Infection characteristics of <i>Diplostomum</i> species (Digenea: Diplostomidae) metacercariae in fishes from Korea

Infection characteristics of Diplostomum spp. metacercariae (DsMc) were analyzed in fishes from 9 major water systems of Korea. A total of 15,879 fishes in 79 species were examined by the artificial digestion method for 8 years (2013-2020). DsMc were detected in 48 (60.8%) out of 79 fish species examined. The prevalence was higher in Pseudogobio esocinus (61.5%), Squalidus chankaensis (56.9%) and Zacco platypus (44.8%). The infection intensities were 22.1, 9.4, 7.5 and 6.7 per fish infected in Hemibarbus longirostris, P. esocinus, Z. platypus, and S. chankaensis respectively. The higher prevalence was shown in fishes from Yeongsan-gang (59.3%) and the middle reaches of Seomjin-gang (48.0%), and the higher infection intensities were revealed in fishes from above 2 regions and streams in east coast (83.1, 7.5, and 11.3 per fish infected). In index fish, Z. platypus, overall prevalence was 44.8% and the higher prevalence were revealed in the middle reaches of Seomjin-gang (79.6%), Geum-gang (79.2%) and Tamjin-gang (64.7%). The susceptibility index in index fish was highest in fish from the streams in east coast (13.64), and followed by fish from the middle reaches of Seomjin-gang (7.56) and Mangyeong-gang (4.75). This study provides several novel characteristics of DsMc infection in fishes with a report of 30 new second intermediate host of Diplostomum spp. in Korea.