In Melachim Bet 5:10 we read:
וַיִּשְׁלַח אֵלָיו אֱלִישָׁע, מַלְאָךְ לֵאמֹר: הָלוֹךְ, וְרָחַצְתָּ שֶׁבַע-פְּעָמִים בַּיַּרְדֵּן, וְיָשֹׁב בְּשָׂרְךָ לְךָ וּטְהָר.
And Elisha sent a messenger unto [Naaman], saying: 'Go and wash in the Jordan seven times, and thy flesh shall come back to thee, and thou shalt be clean.'
I would like to understand the word וּטְהָר in this context. Does it simply mean clean, or is it related to tumah and taharah? If it is the latter how do we reconcile with the mishnayot (Negaim chapters 3, 11, 12 first mishna in each) which state that a non-jew is not susceptible to tumah of tzaras? If, on the other hand, it is not related to tumah, then the word seems superfluous. Please cite sources for your answer.