This is not very likely. Most STIs are only transmitted during sexual contact, either by skin-to-skin contact or through bodily fluids exchanged between partners. Garapata, or pubic lice, may be transmitted through sexual contact, sleeping in infected bedding, sharing infected clothing and possibly through sitting on an infested toilet seat. However, lice cannot survive away from the human body for longer than 24 hours. So contracting pubic lice from a toilet seat is possible, but it's unlikely.