After how many days post tick bite should blood be drawn for antibodies? - briefly
Serologic testing is typically performed 14–21 days after a tick bite, when IgM and IgG antibodies are reliably detectable. Testing earlier may produce false‑negative results.
After how many days post tick bite should blood be drawn for antibodies? - in detail
Blood for serologic testing should be collected no earlier than two weeks after the bite, because detectable antibodies typically appear between days 14 and 21. Testing before this window frequently yields false‑negative results, as the immune response has not yet matured.
- Day 0‑7: No reliable antibodies; clinical diagnosis relies on exposure history and early symptoms.
- Day 8‑13: IgM may begin to rise, but sensitivity remains low; repeat test advisable if suspicion persists.
- Day 14‑21: Both IgM and the first IgG become detectable; this period offers the highest likelihood of a positive result.
- Day 22‑28: IgG levels increase, providing a more robust marker for ongoing infection.
If the initial sample is taken before day 14 and is negative, a second draw after day 21 is recommended to confirm seroconversion. For diseases other than Lyme (e.g., Anaplasma, Ehrlichia, Babesia), similar timing applies, though specific pathogens may have slightly different serologic kinetics; consult disease‑specific guidelines when relevant.