Table 3. PCR detection rates in swab and whole blood samples relative to syphilis serology and syphilis stage.

Samples (total no. of samples)	Swab PCR positivity rate (total no. of positive samples; total no. of samples)	Whole blood PCR positivity rate (total no. of positive samples; total no. of samples)
All seropositive and serodiscrepant samples (n = 815)	76.4% (314/411)	32.7% (132/404)
RPR and treponemal test-positive samples (n = 651)	77.8% (256/329)	34.8% (112/322)
RPR and treponemal test-positive samples from primary and secondary stage (n = 440)	82.5% (207/251)	41.8% (79/189)
RPR and treponemal test-positive samples from primary stage (n = 292)	84.3% (166/197)	42.1% (40/95)