Lyme disease spreads through the bite of an infected tick, not through contact with another person or animal

Lyme disease is transmitted almost entirely by tick bites. A tick carrying the bacterium Borrelia burgdorferi must bite you and stay attached long enough to pass the infection into your bloodstream. The tick does not inject the bacteria immediately — the transfer typically takes 24 to 48 hours of attachment. This means that finding and removing a tick early can prevent infection.

You cannot catch Lyme disease from another person, from a pet, or from touching an infected animal. The only documented human-to-human transmission is from a pregnant woman to her unborn child, which is rare. Lyme disease is not spread through saliva, blood contact, or respiratory droplets the way cold or flu viruses are.

Key Takeaways

  • Infected ticks transmit Lyme disease through their bite, and the bacteria typically require 24 to 48 hours of tick attachment to enter your body.
  • Removing a tick within the first 24 hours significantly reduces your risk of infection.
  • You cannot catch Lyme disease from another person, a pet, or casual contact with someone who has the disease.
  • Ticks that carry Lyme disease are most active in spring, summer, and early fall, when outdoor exposure is highest.
  • Tick bites are painless, which is why many people do not notice a tick until it has been attached for hours or days.

Which ticks carry Lyme disease

Only certain tick species carry the bacteria that causes Lyme disease. In the northeastern and midwestern United States, the primary culprit is the blacklegged tick (also called the deer tick). On the West Coast, the western blacklegged tick transmits Lyme disease. These ticks are much smaller than the common dog tick or wood tick — an infected tick can be as small as a poppy seed in its nymph stage, the life phase when most human infections occur.

Blacklegged ticks pick up the bacteria by feeding on infected animals, particularly white-tailed deer and small rodents like mice. Once infected, the tick carries the bacteria for the rest of its life and can transmit it to any human it bites. Not every blacklegged tick carries the disease — the percentage of infected ticks varies by region, from less than 5 percent in some areas to over 50 percent in others.

How long a tick must stay attached to transmit infection

The bacteria that causes Lyme disease does not move from the tick's mouth into your skin immediately. Research shows that transmission typically requires 24 to 48 hours of continuous attachment. Some studies suggest infection can occur as early as 24 hours, while others indicate the risk rises significantly after 48 hours. The exact timing varies based on the tick's bacterial load and where on your body the tick is attached.

This window of time is why prompt tick removal matters. If you find and remove a tick within 24 hours, your risk of infection drops substantially. After 48 hours, the risk increases. Removing the tick as soon as you notice it — even if you are not certain how long it has been there — is always the right choice.

When and where tick bites happen

Blacklegged ticks are most active from April through October, with peak activity in late spring and summer. They live in wooded areas, tall grass, and brush where deer and rodents travel. You do not need to be deep in the forest to encounter a tick — they are found in suburban yards, parks, and hiking trails. Ticks do not jump or fly; they climb onto your skin when you brush against vegetation they are resting on.

Ticks can attach anywhere on your body, but they prefer warm, moist areas like the groin, armpits, behind the knees, and the scalp. Because tick bites are painless, you may not feel the tick attach or notice it for hours or even days. Many people discover a tick only by accident — while showering, changing clothes, or during a routine skin check.

Why tick removal timing matters

The 24 to 48 hour window is the reason that checking yourself for ticks after outdoor activities is so important. If you spend time in areas where ticks live — hiking, camping, gardening, or even walking through a park — inspect your skin and scalp when you come inside. Pay special attention to warm, hidden areas where ticks prefer to feed.

If you find a tick, remove it promptly using fine-tipped tweezers. Grasp the tick as close to your skin as possible and pull straight out with steady pressure. Do not twist, squeeze, or jerk the tick, as this can cause the mouthparts to break off and remain in your skin. Do not use petroleum jelly, nail polish, or a hot match — these methods do not work and may cause the tick to release more bacteria. After removal, clean the bite area with soap and water or rubbing alcohol.

Other ways Lyme disease does not spread

Lyme disease cannot spread through blood transfusions, organ transplants, or food. You cannot catch it from sharing utensils, drinking from the same glass, or kissing someone with Lyme disease. Pets cannot transmit Lyme disease to humans, though pets can bring infected ticks into your home attached to their fur. If your pet has been outdoors in a tick-prone area, check its fur and skin for ticks and remove any you find.

A person with Lyme disease does not pose a contagion risk to others. You can be around someone with active Lyme disease without any risk of infection. This is an important distinction from diseases like influenza or COVID-19, which spread person-to-person through respiratory droplets or close contact.

Pregnancy and Lyme disease transmission

The only documented route of human-to-human transmission is from a pregnant woman to her unborn child. This is called vertical transmission or congenital transmission. If a pregnant woman has untreated Lyme disease, the bacteria can cross the placenta and potentially affect the developing fetus. The risk and outcomes of congenital Lyme disease are not fully understood, and cases are uncommon.

If you are pregnant and have been bitten by a tick or think you may have Lyme disease, inform your doctor. Early treatment with antibiotics can prevent transmission to the fetus. This is one of the few situations where Lyme disease poses a direct risk to someone other than the infected person.

Frequently Asked Questions

Can I get Lyme disease from a tick bite that happened weeks ago?

No. Lyme disease is transmitted during the tick bite itself, not afterward. Once you remove the tick, transmission cannot occur. If you develop symptoms weeks after a tick bite, the infection began during that bite, not from a later exposure.

If my spouse has Lyme disease, do I need to take precautions around them?

No special precautions are needed. Lyme disease does not spread from person to person. You can share a bed, bathroom, and meals with someone who has Lyme disease without any risk of infection. The only exception is pregnancy, where an untreated infection can affect the fetus.

Can my dog give me Lyme disease?

Your dog cannot transmit Lyme disease to you directly. However, a dog that has been outdoors in tick-prone areas may bring infected ticks into your home on its fur. Check your pet for ticks after outdoor time and remove any you find to reduce your household's tick exposure.

What should I do if I find a tick but do not know how long it has been attached?

Remove it immediately using fine-tipped tweezers, grasping close to the skin and pulling straight out. Even if the tick has been attached for less than 24 hours, removal stops any further transmission. After removal, monitor the bite area for a rash or other symptoms over the next few weeks.

Is it possible to get Lyme disease from a tick that fell off on its own?

A tick that has already detached has finished feeding and cannot transmit more bacteria. However, if a tick was attached long enough before falling off — typically 24 to 48 hours — transmission may have already occurred during the attachment period.