Can someone get trichomoniasis without sexual contact even in rare instances? My wife and I have been faithful for 10 yrs

Yes, but not likely. Anything is possible. The diagnosis could be wrong, (mixed up the slides at the office/lab). Non sexual contact with something like a wet towel or toilet seat, etc. But the overwhelming likely answer is that someone, at some point in time had at least a moment of bad judgement (unprotected sex). Don't let it ruin the relationship. Trich can be fixed. Your wife is more valuable than sex. Fix it.
Never say never. Theoretically one could use a public rest room and sit on someone elses urine and get a "seeded" infection, but it is rare and the likelihood is miniscule but certainly possible. Statistically speaking, trich is a std.

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Can someone get trichomoniasis without sexual contact even in rare instances? My wife and I have been faithful for 10 yrs

Possible. That is one of the potentially sexually transmissible diseases that may on occasion also come from other sources. So could very well be innocent. Read more...