trichomoniasis is a living parasite that requires a host (human). it will not survive in vaseline or other lubricant. re-infection may be from the same original source (another human / sexual partner) who has not be treated or the reinfection may represent a failed treatment so you will need to be treated again.
can trichomoniasis live outside of the body for example (in vasiline used as lubricant? ) i ask because of reinfection.