Hello and welcome to HCM,
Syphilis is detected by performing
VDRL test.
VDRL is the preliminary test.
If it comes out to be positive further TPHA test is done to confirm the infection.
There are certain conditions wherein the VDRL can come out to be falsely positive.
However, TPHA is negative in such cases.
It is unlikely for VDRL to be negative and TPHA to be positive.
There may be some defect in either VDRL or TPHA test.
You need to get the test repeated with other test kits.
The test is reported as the antibody titres.
According to your kit, the titres above 1:20 are considered to be positive.
Thus, the test will be considered positive if antibody titres are above 1:20.
Thanks and take care
Dr Shailja P Wahal