How Long Does It Take to Get Lyme Disease After a Tick Bite?

A study by Eisen and colleagues addressed a frequently asked question: How long does it take to get Lyme disease? According to their findings, the probability of becoming infected with Borrelia burgdorferi (Bb)—the bacterium that causes Lyme disease—increases the longer an infected tick remains attached. [1]

How long must a tick be attached to transmit Lyme disease?

Researchers found the risk increases:

• Approximately 10% after a tick has been attached for 48 hours
• 50% after 63–67 hours
• 70% by 72 hours
• 90% for a complete tick feeding

The time it takes to become infected with Lyme disease bacteria has “generated lively debate in the United States,” writes Eisen.

Several mouse studies suggest that a single bite from an infected nymph tick cannot transmit Lyme disease in less than 24 hours. However, other researchers caution that earlier transmission cannot be completely ruled out.

“The possibility that transmission of Lyme disease spirochetes could occur within 24 hours of nymphal attachment under unusual circumstances should not be discounted,” Eisen writes.

While the tick is attached, Borrelia burgdorferi spirochetes multiply in the tick’s gut, migrate into the hemocoel, and eventually invade the salivary glands before being transmitted to the host.

In a review article, Cook writes, “It is frequently stated that the risk of infection is very low if the tick is removed within 24–48 hours, with some claims that there is no risk if an attached tick is removed within 24 hours or 48 hours.” [2]

However, animal models suggest transmission can occur in less than 16 hours, and the minimum attachment time required for infection has never been firmly established.

Spirochetes in tick salivary glands

Studies have also identified Borrelia burgdorferi spirochetes in the tick salivary glands before feeding begins.

When spirochetes are already present in the salivary glands, they may be injected into the host during the early transfer of anticoagulants and antihistamines released immediately after the tick attaches.

There is also evidence that transmission timing and virulence may vary depending on the tick species and the Borrelia strain involved.

Are you the tick’s second meal?

A partially fed tick may transmit infection more quickly.

“Partially fed ticks able to reattach could result from detachment from dead animals or from host grooming,” Eisen explains.

Researchers have shown that infected Ixodes scapularis nymph ticks previously attached to a host for 24–48 hours can transmit Borrelia burgdorferi within 24 hours after reattaching to a new host.

Ticks harbor multiple diseases

Blacklegged ticks may harbor multiple pathogens, leading to Lyme disease and other tick-borne infections.

Studies suggest ticks can harbor up to a dozen infectious organisms, and some pathogens can be transmitted more quickly than Lyme disease bacteria.

• Powassan virus may be transmitted within about 15 minutes
• Anaplasma phagocytophilum and Borrelia miyamotoi may be transmitted within the first 24 hours
• Rickettsia rickettsii has been transmitted in as little as 10 minutes by partially fed ticks

The longer a tick remains attached, the greater the risk of Lyme disease transmission.

Underestimating tick attachment time

Estimating how long a tick has been attached can be difficult.

“Bites by Ixodes scapularis nymphs often go entirely undetected, and tick-bite victims typically underestimate how long a nymph was attached before it was discovered and removed,” writes Eisen.

One study found that individuals consistently underestimate the actual time the tick had been attached before it was discovered.

Additionally, individuals may not know if they were bitten by a partially fed tick, which could increase their risk of infection and allow transmission to occur more quickly.

Key Point

The risk of Lyme disease increases the longer an infected tick remains attached. Although infection is less likely in the first 24 hours, transmission may occur sooner in certain circumstances.

Clinical Insight

Because tick attachment time is frequently underestimated and partially fed ticks may transmit infection more rapidly, clinicians should consider Lyme disease even when patients believe a tick was attached for only a short period. Learn more in the Lyme disease hub or review common Lyme disease symptoms.

UPDATED: June 7, 2021