Which tests should be performed after a tick bite? - briefly
A blood test for Lyme disease antibodies (ELISA followed by Western blot if positive) and, if the tick was attached >36 hours, a PCR or serology for Anaplasma, Babesia, or Ehrlichia should be considered; additionally, a complete blood count can reveal early infection signs. Immediate medical evaluation is advised to determine the need for prophylactic antibiotics.
Which tests should be performed after a tick bite? - in detail
After a tick attachment, a clinician must order laboratory investigations that identify potential infectious agents and assess organ involvement. The selection of assays depends on the tick species, geographic region, duration of attachment, and presence of symptoms.
Blood work should include a complete blood count with differential to detect leukopenia, thrombocytopenia, or anemia, which are common in several tick‑borne diseases. Liver function tests (ALT, AST) and renal panel (creatinine, BUN) evaluate organ stress that can result from systemic infection.
Serologic testing for Borrelia burgdorferi requires a two‑step approach: an initial enzyme‑linked immunosorbent assay (ELISA) followed by a confirmatory Western blot if the ELISA is positive. Early infection may be missed by serology; in such cases, polymerase chain reaction (PCR) on blood or skin biopsy specimens provides direct pathogen detection.
Additional PCR panels should be ordered when exposure risk includes other agents:
- Anaplasma phagocytophilum – PCR on whole blood.
- Ehrlichia chaffeensis – PCR on blood; indirect immunofluorescence assay (IFA) for IgM/IgG if PCR unavailable.
- Babesia microti – PCR on blood; thick‑smear microscopy for parasites.
- Rickettsia spp. – PCR on blood or tissue; IFA for IgM/IgG when PCR is negative.
If the bite occurred in regions where Powassan virus or tick‑borne encephalitis virus are endemic, request serum or cerebrospinal fluid (CSF) IgM ELISA and, when indicated, viral PCR.
When neurological symptoms are present, perform a lumbar puncture. CSF analysis should include cell count, protein, glucose, and PCR for Borrelia, West Nile virus, and other neurotropic tick‑borne pathogens.
Finally, document the tick’s identification when possible; species‑specific risk profiles guide the choice of targeted tests and inform decisions about prophylactic antibiotics.