Q: If one guy and one girl have only slept with each other in their whole entire life. How can trichomoniasis pop up? I understand it is an STD but I don't believe either of us cheated.
A: It is very unlikely to get trichomoniasis without having sex with someone. This STI (sexualy transmitted infection) is caused by a parasite that lives in either the vagina or urethra. It needs a dark, moist area to survive, so it doesn't last long on dry surfaces (such as door knobs or toilet seats). In order for someone to contract it without having sex, an object would have to be placed into an infected vagina or urethra and then almost immediately placed into the vagina or urethra of someone else. If you can imagine a scenario where that happens that doesn't involve sex, then you're more imaginative than I am.
About 70% of people with trichomoniasis never show symptoms of the STI, so they carry it with them without knowing it. This is why it's one of the most common STIs in the U.S., with an estimated 3% of the U.S. carrying the infection. Others contract the STI and only show symptoms years later. So, it could be that one of you has had it for a very long time and it's just now creating symptoms. Thankfully, trichomoniasis is very easy to treat, usually with just a single dose of an antibiotic.
For more information on trichomoniasis, check out:
Answers provided by Dr. Ross Avilla
Dr. Ross Avilla has been teaching Human Sexuality since 2013 and has a PhD in psychology from UC Davis. Dr. Avilla is not a clinician and all information and advice offered on this website is for educational purposes only.