The disease vector is more modern speculation/post-hoc rationalization for the rules. It's not really anywhere in the text itself aside from references to the a

The disease vector is more modern speculation/post-hoc rationalization for the rules. It's not really anywhere in the text itself aside from references to the animals being 'unclean.' It's likely that a variety of factors went into the rules, not least of which were probably just wanting to maintain some social and cultural separation from the communities around them.