What is Lyme Disease?

Lyme disease, also known as Lyme borreliosis, is an infectious disease caused by a bacterium named Borrelia spread by ticks, spiders, and mosquitoes.(2) The most common sign of infection is an expanding area of redness on the skin,  known aserythema migrans, that appears at the site of the tick bite about a week after it occurred.(1)  The rash is typically neither itchy nor painful.(1) Approximately 70–80% of infected people develop a rash.(1)  Other early symptoms may include fever, headache, and tiredness.(1)  If untreated, symptoms may includeloss of the ability to move one or both sides of the face, joint pains, severe headaches with neck stiffness, or heart palpitations, among others.(1)  Months to years later, repeated episodes of joint pain and swelling may occur.(1)  Occasionally, people develop shooting pains or tingling in their arms and legs.(1)  Despite appropriate treatment, about 10 to 20% of people develop joint pains, memory problems, and tiredness for at least six months.(1)(5)

Lyme disease is transmitted to humans by the bites of infected ticks of the genuslxodes.(6) In the United States, ticks of concern are usually of thelxodes scapularis type.(7)(8)  In Europe ticks of thelxodes ricinus type may spread the bacteria and typically spread more quickly. (8)(9) In North America,Borrelia burgdorferi and Borrelia mayonii are the cause.(2)(10)In Europe and Asia, the bacteriaBorrelia afzelii and Borrelia garinii are also causes of the disease.(2) Diagnosis is based upon a combination of symptoms, history of tick exposure, and possibly testing for specificantibodies in the blood.(3)(11) Blood tests are often negative in the early stages of the disease.(2) 

Prevention includes efforts to prevent tick bites such as by wearing clothing to cover the arms and legs. Ticks can be removed usingtweezers.(13)Some people develop a fever and muscle and joint pains from treatment which may last for one or two days.(2) In those who develop persistent symptoms, long-term antibiotic therapy has not been found to be useful.(2)(14) Testing of individual ticks is not typically useful.(12)


Lyme disease is the most common disease spread by ticks, spiders and mosquitoes in theNorthern Hemisphere.(15) It is estimated to affect 300,000 people a year in the United States and 65,000 people a year in Europe.(2)(4) Infections are most common in the spring and early summer.(2) Lyme disease was diagnosed as a separate condition for the first time in 1975 inOld Lyme, Connecticut.(16)  It was originally mistaken forjuvenile rheumatoid arthritis.(16) The bacterium involved was first described in 1981 byWilly Burgdorfer.(17)  Chronic symptoms following treatment are well described and are known as post-treatment Lyme disease syndrome (PTLDS).(14) PTLDS is different thanchronic Lyme disease: a term no longer supported by the scientific community and used in different ways by different groups.(14) Some healthcare providers claim that PTLDS is caused by persistent infection, but this is not believed to be true because of the inability to detect infectious organisms after standard treatment.(18)


According to the CDC:

Early Signs and Symptoms (3 to 30 days after tick bite) (19)

  • Fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes
  • Erythema migrans (EM) rash:
    • Occurs in approximately 70 to 80 percent of infected persons
    • Begins at the site of a tick bite after a delay of 3 to 30 days (average is about 7 days)
    • Expands gradually over a period of days reaching up to 12 inches or more (30 cm) across
    • May feel warm to the touch but is rarely itchy or painful
    • Sometimes clears as it enlarges, resulting in a target or “bull’s-eye” appearance
    • May appear on any area of the body


Later Signs and Symptoms (days to months after tick bite) (19)

  • Severe headaches and neck stiffness
  • Additional EM rashes on other areas of the body
  • Arthritis with severe joint pain and swelling, particularly the knees and other large joints.
  • Facial palsy (loss of muscle tone or droop on one or both sides of the face)
  • Intermittent pain in tendons, muscles, joints, and bones
  • Heart palpitations or an irregular heart beat (Lyme carditis)
  • Episodes of dizziness or shortness of breath
  • Inflammation of the brain and spinal cord
  • Nerve pain
  • Shooting pains, numbness, or tingling in the hands or feet
  • Problems with short-term memory