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Lyme Disease

• Lyme disease is a rapidly emerging bacterial infection that is spread to people by the bite of infected ticks.
• Lyme disease can cause a rash, flu-like symptoms, and aching joints.
• Lyme disease can be treated with antibiotics. Without treatment, Lyme disease can cause serious, long-term health problems.
• To prevent Lyme disease: 1) protect yourself from tick bites, 2) remove attached ticks promptly, and 3) get early diagnosis and treatment.

What is Lyme disease?

Lyme disease is an infection transmitted by the bite of certain, very small, infected ticks. Lyme disease gets its name from the town of Lyme, Connecticut, where the illness was first identified in the United States in 1975.

What is the infectious agent that causes Lyme disease?

Lyme disease is caused by a corkscrew-shaped bacterium, or spirochete, called Borrelia burgdorferi. Ticks infected with the bacterium spread the disease to humans.

Where is Lyme disease found?

Cases of Lyme disease have been reported by nearly every state in the United States, but the disease is concentrated in the east coastal states, the north central states, and northern California. Connecticut, Rhode Island, New York, New Jersey, Delaware, Pennsylvania, Maryland, and Wisconsin account for about 90% of all cases.

In the Northeast and Great Lakes region, Lyme disease is spread by the black-legged tick, which lives in wooded areas, grasslands, and yards. In the Pacific Northwest, the disease is spread by the western black-legged tick. In the Southeast, the disease is thought to be spread by the black-legged tick.

How do people get Lyme disease?

Ticks become infected with the Lyme disease bacterium by feeding on infected animals, such as mice, chipmunks, and other wild rodents. Lyme disease is passed to humans and other animals when a tick infected with the bacterium bites the person or animal and stays attached long enough (usually more than 36 hours) to take a blood meal.

The tick that spreads Lyme disease has a 2-year life cycle, and feeds once in each of its three life stages -- larvae, nymph, and adult. In the tick's larvae stage, it is tan, the size of a pinhead, and feeds on small animals like mice. During the nymph stage, the tick is the size of a poppy seed, beige or partially transparent, and feeds on larger animals such as cats, dogs, and humans. Adult ticks are black and/or reddish and feed on large mammals such as deer, dogs, and humans.

What are the signs and symptoms of Lyme disease?

The early stage of Lyme disease is usually marked by one or more of these signs and symptoms:

• Tiredness
• Chills and fever
• Headache
• Muscle and/or joint pain
• Swollen lymph glands
• A characteristic skin rash, called erythema migrans

The skin rash is a red circular patch about 2 inches in diameter that appears and expands around the site of the tick bite. The center may clear as it enlarges, resulting in a "bulls-eye" appearance. The rash may be warm, but it usually is not painful or itchy.

Some infected people do not recognize the early symptoms and are diagnosed only after complications occur.

What complications can result from Lyme disease?

Persons who did not have or did not recognize the early symptoms and who did not receive treatment can end up with serious complications:

• Arthritis (swelling and pain) in the large joints, which can recur over many years
• Nervous system problems, such as numbness, meningitis (fever, stiff neck, and severe headache), and Bell's palsy (paralysis of the facial muscles, usually on one side)
• Irregularities of the heart rhythm

How soon after exposure do symptoms appear?

Early symptoms can develop within a week to a few weeks of the tick bite. Other symptoms can appear weeks, months, or years later.

How is Lyme disease diagnosed?

Lyme disease is diagnosed by a physical examination and medical history. The clinical diagnosis is supported by laboratory testing.

Diagnosis of Lyme disease can be difficult. Current tests are not completely accurate, and the symptoms can mimic those of other diseases. Diagnosis is easiest when there is a skin rash.

Who is at risk for Lyme disease?

Lyme disease can affect anyone. Persons who spend time in brushy and wooded areas are at increased risk of exposure. The chances of being bitten by a tick are greatest during times of the year when ticks are most active. Deer ticks in the nymph stage are active from mid-May to mid-August. Adult ticks are most active in mid- to late fall and early spring.

What is the treatment for Lyme disease?

Lyme disease is treatable with antibiotics taken for 3 to 4 weeks. More difficult cases may require longer treatment and combinations of drugs. Re-infection from tick bites is possible after treatment.

How common is Lyme disease?

Lyme disease is the most common disease spread by ticks in the United States. More than 16,000 cases were reported by 45 states in 1996. However, because of considerable under-reporting and misdiagnosis, the actual number of cases is probably several times higher.

Is Lyme disease an emerging infectious disease?

Yes. Lyme disease is a rapidly emerging infectious disease. Since it was first recognized in the United States in 1975, reports of Lyme disease have increased substantially, and the disease is now found in several regions of the country. Factors contributing to the rise in Lyme disease in humans is a thriving tick population and the expansion of suburbs into formerly wooded areas, which increases people's exposure to infected ticks.

How can Lyme disease be prevented?

A Lyme disease vaccine is under development but is not yet available. The only sure way to prevent the disease is to avoid exposure to infected ticks. Especially avoid areas where wild mice might live, such as the edges of yards, fields, and woods with low, dense groundcover.

If this is not possible, you can reduce your risk by taking these precautions:

• During outside activities, wear long sleeves and long pants tucked into socks. Wear a hat, and tie hair back.
• Use insecticides to repel or kill ticks. Repellents containing the compound DEET can be used on exposed skin except for the face, but they do not kill ticks and are not 100% effective in discouraging ticks from biting. Products containing permethrin kill ticks, but they cannot be used on the skin -- only on clothing. When using any of these chemicals, follow label directions carefully. Be especially cautious when using them on children.
• After outdoor activities, check yourself for ticks, and have a "buddy" check you, too. Check body areas where ticks are commonly found: behind the knees, between the fingers and toes, under the arms, in and behind the ears, and on the neck, hairline, and top of the head. Check places where clothing presses on the skin.
• Remove attached ticks promptly. Removing a tick before it has been attached for more than 24 hours greatly reduces the risk of infection. Use tweezers, and grab as closely to the skin as possible. Do not try to remove ticks by squeezing them, coating them with petroleum jelly, or burning them with a match.
• Large brown ticks that are commonly found on dogs and cattle do not carry the Lyme disease bacterium. If you remove a very small tick and want to have it tested for Lyme disease, place it in a clean pill vial or tight-sealed plastic storage bag with a moistened cotton swab. Contact your health-care provider and local health department.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have questions about the disease described above, consult a health-care provider.

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