I’d like to ask a clarifying question regarding a question Dr. Handsfield answered a couple of days ago about syphilis treponema test seroreversion (#9802). My understanding is that the vast majority of people who’ve ever had syphilis, treated or not, will test positive on treponema specific tests for life, and that there are some instances when, if very early treatment is administered, the tests may never become positive. In the question Dr Handsfield answered, he did indeed mention that seroreversion, when it happens, occurs primarily (and he believes ONLY) when syphilis is treated very early in the primary phase, that is, in the first several weeks after transmission, in what I understand to be the “incubation period.” He then says syphilis going untreated for longer than the first few weeks will have a positive treponemal test for life. Further down, however, he says “And by the way, when someone is treated sufficiently early, typically within a month or two of catching it, and if their TP specific confirmatory test later becomes negative…” and this is where I had a question. Was “within a month or two” a typo? Should it have been “within a week or two” instead? It sounded contradictory to say that seroreversion is believed to only happen when treated in the first few weeks but then later to say that there’s a possibility of later seroreversion if treated sufficiently within a month or two. So I would just like to confirm more plainly, with regards to treponema specific tests, is seroreversion only a possibility when treated in the first few weeks, or is it possible for seroreversion to occur beyond that? Thanks. 

Hi Dr. Handsfield, thank you for taking my question. I am not the person asking questions on healthtap.com. You are correct, my concern is whether or not I’ve ever had syphilis, how best to know that, and whether or not I’ve transmitted it to my spouse, who over the years has had various non-specific symptoms that, when added up, I’m afraid are related. We are 13+ years out from my encounters, and in that time I’ve taken antibiotics for unrelated reasons while my spouse has taken none, thus putting him theoretically in late-stage, or, god forbid, tertiary. I’ve relied on my and my former casual partner’s negative treponemal tests as evidence that neither he nor I have ever been infected, but with disease and testing nuances, it’s difficult to believe the results with 100% certainty. My understanding is that treponemal tests remain positive for life for the majority of those who’ve had syphilis, and that the small minority who don’t test positive for life is because they seroreverted due to early treatment. This is the foundation that informs any belief that I’ve never had it. What shakes this foundation is when I find information that refutes these commonly shared beliefs, such as the possibility of later seroreversion.

Regarding your question about the difference between “a month or two” or “a week or two,” the reason I raise the concern is because everything I’ve read on this site indicates that seroreversion is only possible when proper treatment is done early, in the first few weeks after exposure, and prior to symptoms appearing, since symptoms appear on average around the ~3-week mark. If, then, it’s possible for seroreversion to occur outside of this ~3-week window, I wonder if it would be fair to conclude that as long as proper treatment is taken before symptoms begin, whatever timing that may be (even up to 90 days), that seroreversion is then possible in this longer window. If, however, seroreversion is possible under any circumstance, i.e. not because of aborted infection, that would be something new I’d not yet heard, but as you say, data isn’t precise. Can you comfortably say, as far as the available data shows, that you agree that seroreversion when proper treatment is taken is only possible as long as it’s before symptoms begin, and that, conversely, once someone has progressed enough to exhibit symptoms, their chances for seroreversion are unlikely? Would it also be accurate to say that if one has seroreverted, they never developed active infection and were therefore at no time infectious to others? (Is that a natural conclusion of seroreversion, that it means you never developed it?)

I agree that I overthink all of this and am deep in the weeds, and while it’s true this may not be relevant to my situation, which both you and Dr. Hook have agreed was low risk, this additional information/confirmation helps to assuage my fear that negative tests taken years after exposures are not able to be relied upon. Short of overtly asking my spouse to get tested beyond a blood donation, my negative treponemal tests are the only “proof” I have that I’ve never had syphilis, even though the tests were all done many years after exposures. If there’s any chance, even minuscule, that I could’ve been infectious and then later seroreverted, that would negate the only evidence I have that supports this belief, so I certainly hope that’s not the case. I appreciate your time reading this and additional considerations.