Which tests should be done after a tick bite? - briefly
Following a tick exposure, obtain a two‑tiered Lyme serology (ELISA with confirmatory Western blot) and, if the bite was recent (<72 h), perform PCR for Borrelia. Add a complete blood count, liver function panel, and PCR panels for Babesia, Anaplasma, Ehrlichia, and—where relevant—tick‑borne encephalitis antibodies.
Which tests should be done after a tick bite? - in detail
After a tick exposure, the first step is to evaluate the bite’s duration, the tick’s species, and any symptoms that have appeared. Laboratory work should be guided by the epidemiology of local tick‑borne pathogens and the clinical picture.
- Lyme disease – Perform an initial enzyme‑linked immunosorbent assay (ELISA) for IgM and IgG antibodies, followed by a confirmatory Western blot if the ELISA is positive. Repeat serology 2–4 weeks later when early infection is suspected but antibodies may still be absent.
- Anaplasmosis and Ehrlichiosis – Order polymerase chain reaction (PCR) testing on whole blood for Anaplasma phagocytophilum and Ehrlichia chaffeensis. If PCR is unavailable, obtain acute‑phase IgM/IgG serology and repeat after 2–3 weeks for seroconversion.
- Babesiosis – Request a thick‑smear examination of peripheral blood for intra‑erythrocytic parasites and a PCR assay for Babesia microti. Consider a quantitative PCR to assess parasite load in severe cases.
- Rocky Mountain spotted fever – Collect acute‑phase serum for immunofluorescence assay (IFA) IgM/IgG against Rickettsia rickettsii. A second sample 7–10 days later is essential for detecting a four‑fold rise in titer.
- Tick‑borne encephalitis (TBE) – In endemic regions, obtain serum IgM and IgG ELISA for TBE virus. Cerebrospinal fluid analysis should include TBE IgM if neurological symptoms are present.
- Hepatitis C and other viral agents – Screen for hepatitis C antibodies when the tick species is known to transmit this virus, especially in high‑risk areas.
Additional baseline studies support diagnosis and monitor organ involvement:
- Complete blood count with differential – detects leukopenia, thrombocytopenia, or anemia common in several tick‑borne infections.
- Comprehensive metabolic panel – evaluates hepatic transaminases, bilirubin, and renal function, which may be altered in ehrlichiosis, anaplasmosis, or severe babesiosis.
- Inflammatory markers – C‑reactive protein and erythrocyte sedimentation rate provide a nonspecific gauge of systemic inflammation.
- Urinalysis – assesses hematuria or proteinuria that can accompany certain infections.
When neurological signs, such as meningitis or encephalopathy, emerge, lumbar puncture is warranted. Cerebrospinal fluid should be examined for cell count, protein, glucose, and pathogen‑specific PCR or antibody testing (e.g., Borrelia burgdorferi, TBE virus).
Timing of specimen collection influences sensitivity. Acute samples are taken as soon as possible after symptom onset; convalescent samples are collected 2–4 weeks later to identify seroconversion or rising titers. Repeat testing is essential when initial results are negative but clinical suspicion remains high.
Interpretation must consider cross‑reactivity among spirochetal antibodies and the possibility of co‑infection. A comprehensive approach, integrating epidemiologic risk, clinical presentation, and sequential laboratory data, ensures accurate detection and timely treatment of tick‑borne diseases.