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Definition

Lyme disease is a bacterial infection resulting from the bite of an infected deer tick.

Causes

Lyme disease infection is caused by the bacterium Borrelia burgdorferi, carried by deer ticks. An infected tick transmits the bacteria to humans by biting the skin. If untreated, the bacteria is capable of traveling through the bloodstream, settling in various body tissue, and causing a number of acute and persistent symptoms, ranging from mild to severe.

Risk Factors

These factors increase your chance of developing Lyme disease. Tell your doctor if you have any of these risk factors:

  • Living in the northeastern, northwestern, mid-Atlantic, or upper north-central regions of the US (peak tick season in the northeast is April through September)
  • Exposure to deer ticks through outdoor activities, such as hiking, camping, and gardening
  • Living near or frequenting wooded, grassy areas
  • Working outdoors such as surveying, landscaping, forestry, gardening, and utility company service work

Symptoms

The symptoms of Lyme disease are varied and can range from mild to severe. The majority of infected individuals first notice a red rash known as erythema migrans (EM). The rash starts as a small red spot at the site of the tick bite and expands over a period of days or weeks, forming a circular or oval-shaped rash. Sometimes, the rash resembles a bull's eye, a red ring surrounding a clear area with a red center. The size of the rash can range from dime-sized to the entire width of a person's back.

Lyme Disease Rash

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Early Infection

  • EM rash
  • Muscle and joint aches
  • Headache
  • Fever
  • Fatigue

Early Disseminated Infection

  • Multiple EM lesions
  • Facial paralysis (Bell's palsy]]>)
  • Persistent headache, stiff neck
  • Diffuse numbness, tingling, burning
  • Intermittent joint pain and swelling
  • Impaired motor coordination
  • Irregular heart rhythm
  • Muscle pain and swelling

Late Infection

  • Painful inflammation of the joints, intermittent or chronic (]]>arthritis]]>)
  • Mild to moderate confusion

Less Common Symptoms of Late Lyme Disease

  • Heart abnormalities
  • Eye problems, such as ]]>conjunctivitis]]>
  • Chronic skin disorders
  • Limb weakness
  • Persistent motor coordination problems
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Diagnosis

The diagnosis of Lyme disease is usually based on the presence of symptoms and the history of a tick bite. Many people with typical symptoms do not have Lyme disease, even if they have spent time outdoors. If you think you have the symptoms and believe you may have been exposed to a tick, see your doctor right away.

After four weeks, people with Lyme disease usually have antibodies against B. burgdorferi in their blood. A blood test, called an ELISA, can test for the antibodies. When an ELISA is positive, the results should be confirmed with a second blood test called a Western blot.

However, a negative test does not completely exclude the disease, and a positive test alone does not confirm the diagnosis. Blood tests are used to support a diagnosis that is also based on symptoms and risk factors.

Treatment

Lyme disease responds well to antibiotics. Antibiotics, including doxycycline]]> (Vibramycin, Adoxa, and others) and ]]>amoxicillin]]> (Amoxil, Dispermox, Trimox), are usually effective. (Note: Young children and pregnant women should not take doxycycline.)

You will need to take antibiotics for 10 days to four weeks. Some symptoms may continue after treatment. For persistent or severe cases that do not respond to oral antibiotics, intravenous (IV) antibiotic treatments (usually ]]>ceftriaxone]]>) may be given.

Chronic arthritis may require anti-inflammatory medication or joint injection with steroids.

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Prevention

To help prevent Lyme disease, try the following:

Outdoors

  • Avoid areas that are likely to be infested with deer ticks—moist, shaded, wooded, or grassy areas (especially in northeastern, mid-Atlantic, and upper north-central regions of the US and northwestern California)
  • Do the following when going to wooded grassy areas, especially in spring and summer:
    • Wear light-colored clothing with a tight weave to spot ticks easily.
    • Wear enclosed shoes.
    • Wear a long sleeve shirt and tuck it into your pants.
    • Tuck pants into socks or boot tops.
    • Wear a hat.
  • Apply insect repellent containing DEET to clothes and exposed skin. Insect repellents]]> containing permethrin can be applied to pants, socks, and shoe, but not to skin. Both products can cause eye irritation and DEET can cause skin reactions, so be sure to follow label directions for application, including:
    • Do not apply near eyes, nose, or mouth.
    • Do not apply to children's hands.
    • Wash your skin when you return indoors.
  • Stay on cleared, well-traveled paths and walk in the center of trails to avoid overgrown grass and brush. Avoid sitting on the ground or stone walls.
  • Remove leaf litter, brush, and woodpiles from around the home and the edges of the yard.

Tick Management

  • Put clothes worn outdoors in the dryer for 20 minutes to kill unseen ticks.
  • Deer ticks are unlikely to infect unless they remain in contact with the skin for at least 24 hours. This leaves ample time to do a full-body check for ticks at the end of a day spent outdoors.
  • Check pets for ticks.
  • Not all ticks carry Lyme disease. Deer ticks are very small, approximately the size of a poppy seed.
  • If you do find a tick, remove it by doing the following:
    • Use a pair of tweezers to grasp the tick by the head or mouthparts as close to the skin as possible.
    • Pull directly outward, gently but firmly, with steady even force. Do not twist the tick out. Try not to crush the tick's body or handle it with bare fingers because this can spread infection.
    • Do not put a hot match to the tick or cover it with petroleum jelly, nail polish, or any other substance.
    • After the tick is removed, swab the site thoroughly with an antiseptic to prevent infection.

Medication

Taking antibiotics, including a single dose of doxycycline, within 72 hours after a known tick bite has been shown to reduce the risk of contracting Lyme disease.

The risk of catching Lyme disease after a single tick bite is low, and many experts do not necessarily recommend preventive antibiotic treatment even in parts of the country with relatively high Lyme disease risk.