Laboratory Test Guide

Rocky Mountain Spotted Fever Antibodies, IgG and IgM (Sendout)

General Information

Lab Name

Lab Code

453

External Test Id

0050371

Description

Ordering Recommendation: Rocky Mountain spotted fever (RMSF) is a severe tick-borne infection caused by the bacterium Rickettsia rickettsii. Preferred test for acute or convalescent phase of disease. Acute and convalescent titers often necessary.

References

ARUP Consult® Tickborne Diseases

Synonyms

0050371, Rickettsia Rickettsii, RMSF, Rocky Mountain Spotted Fever

Interpretation

Method

Semi-Quantitative Indirect Fluorescent Antibody

Ref. Range Notes

Reference Ranges:

Rocky Mt Spotted Fever IgG:	<1:64
Rocky Mt Spotted Fever IgM:	<1:64

Interpretation:

Rickettsia rickettsii (Rocky Mountain Spotted Fever) Antibody, IgG:

Less than 1:64:	Negative - No significant level of IgG antibody detected.
1:64 - 1:128:	Low Positive - Presence of IgG antibody detected, suggestive of current or past infection.
1:256 or greater:	Positive - Presence of IgG antibody suggestive of recent or current infection.

Rickettsia rickettsii (Rocky Mountain Spotted Fever) Antibody, IgM:

Less than 1:64:	Negative - No significant level of IgG antibody detected.
1:256 or greater:	Presence of IgM antibody 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.

Guidelines

Washington DOH Notifiable Conditions

Ordering & Collection

Specimen Type

Blood

Collection

3 mL blood in RED TOP tube or GOLD SST

Handling Instructions

Outside Laboratories: Centrifuge sample and transfer serum to a separate plastic vial within 2 hours of collection. Refrigerate serum.

Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Samples must be clearly marked as "acute" or "convalescent."

Stability: Refrigerated (preferred): 2 weeks; Frozen: 1 year (avoid repeat freeze/thaw cycles); Ambient: 48 hours.

Unacceptable Conditions: Contaminated, hemolyzed, or severely lipemic specimens.

Quantity

requested: 1 mL serum
minimum: 0.5 mL serum

Processing

Centrifuge sample and transfer serum to a separate plastic vial within 2 hours of collection. Refrigerate serum.

Sendouts:

Order ARUP Test: 0050371
Interfaced: Yes [Interface: 602; Department: ARPR]
Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Samples must be clearly marked as "acute" or "convalescent."