There had been seven extensive epidemics in the world since 1817. Cholera enterotoxin (CT) composed of one A subunit (CTA) and five B subunits (CTB) is an major causative agent of vibrio cholerae.

• 自1817年以来，已发生过7次世界大流行。 霍乱肠毒素(Cholera enterotoxin，CT)是引起霍乱的主要致病因子，由一个A亚单位(CTA)和5个相同的B亚单位(CTB)组成。