For many years it has been considered that there are three basic developmental stages of Trypanosoma cruzi: Epimastigote (Epi), Amastigote (Ama) and Trypomastigote (Typo). Epi and Ama are able to divide while Trypo does not divide. Epi are not infective while Ama and Trypo are able to infect host cells. Here we review the available data for the epimastigote form. Taken together the data show that (a) there are intermediate forms between epimastigotes and trypomastigotes in axenic cultures as well as between amastigote and trypomastigote forms within the cells (both in vitro and in vivo), and (c) that the intermediate forms, here designated as “Transitional Epimastigote”, most of the time considered as epimastigotes, are able to infect cells. The recognition of the existence of this stage is of practical importance for those work with T. cruzi. Many laboratories working only with T. cruzi in axenic cultures usually consider to work with nonpathogenic cultures. This attitude needs to be changed requiring special care by those working with this protozoan to avoid accidental infections in the laboratory. In view of these observation a new scheme for the life cycle of T. cruzi is proposed.

多年来，人们一直认为克鲁斯锥虫有三个基本的发育阶段：Epimastigote（Epi），Amastigote（Ama）和Trypomastigote（Typo）。Epi和Ama可以分裂，而Trypo不分裂。Epi不会感染，而Ama和Trypo能够感染宿主细胞。在这里，我们回顾了淫后鞭炮形式的可用数据。数据汇总显示：（a）在轴突培养物中，表鞭鞭毛纲和锥鞭形纲之间存在中间形式，并且在细胞内（体外和体内）存在a形鞭突和锥形伪娘之间的中间形式。），以及（c）在大多数情况下，这种中间形式（在这里被称为“过渡性淫前鞭毛虫”）被认为能够感染细胞。对这一阶段的存在的认识对于那些使用克鲁氏梭菌进行的工作具有现实意义。许多实验室仅在T. cruzi的无性培养中工作，通常考虑与非致病性培养一起工作。需要改变这种态度，需要使用这种原生动物的人员进行特别护理，以避免在实验室中意外感染。鉴于这些观察，提出了一种新的克氏锥虫生命周期方案。