Introduction
In the early 1970s, a mysterious clustering of arthritis cases occurred among children in Lyme, Connecticut, and surrounding towns. Puzzled medical experts eventually labeled the illness as a new disease, which they called Lyme disease. By the mid-1970s, scientists were busy describing signs and symptoms of Lyme disease to help doctors diagnose patients. Scientists eventually learned that antibiotics were an effective treatment, and that the bite of the deer tick was the key to the spread of disease.
None of these findings, however, happened overnight. In fact, it wasn’t until 1981—through a bit of puzzle solving and keen recollection—that the cause of Lyme disease was identified and the connection between the deer tick and the disease was discovered.
Lyme disease is still mistaken for other illnesses, and it continues to pose many other challenges, including the following:
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It can be difficult to diagnose.
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It can be hard to treat in its later phases.
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A number of different ticks can transmit diseases with symptoms like Lyme disease.
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Deer ticks can pass on diseases other than Lyme disease.
This booklet presents the most recently available information on the diagnosis, treatment, and prevention of Lyme disease.

How Lyme DiseaseBecame Known
Lyme disease was first recognized in 1975 after researchers tried to find out why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme, Connecticut, and two neighboring towns. After considering several possible causes, such as contact with germs (microbes) in water or air, researchers focused their attention on deer ticks. They realized that most of the affected children lived and played near wooded areas.
Researchers knew that the children’s first symptoms typically started during summer—the height of tick season. Several of the children reported having a skin rash just before developing their arthritis. Many of them recalled being bitten by a tick where the rash appeared.
Before Lyme Disease Became Known
Around the same time, about 2,500 miles away from Lyme, Willy Burgdorfer, Ph.D., was conducting research at Rocky Mountain Laboratories (RML) in Hamilton, Montana, part of the National Institute of Allergy and Infectious Diseases (NIAID). Dr. Burgdorfer was studying Rocky Mountain spotted fever, which is also caused by the bite of a tick.
In the summer of 1977, Allen C. Steere, M.D., was investigating the Lyme disease cases for the Yale University School of Medicine in Hartford, Connecticut. During conversations with Dr. Burgdorfer, Dr. Steere mentioned the deer tick as the likely carrier for Lyme disease.
Researchers in Europe had written about a skin rash similar to that of Lyme disease in medical literature dating back to the turn of the 20th century. Dr. Burgdorfer wondered if the European rash, called erythema migrans, and Lyme disease might have the same cause.
As Dr. Burgdorfer and his RML colleague Alan Barbour, M.D., continued to study spiral-shaped bacteria, or spirochetes, from infected deer ticks, they eventually achieved success. In late November 1981, the scientists found the cause of both Lyme disease and the European skin rash. The spirochete was later named Borrelia burgdorferi in honor of Dr. Burgdorfer for his role in discovering it.
Although Lyme disease may have spread from Europe to the United States in the early 1900s, health experts only recently recognized it as a distinct illness.

Deer Ticks
Small rodents and deer play an important role in a deer tick’s life cycle. Today, scientists who study Lyme disease are learning much more about that role.
Both nymphs (immature ticks) and adult ticks can transmit Lyme disease-causing bacteria. The recent increase of the deer population in the Northeast, and of housing developments
in rural areas where deer ticks are commonly found, probably have contributed to the spread of the disease.
The numbers of cases of Lyme disease and of geographic areas in which it is found have increased. Healthcare providers have seen cases of Lyme disease in nearly all states in the United States. However, most reported cases are concentrated in the coastal Northeast, the mid-Atlantic states, Wisconsin, Minnesota, and northern California. Lyme disease is also found in large areas of Asia and Europe.

Symptoms of Lyme Disease
Erythema Migrans
Erythema migrans (EM) is usually the first symptom of Lyme disease.
• The telltale rash starts as a small red spot at the site of the tick bite.
• The spot gets larger over a period of days or weeks and forms a red rash shaped like a circle or an oval.
Sometimes the rash looks like a bull’s eye, appearing as a red ring surrounding a clear area with a red center. The rash, which can range in size from that of a small coin to the width of your back, appears within a few weeks of a tick bite and usually at the place of the bite. As infection spreads, rashes can appear at different places on the body.
Other symptoms that often appear with EM can include:
• Fever
• Headache
• Stiff neck
• Body aches
• Tiredness
Although these symptoms may be like those of common viral infections such as the flu, Lyme disease symptoms tend to continue longer or may come and go.

Arthritis
After several months of infection with Lyme bacteria, slightly more than half of people not treated with antibiotics develop recurrent attacks of painful and swollen joints. These attacks last a few days to a few months. The arthritis can move from one joint to another. The knee is most commonly affected.
About 10 to 20 percent of people who have not taken antibiotics will go on to develop chronic (long-lasting) arthritis.
Neurological Symptoms
Lyme disease can also affect your nervous system, causing symptoms such as the following:
• Stiff neck and severe headache (meningitis)
• Temporary paralysis of your facial muscles (Bell’s palsy)
• Numbness, pain, or weakness in your limbs
• Poor muscle movement
Lyme disease can also cause more subtle changes such as
• Memory loss
• Difficulty with concentration
• Change in mood or sleep habits

Neurological problems usually develop several weeks, months, or even years following untreated infection. These symptoms often last for weeks or months and may return.
Less commonly, people who have not taken antibiotics may develop heart or other problems weeks, months, or even years after they were infected with Lyme bacteria.
Heart Problems
Fewer than 1 out of 10 people with Lyme disease develop heart problems, such as irregular heartbeat, which can start with dizziness or shortness of breath. These symptoms rarely last more than a few days or weeks. Such heart problems generally show up several weeks after a person is infected with Lyme bacteria.
Other Symptoms
Less commonly, Lyme disease can cause eye inflammation, hepatitis (liver disease), and severe fatigue. None of these problems, however, is likely to appear without other Lyme disease symptoms being present.

How Lyme Disease Is Diagnosed
Your healthcare provider may have difficulty diagnosing Lyme disease because many of its symptoms are similar to those of other illnesses. In addition, the only symptom that is unique to Lyme disease is the rash. That rash is absent in at least one-fourth of the people who become infected.
The results of recent research studies show that an infected tick must be attached to the skin for at least 2 days to transmit Lyme bacteria. Although a tick bite is an important clue for diagnosis, many people cannot recall having been bitten recently by a tick. This is not surprising because the deer tick is tiny, and a tick bite is usually painless.
If you have Lyme disease symptoms, but do not develop the distinctive rash, your healthcare provider will rely on a detailed medical history and a careful physical exam for clues to diagnose it. You will also be given laboratory tests to help diagnose the disease.
Medical History
If you don’t have the EM rash, your healthcare provider will diagnose Lyme disease based on
• Whether your symptoms first appeared during the summer months when tick bites are most likely to occur
• Whether you were outdoors in an area where Lyme disease is common
• Whether you have been bitten by a tick
• Whether you have other symptoms of Lyme disease
In addition, your healthcare provider will rule out other diseases that might be causing your symptoms.

Lab Tests
It is difficult for healthcare providers to find the bacterium that causes Lyme disease in lab tests of body tissues or fluids. Therefore, most look for evidence of antibodies against B. burgdorferi in the blood to confirm that the bacterium is causing the symptoms.
Healthcare providers cannot always find out whether Lyme disease bacteria absolutely are causing symptoms. In the first few weeks following infection, antibody tests are not reliable because your immune system has not produced enough antibodies to be found. Antibiotics given early during infection may also prevent antibodies from reaching levels that a test can find, even though Lyme disease bacteria are causing your symptoms.
The antibody test most often used is called an ELISA (enzyme-linked immunosorbent assay) test. The Food and Drug Administration (FDA) has approved two antibody tests:
• Prevue B, a rapid test, can give results within an hour.
• The C6 Lyme Peptide ELISA is very sensitive and specific.
If your ELISA is positive, your healthcare provider should confirm it with a second, more specific test called a Western blot.
If you have nervous system symptoms, you may also get a spinal tap. Using this test, your healthcare provider can find any inflammation in your brain and spinal cord and can look for antibodies or genetic material of
B. burgdorferi in your spinal fluid.
FDA has not approved tests for Lyme disease that use urine or some other body fluids to diagnose infection caused by Lyme bacteria.
New Tests Being Developed
Healthcare providers need tests to tell apart people who have recovered from previous Lyme infection and those who continue to suffer from active infection.
To improve the accuracy of diagnosing Lyme disease, National Institutes of Health (NIH)-supported researchers are re-evaluating current tests. They are also developing a number of new tests that promise to be more reliable than those currently available.
NIH-supported scientists are developing tests that use the highly sensitive genetic engineering technique known as PCR (polymerase chain reaction) as well as microarray and high-throughput genomic sequencing technology to detect extremely small quantities of the genetic material of the Lyme disease bacterium or its products in body tissues and fluids.
A bacterial protein, outer surface protein (Osp) C, is proving useful for detecting specific antibodies early in people with Lyme disease. Because researchers have determined the genome of B. burgdorferi, there are now new avenues for improving their understanding of the disease and its diagnosis.

How Lyme Disease Is Treated
Using antibiotics appropriately, your healthcare provider can effectively treat your Lyme disease. In general, the sooner you begin treatment after you have been infected, the quicker and more complete your recovery.
Antibiotics such as doxycycline, cefuroxime axetil, or amoxicillin, taken orally for a few weeks, can speed the healing of the EM rash and usually prevent symptoms such as arthritis or neurological problems.
Doctors usually treat Lyme disease in children younger than 9 years, or in pregnant or breast-feeding women, with amoxicillin, cefuroxime axetil, or penicillin. They do not use doxycycline in these groups because the antibiotic can stain the permanent teeth developing in young children or unborn babies.
Arthritis
If you have Lyme arthritis, your healthcare provider may treat you with oral antibiotics. If your arthritis is severe, you may be given ceftriaxone or penicillin intravenously (through a vein). To ease any discomfort and to help with healing, your healthcare provider might also do one of the following:
• Give you anti-inflammatory drugs
• Draw fluid from your affected joints
• Perform surgery to remove the inflamed lining of those joints
In most people, Lyme arthritis goes away within a few weeks or months following antibiotic treatment. In some, however, it can take years to disappear completely. Some people with Lyme disease who are untreated for several years may be cured of their arthritis with the proper antibiotic treatment.
The disease, however, does not always go away with treatment. If it has lasted long enough, it may permanently damage the structure of your joints.
Neurological Problems
If you have neurological symptoms, your healthcare provider will probably treat you with the antibiotic ceftriaxone given intravenously once a day for a month or less. Most people recover completely.
Heart Problems
Healthcare providers prefer to treat people with Lyme disease who have heart symptoms with antibiotics such as ceftriaxone or penicillin given intravenously for about 2 weeks. People with Lyme disease rarely have long-term heart damage.

Problems After Treatment
Following treatment for Lyme disease, you might still have muscle aches, and neurological problems such as tiredness and trouble with memory and concentration.
NIH-sponsored researchers are doing research to find out the cause of these symptoms and the best ways to treat them. Research studies suggest that people who suffer from post-Lyme disease symptoms may be genetically predisposed to develop an autoimmune response that contributes to their symptoms. Researchers are now examining the significance of this finding in greater detail.
Researchers also are trying to find out the best length of time to give antibiotics for the various symptoms of Lyme disease.
Unfortunately, having a bout with Lyme disease once is no guarantee that you will not get the illness again. It can strike more than once if you are reinfected with Lyme disease bacteria.

How Lyme Disease Is Prevented
Avoid Ticks
At present, the best way you can avoid Lyme disease is to avoid deer ticks. Although generally only about 1 percent of all deer ticks are infected with Lyme disease bacteria, in some areas more than half of the ticks have the microbes.
More people with Lyme disease become infected during the summer, when immature ticks are found most often. In warm climates, deer ticks thrive and bite during the winter months as well.