How should a test be taken after a tick bite?

How should a test be taken after a tick bite? - briefly

Obtain a blood sample for serologic testing (e.g., ELISA) as soon as possible, ideally within 2–3 weeks after the bite. If the initial assay is positive, confirm the result with a Western blot.

How should a test be taken after a tick bite? - in detail

After a tick attachment, the first step is to remove the arthropod promptly with fine‑tipped tweezers, grasping close to the skin and pulling upward with steady pressure. Clean the bite site with antiseptic and document the date of the encounter.

Observe the patient for signs of infection for at least 30 days. Symptoms that trigger diagnostic testing include fever, headache, fatigue, myalgia, arthralgia, rash (especially erythema migrans), or neurological manifestations.

When clinical suspicion arises, arrange laboratory evaluation according to the following schedule:

1. Initial serology (approximately 2–4 weeks post‑exposure).

   • Order an enzyme‑linked immunosorbent assay (ELISA) for IgM and IgG antibodies.
   • Use a validated commercial kit; follow manufacturer’s protocol for sample dilution, incubation times, and substrate development.
   • Record optical density values and compare with the established cutoff.

2. Confirmatory testing (if ELISA is positive or equivocal).

   • Perform a Western blot assay.
   • Separate Borrelia‑specific proteins by electrophoresis, transfer to a membrane, and probe with patient serum.
   • Interpret bands according to CDC criteria: ≥2 IgM bands (23‑kDa, 39‑kDa, 41‑kDa) for early infection; ≥5 IgG bands (18‑kDa, 23‑kDa, 28‑kDa, 30‑kDa, 39‑kDa, 41‑kDa, 45‑kDa, 58‑kDa, 66‑kDa) for later stages.

3. Polymerase chain reaction (PCR) when indicated.

   • Collect whole blood, cerebrospinal fluid, or synovial fluid depending on symptom location.
   • Extract nucleic acid using a silica‑column kit, then amplify Borrelia‑specific flagellin (flaB) or 16S rRNA genes.
   • Confirm positive amplification by gel electrophoresis and sequencing.

4. Follow‑up testing.

   • Repeat serology at 6‑month intervals if initial results are negative but symptoms persist.
   • Document changes in antibody titers; a four‑fold rise in IgG indicates recent infection.

Laboratory specimens must be processed within the time frame specified by the test manufacturer to preserve antigenicity. Store serum at –20 °C if delayed beyond 24 hours. Ensure chain‑of‑custody documentation for each sample.

Interpretation guidelines:

• Positive ELISA with confirmatory Western blot confirms infection; initiate antibiotic therapy promptly.
• Negative ELISA in the early window period (first 2 weeks) does not exclude disease; repeat testing after the window closes.
• PCR positivity supports active infection, especially in neurologic or joint involvement, even if serology is inconclusive.

Document all findings, test dates, and results in the patient’s record. Communicate results to the treating clinician for appropriate management.