Third-stage syphilis can be detected. Syphilis is divided into primary, secondary, and tertiary stages, with the severity progressively increasing from the primary to tertiary stage, making tertiary syphilis a relatively advanced and serious condition. It can be detected by measuring the titers in serum, although the titers in tertiary syphilis may be lower than in the primary and secondary stages, and may sometimes present as negative. However, through the symptoms of tertiary syphilis, particularly some complications affecting the skin, cardiovascular system, bones, joints, and other organs, combined with the titer levels, it can definitely be detected.