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Testing Results
IMPORTANT! Sites requesting testing must have approval from the appropriate state or local health department before submitting specimens. Approval must be sent to NPHL by email at or by calling (402) 559-9444.

A Special Microbiology Form must accompany the specimens. Some tests require additional forms and patient history. This will be listed below when applicable. When requested, testing will not be performed without all required information.

Please call NPHL Client Services at (402) 559-2440 or toll free at (866) 290-1406 for further clarification.


  Test: Rocky Mountain Spotted Fever Antibodies, IgG & IgM 
  Synonym: Rickettsia rickettsii (Rocky Mountain Spotted Fever) Antibodies, IgG & IgM by ELISA 
  Method: Indirect Immunofluorescence Assay 
  Availability: Monday-Friday; results in 1-5 days 
  Specimen: Blood 
  Collection Device: 6.0 mL Gold (SST) tube 
  Volume: 1.0 mL serum (Min: 0.5 mL) 
  Storage/Transport: Refrigerate; separate serum from cells ASAP 
  Unacceptable: Severely lipemic, contaminated, or hemolyzed samples 
  Specimen Stability: After separation from cells, ambient, not stable; refrigerated, 2 weeks; frozen, 1 year
Avoid multiple freeze/thaw cycles 
  Reference Interval: IgG:
< 1:64: Negative - No significant level ofIgG detected.
1:64 - 1:128: Low Positive - Presence of IgG detected, suggestive of current or past infection.
≥ 1:256: Positive - IgG detected, suggestive of recent or current infection.

< 1:64: Negative - No significant level of IgM detected.
≥ 1:64: Positive - IgM detected, which may indicate a current or recent infection. However, low levels of IgM antibodies may occasionally persist for more than 12 months post-infection. 
  Reportable Disease:  
  Comments: Acute and convalescent samples must be labeled as such; parallel testing is preferred and convalescent samples must be received within 30 days from receipt of the acute samples. Please mark sample plainly as "acute" or "convalescent." The best evidence for current infection is a significant change on two appropriately timed specimens, where both tests are done in the same laboratory at the same time. The CDC does not use IgM results for routine diagnostic testing of Rocky Mountain Spotted Fever, as the response may not be specific for the agent (resulting in false positives) and the IgM response may be persistent from past infection. 
  Revised: 2/13/2012 


If you have questions about proper specimen collection, please call NPHL Client Services at (402) 559-2440 or toll free at (866) 290-1406.