Lyme disease is the most common tick-borne disease in the United States, with approximately 16,000 new cases reported each year. The disorder was first identified in 1975 when a group of children in Lyme, Connecticut, experienced mysterious arthritis-like symptoms. The deer tick carrying the bacterium B. burgdorferiis responsible for the spread of the disease in the United States. Cases have been reported in nearly all states, and the disease is also on the rise in large areas of Asia and Europe.

Signs and Symptoms

Lyme disease is accompanied by the following signs and symptoms:

  • Red rash that appears within a few weeks of a tick bite, initially as a small red spot at the site of the bite. The spot expands over time, forming a circle or oval and sometimes resembling a bull’s eye. The rash can range in size from that of a dime to the entire width of a person’s back. As the infection spreads, rashes can appear at different places on the body.
  • Flu-like symptoms – fever, headache, stiff neck, body aches, and fatigue.
  • Arthritis – 60 percent of people not treated with antibiotics develop recurring attacks of arthritis, most commonly in the knees, that last a few days to a few months. About 10 to 20 percent of untreated individuals will develop ongoing arthritis.
  • Neurological symptoms – stiff neck and severe headache (may indicate meningitis), temporary paralysis of muscles in the face (Bell’s palsy), numbness, pain or weakness in the limbs, or poor motor coordination. Symptoms can develop weeks, months, or even years following an untreated infection, and can last for weeks or months. Symptoms usually resolve completely, but they may recur.
  • Heart problems – heart abnormalities such as palpitations, lightheadedness, fainting, chest pain, and shortness of breath are uncommon. Symptoms may appear several weeks after infection and last a few days or weeks.


Ixodes ticks carrying the bacterium B. burgdorferi bite people. The bacteria enter the skin at the site of the bite, after the infected tick has been in place 36 to 48 hours. Symptoms are primarily due to the body’s response to this invasion.

Who is at risk?

The following factors increase the risk for developing Lyme disease.

  • Environment: exposure to heavily wooded areas
  • Season: infection is most likely during the summer and fall
  • Age: most common in children and young adults
  • Location: 90 percent of cases occur in the coastal northeast, as well as in Wisconsin, Minnesota, California, and Oregon