Lyme disease is caused by a bacterium known as Borrelia burgdorferi. It is transmitted to people through the bite of an infected tick. In the southeastern U.S. the black-legged tick (Ixodes scapularis) is the suspected vector.
The disease is the most commonly reported vector-borne disease in the U.S. However, most cases are reported in the northeastern, Mid-Atlantic, and north central regions of the country.
Most cases of Lyme disease can be treated successfully with a few weeks of antibiotics.
Disease Prevention
Learn about steps that can be taken to help prevent mosquito and tick bites and ways to maximize protection against vector-borne illnesses.
Transmission
Normally, the life cycle of the black-legged tick begins with eggs in the spring. The eggs hatch into larvae and then feed once before they molt into nymphs and go dormant until the following spring. Then they feed again and molt into adults.
The larvae and nymphs feed on rodents, and it is usually at this stage when the tick becomes infected. The nymphs and adults feed on larger mammals, including humans.
Most humans are infected through the bites of nymphs. Studies have shown that both nymph and adult ticks need to be attached for more than 24 hours to effectively transmit the infection. For this reason, it is important to regularly check for ticks and remove them immediately.
Symptoms
Between 60-80% of people will develop a red, “bull’s eye” rash (erythema migrans) 3-30 days after being bitten by an infected tick. This rash does not always appear at the site of the bite, and may occur on another part of the body.
Other symptoms include fever, headache, chills, fatigue, stiff neck or muscle aches. Later stage symptoms may not appear until months or years after the bite and can include problems with the brain, heart, joints and muscles.
Patients treated with antibiotics early after the infection usually recover quickly and completely. A few patients, especially those diagnosed in the later stages of disease, may have persistent or recurrent symptoms. These patients may benefit from a second course of antibiotic therapy. However, longer courses of antibiotic treatment have not been shown to be beneficial and have been linked to serious complications.
Treatment
- Most cases of Lyme disease can be treated with 10-14 days of antibiotics
- People treated with appropriate antibiotics in the early stages of Lyme disease usually recover rapidly and completely
- Clinical Care and Treatment of Lyme Carditis