pustules; a sign of venereal disease
See an image that represents nanahuatl in the Visual Lexicon of Aztec Hieroglyphs, ed. Stephanie Wood (Eugene, Ore.: Wired Humanities, 2020-present).
"the Indian disease which the natives call nanahuatl (which infected the entire globe)" ("a venereal disease") (Central Mexico, 1571–1615)
a sick and pustulous person, Nanāhuatzin, they give this name to the man converted into the sun (Atenango, between Mexico City and Acapulco, 1629)