Makattack, do you feel that there is a historical record showing the use of this term in an anti-Semitic context for centuries? Yes or no?
Historical use as it applies to a libel against Jews, yes.
Exclusive historical use for the lies against Jews, no.
Your argument seems to be it only applies to Jews. (And then you walked it back to "generally.") It has had a use beyond simply applying to lies against a Jewish minority for some time, enough so that multiple sources will explicitly include blood libels against Christians, druids, neo-pagans, Roman Catholics, Protestants, etc...