Some fish blood flukes of the genus Cardicola (Aporocotylidae) are considered important pathogens of farmed/ranched tuna, Thunnus spp. Infections with Cardicola spp. might obstruct the blood flow in the gills via massive accumulations of eggs and often lead to mass mortalities in captive tuna. At present, oral administration of an anthelminthic drug, praziquantel is the most effective treatment, but the tuna farming industries are seeking non-drug control measures. Development of prophylactic and holistic measures have been difficult, owing to a lack of basic knowledge about these parasites. Unlike other trematodes which use molluscs, blood flukes of marine actinopterygian fish use terebellid polychaetes as intermediate hosts. However, information about the development of Cardicola spp. within intermediate hosts is very limited. Recent success in Cardicola opisthorchis sporocyst transplantation into the host polychaete has opened possibilities for the cultivation of Cardicola in the laboratory. Here, we conducted several transplantation trials with another tuna blood fluke, Cardicol orientalis, into its natural and surrogate polychaete hosts. Cardicola orientalis sporocysts were injected into a total of 195 Nicolea gracilibranchis, the natural host, and clear sporocyst development and reproduction was observed in 32 recipients (overall success rate 16.4%). The production of daughter sporocysts in the transplanted polychaete occurred within 14 days post injection, and one sporocystogenous cycle took approximately 4 weeks. Serial passage culture via transplantation of in vivo-cultured sporocysts was also achieved, but with limited sporocyst reproduction. In addition, sporocysts were successfully retrieved from six and one individuals of the surrogate hosts, Thelepus setosus (n = 10) and Thelepus japonicus (n = 5), respectively. These results indicate that the in vivo cultivation of C. orientalis sporocysts is possible, not only in its natural host but also in other terebellids, although the problems of high mortality and inconsistency in successful transplantation need to be resolved.

Cardicola属（Aporocotylidae）的一些鱼血吸虫被认为是养殖/牧场金枪鱼Thunnus spp 的重要病原体。感染心脏疾病属 卵的大量堆积可能会阻碍鳃中的血液流动，并经常导致圈养金枪鱼大量死亡。目前，口服驱虫药吡喹酮是最有效的治疗方法，但金枪鱼养殖业正在寻求非药物控制措施。由于缺乏对这些寄生虫的基本知识，制定预防性和整体性措施一直很困难。与其他使用软体动物的吸虫不同，海洋放线鳍鱼的血吸虫使用 terebellid 多毛类动物作为中间宿主。然而，关于Cardicola spp发展的信息。在中间宿主内是非常有限的。Cardicola opisthorchis最近的成功孢子囊移植到宿主多毛类动物为在实验室培养Cardicola开辟了可能性。在这里，我们使用另一种金枪鱼血吸虫 Cardicol orientalis对其天然和替代多毛类宿主进行了几次移植试验。将东方心虫孢子囊注射到自然寄主Nicolea gracilibranchis共 195只，在 32 名受者中观察到明显的孢子囊发育和繁殖（总成功率为 16.4%）。注射后 14 天内在移植的多毛类动物中产生子孢子囊，一个孢子囊生成周期大约需要 4 周。通过体内移植连续传代培养-也实现了培养的孢子囊，但孢子囊繁殖有限。此外，分别从6只和1只替代宿主Thelepus setosus ( n  = 10)和Thelepus japonicus ( n  = 5)中成功回收了孢子囊。这些结果表明，东方梭菌孢子囊的体内培养是可能的，不仅在其自然宿主中，而且在其他 terebellids 中也是可能的，尽管需要解决高死亡率和成功移植不一致的问题。