Rocky Mountain Spotted Fever Antibodies, IgG & IgM  

IMPORTANT! Pre-approval needed from state or local health department. Local or State Health Department. Send approval to or call (402) 559-9444.

NPHL has moved to an electronic ordering system, NUlirt, and it is now the preferred method to order all tests. Once ordered, print a "batch list" (see NUlirt Guide).

Forms Required - Nulirt batch list or NPHL Test Request Form (completed in entirety) must accompany the specimen to include the following information: symptoms and date of onset, pregnancy status, travel and vaccine history. Testing will not be performed without all required information.

Please call NPHL Client Services at (402) 559-2440 or toll free at (800) 334-0459 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 (800) 334-0459.