Only italicize et al., meaning “and others,” if it is referred to as a term, as the examples in this sentence and the question above show. In parenthetical citations and works-cited-list entries, the abbreviation should be set roman, as shown in the MLA Handbook (116, 22):
(Burdick et al. 42)
Burdick, Anne, et al. Digital_Humanities. MIT P, 2012.
MLA Handbook. 8th ed., Modern Language Association of America, 2016.
Published 17 January 2019