When should blood be drawn for tick-borne encephalitis after a tick bite? - briefly
Blood should be sampled 7 – 14 days post‑exposure, preferably before any clinical signs appear, to detect seroconversion; if symptoms develop earlier, testing should be performed at symptom onset.
When should blood be drawn for tick-borne encephalitis after a tick bite? - in detail
Blood sampling for tick‑borne encephalitis (TBE) should be performed according to the serologic window periods of IgM and IgG antibodies. The first specimen is taken as soon as possible after the bite, ideally within 3–5 days, to establish a baseline. This early sample serves as a reference for later comparison and helps to rule out pre‑existing antibodies in individuals who may have been vaccinated or previously infected.
A second sample is required during the incubation phase, when the immune response becomes detectable. The optimal window for the first serologic detection is 7–14 days post‑exposure. Testing at this point captures the rise of IgM, which appears first and indicates recent infection. If the initial post‑exposure sample was negative, a follow‑up draw at 14–21 days confirms seroconversion or persistent negativity.
A third specimen may be necessary if clinical symptoms develop after the bite. In such cases, draw blood at the onset of neurological signs (e.g., headache, fever, meningitis) and repeat after 5–7 days to monitor the progression of IgM and the emergence of IgG, which typically appears 2–3 weeks after infection.
Key timing points:
- Baseline sample: 3–5 days after tick attachment.
- First serologic window: 7–14 days post‑bite for IgM detection.
- Secondary window: 14–21 days for confirmation of seroconversion.
- Symptomatic testing: at symptom onset and again 5–7 days later.
Interpretation follows standard guidelines: a negative baseline with a subsequent positive IgM indicates recent infection; the appearance of IgG alongside or after IgM confirms ongoing or past exposure. In vaccinated individuals, the presence of IgG without IgM suggests vaccine‑derived immunity, not acute infection. Accurate timing of blood draws therefore ensures reliable diagnosis and appropriate clinical management.