How many days after should tick tests be performed? - briefly
The tick should be submitted for testing within about one week of removal, preferably between five and seven days.
How many days after should tick tests be performed? - in detail
The appropriate interval for laboratory evaluation after a tick bite depends on the pathogen being investigated.
For Borrelia burgdorferi, the causative agent of Lyme disease, serologic assays (ELISA followed by Western blot) become reliable only after the immune response has developed. Antibodies are usually detectable 2 – 3 weeks post‑exposure; a second sample collected 4 – 6 weeks after the bite increases diagnostic sensitivity. Early-stage disease may be confirmed by PCR of skin biopsy or synovial fluid, but these tests are most useful after the initial inflammatory response, typically beyond day 5.
Rickettsial infections such as Rocky Mountain spotted fever produce detectable IgM antibodies roughly 7 – 10 days after the bite. Acute‑phase serum should be drawn at that point, with a convalescent sample obtained 2 weeks later to demonstrate a four‑fold rise in titer.
Anaplasma phagocytophilum and Ehrlichia species generate PCR‑positive results within the first week of infection, but serology becomes reliable only after day 10. A paired‑sample approach, with the first specimen at 7 – 10 days and the follow‑up at 3 weeks, maximizes detection.
Babesia microti DNA can be identified by PCR as early as day 3, while serologic conversion generally occurs after 2 weeks. For patients with persistent symptoms, repeat testing at 4 weeks is advisable.
In practice, the following schedule is recommended:
- Day 0‑5: Observe for local reaction; no laboratory testing required unless severe symptoms appear.
- Day 7‑10: Obtain acute serum for IgM antibodies (Rickettsia, Anaplasma, Ehrlichia) and consider PCR for early‑detectable pathogens.
- Day 14‑21: Perform ELISA for Lyme disease; PCR may still be useful for early disseminated infection.
- Day 28‑42: Collect convalescent serum for all serologic tests to confirm seroconversion or rising titers.
Testing earlier than the specified windows often yields false‑negative results because the host immune response has not yet produced measurable markers. If clinical suspicion remains high, clinicians should repeat the appropriate assay after the recommended interval rather than rely on a single early test.