Lyme Disease

Black-legged tick
Lyme disease

Lyme disease is a tick-borne disease caused by the bacteria Borrelia burgdorferi. In Tennessee, it is transmitted by the Ixodes scapularis, also known as the black-legged or deer tick.

In Tennessee, Lyme disease is the third highest reported tick-borne disease. There were 58 cases of Lyme disease in 2021, an increase of 66% compared to 38 cases in 2020. Although Lyme disease is commonly associated with northeastern and midwestern U.S. states, the expansion of black-legged ticks into the southeast U.S. within the past decade has made Lyme disease a growing concern in the northern and eastern regions of Tennessee.

For more information about this disease, see the CDC's Lyme Disease Home Page.

On the map below, each dot represents one case of Lyme disease that occurred in 2021. Each dot is placed randomly in the patient's county of residence. The gradient refers to Lyme disease incidence rates for each county in Tennesee from 2011-2021, which was calculated using county population data from the 2020 U.S. Census.

From 2011-2021, there were 379 Lyme disease cases reported; 93% of those cases were in residents from the Middle and Eastern grand divisions of the state. In the last decade, 12 of the top 15 counties with the highest incidence rate of Lyme are in the northeast region that borders Virginia and North Carolina. The other counties with the highest incidence rates tend to fall along the northern part of the state that borders Kentucky. This may indicate a need for enhanced surveillance and messaging to healthcare providers in these regions.

Lyme disease case map across Tennessee by county

In Tennessee, illness onset for cases of Lyme disease is mainly reported in the warmer months of the year. The number of reported Lyme disease cases is lowest in the winter (December-February), slightly increases in the spring (March-May), peaks in the early to late summer (June-August), and then gradually declines through autumn (October-November).

Signs and symptoms of Lyme disease typically begin 3-30 days after being bitten by an infected black-legged tick. Therefore, late spring through mid summer is the time of year when Tennesseans are most at risk for contracting Lyme disease.

Lyme disease cases by onset week
Note: The n=281 in this chart refers to reported cases of Lyme disease from 2011-2021 with recorded illness onset dates. Thus, this figure only accounts for a portion of the total number of Lyme disease cases reported during this time period.

Anyone who spends time outdoors in Tennessee is at risk of contracting Lyme disease, because the black-legged tick that spreads this disease are most often found in wooded, brushy areas. People holding outdoors-based occupations, such as farmers and landscapers, may be at increased risk of getting bitten by an infected tick, as are people who regularly hike, camp, hunt, or garden in or around wooded areas.

Black-legged ticks may also dwell in the property surrounding Tennessee homes, especially if your yard is either next to a brushy area or has tall grass and/or leaf litter. Even outside of our state's forests, it is important to take the necessary steps to prevent tick bites in any environment habitable by these ticks.

Individuals of any reported gender, sex, and age group in Tennessee can get sick with Lyme disease. However, a relatively larger number of cases of Lyme disease are reported in female-identifying patients ages 30-55.

Lyme disease cases by age group and reported sex

The number of Lyme disease cases reported per year in Tennessee has been steadily increasing since 2014. In 2021, a record-breaking 58 cases were reported. This rise can be attributed to the expansion of Ixodes ticks from the northeastern to the southeastern U.S. region.

Hospitalization rates for Lyme disease patients in Tennessee have been consistently low.

Lyme disease cases by year and hospitalization status

Signs and symptoms of Lyme disease typically develop between 3-30 days after being bitten by an infected tick. Early signs and symptoms may include:

  • Fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes
  • Erythema migrans (EM) rash (see photos here):
    • Occurs in approximately 70-80% of infected persons
    • Begins at the site of a tick bite after a delay of 3-30 days (average is about 7 days)
    • Expands gradually over several days, reaching up to 12 inches or more across
    • May feel warm to the touch, but is rarely itchy or painful
    • Sometimes clears as it enlarges, resulting in a target or "bull's-eye" appearance
    • May appear on any area of the body
    • Does not always appear as a "classic" EM rash

If antibiotic treatment is delayed, Lyme disease can produce a wide array of symptoms, depending on the stage of infection. Late stage signs and symptoms occur days to months after a tick bite and can include:

  • Severe headaches and neck stiffness
  • Additional EM rashes on other areas of the body
  • Facial palsy (loss of muscle tone or droop on one or both sides of the face)
  • Arthritis with severe joint pain and swelling, particularly in the knees and other large joints
  • Intermittent pain in tendons, muscles, joints, and bones
  • Heart palpitations or an irregular heart beat
  • Episodes of dizziness or shortness or breath
  • Inflammation of the brain and spinal cord
  • Nerve pain
  • Shooting pains, numbness, or tingling in the hands or feet

For more information, see the CDC's Lyme Disease Signs and Symptoms web page.

Lyme disease is diagnosed by a healthcare provider, who will use a combination of clinical observations and laboratory testing to assess whether Borrelia burgdorferi is present. Providers will consider the signs and symptoms of Lyme disease, the likelihood that the patient has been exposed to infected black-legged ticks, the possibility that other illnesses may cause similar symptoms, and the results of laboratory testing to decide whether a diagnosis should be made.

The laboratory criteria recommended by the CDC involves two tests, both of which can be done using the same blood sample. It may take several weeks for test results to return. If your provider is concerned, they may prescribe you with antibiotics while you wait for the results.

For more information, see the CDC's Lyme Disease Diagnosis and Testing web page.