VDRL (RPR) – Titre is a quantitative version of the VDRL test, used to measure the concentration of antibodies against *Treponema pallidum* (the bacteria causing syphilis) in the blood. The titre represents the dilution factor at which antibodies are still detectable.

– A high titre indicates active syphilis infection or a recent outbreak.
– A low titre suggests past infection, potential treatment success, or low levels of infection.

This test is used not only for diagnosing syphilis but also to monitor the effectiveness of treatment over time. A decreasing titre generally indicates successful treatment, while a rising titre may suggest treatment failure or reinfection.