It can transmit STIs, but that depends on the health of the producer. But that covers more “is it sterile” than “is it hygienic”. It has a bunch of things that are great for sperm that are also great for many microorganisms if it’s left around. So: clean in up and dispose of it. It will quickly become a medium for all sorts of things to grow. Do not keep it in a jar with Rainbow Dash on a radiator.