传染免疫由以前同一病原体所引起的慢性低度传染而造成的特定病原体对严重感染的相对免疫 Relative immunity to severe infection by a particular pathogen as a result of a chronic low-grade infection induced earlier by the same pathogen.
初疮病原体最初侵入的那点处的溃疡 An ulcer located at the initial point of entry of a pathogen.
