Prevalence and Density of Digenetic Trematode Metacercariae in Clams and Oysters from Western Coastal Regions of the Republic of Korea

Abstract

A survey was performed to know the recent infection status of digenetic trematode metacercariae in clams and oysters from 4 sites in western coastal regions of the Republic of Korea (=Korea). Four species of clams (Mactra veneriformis, Ruditapes philippinarum, Cyclina sinensis, and Saxidomus purpuratus) were collected from Taean-gun, Chungcheongnam-do (Province), Buan-gun (County) and Gochang-gun, Jeollabuk-do, and oysters, Crassostrea gigas, from Shinan-gun, Jeollanam-do were transferred to our laboratory on ice and examined by the artificial digestion method. The metacercariae of Himasthla alincia were detected in 3 species of clams, M. veneriformis, R. philippinarum, and C. sinensis from the 3 surveyed areas. The positive rate and the mean density per clam infected were 98.9% (30.8 metacercariae) in M. veneriformis, 60.0% (5.0) in R. philippinarum, and 96.0% (28.4) in C. sinensis. The positive rate (mean density) of Acanthoparyphium tyosenense metacercariae in M. veneriformis was 50.0% (2.1) from Taean-gun and 70.0% (2.8) from Gochang-gun. The metacercariae of Parvatrema spp. were detected in M. veneriformis and R. philippinarum from Taean-gun and Gochang-gun; the positive rate (mean density) was 63.3% (4,123) and 50.0% (19) in M. veneriformis, and 6.7% (126) and 100% (238) in R. philippinarum from the 2 regions, respectively. The metacercariae of Gymnophalloides seoi were detected in all 30 oysters from Shinan-gun, and their average density per oyster was 646. From the above results, it has been confirmed that more than 3 species of metacercariae are prevalent in clams from the western coastal regions, and G. seoi metacercariae are still prevalent in oysters from Shinan-gun, Jeollanam-do, Korea

Survey of Gymnophalloides seoi Metacercariae in Natural and Cultured Oysters from Several Western Coastal Areas, Korea

“…In previous studies, it was suggested that the geographical distribution of G. seoi metacercariae might be wider than expected, and the metacercarial prevalence might be high in some localities [7,[10][11][12]. However, based on the present results, the prevalence and intensity of G. seoi metacercariae seem to be decreasing in oysters from western coastal areas, including Aphae Island.…”

“…Epidemiological investigations have reported that human G. seoi infection is widespread along the western and southern coastal areas of Korea, including islands [2,[6][7][8][9]. It is also known that natural oysters produced from various localities of western and southern coastal areas are infected with the metacercariae [10][11][12][13]. However, the status of G. seoi metacercarial infection in cultured oysters has seldom been the subject of study.…”

Infections with Digenetic Trematode Metacercariae in Freshwater Fishes from Two Visiting Sites of Migratory Birds in Gyeongsangnam-do, Republic of Korea

“…Fish species (No. of fish) examined were Pseudorasbora parva (40), L. macrochirus (28), C. auratus (20), E. erythropterus (16), M. salmoides (15), H. eigenmanni (6), C. carpio (2).…”

“…On the other hand, many Korean workers have been investigated the infection status with digenetic trematode metacercariae (DTM) including Clonorchis sinensis in fishes from various ecological environments, such as river, stream, lake, pond, swamp and even coast, to estimate the DTM endemicities [18][19][20][21][23][24][25][26][27][28][29]. Most of these studies were performed on the specific trematode species related with human infections, such as C. sinensis, heterophyid including Metagonimus yokogawai and echinostomatid flukes, in Korea [23][24][25][26][27][28][29]. However, there have been not so many studies on the avian trematode metacercariae (ATM) in fishes from the visiting sites of migratory birds in Korea.…”

Morphological and Molecular Confirmation of Parvatrema duboisi Metacercariae in the Manila Clam Ruditapes philippinarum from Gochang-gun, Korea

“…Their differential points from our specimens were as follows. P. borinqueñae is characterized by its small egg size (12)(13)(14)(15)(16)(17)(18)(19) μm long) and the presence of gland cells around the oral sucker [4]. P. bushi has a small delicate body with fewer body spines, smaller lateral papillae, smaller pharynx, and shallower genital atrium [4].…”