Rocky Mountain Spotted Fever Serologies

Tube Type

Test ID		LAB1265
EPIC Order		RMSF SEROLOGIES
CPT Code(s)		86757
Group/Individual Test		Group
Laboratory		Clinical Immunology
Tube Station		30
Specimen	Routine:	3 mL blood/Gold SST tube
Availability	Routine:	See Comments
	STAT:	N/A
Turnaround Time		In season: 3-5 days Off season: 3-8 days
Reference Range	Normal:	<1:128

Comments	Tick-Borne Illness Panel (see the table) as the preferred laboratory test for tick-borne infections in North Carolina. The panel order includes tests for IgG antibody to Ehrlichia chaffeensis, IgG antibody to Spotted Fever Group Rickettsia and total antibody (IgG and IgM) to Borrelia burgdorferi. This panel is offered in response to evolving epidemiology of tick-borne infections and to promote appropriate testing (see Brown-Marusiak. 2022. JAMA Netw Open). The panel is the preferred order for patients with suspected tick-borne infection although each test can be ordered individually. Results of single serological test cannot be used to confirm diagnosis without a paired convalescent result obtained 2-6 weeks later. For suspect patients with new onset symptoms (i.e., fever, headache, myalgia, fatigue) and typical laboratory abnormalities (e.g., leukopenia, thrombocytopenia, or elevated transaminase levels), consider Ehrlichia PCR testing. Spotted Fever Group Rickettsia Group acute samples will be tested for IgG antibody at a 1:128 dilution and reported as positive (>1:128) or negative (<1:128). Acute samples will not have an endpoint titer determined unless a convalescent sample (collected 2 to 3 weeks after the acute sample) is received. Upon receipt of a convalescent sample both the acute and convalescent samples will be titered to endpoint in order to assess seroconversion or the presence of a four-fold increase in titer which indicate recent infection.

Reviewed by J. Carr on November 04, 2025

UNC Hospitals
McLendon Clinical Laboratories
101 Manning Drive
Chapel Hill, NC 27514