I found out that I have trich. I am so fortunate to have a treatment, but so confused about this emotionally. I have been with the same sexual partner all year. Prior to him the last person I slept with was over 18 months ago and we used condoms. I was tested for stds in earlier this year at my primary care visit, they did not screen for trich. The urgent care clinician told me to talk to my partner about whether he cheated on me. He told me he was tested before we stopped using condoms. He also told me I am the only person he slept with this year. We started dating in February of this year and sleeping together without condoms in June of this year.

Is there any clinical chance this could be true? I am finding all kinds of things online about asymptomatic trich infections and they are very confusing to me. My partner got tested but has not received results. If he is negative, could he still have given it to me? If he doesn't have it, could I have had trich for years and not known? Does trich ever switch from being asymptomatic to symptomatic in women? 

On CDC's website it says "Some people get symptoms within 5 to 28 days after getting the infection. Others do not develop symptoms until much later. Symptoms can come and go." This is so confusing to me. What is the probability of each of these scenarios? 

I know my truth, but I am so confused on what to trust from my partner. How can I use the evidence to know what to trust from my partner and what is true in my case? 

I'm afraid there aren't very clear answers to your questions. Although trichomoniasis has been recognized for 100+ years, it has been studied far less than other STIs (like gonorrhea and chlamdia), especially in regard to natural course, transmission risk, and so on. The available information is just expert opinion based on patient care, with few (if any) systematic or controlled studies on transmission risks, diagnosis, etc. It is well established that trich does indeed persist for years and is often diagnosed months or even years after being acquired. Most standard STI testing doesn't include trich at all, so it isn't surprising you weren't tested. Men usually have no symptoms, hence no clue they might have it; and it often (usually?) is cleared by the immune system fairly quickly, probalby faster in males than females. 

All this makes it difficult, or in most cases impossible, to know when and from whom any particular infection was acquired. Given your sexual history, it seems likely your current partner had it and introduced it into your relationship, and that would be my best estimate even if his current pending test turns out negative. Most likely you'll never know for sure the source of your infection. However, your infection definitely does not necessarily imply your partner has had other partners recently; most likely it goes back to some partner in his past, perhaps long ago.

The important thing now is that you both be treated. presumably you both were prescribed metronidazole (?). Once taken as directed, this should be a done deal, with no further impact on your health or relationship.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD