Commentary for Berakhot 42:17

עד כאן לא פטר רבי יהודה אלא בזב שראה קרי דמעיקרא לאו בר טבילה הוא אבל בעל קרי גרידא מחייב

Only in the case of a roan with a running issue who has experienced emission does R. Judah grant exemption, because he was not originally under the obligation to bathe ; but [it may be argued] a man who is merely a Ba'al Keri he does compel [to have immersion].

Abraham Cohen Footnotes to the English Translation of Masechet Berakhot