How many days after a tick bite should blood be tested for encephalitis? - briefly
Blood should be drawn for TBE antibody testing about 7–14 days after the bite, with a second sample taken 2–3 weeks later to confirm seroconversion. This timing captures the typical incubation period and the rise of detectable IgM/IgG.
How many days after a tick bite should blood be tested for encephalitis? - in detail
A blood sample should be taken when the immune response to the virus is likely detectable. Serological markers (IgM antibodies) typically appear 7–10 days after the bite; testing earlier may give false‑negative results. To increase diagnostic accuracy, a second specimen is recommended 2–3 weeks after the initial exposure, allowing for seroconversion or a rise in antibody titer.
Key points for timing the assay:
- First draw: 7–10 days post‑exposure; suitable for detecting early IgM.
- Second draw: 14–21 days post‑exposure; confirms seroconversion or rising titers.
- PCR testing: May be performed as early as 3–5 days if neurological symptoms are present, because viral RNA can be present before antibodies develop.
- Clinical context: Presence of fever, headache, neck stiffness, or neurologic deficits warrants immediate testing regardless of the interval, with follow‑up sampling at the later time points.
Factors influencing the schedule include patient age, immune status, and the tick species involved. Immunocompromised individuals may exhibit delayed antibody production, necessitating a longer interval before the first reliable serology. Conversely, severe early neurological signs justify prompt molecular testing even within the first few days after the bite.