A very common STD also referred to as Trichomonas or Tric. It is caused by a small one-celled organism that is a parasite. This parasite can be passed through sexual contact and by sharing damp bathing suits, towels, or washcloths, where it survives for a few hours.  Trichomonas causes vaginitis, a condition that produces inflammation of the vagina. Symptoms include a heavy discharge from vagina, itching, pain when urinating or having sex.