Hematodinium infections in cultured Chinese swimming crab, Portunus trituberculatus, in northern China
2013
Li, Caiwen | Song, Shuqun | Liu, Yun | Chen, Tiantian
Since 2004, the parasitic dinoflagellates Hematodinium emerged as causative agent of the “milky blood disease” in cultured Portunus trituberculatus, Scylla serrata and Exopalaemon carinicauda along the coastal areas of southern China; while, no Hematodinium infections had been reported in northern China. We sampled P. trituberculatus in polyculture ponds and adjacent coastal waters from two sites in Shandong Peninsula, the major culture region in northern China which contributes to one third of the national gross outcome of the crab species. Hematodinium infections were identified in 10% of P. trituberculatus randomly sampled from polyculture ponds, while no infections were observed in wild crabs collected from adjacent coastal waters. Filamentous trophonts and amoeboid trophonts were observed in diseased crabs. The Hematodinium sp. shares similar morphologic features and causes typical pathological changes in hepatopancreas, heart, and muscles of infected hosts as other Hematodinium spp. The laboratory trials indicated that this parasite was infectious and caused pathological alterations to crab hosts as those diseased crabs from culture ponds. Molecular analysis indicated that the isolates were closely related to those reported in southern China. Our findings indicate an alarming broad distribution of the infectious pathogen along the coastal areas of China. The polyculture pond system widely used in major culture regions in China may prompt transmission or spread of Hematodinium among susceptible hosts, which urges pressing investigation of its major routes of transmission in such culture system along with better understanding of its life cycle.
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