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A B C D E F G H I J K LM N O P Q R S T U V W X Y Z 0-9
(A-Z listing includes diseases, conditions, tests and procedures)

Lyme Disease

What You Need to Know About Lyme Disease

Lyme disease rash
  • Lyme disease is an infection caused by the spiral-shaped bacteria Borrelia burgdorferi, which is most commonly transmitted by a tick bite.

  • There are over 300,000 estimated new cases of Lyme disease in the United States each year.

  • The symptoms of Lyme disease depend on the how long the infection has been present in the body. The first sign of Lyme disease is often an expanding round or oval red "bullseye" rash.

  • If left untreated, people may develop neurological symptoms and heart problems, and have an approximately 60 percent chance of developing Lyme arthritis.

What is Lyme disease?

Lyme disease is an infection caused by the spiral-shaped bacteria Borrelia burgdorferi, which is most commonly transmitted by a tick bite.

The disease was first identified in Lyme, Connecticut, in 1975. Cases of Lyme disease have been reported in nearly all states in the United States, with a concentration of cases in the Northeast, mid-Atlantic and upper north-central U.S., and in large areas in Europe and Asia.

There are over 300,000 estimated new cases in the United States each year.

What causes Lyme disease?

Lyme disease is a caused bacteria that is spread to humans by tick bites. Within the United States, the ticks that carry Lyme disease are:

  • Black-legged deer tick: mostly located in the Northeastern, mid-Atlantic and north-central United States

  • Western black-legged tick: located in the Pacific coastal United States

While many tick bites are harmless, ticks can transmit many serious diseases. Depending on the location, anywhere from less than 1 percent to more than 50 percent of ticks are infected with Lyme disease. Tick-borne diseases due to bacteria or viral infections include:

  • Lyme disease

  • Anaplasmosis

  • Babesiosis

  • Borrelia miyamotoi

  • Powassan encephalitis

  • Rocky Mountain spotted fever

  • Colorado tick fever

  • Heartland virus

  • Tularemia

  • Ehrlichiosis

  • Southern tick-associated rash illness

  • Relapsing fever

More Information About Lyme Disease from Johns Hopkins Medicine

Mom and daughter hiking in the woods

Lyme Disease: 3 Things You Should Know

Ticks can carry a number of diseases, and often, they can be transferred to a human host. One of the more common conditions, Lyme disease, affects thousands of Americans and numerous others worldwide annually.

Read more

Who is at risk for Lyme disease?

People who spend a lot of time outdoors and pet owners are most at risk to contract Lyme disease. Ticks prefer to live in wooded or brush areas, tall grasslands, and the unkempt perimeter of yards. Factors that can increase your risk for getting Lyme disease include:

  • Working or spending time outdoors in areas where the black-legged deer tick and Western black-legged deer tick are found; observing deer in the environment is a good measure of the risk of Lyme disease in your region

  • Having pets that can bring the ticks into the home

What are the symptoms of Lyme disease?

The symptoms of Lyme disease depend on the how long the infection has been present in the body. The following are the most common symptoms of Lyme disease at each stage of infection.

Early Stages: Skin Infection

The first sign of Lyme disease is often an expanding round or oval rash that:

  • Can appear several days after infection, or not at all.

  • Can last up to several weeks before disappearing even without treatment.

  • Is usually larger than 5 centimeters (2 inches) and can be very large (up to 12 inches across).

  • May resemble a bulls-eye or may be uniformly red.

  • Can mimic a spider or other large bug bites.

  • Can itch or feel hot, or may not be felt at all.

Several days or weeks after a bite from an infected tick, you may have flulike symptoms, such as:

  • Headache

  • Stiff neck

  • Aches and pains in muscles and joints

  • Low-grade fever and chills

  • Fatigue

  • Poor appetite

Middle Stage: Bacteria Leaves Skin, Spreads to the Joints

Between four to six weeks after the bite, the following symptoms may develop:

  • Neurological symptoms, including inflammation of the nervous system (meningitis), weakness and paralysis of the facial muscles (Bell’s palsy)

  • Heart problems, including inflammation of the heart’s electrical system, which causes problems with heart rate and a slow pulse

Late Stages

Six-plus months to a few years after a bite, the following symptoms may include:

  • Inflammation of the joints (arthritis)

  • Neurological symptoms, including numbness in the extremities, tingling and pain

If untreated, people have approximately a 60 percent chance of developing Lyme arthritis.

Keep in mind that symptoms can be different for each person — it largely depends on the strain of bacteria someone receives and the body’s autoimmune response. The incubation period — the period between the bite and the first signs — can last up to 30 days.

Can Lyme disease be prevented?

People can’t develop immunity to Lyme disease — if you’ve had it once, you can get it again. There are currently no vaccines available for humans.

The easiest way to prevent Lyme disease is to stay out of high-risk areas. Stay on trails and out of the brush, especially during the late spring and summer. Ticks are particularly active from March through November.

Dress appropriately by wearing:

  • Light-colored clothing

  • Long-sleeved shirts

  • Socks and closed-toe shoes

  • Long pants with legs tucked into socks

Frequently check for ticks on:

  • All parts of the body that bend: behind the knees, between fingers and toes, and under arms

  • Other areas where ticks are commonly found: belly button, in and behind the ears, neck, hairline and top of the head

  • Areas of pressure points, including:

    • Where underwear elastic touches the skin

    • Where bands from pants or skirts touch the skin

    • Anywhere else clothing presses on the skin

Visually check all other areas of the body and run fingers gently over skin.

Also remember to:

  • Shower after all outdoor activities are over for the day.

  • Consider using repellents.

    • Products that contain DEET are tick repellents, but they do not kill the tick and are not 100 percent effective in discouraging a tick from biting you.

    • Products that contain permethrin are known to kill ticks, but they should be sprayed on clothing, not on skin.

  • Check pets and children for ticks. Avoid allowing animals to sleep on the bed.

What should I do if I find a tick?

When a tick is found, remove it carefully and do not squeeze the body. Remember that any method of removal could cause transmission of the bacteria. The infection lives in the gut of the tick. Ticks can be tested for spirochetes, so place the removed tick in a glass, plastic vial or plastic storage bag with a moistened cotton swab.

When should I call my health care provider?

If you have an unexplained flulike summer illness or a skin lesion suspicious for Lyme disease, let your health care provider know.

Recent Studies

Probable late lyme disease: a variant manifestation of untreated Borrelia burgdorferi infection.

We suggest that patients with probable late Lyme disease share features with both confirmed late Lyme disease and post-treatment Lyme disease syndrome. Physicians should consider the recent inclusion of probable Lyme disease in the CDC Lyme disease surveillance criteria when evaluating patients, especially in patients with a history suggestive of misdiagnosed or inadequately treated early Lyme disease.

Read more

Development of a Multiantigen Panel for Improved Detection of Borrelia burgdorferi Infection in Early Lyme Disease.

The Centers for Disease Control and Prevention recommends a two-tiered testing algorithm for Lyme disease; however, this scheme has limited sensitivity for detecting early Lyme disease. Thus, there is a need to improve diagnostics for Lyme disease at the early stage, when antibiotic treatment is highly efficacious.

Read more

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