Table 1.

Specimen sample combinations submitted for imported spotted fever group Rickettsia infections in travelers by disease case classification—United States, 2007–2016

Specimen samples submitted per patient	Probable SFGR	Confirmed SFGR by paired serology*	Confirmed SFGR by IHC†	Confirmed Rickettsia africae	Total
Only one serum sample	59	0	0	0	59
Paired serum samples	26	10	0	0	36
Tissue/eschar sample only	0	0	3	14	17
Tissue/eschar sample plus serum sample(s)	0	0	2	13	15
Total	85	10	5	27	127

IgG = immunoglobulin G; IHC = immunohistochemistry; SFGR = spotted fever group rickettsiosis.

^*Confirmed SFGR infection through 4-fold increase in IgG antibody titers between paired serum samples.

^†Confirmed SFGR infection through positive IHC staining.