Pygidiopsis summa (Digenea: Heterophyidae): Status of Metacercarial Infection in Mullets from Coastal Areas in the Republic of Korea

Abstract

To know the infection status of zoonotic trematode metacercariae in brackish water fish, we surveyed mullets collected from 18 coastal areas in the Republic of Korea. The metacercariae of Pygidiopsis summa were detected in 236 (68.2%) out of 346 mullets examined. They were found in mullets from 15 areas except for those from Boseong-gun (Jeollanam-do), Pohang-si, and Uljin-gun (Gyeongsangbuk-do). Especially in mullets from Taean-gun (Chungcheongnam-do) and Geoje-si (Gyeongsangnam-do), their prevalences were 100% and 95.5%, and the average metacercarial density was more than 1,000 per fish. They were also detected in mullets from 3 coastal lakes, Gyeongpoho, Songjiho, and Hwajinpoho, in Gangwon-do, and their average densities were 419, 147, and 672 per infected fish, respectively. The metacercariae of 5 other heterophyid species, including Heterophyes nocens, Heterophyopsis continua, Metagonimus sp., Stictodora fuscata, and Stictodora lari, were found in the mullets examined. The metacercariae of H. nocens were detected in 66.7, 100, 28.6, 81.6, 3.9, 61.5, and 27.3% of mullets from Muan-gun, Shinan-gun, Haenam-gun, Gangjin-gun, and Boseong-gun (Jeollanam-do), Hadong-gun, and Geoje-si (Gyeongsangnam-do), and their metacercarial intensities were 64, 84, 119, 99, 1, 24, and 24 per fish infected, respectively. From the above results, it has been confirmed that P. summa metacercariae are heavily infected in mullets from coastal areas of Korea. It is suggested that residents who frequently consume raw mullet dish can be easily infected with heterophyid flukes.

Infection Status with Digenetic Trematode Metacercariae in Fishes from Coastal Lakes in Gangwon-do, Republic of Korea

“…Guk et al [28] found total 8 PsMc in only one mullet from Donghae-si, Gangwon-do, and they could not detect PsMc at all in mullet from Yeongdeok-gun, Gyeongsangbuk-do, and Sokcho-si, Gangwon-do. In Sohn et al [29], PsMc were detected in 38 (63.3%) out of 60 mullet from 5 eastern coastal sites, i.e., Ulsan Metropolitan City, Yeongdeokgun, Gyeongsangbuk-do, and Gangneung-si, 2 sites in Goseong-gun, Gangwon-do, but they were not found in 29 mullet from Pohang-si and Uljin-gun, Gyeongsangbuk-do. However, in the present study, P. summa metacercariae (PsMc) were found in 48 (84.2%) out of 57 mullets examined, and their density was 316 per fish infected.…”

“…They reported 87.0%, 54.1%, and 4.0% PsMc prevalences and 177, 47, and 8 PsMc densities in mullet from coastal areas of Yellow Sea, South Sea and East Sea respectively. Recently, Sohn et al [29] also reported 93.8%, 69.3%, and 42.7% PsMc prevalences, and 496, 369, and 291 PsMc densities in mullets from the coastal areas of upper 3 Seas respectively. From the 2 studies aforementioned, we can know that the endemicity of PsMc in mullet from eastern coastal areas is much lower than those in mullet from southern and western coastal areas of Korea.…”

“…However, only 2 species, P. summa and Stictodora sp., of metacercariae were found. Moreover, P. summa metacercariae were detected in only 2 species of mullet, M. cephalus and C. haematocheilus, but not in yellowfin goby, A. flavimanus, which was already known as the second intermediate host of this heterophyid fluke [25][26][27][28][29]. [34].…”

Infections with Zoonotic Trematode Metacercariae in Yellowfin Goby, Acanthogobius flavimanus, from Coastal Areas of Republic of Korea

“…Recently, Cho et al [ 26 ] surveyed the infection status of trematode metacercariae in estuarine fishes including yellowfin goby from Muan-gun, Jeollanam-do. Sohn et al [ 27 ] investigated the infection status of P. summa metacercariae in mullets from coastal areas of Korea. However, most of studies were performed in limited areas and the number of fish was not enough to evaluate the metacercarial endemicity in each surveyed area.…”