Search

The infection status of zoonotic trematode metacercariae was investigated in a total of 2,293 freshwater fish collected from 11 rivers or streams in 9 administrative regions of Gangwon-do, Korea for 5 years (2009-2013). All fish were collected by netting methods and examined using the artificial digestion methods. Clonorchis sinensis metacercariae were detected in 4 fish species, i.e., Pungtungia herzi, Squalidus japonicus coreanus, Acheilognathus rhombeus, and Ladislabia taczanowskii, from only Hantangang in Cheorwon-gun. Metagonimus spp. metacercariae were found in 1,154 (50.3%) fish and their average number per infected fish was 55.8. Among the positive fish species, especially Tribolodon hakonensis from Namdaecheon in Yangyang-gun and Plecoglossus altivelis from Osipcheon in Samcheok-si were most heavily infected. Centrocestus armatus metacercariae were detected in 611 (26.7%) fish and the average metacercarial burden per infected fish was 1,032. Two chub species, Zacco platypus and Zacco temminckii were highly and heavily infected with C. armatus metacercariae in almost all regions surveyed. Echinostoma spp. metacercariae were also found in 24 fish from a few localities, but their numbers per fish infected were very low. From the above results, it is confirmed that the metacercariae of intestinal flukes, especially Metagonimus spp. and C. armatus, were heavily infected, while C. sinensis metacercariae were rarely found in fish from Gangwon-do, Korea. [ABSTRACT FROM AUTHOR]

Anisakiasis, a human infection of Anisakis L3 larvae, is one of the common foodborne parasitic diseases in Korea. Studies on the identification of anisakid larvae have been performed in the country, but most of them have been focused on morphological identification of the larvae. In this study, we analyzed the molecular characteristics of 174 Anisakis type I larvae collected from 10 species of fish caught in 3 different sea areas in Korea. PCR-RFLP and sequence analyses of rDNA ITS and mtDNA cox1 revealed that the larvae showed interesting distribution patterns depending on fish species and geographical locations. Anisakis pegreffii was predominant in fish from the Yellow Sea and the South Sea. Meanwhile, both A. pegreffii and A. simplex sensu stricto (A. simplex s.str .) larvae were identified in fish from the East Sea, depending on fish species infected. These results suggested that A. pegreffii was primarily distributed in a diverse species of fish in 3 sea areas around Korea, but A. simplex s.str . was dominantly identified in Oncorhynchus spp. in the East Sea. [ABSTRACT FROM AUTHOR]

Background: The merozoite surface protein-3β of Plasmodium vivax (PvMSP-3β) is one of the candidate antigens for blood stage malaria vaccine development. The polymorphisms in PvMSP-3β have been reported in certain P. vivax isolates. However, the diversity of PvMSP-3β throughout its global distribution has not been well understood. In this study, the genetic diversity and the effects of natural selection in PvMSP-3β among P. vivax Korean isolates were analysed. Methods: Blood samples were collected from 95 patients with vivax malaria in Korea. The region flanking full-length PvMSP-3β was amplified by polymerase chain reaction and cloned into a TA cloning vector. The PvMSP-3β sequence of each isolate was determined and the polymorphic characteristics and effects of natural selection were analysed using the DNASTAR, MEGA4, and DnaSP programs. Results: Five different subtypes of PvMSP-3β were identified based on single nucleotide polymorphisms (SNPs), insertions, and deletions. Although a high level of sequence diversity was observed in the PvMSP-3β gene, the coiled-coil tertiary structure of the PvMSP-3β protein was well conserved in all of the sequences. The PvMSP-3β of Korean isolates is under natural selection. DNA polymerase slippage and intragenic recombination likely contributed to PvMSP-3β diversity in Korean P. vivax isolates. Conclusions: The PvMSP-3β of Korean P. vivax isolates displayed polymorphisms, with SNPs, insertions and deletions scattered throughout of the gene. These results of parasite heterogeneity are relevant to the development of a PvMSP-3β based vaccine against P. vivax and the implementation of malaria control programmes in Korea. [ABSTRACT FROM AUTHOR]

The source of human infection with intestinal flukes was surveyed in estuarine fishes, including the dotted gizzard shad, common sea bass, common blackish goby, redlip mullet, black sea bream, and oyster collected from Muangun, Jeollanam-do, Korea during August and September 2007. Collected fishes and oysters were artificially digested in pepsin-HCI solution and examined under a stereomicroscope. In 36 shads (Konosirus punctatus) and 20 basses (Lateolabrax japonicus) examined, Heterophyopsis continua metacercariae were found in 58.3% and 100%, and their average numbers were 12.0 and 6.3 per infected fish, respectively. In 34 gobies (Acanthogobius flavimanus) examined, metacercariae of H. continua were detected in 79.4%, Stictodora lari in 97.1%, and Acanthotrema felis in 92.1%, and their average numbers were 45.8, 189.3, and 235.3 per infected fish, respectively. In 37 redlip mullets (Chelon haematocheilus), Heterophyes nocens metacercariae were found in 56.8%, Pygidiopsis summa in 94.6%, and Stictodora fuscata in 45.9%, and the average metacercarial densities were 17.4, 31.3, and 35.1 per infected fish, respectively. In 30 black sea breams (Acanthopagrus schlegeh) and 45 oysters (Crassostrea gigas) examined, no metacercariae were detected. From the above results, it has been confirmed that the dotted gizzard shad, common sea bass, common blackish goby, and redlip mullet from Muan-gun, Jeollanam-do, Korea are infected with the metacercariae of heterophyid flukes. [ABSTRACT FROM AUTHOR]

Background: The carboxy-terminal 42 kDa region of Plasmodium vivax merozoite surface protein-1 (PvMSP-142) is a leading candidate antigen for blood stage vaccine development. However, this region has been observed to be highly polymorphic among filed isolates of P. vivax. Therefore it is important to analyse the existing diversity of this antigen in the field isolates of P. vivax. In this study, the genetic diversity and natural selection in PvMSP-142 among P. vivax Korean isolates were analysed. Methods: A total of 149 P. vivax-infected blood samples collected from patients in Korea were used. The region flanking PvMSP-142 was amplified by PCR, cloned into Escherichia coli, and then sequenced. The polymorphic characteristic and natural selection of PvMSP-142 were analysed using the DNASTAR, MEGA4 and DnaSP programs. Results: A total of 11 distinct haplotypes of PvMSP-142 with 40 amino acid changes, as compared to the reference Sal I sequence, were identified in the Korean P. vivax isolates. Most of the mutations were concentrated in the 33 kDa fragment (PvMSP-133), but a novel mutation was found in the 19 kDa fragment (PvMSP-119). PvMSP-142 of Korean isolates appeared to be under balancing selection. Recombination may also play a role in the resulting genetic diversity of PvMSP-142. Conclusions: PvMSP-142 of Korean P. vivax isolates displayed allelic polymorphisms caused by mutation, recombination and balancing selection. These results will be useful for understanding the nature of the P. vivax population in Korea and for development of a PvMSP-142 based vaccine against P. vivax. [ABSTRACT FROM AUTHOR]

A survey was performed to find out the intermediate hosts of Gnathostoma nipponicum in Jeju-do (Province), the Republic of Korea. In August 2009 and 2010, a total of 82 tadpoles, 23 black-spotted pond frogs (Rana nigromaculata), 7 tiger keelback snakes (Rhabdophis tigrinus tigrinus), 6 red-tongue viper snakes (Agkistrodon ussuriensis), and 2 cat snakes (Elaphe dione) were collected in Jeju-do and examined by the pepsin-HCl digestion method. Total 5 gnathostome larvae were detected in 3 (50%) of 6 A. ussuriensis, 70 larvae in 3 of 7 (42.9%) R. tigrinus tigrinus, and 2 larvae in 2 of 82 (8.7%) frogs. No gnathostome larvae were detected in tadpoles and cat snakes. The larvae detected were a single species, and 2.17x0.22 mm in average size. They had characteristic head bulbs, muscular esophagus, and 4 cervical sacs. Three rows of hooklets were arranged in the head bulbs, and the number of hooklets in each row was 29, 33, and 36 posteriorly. All these characters were consistent with the advanced third-stage larvae of G. nipponicum. It has been first confirmed in Jeju-do that R. nigromaculata, A. ussuriensis, and R. tigrinus tigrinus play a role for intermediate and/or paratenic hosts for G. nipponicum. [ABSTRACT FROM AUTHOR]

A large-scale survey was conducted to investigate the infection status of fresh water fishes with Clonorchis sinensis metacercariae (CsMc) in 3 wide regions, which were tentatively divided by latitudinal levels of the Korean peninsula. A total of 4,071 freshwater fishes were collected from 3 regions, i.e., northern (Gangwon-do: 1,543 fish), middle (Chungcheongbuk- do and Gyeongsangbuk-do: 1,167 fish), and southern areas (Jeollanam-do, Ulsan-si, and Gyeongsangnam-do: 1,361 fish). Each fish was examined by the artificial digestion method from 2003 to 2010. In northern areas, only 11 (0.7%) fish of 2 species, Pungtungia herzi and Squalidus japonicus coreanus from Hantan-gang, Cheolwon-gun, Gangwon- do were infected with av. 2.6 CsMc. In middle areas, 149 (12.8%) fish were infected with av. 164 CsMc. In southern areas, 538 (39.5%) fish were infected with av. 159 CsMc. In the analysis of endemicity in 3 regions with an index fish, P. herzi, 9 (6.2%) of 146 P. herzi from northern areas were infected with av. 2.8 CsMc. In middle areas, 34 (31.8%) of 107 P. herzi were infected with av. 215 CsMc, and in southern areas, 158 (92.9%) of 170 P. herzi were infected with av. 409 CsMc. From these results, it has been confirmed that the infection status of fish with CsMc is obviously different among the 3 latitudinal regions of the Korean peninsula with higher prevalence and burden in southern regions. [ABSTRACT FROM AUTHOR]

Adult gnathostomes were discovered in the stomach of the Jeju weasel, Mustela sibilica quelpartis, road-killed in Jeju-do (Province). Their morphological characters were examined to identify the species. Total 50 gnathostome adults were collected from 6 out of 10 weasels examined. In infected weasels, 4-6 worms were grouped and embedded in each granulomatous gastric tumor, except 1 weasel. Male worms were 25.0 x 1.4 mm in average size, and had a tail with pedunculate papillae, a spicule, and minute tegumental spines. Females were 40.0 x 2.5 mm in average size, and had a tail without tegumental spines. Pointed and posteriorly curved hooklets were arranged in 8-10 rows on the head bulb. Tegumental spines were distributed from behind the head bulb to the middle portion of the body. The spines were different in size and shape by the distribution level of the body surface. Fertilized eggs were 65.5 x 38.9 µm in average size, and had a mucoid plug at 1 pole. These gnathostomes from Jeju weasels were identified as Gnathostoma nipponicum Yamaguti, 1941. By the present study, it was confirmed for the first time that G. nipponicum is distributed in Jeju-do, the Republic of Korea, and the Jeju weasel, M. sibilica quelpartis, plays a crucial role for its definitive host. [ABSTRACT FROM AUTHOR]

The present study was performed to determine the current infecion status of Metagonimus yokogawai metacercariae in sweetfish, P/ecog/ossus attire/is, collected from several streams in eastern and southern coastal areas of Korea. The sweetfish collected were artificially digested with pepsin-HCI solution and examined under a stereomicroscope in August and September, 2007. Out of 145 sweetfish collected from 10 streams in eastern coasts (Gangwon-do and Gyeongsangbuk-do), 88 (60.7%) were infected with Metagonimus metacercariae. The average metacemarial density was 61 per infected fish. Among 141 sweetfish collected from 10 streams in southern coasts (Gyeongsangnam-do, Ulsan Metropolitan city, and Jecllanam-do), 140 (99.3%) were infected with Metagonimus metacercariae, and their average density was 949 per infected fish. The present study confirmed that M. yokogawai metacercariae are still prevalent in the sweetfish from several eastern and southern coastal localities. The prevalence and metacemarial density were much higher in the sweetfish from streams of southern coasts than in those of eastern coasts. Therefore, attention should be paid to this small fluke infection, and consumption of raw sweetfish naturally produced in these areas should be prohibited. [ABSTRACT FROM AUTHOR]

Fishborne trematode (FBT) metacercariae were investigated in yellowfin goby, Acanthogobius flavimanus, collected from Shinan-gun and Muan-gun, Jeollanam-do (province), Korea. All collected fishes were examined using the artificial digestion method. In all of 15 gobies from Aphae-myeon in Shinan-gun, metacercariae of Stictodora spp. (334 metacercariae/fish), Heterophyes nocens (153/fish), and Heterophyopsis continua (20/fish) were detected. In 2 of 14 gobies from Jido-myeon in Shinan-gun, 8 Echinostoma hortense metacercariae in total were detected. In 15 gobies from Haeje-myeon in Muan-gun, the metacercariae of H. continua were found in 100%, Stictodora spp. in 86.7%, and H. nocens in 6.7% of fish examined. The average numbers of metacercariae per infected fish were 23.3 (H. continua), 416.0 (Stictodora spp.), and 2.0 (H. nocens), respectively. The metacercariae of E. hortense found in gobies were elliptical, with 150 x 138 µm in average size, and had 27 collar spines on the head crown. The above results suggest that yellowfin gobies from 2 localities may be the potential infection sources of FBT. Moreover, it is proved for the first time that the yellowfin goby, A. flavimanus, acts as a second intermediate host for E. hortense. [ABSTRACT FROM AUTHOR]