The preferred diagnostic approach is two‑tier serologic testing: an initial sensitive enzyme immunoassay (EIA/ELISA) followed by a confirmatory Western blot (or a validated second EIA per newer guidelines). Note tests often remain negative very early after a tick bite; clinical diagnosis (erythema migrans) or PCR of joint fluid for suspected Lyme arthritis may be used when appropriate. Blood PCR is not sensitive.

Get Lyme serology when you have compatible symptoms plus exposure—especially suspected disseminated or late disease (multiple erythema migrans, neurologic, cardiac, or joint involvement) or when the rash is absent or atypical. Don’t test asymptomatic tick bites. Antibody tests are often negative in the first 2–6 weeks after infection, so delay testing or repeat if early results are negative but symptoms develop.

The IgM and IgG tests for Lyme disease detect antibodies your immune system makes against Borrelia burgdorferi. IgM appears early (usually within 1–4 weeks) and suggests recent infection; IgG develops later (often after 4–6 weeks) and indicates prior or ongoing infection. Results should be interpreted with clinical symptoms and exposure history, as timing and cross-reactions can cause false negatives or positives.

The most common confirmatory test for Lyme disease is the Western blot (immunoblot), performed after a positive or equivocal ELISA/EIA. It detects IgM and IgG antibodies to specific Borrelia burgdorferi proteins; IgM is useful early in infection, while IgG indicates later or past infection. This two-step approach reduces false positives and improves diagnostic accuracy.

The gold standard for Lyme disease diagnosis is two‑tier serologic testing: an initial sensitive enzyme immunoassay (ELISA or EIA) followed by a confirmatory Western blot (immunoblot) for IgM and IgG antibodies. Serology may be negative very early after infection, so early diagnosis is often clinical; PCR or direct testing of skin, synovial fluid, or cerebrospinal fluid is used in selected cases.

Lyme is usually diagnosed with a two-step blood test: an initial antibody screening (ELISA) followed by a confirmatory immunoblot (Western blot). Tests detect IgM (early) and IgG (later) antibodies; PCR can identify bacterial DNA in joint or cerebrospinal fluid in some cases. Note early localized infection (erythema migrans) may be diagnosed clinically because antibodies can be negative in the first few weeks.