To protect yourself from trich abstain, be faithful to 1 partner you have tested with, or use condoms EVERY time you have sex. Trich parasites live in the urinary and genital tracts (tubes) of infected men and women, meaning that they are in sexual fluids and urine. Condoms are made of solid rubber-semen and vaginal discharge cannot pass through so condoms give VERY good protection from trich and other Sexually Transmitted Infections (STIs), including HIV/AIDS. Condoms only work if used correctly. Trich parasites can live outside the body for 45minutes so very rarely you can become infected by sharing soiled towels/clothes/baths.
Attribution: Straight Talk Foundation & Marie Stopes