Fig. 1

Participant flow diagram. Individuals with neuropsychiatric symptoms or signs and those who were TP-CLIA positive, individuals with failure of TRUST decline after antibiotic exposure, and others (with TP-CLIA positive) who requested further diagnosis were included (A). Reactive neurosyphilis refers to syphilis patients with positive results in both CSF-TRUST and CSF-TPPA. Non-reactive neurosyphilis refers to syphilis patients with negative results in CSF-TRUST but positive results in CSF-TPPA. Syphilis patients with negative results in both CSF-TRUST and CSF-TPPA were regarded as “Not neurosyphilis” (B). CSF, cerebrospinal fluid; TRUST, Toluidine red unheated serum test; TP-CLIA, Treponema pallidum chemiluminescence assay; TPPA, Treponema pallidum particle agglutination assay