Lyme disease is an infectious disease caused by the bacteria Borrelia burgdorferi sensu lato. B. burgdorferi is transmitted to humans by a bite from an infected black-legged or deer tick. The tick becomes infected after feeding on infected deer or mice.
A tick has to be present on the skin for 24 to 48 hours to transmit the infection. Most people with Lyme disease have no memory of a tick bite.
Lyme disease was first reported in the town of Old Lyme, Connecticut, in 1975. It’s the most common tick-borne illness in Europe and the Pacific Northwest, Northeast, and Upper Midwest regions of the United States. People who live or spend time in wooded areas are more likely to get this illness. People with domesticated animals that are let out in wooded areas also have a higher risk of contracting Lyme disease.
Lyme disease occurs in three stages: early localized, early disseminated, and late disseminated. The symptoms you experience will depend on which stage the disease is in.
Symptoms of Lyme disease start one to two weeks after the tick bite. One of the earliest signs is a “bull’s-eye” rash, which is a sign that bacteria are multiplying in the bloodstream. The rash occurs at the site of the tick bite as a central red spot surrounded by a clear spot with an area of redness at the edge. It may be warm to the touch, but it isn’t painful and doesn’t itch. This rash will disappear after four weeks.
The formal name for this rash is erythema migrans. Erythema migrans is said to be characteristic of Lyme disease. However, many people don’t have this symptom. Some people have a rash that is solid red, while people with dark complexions may have a rash that resembles a bruise.
Early disseminated Lyme disease occurs several weeks after the tick bite. During this stage bacteria are beginning to spread throughout the body. It’s characterized by flu-like symptoms, such as:
During early disseminated Lyme disease you’ll have a general feeling of being unwell. A rash may appear in areas other than the tick bite, and neurological signs such as numbness, tingling, and Bell’s palsy can also occur. This stage of Lyme disease can be complicated by meningitisand cardiac conduction disturbances. The symptoms of stages 1 and 2 can overlap.
Late disseminated Lyme disease occurs when the infection hasn’t been treated in stages 1 and 2. Stage 3 can occur weeks, months, or years after the tick bite. This stage is characterized by:
How is Lyme disease diagnosed?
The diagnosis of Lyme disease begins with an assessment of your health history and a physical exam. Blood tests are most reliable a few weeks after the initial infection, when antibodies are present. Your doctor may order the following tests:
How is Lyme disease treated?
Lyme disease is best treated in the early stages. Early treatment is a simple 14 to 21 day course of oral antibiotics to eliminate all traces of infection. Medications used to treat Lyme disease include:
Persistent or chronic Lyme disease is treated with intravenous antibiotics for a period of 14 to 21 days. Though this treatment eliminates the infection, your symptoms improve more slowly.
It’s unknown why symptoms, like joint pain, continue after the bacteria have been destroyed. Some doctors believe that persistent symptoms occur in people who are prone to autoimmune disease.
How to prevent Lyme disease
Lyme disease prevention mostly involves decreasing your risk of experiencing a tick bite. Take the following steps to prevent tick bites: