because they don't routinely test men for trichomonas. men tend to pee it out. it can be seen (sometimes) but it is often missed in routine urine tests in women and men. women on the other hand can have trich happily colonized in their vagina or urinary tract for long periods of time. it may have been missed in august. i suspect that both you and your partner have had previous partners so let it go. get it treated and be monogamous from now on and you will both be fine.
i was tested for all std's in august and was cleared. my partner tested positive for trichomoniais. how?