Treponema pallidum should be distinguished from other nonpathogenic spirochaete by their morphology and movement. Typically they have 5-20 regular spirals and far greater activity than the other spirochaete. Their characteristic movement include angulation, rotation, undulation, compression and expansion. This flocculation test is routinely done in Social Hygiene Clinic for all the patients. It is the commonest test used for screening and monitoring of the disease activity after treatment.
Quantitative titre is measured for the latter purpose.
Confirmation with specific tests is therefore necessary. Those with negative test should have the test repeated three months later to cover for the incubation period of syphilis. This is a specific confirmatory test in syphilis. It becomes positive earlier than VDRL and is the first serological test to become positive. However it is not suitable for large scale screening and the titre does not reflect the disease activity.