Signs and Symptoms
Initial Signs and Symptoms
It takes about 48 hours for the bacterium to establish itself in the host. Usually, symptoms start to appear between 3 and 30 days after being bitten. The best clinical indication of the disease is the initial bull's eye rash, but the rash only occurs in 60-80% of patients. The concentric rash formed represents the spreading of the infection past the dermal layer and into other areas of the body. It is usually 5 centimeters (2 inches) or more in diameter, expanding about ½ to ¾ inch per day. It can last about three to five weeks, and it is generally not itchy. The bull's eye rash is usually accompanied by other symptoms, such as fatigue, fever, headache, mildly stiff neck, arthralgia, or myagia.
Late Signs and Symptoms
Without treatment, the infection may spread to other parts of the body within a few days to weeks and may produce the following problems:
- Nervous system disorders;
- Cardiovascular problems, such as heart palpitations and dizziness due to conduction disturbances in the heart and abnormal heart rhythm; and/or
- Swelling and pain in joints- these may be recurrent brief (week to months) attacks of joint swelling and arthritis.
Table of Early and Late Symptoms of Lyme Disease
|
Early Symptoms (3-30 days) |
Late Symptoms (1-4 months) |
|---|---|
|
|
The course and severity of Lyme disease are variable with each individual. Some individuals develop mild symptoms or may be asymptomatic for some time, while others can experience chronic and debilitating symptoms if left untreated. However, many of these symptoms will resolve, even without treatment.
Laboratory Diagnosis
Most cases of Lyme disease are associated with known exposure to a nymph or adult female deer tick bite and the appearance of the erythema migrans rash. Many physicians will diagnose patients on these criteria alone. Lyme disease is a reportable disease to local and state health departments, so laboratory confirmation of cases is important. There are three tests available to diagnose the disease:
- ELISA - an assay for the presence of specific antibodies. Has a low specificity, leading to a large number of false-positives.
- Western Blot - confirms positive cases from the ELISA assay.
- PCR (Polymerase Chain Reaction) - has a high sensitivity and specificity, since it amplifies and properly identifies the spirochete if it is present.
CDC recommends a two-step process when testing blood for evidence of Lyme disease. Both steps can be done using the same blood sample, but CDC does not recommend testing blood by immunoblot without first testing it by ELISA (see below).
- An ELISA or Immune-fluorescence antibody (IFA) test. These tests are designed to be very "sensitive," meaning that almost everyone with Lyme disease, and some people who don't have Lyme disease, will test positive. If the ELISA is negative, it is highly unlikely that the person has Lyme disease, and no further testing is recommended. If the ELISA is positive or indeterminate (sometimes called "equivocal"), a second step should be performed to confirm the results.
- An immunoblot such as a Western blot or striped blot test. This test is more "specific," meaning that people who do not have Lyme disease will usually have a negative test. If the ELISA is positive, but the immunoblot is negative, it suggests that the first test was a false positive. Sometimes two types of Western blot are performed, "IgM" and "IgG." Patients who are positive by IgM but not IgG should have the test repeated a few weeks later if they remain ill. If they are still positive only by IgM and have been ill longer than one month, this is likely a false positive.
- Link to Lyme Disease Reporting Criteria and Laboratory Testing
- Link to additional information about interpretation of Lyme disease tests and test limitations
Other Types of Laboratory Testing
Some laboratories offer Lyme disease testing using assays whose accuracy and clinical usefulness have not been adequately established. Click here for more information. Patients should be encouraged to ask their physicians whether their testing for Lyme disease was performed using validated methods and whether results were interpreted using appropriate guidelines.
