What is the test called for encephalitis after a tick bite? - briefly
The standard diagnostic work‑up is a cerebrospinal fluid Borrelia burgdorferi antibody assay, typically performed by ELISA and confirmed with Western blot. PCR detection of Borrelia DNA in CSF may also be employed.
What is the test called for encephalitis after a tick bite? - in detail
The diagnostic work‑up for suspected encephalitis following a tick exposure centers on serologic and molecular assays that identify the responsible pathogen.
First, cerebrospinal fluid (CSF) is obtained via lumbar puncture. Analysis includes cell count, protein, glucose, and the presence of intrathecal antibody synthesis. Elevated lymphocytes and protein with normal glucose strongly suggest viral or spirochetal infection.
For Borrelia burgdorferi‑related neuroborreliosis, the standard approach combines:
- Enzyme‑linked immunosorbent assay (ELISA) for IgM and IgG antibodies in serum.
- Confirmatory Western blot to verify ELISA reactivity.
- CSF/serum antibody index (AI) calculation; an AI > 1.5 indicates intrathecal production of Borrelia‑specific antibodies, confirming central nervous system involvement.
Polymerase chain reaction (PCR) targeting Borrelia DNA in CSF is available but has limited sensitivity; a positive result provides definitive evidence.
If the clinical picture aligns with tick‑borne encephalitis virus (TBEV) infection, the recommended test is a TBE‑specific serology:
- IgM ELISA performed on acute‑phase serum; a positive result within the first week of symptoms is diagnostic.
- Follow‑up IgG ELISA after 2–3 weeks confirms seroconversion.
- CSF IgM detection may be added for increased specificity.
In some regions, multiplex panels that simultaneously detect antibodies against TBEV, West Nile virus, and other arboviruses are employed, reducing the need for multiple separate assays.
Interpretation guidelines:
- Positive serum IgM with corresponding CSF IgM or AI supports acute encephalitis of tick‑borne origin.
- Isolated IgG without IgM suggests past exposure; clinical correlation required.
- Negative serology does not exclude early infection; repeat testing after 7–10 days is advised.
Overall, the combination of CSF analysis, pathogen‑specific ELISA, intrathecal antibody index, and, when appropriate, PCR constitutes the definitive diagnostic strategy for encephalitis after a tick bite.