Besides intercourse, how can you get trichonomas vaginitis?

That's the only way: You can only get trichomonas vaginalis by having intercourse with some one who is carrying it.Thats the reason both partners have to be treated to prevent recurrence.

Clean all toys: Besides intercourse, trichomoniasis can be transmitted via sex toys. It is very important to clean any toy with the proper antiseptic or at least warm soapy water.