Lyme Disease Facts

by National Institute of Health

In the early 1970s, a mysterious clustering of arthritis cases occurred among children in Lyme, Connecticut, and surrounding towns. Medical experts soon recognized the illness as a distinct disease, which they called Lyme disease. They subsequently described the signs and symptoms of Lyme disease, established the usefulness of antibiotics for treating it, identified the deer tick as the key to its spread, and isolated the bacterium that caused it.

Lyme disease is still mistaken for other ailments, and it continues to pose many other challenges, including the following: it can be difficult to diagnose, it can be troublesome to treat in its later phases, a number of different ticks can transmit diseases with symptoms similar to Lyme disease, deer ticks can transmit diseases other than Lyme disease.

This booklet presents the most recently available information on the diagnosis, treatment, and prevention of Lyme disease.

How Lyme Disease Became Known

Lyme disease was first recognized in 1975 after researchers investigated why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme, Connecticut, and two neighboring towns. The researchers discovered that most of the affected children lived and played near wooded areas where ticks live. They also found that the children's first symptoms typically started in the summer months, the height of the tick season. Several of the patients interviewed reported having a skin rash just before developing their arthritis. Many also recalled being bitten by a tick at the rash site.

Further investigations discovered that tiny deer ticks infected with a spiral-shaped bacterium or spirochete (which was later named Borrelia burgdorferi) were responsible for the outbreak of arthritis in Lyme.

In Europe, a skin rash similar to that of Lyme disease had been described in medical literature dating back to the turn of the 20th century. Lyme disease may have spread from Europe to the United States in the early 1900s, but health experts only recently recognized it as a distinct illness.

Small rodents and deer play an important role in a deer tick's life cycle.

Both nymphs and adult ticks can transmit Lyme diseasecausing 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 contributed to the disease's increased spread.

The number of reported cases of Lyme disease as well as the number of geographic areas in which it is found have increased. Lyme disease has been reported in nearly all states in the United States, although more than 95 percent of all reported cases are concentrated in the coastal Northeast, 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

Usually, the first symptom of Lyme disease is a red rash known as erythema migrans (EM). The telltale rash starts as a small red spot at the site of the tick bite. The spot expands over a period of days or weeks, forming a circular or oval-shaped rash. Sometimes the rash resembles 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 dime to the width of your back, appears within a few weeks of a tick bite and usually at the site of the bite. As infection spreads, rashes can appear at different sites on the body.

Erythema migrans is often accompanied by symptoms such as fever, headache, stiff neck, body aches, and fatigue. Although these flu-like symptoms may resemble those of common viral infections, Lyme disease symptoms tend to persist or may come and go.

Arthritis

After several months of B. burgdorferi infection, slightly more than half of people not treated with antibiotics develop recurrent attacks of painful and swollen joints that last a few days to a few months. The arthritis can shift from one joint to another. The knee is most commonly affected.

About 10 to 20 percent of untreated people will go on to develop chronic (long-lasting) arthritis.

Neurologic Symptoms

Lyme disease also can affect your nervous system, causing symptoms such as stiff neck and severe headache (meningitis), temporary paralysis of facial muscles (Bell's palsy), numbness, pain, or weakness in the limbs, poor muscle movement.

More subtle changes such as memory loss, difficulty concentrating, and a change in mood or sleep habits also have been associated with Lyme disease. Nervous system problems usually develop several weeks, months, or even years following an untreated infection. These symptoms often last for weeks or months and may return.

Less commonly, untreated people may develop other problems weeks, months, or even years after infection.

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 infection.

Other Symptoms

Less commonly, Lyme disease can result in eye inflammation, hepatitis (liver disease), and severe fatigue, although none of these problems is likely to appear without other Lyme disease symptoms being present.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.