Lyme disease is a bacterial infection that is spread through the bite of one of several types of ticks.
Lyme disease is caused by bacteria called Borrelia burgdorferi (B. burgdorferi). Blacklegged ticks and other species of ticks can carry these bacteria. The ticks pick up the bacteria when they bite mice or deer that are infected with B. burgdorferi. You can get the disease if you are bitten by an infected tick.
Lyme disease was first reported in the United States in 1977 in the town of Old Lyme, Connecticut. The same disease occurs in many parts of Europe and Asia. In the United States, most Lyme disease infections occur in the following areas:
- Northeastern states, from Virginia to Maine
- North-central states, mostly in Wisconsin and Minnesota
- West Coast, mainly in the northwest
There are 3 stages of Lyme disease.
- Stage 1 is called early localized Lyme disease. The infection has not yet spread throughout the body.
- Stage 2 is called early disseminated Lyme disease. The bacteria have begun to spread throughout the body.
- Stage 3 is called late disseminated Lyme disease. The bacteria have spread throughout the body.
Risk factors for Lyme disease include:
- Doing outside activities that increase tick exposure (for example, gardening, hunting, or hiking) in an area where Lyme disease is known to occur
- Having a pet that may carry ticks home
- Walking in high grasses
Important facts about tick bites and Lyme disease:
- In most cases in the U.S. a tick must be attached to your body for 24 - 36 hours to spread the bacteria to your blood. Ticks that cause Lyme disease in Europe transmit
the bacteria more quickly, within 24 hours.
- Blacklegged ticks can be so small that they are almost impossible to see. Many people with Lyme disease never even see or feel a tick on their body.
- Most people who are bitten by a tick do not get Lyme disease.
Symptoms of early localized Lyme disease (stage 1) begin days or weeks after infection. They are similar to the flu and may include:
There may be a "bull's eye" rash, a flat or slightly raised red spot at the site of the tick bite. Often there is a clear area in the center. It can be large and expanding in size. This rash is called erythema migrans. Without treatment, it can last 4 weeks or longer.
Symptoms may come and go. Untreated, Lyme disease can spread to the brain, heart, and joints.
Symptoms of early disseminated Lyme disease (stage 2) may occur weeks to months after the tick bite, and may include:
- Numbness or pain in the nerve area
- Paralysis or weakness in the muscles of the face
- Heart problems, such as skipped heartbeats (palpitations), chest pain, or shortness of breath
Symptoms of late disseminated Lyme disease (stage 3) can occur months or years after the infection. The most common symptoms are muscle and joint pain. Other symptoms may include:
- Abnormal muscle movement
- Joint swelling
- Muscle weakness
- Numbness and tingling
- Speech problems
- Thinking (cognitive) problems
Exams and Tests
A blood test can be done to check for antibodies to the bacteria that cause Lyme disease. The most commonly used is the ELISA for Lyme disease test. An immunoblot test is done to confirm ELISA results. Be aware, though, in the early stage of infection, blood tests may be normal.