Or the avoidance of pork- it’s distressingly easy to pick up parasites from consuming pork.

Only if you feed the pigs carrion and under cook it. There was a big trichinosis issue in the mid-20th century, which is when some people speculated on its connection to religious pork taboos, but nobody really takes that idea seriously any more.

You act like that is the only possible infectious agent. In addition to Trichinosis, Taenia solium and Toxoplasma gondii are also spread in undercooked pork- and those are modern health concerns. The animal eats almost anything and is capable of spreading more diseases than worms. It is no wonder it would be considered ‘unclean’ given the rudimentary cleansing rituals of the Old Testament Jews.