Trichomoniasis (TRIK-uh-muh-NEYE-uh-suhss) or "trich" is a s..exually transmitted infection (STI) caused by a parasite. The parasite is spread most often through v..aginal, o..ral, or a..nal s..e..x. It is one of the most common STIs in the United States and affects more women than men.
