From the Guidelines
Lyme disease is diagnosed through a combination of clinical evaluation and laboratory testing, with a two-step process of enzyme immunoassay (EIA) or immunofluorescence assay (IFA) followed by a Western blot test, as recommended by the most recent guidelines 1.
Clinical Evaluation
The diagnosis of Lyme disease starts with a healthcare provider assessing symptoms and exposure history, looking for signs like the characteristic bull's-eye rash (erythema migrans), fever, fatigue, headache, and joint pain.
- Clinical findings are sufficient for the diagnosis of erythema migrans, but not for extracutaneous manifestations of Lyme disease or for diagnosis of human granulocytic anaplasmosis (HGA) or babesiosis 1.
- Patients who have a lesion consistent with erythema migrans and live in or have traveled to Lyme-endemic areas can be given a diagnosis without laboratory testing 1.
Laboratory Testing
Laboratory diagnosis typically follows a two-step process:
- An initial enzyme immunoassay (EIA) or immunofluorescence assay (IFA) is performed, followed by a Western blot test if the first test is positive or equivocal 1.
- Both tests detect antibodies against Borrelia burgdorferi, the bacterium causing Lyme disease.
- Early testing (within the first few weeks of infection) may yield false negatives because antibodies take time to develop.
- In some cases, polymerase chain reaction (PCR) tests on joint fluid or tissue samples may help detect bacterial DNA.
Importance of Clinical Judgment
It's essential to note that diagnosis should not rely solely on laboratory results but should consider clinical symptoms and potential tick exposure, particularly in endemic areas 1.
- Treatment should begin promptly if Lyme disease is suspected, even before test results are available, to prevent progression to later stages of the disease.
- The recommended approach for laboratory diagnosis of Lyme disease is a 2-tiered serologic test comprised of an enzyme-linked immunoassay (EIA or ELISA) or immunofluorescence assay (IFA), followed by a reflex Western immunoblot 1.
From the Research
Diagnosis of Lyme Disease
The diagnosis of Lyme disease can be made on clinical grounds alone in patients from endemic areas who present with erythema migrans, without the need for serologic testing 2. However, in patients with a moderate pretest probability of disease, serologic testing should be performed using a two-step approach, consisting of an initial screening test followed by a Western blot test if the result is positive or equivocal 2, 3.
Serologic Testing
Serologic testing for Lyme disease has limitations, including poor sensitivity in the early stages of the disease and the potential for false-positive results 2, 3. The use of Western blot testing can help to confirm the diagnosis, but it is not recommended for patients with a low probability of disease due to the risk of false-positive results 2.
Clinical Presentation
The clinical presentation of Lyme disease can vary, with early localized infection characterized by erythema migrans, fever, and flu-like symptoms, while early disseminated infection may present with neurologic, musculoskeletal, or cardiovascular symptoms 4. Late disseminated infection can cause intermittent swelling and pain in one or more joints, particularly the knees 4.
Diagnostic Approach
The diagnostic approach to Lyme disease depends on the stage of the disease and the patient's clinical presentation 2, 4. In patients with erythema migrans, the diagnosis can be made clinically, while in patients with advanced manifestations of the disease, serologic testing should be performed using a two-step approach 2.
Laboratory Tests
Laboratory tests, including ELISA and Western blot, can be used to support the diagnosis of Lyme disease, but they should be interpreted in the context of the patient's clinical presentation and medical history 3, 5. The results of these tests should be used to guide treatment decisions, rather than as the sole basis for diagnosis 2, 3.
Treatment
The treatment of Lyme disease typically involves the use of antibiotics, such as doxycycline or amoxicillin, with the specific treatment regimen depending on the stage and severity of the disease 4, 3, 6. In some cases, intravenous antibiotics may be necessary, particularly for patients with neurologic or cardiovascular manifestations of the disease 4, 3.