What is the name of the blood test after a tick bite? - briefly
The test is a Lyme disease serology panel, typically an ELISA screen followed by a confirmatory Western blot if positive. It detects antibodies to Borrelia burgdorferi after a tick exposure.
What is the name of the blood test after a tick bite? - in detail
The laboratory assay most frequently ordered after a tick exposure is a serologic panel for Lyme disease. The initial step is an enzyme‑linked immunosorbent assay (ELISA) that detects immunoglobulin M and G antibodies against Borrelia burgdorferi. A positive or equivocal ELISA result must be confirmed with a Western blot, which identifies antibodies to specific bacterial proteins. The Western blot is interpreted according to CDC criteria: a minimum of five of ten IgG bands or two of three IgM bands constitute a positive result.
Timing of specimen collection influences sensitivity. Antibodies generally become detectable 2–4 weeks after the bite; testing earlier may yield false‑negative results. If clinical suspicion is high and the test is performed before seroconversion, repeat testing after two weeks is recommended.
In addition to Lyme serology, clinicians often request panels that include polymerase chain reaction (PCR) assays for Anaplasma phagocytophilum, Ehrlichia chaffeensis, and Babesia microti. PCR provides direct detection of pathogen DNA and is most useful during the acute phase, typically within the first two weeks after exposure. Positive PCR results are interpreted as definitive evidence of infection.
A typical work‑up after a tick bite may therefore comprise:
- ELISA for Lyme disease antibodies
- Confirmatory Western blot (if ELISA positive/equivocal)
- PCR for Anaplasma, Ehrlichia, and Babesia (if indicated by symptoms)
- Complete blood count and liver function tests (to assess systemic involvement)
Interpretation follows established guidelines: a confirmed Lyme result combined with compatible clinical signs warrants antibiotic therapy; a negative result does not exclude early infection if the test was performed before seroconversion. PCR positivity for the other agents dictates pathogen‑specific treatment.