There are blood tests to check for antibodies to the
bacterium that causes Lyme disease. The tests, however,
are not useful if done soon after a tick bite, because
it takes 2 to 5 weeks after being bitten by an infected
tick for antibodies to develop. Even when an antibody
(blood) test is done later, the result alone does
not reliably predict the presence or absence of
Lyme disease. (See "How is Lyme disease diagnosed?"
below.) The Food and Drug Administration (FDA), which
regulates diagnostic tests for Lyme disease, has cleared
for commercial sale and distribution only blood tests
for antibodies that may be present in Lyme disease. Tests
for Lyme disease that use urine or other body
fluids have not been cleared by FDA.
How is Lyme disease spread?
Lyme disease is spread by the bites of Ixodes
ticks (the deer tick, bear tick, western black-legged
tick, or black-legged tick, depending on the region of
the country). These ticks are much smaller than the common
dog or cattle ticks. They can attach to any part of the
body, often to moist or hairy areas such as the groin,
armpits, and scalp.
Campers, hikers, outdoor workers, and gardeners are at the
greatest risk of exposure to infected ticks. Lyme disease
is widely distributed in northern temperate regions of the
world. In the United States, the highest incidence occurs
in the Northeast, North Central states, and the West Coast
(particularly in northern California).
What are the symptoms
of Lyme disease?
The symptoms of early Lyme disease
- a characteristic skin rash (called erythema migrans),
- muscle and joint aches,
- chills and fever,
- fatigue, and
- swollen lymph nodes.
Erythema migrans is a circular red patch that usually
appears in 3 to 30 days after being bitten by an infected
tick. The patch expands (to an average of 5 to 6 inches
in diameter) and persists for 3 to 5 weeks. Sometimes
many patches appear and vary in shape depending on their
locations. The center of the patch may clear as the rash
enlarges, giving a "bull's-eye" appearance.
In some persons, the characteristic rash never
forms or is not noticed, and not every rash that occurs
at the site of a tick bite is due to Lyme disease. In
some cases, the rash can be an allergic reaction to the
The symptoms of late Lyme disease may not appear
until weeks, months, or even years after a tick bite and
- arthritis (usually as pain and swelling in large
joints, especially the knee);
- nervous system abnormalities such as numbness, pain,
facial paralysis similar to Bell's palsy, and meningitis
(fever, stiff neck, and severe headache); and
- irregularities of the heart rhythm.
How is Lyme disease
Lyme disease can be difficult to diagnose, because its
symptoms mimic those of other diseases. For example, the
fever, fatigue, and muscle aches can be mistaken for influenza
or infectious mononucleosis. Joint pain can be mistaken
for rheumatoid arthritis and neurologic signs for multiple
sclerosis. Conversely, other types of arthritis or neurologic
diseases can be misdiagnosed as Lyme disease.
To make a diagnosis of Lyme disease, the following should
- a history of possible tick bite, especially in areas
of the country known to have Lyme disease;
- symptoms; and
- results of blood tests done at least 5 weeks after
the tick bite to determine if antibodies to the bacterium
Borrelia burgdorferi are present in the patient.
Can Lyme disease be treated?
If there are definite symptoms of Lyme disease, the doctor
may prescribe antibiotics which are usually given by mouth.
Antibiotics should not be given only
because a person was bitten by a tick. Patients who are
diagnosed and treated with antibiotics in the early stages
of Lyme disease usually recover quickly and completely.
Most patients treated in the later stages of Lyme disease
also respond well to antibiotics. A few patients may have
relapses and need additional antibiotic treatment. Permanent
damage to the joints or the nervous system can develop
in patients with chronic late Lyme disease. Usually these
are patients not diagnosed in the early stages or their
initial treatments were unsuccessful.
What precautions can
be taken to reduce the chance of getting Lyme disease?
To decrease the chance of being bitten by a tick:
- avoid wooded, brushy, and grassy areas, especially
in May, June, and July. (Contact the local health
department or park/extension service for information
on local distribution of ticks.)
- wear light-colored clothing, so that ticks can be
seen more easily.
- wear long pants and long-sleeved shirts.
- wear shoes that cover the entire foot.
- tuck pant legs into socks or shoes and shirt into
- wear a hat for extra protection.
- spray insect repellent containing DEET on clothes
and exposed skin other than the face, or treat clothes
with permethrin that kills ticks on contact.
- walk in the center of trails to avoid brush and
- after being outdoors, remove clothing and wash and
dry it at high temperatures.
- do a careful body check for ticks. To remove a tick,
use tweezers and grasp the tick close to the skin.
Pull straight back and avoid crushing the tick's body.
Save the tick for possible identification by a doctor
or the local health department.
Is there a vaccine for
FDA recently licensed the first vaccine to aid in the
prevention of Lyme disease. The new vaccine (trade-name
Lymerix) is approved for use in persons 15 to 70 years
of age who live or work in grassy or wooded areas where
infected ticks are present. It is not currently available
for persons under the age of 15 years.
Three doses of the vaccine, given over a period of one
year, are needed. Although Lymerix may provide protection
for a majority of people, it does not prevent all cases
of Lyme disease. Studies by the manufacturer showed that
after two doses of the vaccine in the first year, the
protection rate against definite Lyme disease was 50 percent.
In the second year after three doses, it was 78 percent.
Since the vaccine is not 100 percent effective, continued
preventive measures are still necessary for immunized
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