The Literal Commandment
For I am the LORD your God. Consecrate yourselves therefore, and be holy, for I am holy. And you shall not make yourselves unclean with any of the swarming things that swarm on the earth. (Leviticus 11:44)
The literal commandment is that we are not to make ourselves unclean with any of the swarming things [vermin] that swarm on the earth.