What labs should be drawn for someone bitten by turkey mites?

Laboratory Testing for Turkey Mite Bites

For suspected turkey mite bites, a complete blood count (CBC) with differential, liver function tests, and serological testing for tick-borne rickettsial diseases should be performed, along with PCR testing of whole blood if symptoms are present. 1

Initial Diagnostic Approach

When evaluating a patient with suspected turkey mite bites, the following laboratory tests should be ordered:

1. Complete Blood Count (CBC) with differential

   • Look for leukopenia, thrombocytopenia, or anemia which may indicate tick-borne illness
   • Examine for presence of morulae in leukocytes (particularly for ehrlichiosis or anaplasmosis)

2. Liver Function Tests

   • Elevated transaminases may indicate systemic involvement in tick-borne diseases

3. Serological Testing

   • IFA (Indirect Immunofluorescence Antibody) assay for rickettsial diseases
   • Paired serum samples (acute and convalescent, 2-4 weeks apart) are recommended
   • A fourfold rise in antibody titer confirms acute infection 2

4. PCR Testing of Whole Blood

   • Particularly useful for early diagnosis of ehrlichiosis and anaplasmosis
   • Should be collected before antibiotic administration 2, 1

Timing Considerations for Testing

The timing of laboratory testing is critical for accurate diagnosis:

• Days 0-7 post-bite: Serologic tests are generally negative and insensitive
• Days 7-15 post-bite: Both IgM and IgG antibodies usually become detectable
• 2-3 weeks post-bite: Highest sensitivity for antibody detection 1

Important Diagnostic Principles

1. Never delay treatment while awaiting laboratory confirmation if clinical suspicion is high for a tick-borne illness 2

2. Blood smear examination can be useful to detect morulae in leukocytes for ehrlichiosis or anaplasmosis (though this requires an experienced microscopist) 2

3. Single elevated antibody titers are insufficient to confirm acute infection; paired samples showing a fourfold increase in titer are required 2

4. PCR sensitivity decreases after antibiotic administration, so collect specimens before starting treatment 2

Special Considerations

• If the patient presents with an eschar (localized, necrotic skin lesion), consider:

  • Eschar biopsy or swab for PCR testing
  • Immunostaining of skin biopsy specimens (100% specific and 70% sensitive for RMSF) 2

• For patients with neurological symptoms:

  • Consider CSF analysis for tick-borne diseases with neurological involvement 1

Caveats and Pitfalls

• Antibodies may persist for months to years after infection, so a positive result without compatible clinical symptoms should not trigger treatment 2

• Early doxycycline therapy may diminish or delay antibody development, potentially affecting serologic diagnosis 2

• Up to 40% of patients with tick-borne diseases like RMSF do not report a history of tick bite, so absence of known exposure should not exclude testing when clinically indicated 1

By following this systematic approach to laboratory testing for suspected turkey mite bites, clinicians can optimize diagnostic accuracy while ensuring timely treatment for potentially serious tick-borne illnesses.