare cases of transmission have been documented with shorter attachment times. This is why removing ticks promptly is important, even if you catch them quickly.

Can you get Lyme disease from a tick bite during winter?

Deer ticks are less active in winter, but they do not die in cold weather. They can bite on warm winter days when they become active. In milder climates, ticks may be active year-round. Risk is lower in winter but not zero.

What should you do if you cannot remove the entire tick?

If the tick's head breaks off and remains in your skin, do not panic. The head alone cannot transmit Lyme disease because the bacteria are in the tick's gut and salivary glands, not in the mouthparts. Clean the area with soap and water. If the area becomes infected or inflamed, contact your doctor.

Can pets bring infected ticks into your home and transmit Lyme disease to you?

Pets can carry ticks into your home, and you can be bitten by those ticks. However, the tick must still attach to you and feed for at least 24 hours to transmit the bacteria. You cannot catch Lyme disease from your pet directly, only from a tick that bites you.