What is it?
In the early 1970's, a mysterious clustering
of arthritis occurred among children in Lyme, Connecticut,
and surrounding towns. Medical researchers soon recognized
the illness as a distinct disease, which they called Lyme disease. They
subsequently described the clinical features of Lyme disease,
established the usefulness of antibiotic therapy in its treatment,
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: it
can be difficult to diagnose because of the inadequacies of
today's laboratory tests; it can be troublesome to treat in
its later phases; and its prevention through the development
of an effective vaccine is hampered by the elusive nature of
the bacterium.
The National Institutes of Health (NIH),
a part of the U.S. Public Health Service, conducts and supports
biomedical research aimed at meeting the challenges of Lyme
disease. This page 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 and two neighboring towns. The investigators
discovered that most of the affected children lived near wooded
areas like to harbor ticks. They also found that the
children's first symptoms typically started in the summer months
coinciding with the height of the tick season. Several
of the patients interviewed reported having a skin rash just
before developing the arthritis, and many also recalled being
bitten by a tick at the rash site.
 Further
investigations resulted in the discovery 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 century. Lyme disease may have
spread from Europe to the United States in the early 1900's
but only recently became common enough to be detected.
The ticks most commonly infected with B.
burgdorferi usually feed and mate on deer during part
of their life cycle. The recent resurgence of the deer
population in the northeast and the influx of suburban developments
into rural areas where deer ticks are commonly found have
probably contributed to the disease's rising prevalence.
The number of reported cases of Lyme disease,
as well as the number of geographic areas in which it is found,
has been increasing. Lyme disease has been reported
in nearly all states in this country, although most cases are
concentrated in the coastal northeast, mid-Atlantic states,
Wisconsin and Minnesota, and northern California. Lyme
disease is endemic in large areas of Asia and Europe. Recent
reports suggest that it is present in South America, too.
Ticks that Most Commonly Transmit B.
burgdorferi in the U.S.
-
Ixodes dammini - most common
in the northeast and Midwest
-
Ixodes scapularis - found
in south and southeast
-
Ixodes pacificus - found on
the west coast
Most Common Symptoms of Lyme Disease
Early Infection
Less Common
Late Infection
Less Common
Symptoms of Lyme Disease in Detail
Erythema Migrans
In most people, the first symptom of Lyme
disease is a red rash known as erythema migrans (EM). The
telltale rash starts as a small red spot that expands over
a period of days or weeks, forming a circular, triangular,
or oval-shaped rash. Sometimes the rash resembles a bull's
eye because it appears as a red ring surrounding a central
clear area. The rash, which can range in size from that
of a dime to the entire width of a person's back, appears within
a few weeks of a tick bite and usually occurs at the site of
a bite. As infection spreads, several 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 occur intermittently.
Arthritis
After several months of being infected
by B. burgdorferi, slightly more than half of those
people not treated with anti-biotics 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 un-treated patients will go on to develop chronic arthritis.
Neurological Symptoms
Lyme disease can also affect the 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, or poor motor
coordination. More subtle changes such as memory loss,
difficulty with concentration, and a change in mood or sleeping
habits have also been associated with Lyme disease.
Nervous system abnormalities usually develop
several weeks, months, or even years following an untreated
infection. These symptoms often last for weeks or months
and may recur.
Heart Problems
Fewer than one out of ten Lyme disease
patients develops heart problems, such as an irregular heartbeat,
which can be signaled by dizziness or shortness of breath. These
symptoms rarely last more than a few days or weeks. Such
heart abnormalities generally surface several weeks after infection.
Other Symptoms
Less commonly, Lyme disease can result
in eye inflammation, hepatitis, and severe fatigue, although
none of these problems are likely to appear without other Lyme
disease symptoms being present.
How Lyme Disease is Diagnosed
Lyme disease may be difficult to diagnose
because many of its symptoms mimic those of other disorders. In
addition, the only distinctive hallmark unique to Lyme disease
- the erythema migrans rash - is absent in at least one-fourth
of the people who become infected. Although a tick bite
is an important clue for diagnosis, many patients cannot recall
having been bitten recently by a tick. This is not surprising
because the tick is tiny, and a tick bite is usually painless.
When a patient with possible Lyme disease
symptoms does not develop the distinctive rash, a physician
will rely on a detailed medical history and a careful physical
examination for essential clues to diagnosis, with laboratory
tests playing a supportive role.
Blood Tests
Unfortunately, the Lyme disease microbe
itself is difficult to isolate or culture from body tissues
or fluids. Most physicians look for evidence of antibodies
against B. burgdorferi in the blood to confirm the bacterium's
role as the cause of a patient's symptoms. Antibodies
are molecules or small substances tailor-made by the immune
system to lock onto and destroy specific microbial invaders.
Some patients experiencing nervous system
symptoms may also undergo a spinal tap. Through this
procedure doctors can detect brain and spinal cord inflammation
and can look for antibodies in the spinal fluid.
The inadequacies of the currently available
antibody tests may prevent them from firmly establishing whether
the Lyme disease bacterium is causing a patient's symptoms. In
the first few weeks following infection, antibody tests are
not reliable because a patient's symptoms. In the first
few weeks following infection, antibody tests are not reliable
because a patient's immune system has not produced enough antibodies
to be detected. Antibiotics given to a patient early
during infection may also prevent antibodies from reaching
detectable levels, even though the Lyme disease bacterium is
the cause of the patient's symptoms.
Because some tests cannot distinguish Lyme
disease antibodies from antibodies to similar organisms, patients
may test positive for Lyme disease when their symptoms actually
stem from other bacterial infections. A lack of standardization
of antibody tests and poor quality control also contribute
to inaccuracies in test results.
Due to these pitfalls, physicians must
rely on their clinical judgment in diagnosing someone with
Lyme disease even though the patient does not have the distinctive
erythema migrans rash. Such a diagnosis would be based
on the history of a tick bite, the patient's symptoms, a thorough
ruling out of other diseases that might cause those symptoms,
and other implicating evidence. This evidence could include
such factors as an initial appearance of symptoms during the
summer months when tick bites are most likely to occur outdoor
exposure in an area where Lyme disease is common, and a clustering
of Lyme disease symptoms among family members.
New Tests Under Development
To improve the accuracy of Lyme disease
diagnosis. NIH-supported researchers are developing a
number of new tests that promise to be more reliable than currently
available procedures. Some of these detect distinctive
protein fragments of the Lyme disease bacterium in fluid samples.
Treatment
The treatment of lyme disease is medical
therapy with antibiotics. Dosage and duration depends
on the stage of disease.
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