[DoctorTan]

Good question. I love questions about Syphilis testing. It is so complex. This is going to be a long one so bear with me.

You must first understand that there is NO test that actually detects the Syphilis bacteria in the body. We have 2 types of tests to diagnose Syphilis:

1. Non-Treponemal tests (VDRL, RPR etc)
This test was developed in 1906 (WTF!!! And Doctors are still using it now?! YES we are). Some smart guy found that blood from a person infected with Syphilis will react with pieces of Ox heart and cause the test tube fluid to foam.

The level of disease activity of Syphilis can be determined by seeing how much you can dilute the patient's blood and still get a foamy reaction. If you dilute it 2x and still get a reaction it is reported as 1:2. If you dilute again it's 1:4 then 1:8 all the way to 1:256. You get the idea.

As you can obviously see, this test is very prone to false positive. People can have all sorts of antibodies in their blood that reacts with Ox heart.

So if a person tests positive on VDRL or RPR, the result is always confirmed with another test called.....

2. Treponemal tests (TPHA, TPPA)

These tests are more specific for antibodies to Treponema Pallidum which is the bacteria that causes the disease Syphilis.

So if a person is positive for both VDRL and TPHA, he/she is diagnosed as having a Syphilis infection. They are then put on treatment.

Now comes your question: How do we know that they are cured or not?

You might think the answer is obvious. Both these tests will become negative! Right? Uhh. Not right.

Both these tests will remain positive for many many years. Sometimes for a lifetime. That is because both these tests test for antibodies which we know will persist in the patient's body long after the infection is gone.

So how? Well, current guidelines say that if we see a 4-fold drop in titer of the VDRL within 3 to 6 months of therapy, we can assume the patient is no longer infected. (eg. if the person tested 1:8 before treatment, the number has to drop to 1:2 after treatment - 4 fold drop). However, the patient has to be followed up for a total of 2 years ensuring that the VDRL titer stays low before he/she is discharged from care.

This is a very rough overview. There are many details and caveats to Syphilis testing. It is still best to see a doctor for your specific concerns.

WRT your question, if it was me, I would not touch the girl for at least 2 years if she has been diagnosed with Syphilis. And she had better have the 6 sequential blood tests to prove that she is cleared before thinking of getting into any action.

However, once the 2 years is over and she is certified clear, she can lead a completely normal life. Except when she goes for health screening, the Syphilis will always test positive and she will always have to explain to the doctor her past medical history of having had Syphilis and received treatment.