Larval trematodes from Semisulcospira snails in Kyungpook Province, Korea

Abstract

In an attempt to determine the incidence of the cercarial larvae of trematodes, Semisulcospira snails collected in Judong stream, an endemic area of Paragonimus westermani, in Kyungpook Province, Korea, were examined from 1965 to 1980. The infestation rate for cercariae in the snails was 5.4 per cent, but in 1970 dropped to 4.0 per cent and remained at the same level, 4.2 per cent, in 1975. It then decreased to 3.5 per cent in 1980. Seven species of cercariae, Cercaria incerta(Kobayashi, 1992) Faust, 1924, Cercaria nipponensis(Ando, 1915) Faust, 1924, Cercaria yoshidae(Osafune, 1898) Cort et Nichols, 1920, Centrocestus armatus(Tanabe, 1922) Yamaguti, 1934, Metagonimus species, Notocotylus magniovatus Yamaguti, 1934, and Paragonimus westermani(Kerbert, 1878), and five kinds of undeterminced cercariae were found. Of these, the most freqently emerged cercaria was Metagonimus species, folllowed by Notocotylus magniovatus. The least freqently emerged was Paragonimus westermani, with the rate of 0.04 per cent. The liberation rates in the five kinds of undetermined species varied from 0.04 to 0.15 per cent. In the monthly liberaton rates for cercariae, the highest rate was encountered in May, and decreased in the period from June to November. It then somewhat increased again in December. There was no correlation in the liberation rate for cercariae and length of snails. The results of this study indicate that the infestation of Semisulcospira snails with the cercariae of trematodes has decreased over the fifteen year period from 1965 to 1980.

Infections with Centrocestus armatus Metacercariae in Fishes from Water Systems of Major Rivers in Republic of Korea

“…In Korea, 3 species of Centrocestus fluke, i.e., C. armatus , C. asadai and C. formosanus , were reported in the literatures [ 2 , 4 , 6 , 22 , 23 ]. Choi et al [ 22 ] described C. asadai adults, which were recovered in the small intestines of mouse experimentally infected with the metacercariae from Tribolodon taczanowskii .…”

“…They found these cercariae from Semisulcospira libertina snails collected around the Jinyang-ho (ho means lake) in Gyeongsangnam-do, Korea. In regard to C. armatus , a lot of findings on the intermediate and definitive hosts were revealed by many Korean workers [ 2 , 4 , 6 – 17 ]. Adult worms were recovered from a human, the large egret ( Egretta alba modesta ) and stray cats ( Felis catus ) naturally infected [ 2 , 14 – 17 ].…”

“…Adult worms were recovered from a human, the large egret ( Egretta alba modesta ) and stray cats ( Felis catus ) naturally infected [ 2 , 14 – 17 ]. Cercariae of this fluke were detected from Semisulcospira snails collected in Judongcheon in Dalseong-gun, Gyeongsangbuk-do [ 4 ]. Metacercarial infections were verified in the surveys of freshwater fish including Z. platypus and Z. temminckii [ 5 – 13 ].…”

“…Human infections were experimentally proven in Japan, and a natural human case was reported in the Republic of Korea (Korea) [ 1 , 2 ]. The freshwater snails, Semisulcospira spp., are known to be the first intermediate hosts in Japan and Korea [ 3 , 4 ]. Various species of freshwater fish, including Zacco platypus and Z. temminckii , were reported as the second intermediate hosts in Japan and Korea [ 5 – 13 ].…”

Identification of Trematode Cercariae Carrying Neorickettsia risticii in Freshwater Stream Snails

“…But, little data can be found on the ecology of Semisulcospira snails and infestation of the snails with the cercariae of digenial trematodes. Choi17 reported, in snails, seven species of known cercaria ( Cercaria incerta , Cercaria nipponensis , Cercaria yoshidae , Centrocestus armatus , Metagonimus species, Notocotylus magniovatus , and Paragonimus westermani ) and four kinds of undetermined cercariae. The life cycles of Cercaria incerta , Cercaria nipponensis , Cercaria yoshidae , and Notocotylus magniovatus are undetermined.…”