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Lyme Disease

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Disease Details

Incubation Period:

  • 3 - 32 days

Transmission Type(s):

Disease Reservoirs

Disease Agents

About Lyme Disease

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of infected blacklegged ticks.

Ticks can attach to any part of the human body but are often found in hard-to-see areas such as the groin, armpits, and scalp. In most cases, the tick must be attached for 36 to 48 hours or more before the Lyme disease bacterium can be transmitted.

Most humans are infected through the bites of immature ticks called nymphs. Nymphs are tiny (less than 2 mm) and difficult to see; they feed during the spring and summer months. Adult ticks can also transmit Lyme disease bacteria, but they are much larger and are more likely to be discovered and removed before they have had time to transmit the bacteria. Adult Ixodes ticks are most active during the cooler months of the year.

Geographic Distribution

Lyme disease is the most commonly reported vectorborne illness in the United States. In 2013, it was the fifth most common Nationally Notifiable disease. However this disease does not occur nationwide and is concentrated heavily in the northeast and upper Midwest.

Reported cases of Lyme Disease, 2013. Though Lyme disease cases have been reported in nearly every state, cases are reported from the infected person's county of residence, not the place where they were infected. (CDC)

Reported cases of Lyme Disease, 2013. Though Lyme disease cases have been reported in nearly every state, cases are reported from the infected person’s county of residence, not the place where they were infected. (CDC)

Seasonality

Lyme disease patients are most likely to have illness onset in June, July, or August and less likely to have illness onset from December through March.

Persons at Risk

Lyme disease cases are especially prevalent among the very young and those aged 35-60.

Reported cases of Lyme disease are most common among boys aged 5-9. (CDC)

Reported cases of Lyme disease are most common among boys aged 5-9. (CDC)

Symptoms

Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, infection can spread to joints, the heart, and the nervous system. Lyme disease is diagnosed based on symptoms, physical findings (e.g., rash), and the possibility of exposure to infected ticks. Laboratory testing is helpful if used correctly and performed with validated methods. Most cases of Lyme disease can be treated successfully with a few weeks of antibiotics.

Erythema migrans (EM) or “bull’s-eye” rash

This image depicts the posterior right shoulder region of a patient who’d presented with the erythema migrans (EM) rash characteristic of what was diagnosed as Lyme disease, caused by the bacterium, Borrelia burgdorferi. (CDC)

Typical example of a “Bull’s-eye” rash characteristic of Lyme Disease infection. (CDC)

  • Rash occurs in approximately 70-80% of infected persons1 and begins at the site of a tick bite after a delay of 3-30 days (average is about 7 days).
  • Rash gradually expands over a period of several days, and can reach up to 12 inches (30 cm) across. Parts of the rash may clear as it enlarges, resulting in a “bull’s-eye” appearance.
  • Rash usually feels warm to the touch but is rarely itchy or painful.
  • EM lesions may appear on any area of the body.

“Chronic” Lyme Disease

Physicians sometimes describe patients who have non-specific symptoms (like fatigue, pain, and joint and muscle aches) after the treatment of Lyme disease as having post-treatment Lyme disease syndrome (PTLDS) or post Lyme disease syndrome (PLDS).

The term “chronic Lyme disease” (CLD) has been used to describe people with different illnesses. While the term is sometimes used to describe illness in patients with Lyme disease, in many occasions it has been used to describe symptoms in people who have no evidence of a current or past infection with B. burgdorferi (Infect Dis Clin N Am 22:341-60, 2008). Because of the confusion in how the term CLD is employed, experts in this field do not support its use (New Engl J Med 357:1422-30, 2008).

More about Chronic Lyme Disease can be found at the National Institute of Allergy and Infectious Disease.

Lyme Disease Prevention

While it is a good idea to take preventive measures against ticks year-round, be extra vigilant in warmer months (April-September) when ticks are most active.

Avoid Direct Contact with Ticks

  • Avoid wooded and bushy areas with high grass and leaf litter.
  • Walk in the center of trails.

Repel Ticks with DEET or Permethrin

  • Use repellents that contain 20 to 30% DEET (N, N-diethyl-m-toluamide) on exposed skin and clothing for protection that lasts up to several hours. Always follow product instructions. Parents should apply this product to their children, avoiding hands, eyes, and mouth.
  • Use products that contain permethrin on clothing. Treat clothing and gear, such as boots, pants, socks and tents with products containing 0.5% permethrin. It remains protective through several washings. Pre-treated clothing is available and may be protective longer.
  • Other repellents registered by the Environmental Protection Agency (EPA) may be found at http://cfpub.epa.gov/oppref/insect/.External Web Site Icon

Find and Remove Ticks from Your Body

  • Bathe or shower as soon as possible after coming indoors (preferably within two hours) to wash off and more easily find ticks that are crawling on you.
  • Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body upon return from tick-infested areas. Parents should check their children for ticks under the arms, in and around the ears, inside the belly button, behind the knees, between the legs, around the waist, and especially in their hair.
  • Examine gear and pets. Ticks can ride into the home on clothing and pets, then attach to a person later, so carefully examine pets, coats, and day packs.
  • Tumble clothes in a dryer on high heat for an hour to kill remaining ticks. (Some research suggests that shorter drying times may also be effective, particularly if the clothing is not wet.)

Read More

Read more about Lyme Disease at the Centers for Disease Control (CDC) Website

About the Header Image

This image depicts the posterior right shoulder region of a patient who’d presented with the erythema migrans (EM) rash characteristic of what was diagnosed as Lyme disease, caused by the bacterium, Borrelia burgdorferi. (CDC)