—Had sexual encounter with a man a few years ago (timeline is fuzzy, definitely before March 15, 2020). He put his mouth around my scrotum for ~one minute. Around this time, my wife (who was aware) was pregnant. I cannot remember exact timelines. They could have overlapped. I also may have slept with her in this time.
—Wife had non-reactive VDRLs at 3mo, 6mo, and at time of birth (May 2020).
—I *did* have a Z-pack for respiratory infection in September of 2020. 
—I became aware of the possibility of syphilis just last year. Scared the crap out of me. Talked with wife, we both tested non-reactive for ECLIA, CMIA. I was also non-reactive for FTA-ABS.

How low-risk was encounter, since it's male to male? I thought syphilis can transmit to mucus membranes or skin. If I contracted it, and that Z-pack cured me after 5 months, would CMIA become positive? Finally, as our child is now 3, would she have exhibited congenital symptoms by now?

I know repetitive questions are not helpful. And yes, part of this is psychological, but the reason you probably get a lot of syphilis concern is because of the scary things people see about syphilis online. The idea that my child could have congenital syphilis because of a stupid mistake would terrify anyone.

Your and your wife's tests are conclusive:  you do not have and never had syphilis. Azithromycin (Z-pack) might or might not have cured it, if you were infected at the time. (Some syphilis strains are resistant to azithromycin.) Intact skin of the scrotum (or anywhere else) is not likely to be infected unless injured in the process. But the risk of infection at the time of exposure is irrelevant, since we know you were not infected. There is no possibility your child has congenital syphilis. Believe it.

It sounds like this obsession is dominating your life and happiness at least some of the time. Such obsessions never resolve with factual understanding alone, no matter how often people are told; there's always a "yes but" or "could I be the exception" sort of response. The answer lies in professional mental health care; I urge you to speak with your physician about referral for counseling. I suggest it from compassion, not criticism.

I hope these comments are at least a little bit helpful. You also may wish to read through your previous forum questions on this topic. In any case, this must be your last question along these lines. Future ones will be subject to deletion without reply. Thanks for your understanding.

HHH, MD