Lyme Disease Tests

Lyme disease tests are used to diagnose Lyme disease, a bacterial infection caused by Borrelia burgdorferi, which is transmitted to humans through the bite of an infected blacklegged tick (Ixodes scapularis).

Types of Tests

• Enzyme-Linked Immunosorbent Assay (ELISA): This test measures the levels of antibodies against B. burgdorferi in the blood. It is commonly used as an initial screening test.
• Western Blot Test: This test is used to confirm a positive ELISA result. It detects the presence of specific antibodies against B. burgdorferi proteins.
• Polymerase Chain Reaction (PCR) Test: This test detects the genetic material of B. burgdorferi in fluid samples, such as cerebrospinal fluid or synovial fluid.

How the Tests are Performed

A healthcare provider will typically draw a blood sample from a vein in the arm to perform an ELISA or Western Blot test. For PCR testing, a sample of fluid may be collected from the affected area, such as the joint or spinal canal.

Interpretation of Results

The results of Lyme disease tests are interpreted as follows:

• Positive ELISA result: Indicates that antibodies against B. burgdorferi are present in the blood, but may not necessarily confirm the diagnosis.
• Positive Western Blot result: Confirms the presence of specific antibodies against B. burgdorferi and supports the diagnosis of Lyme disease.
• Positive PCR result: Indicates that genetic material from B. burgdorferi is present in the fluid sample, confirming the diagnosis.
• Negative test results: Do not rule out the possibility of Lyme disease, as false-negative results can occur, especially in the early stages of the infection.

Limitations and False-Negative Results

Lyme disease tests may produce false-negative results if:

• The test is performed too early in the course of the infection, before antibodies have developed.
• The patient has received antibiotics, which can suppress the immune response and reduce the accuracy of the test.
• The patient has a weakened immune system, which can affect the production of antibodies.

Centers for Disease Control and Prevention (CDC) Recommendations

The CDC recommends a two-step testing process for diagnosing Lyme disease:

1. Perform an ELISA test to detect antibodies against B. burgdorferi.
2. If the ELISA result is positive or equivocal, perform a Western Blot test to confirm the diagnosis.

Additional Diagnostic Tools

In addition to laboratory tests, healthcare providers may use clinical evaluation and medical history to diagnose Lyme disease. Symptoms such as fever, headache, fatigue, and a characteristic "bull's-eye" rash (erythema migrans) can support the diagnosis.