When should a borreliosis test be taken after a tick bite? - briefly
Testing for Lyme disease is recommended 2–4 weeks after the bite, when antibodies are likely detectable. Testing sooner often produces false‑negative results.
When should a borreliosis test be taken after a tick bite? - in detail
The optimal interval for ordering a Lyme disease diagnostic test after a tick bite depends on the pathogen’s serological response timeline and the presence of clinical signs.
Serological testing becomes reliable only after the immune system has produced detectable antibodies. In most cases, IgM antibodies appear 2–4 weeks post‑exposure, while IgG antibodies develop 4–6 weeks later. Testing before this window yields a high false‑negative rate because the assay cannot detect low‑level antibodies.
Guidelines for timing
- Immediate testing (within 48 hours): not recommended for routine screening; can be considered only if the tick is known to be infected and the patient is immunocompromised.
- If erythema migrans or other early symptoms appear: order a test at the time of presentation, but interpret negative results with caution; clinical diagnosis may warrant treatment regardless of serology.
- Asymptomatic individuals: schedule the first serology at 2–3 weeks after removal of the tick. If the initial result is negative and symptoms develop later, repeat testing at 4–6 weeks.
- Persistent or late manifestations (arthritis, neurologic signs): perform serology at least 6 weeks after the bite, when IgG titres are most likely to be positive.
Testing strategy
- Screening assay (ELISA or chemiluminescence immunoassay). Positive or equivocal results must be confirmed.
- Confirmatory assay (Western blot). Separate IgM and IgG interpretations according to established criteria.
- Supplementary methods (PCR, culture). Reserved for cerebrospinal fluid or synovial fluid when early serology is inconclusive.
Key points
- Antibody production dictates the earliest reliable detection point; therefore, a minimum of 2 weeks is required before a standard serologic test can be trusted.
- Clinical judgment overrides serology in the presence of characteristic rash or neurological involvement.
- Repeat testing is essential if initial results are negative but symptoms emerge after the early window.