Spotted Fever Group Antibody, IgG and IgM, Serum

Casandra

Casandra Test Code MC95127Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID SFGPCPT Code 86757

Spotted Fever Group Antibody, IgG and IgM, Serum

Clinical Use

Use

This test aids in the diagnosis of spotted fever group rickettsial infections. Rickettsial infections in the United States are caused by 2 major groups within the genus Rickettsia: the spotted fever group and the typhus fever group. The spotted fever group includes Rickettsia rickettsii (Rocky Mountain spotted fever), Rickettsia akari, Rickettsia conorii (Boutonneuse fever), Rickettsia australis (Queensland tick typhus), and Rickettsia sibirica (North Asian tick typhus). Antibodies to the spotted fever group agents are detectable within 7 to 10 days after illness onset. Demonstration of either seroconversion or a 4-fold change in IgG-specific antibody titers in acute and convalescent serum samples is consistent with acute or ongoing disease.

Special Instructions

If not ordering electronically, complete, print, and send 'Infectious Disease Serology Test Request' (T916) with the specimen.

Limitations

Cross-reactivity within the spotted fever group precludes the speciation of the infecting rickettsia by this procedure. Sera reactive with Rickettsia rickettsii must be termed 'spotted fever group-positive.' Spotted fever and typhus fever intragroup cross-reactivity is weak: cross-reactive titers are typically at least 16-fold lower than group-specific titers. Antibody is variably absent for 1 to 2 weeks after onset of symptoms and an initial negative titer should not be used to exclude the diagnosis of rickettsial disease. IgM titers must be interpreted with caution, especially in the absence of IgG.

Test Details

FDA Approved