Overview
Lyme disease is an infectious disease caused by the bacterium Borrelia burgdorferi and, in rare cases, Borrelia mayonii. It is primarily transmitted to humans through the bite of infected blacklegged ticks, also known as deer ticks (Ixodes scapularis). The disease is most prevalent in the northeastern, mid-Atlantic, and upper Midwest regions of the United States, as well as in parts of Europe and Asia. (cdc.gov)
Transmission
The life cycle of the blacklegged tick includes four stages: egg, larva, nymph, and adult. Ticks become infected with Borrelia bacteria when they feed on infected small mammals, such as white-footed mice (Peromyscus leucopus). Humans typically contract Lyme disease through the bite of nymphal ticks, which are smaller and more difficult to detect. (ncbi.nlm.nih.gov)
Symptoms
Lyme disease symptoms often appear in stages:
Early Localized Stage (3 to 30 days post-bite)
- –Erythema migrans (EM) rash: A circular or oval rash that expands over several days, often resembling a bull's-eye. It may feel warm but is usually not painful or itchy. (
mayoclinic.org)
- –Flu-like symptoms: Fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes. (
familydoctor.org)
Early Disseminated Stage (days to weeks post-bite)
- –Multiple EM rashes: Indicating the spread of the bacteria.
- –Neurological symptoms: Facial palsy (loss of muscle tone or droop on one or both sides of the face), severe headaches, neck stiffness, and nerve pain.
- –Cardiac symptoms: Heart palpitations or irregular heartbeat. (
Late Disseminated Stage (months to years post-bite)
- –Arthritis: Severe joint pain and swelling, particularly in large joints like the knees.
- –Neurological issues: Numbness or tingling in the hands or feet, problems with concentration and memory, and inflammation of the brain and spinal cord. (
Diagnosis
Diagnosis is based on:
- –Clinical evaluation: Assessment of symptoms and physical findings, such as the EM rash.
- –Exposure history: Consideration of potential exposure to tick habitats.
- –Laboratory tests: Detection of antibodies against Borrelia bacteria. (
Treatment
Early-stage Lyme disease is typically treated with oral antibiotics, such as doxycycline or amoxicillin, for 10 to 14 days. In cases involving severe neurological or cardiac symptoms, intravenous antibiotics may be required. (mayoclinic.org)
Prevention
Preventive measures include:
- –Avoiding tick-infested areas: Especially during warmer months.
- –Using insect repellents: Products containing DEET on skin and permethrin on clothing.
- –Wearing protective clothing: Long-sleeved shirts and long pants.
- –Performing tick checks: Thoroughly checking the body for ticks after outdoor activities.
- –Prompt tick removal: Using fine-tipped tweezers to remove ticks as soon as possible. (
fda.gov)
Epidemiology
Lyme disease is the most common tick-borne illness in the United States and Europe. In the U.S., an estimated 476,000 people are diagnosed and treated annually. The incidence has been increasing, partly due to climate change expanding the habitat of ticks. (en.wikipedia.org)
Notable Cases
In August 2025, singer Justin Timberlake disclosed his diagnosis with Lyme disease, bringing renewed attention to the risks associated with tick-borne illnesses. (apnews.com)
Related Conditions
Some individuals experience persistent symptoms after treatment, a condition referred to as post-treatment Lyme disease syndrome (PTLDS). Research into PTLDS is ongoing to better understand its causes and develop effective treatments. (time.com)