The parallel structure of this verse is common in Hebrew. The words make yourselves abominable are parallel to defile yourselves. And the pronoun them in the second part corresponds to any swarming thing that swarms in the first. If the repetition of the same idea using two different sets of words is unnatural in the receptor language, then it will be acceptable to translate the meaning once. Good News Translation makes explicit that the uncleanness comes to a person as a result of eating these unclean animals.

Quoted with permission from Péter-Contesse, René and Ellington, John. A Handbook on Leviticus. (UBS Helps for Translators). New York: UBS, 1990. For this and other handbooks for translators see here .