• Parasites, Hosts and Diseases
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• v.46 no.4
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• pp.247-251
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• 2008

This study investigated freshwater fish for their current infection status with metacercariae of Clonorchis sinensis in Korea. Twenty-one species of freshwater fish (n = 677) were collected from 34 regions nationwidely from February 2007 to June 2008. They were individually examined by digestion technique. Eight species of freshwater fish from 17 different regions were recognized positive for the metacercariae of C. sinensis. The positive rates (range of metacercariae number per fish) of fish by the species were as follows: 48% (1-1,142) in Pseudorasbora parva, 60% (1-412) in Pungtungia herzi, 15.7% (1-23) in Pseudogobio esocinus, 29% (1-7) in Acheilognathus intermedia, 21% (1-4) in Odontobutis interrupta, 33% (1-6) in Zacco temmincki, 3.6% (1-4) in Zacco platypus, and 26.3% (1) in Hemibarbus labeo. The two species, P. parva and P. herzi, are able to be the index fish for estimation of C. sinensis transmission in a certain locality. Still several species of freshwater fish are briskly transmitting C. sinensis infection in many riverside areas of southern Korea.

• Proceedings of the Microbiological Society of Korea Conference
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• 1999.04a
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• pp.45.1-45.1
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• 1999

• Parasites, Hosts and Diseases
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• v.37 no.1
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• pp.27-32
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• 1999

A total of 542 children under 10 years of age, admitted to the Seoul National University Children's Hospital, was examined for antibody titers of Toxoplasma gondii using indirect latex agglutination (ILA) test. Among them, 7.7% showed positive titers higher than 1:32, without significant difference between males (7.3%) and females (8.5%). The seropositive rate increased with age although the statistical significance was negligible (0.05

• Parasites, Hosts and Diseases
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• v.46 no.4
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• pp.289-291
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• 2008

The Tamjin River which flows from Jangheung-gun via Gangjin-gun to the South Sea was reported to be a highly endemic area of Metagonimus yokogawai infection in 1977 and 1985. However, there were no recent studies demonstrating how much change occurred in the endemicity, in terms of prevalence and worm burden, of metagonimiasis in this river basin. Thus, a small-scale epidemiological survey was carried out on some residents along the Tamjin River basin in order to determine the current status of M. yokogawai infection. A total of 48 fecal samples were collected and examined by the Kato-Katz thick smear and formalin-ether sedimentation techniques. The egg positive rate of all helminths was 50.0%, and that of M. yokogawai was 37.5%, followed by C. sinensis 22.9% and G. seoi 4.2%. To obtain the adult flukes of M. yokogawai, 6 egg positive cases were treated with praziquantel 10 mg/kg in a single dose and purged with magnesium sulfate. A total of 5,225 adult flukes (average 871 specimens per person) of M. yokogawai were collected from their diarrheic stools. Compared with the data reported in 1977 and 1985, the individual worm burdens appeared to have decreased remarkably, although the prevalence did not decrease at all. It is suggested that the endemicity of M. yokogawai infection along the Tamjin River has been reduced. To confirm this suggestion, the status of infection in snail and fish intermediate hosts should be investigated.

• Parasites, Hosts and Diseases
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• v.42 no.1
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• pp.19-26
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• 2004

We investigated the induction of resistance to Clonorchis sinensis infection by prior infection in rat and hamster models. Animals were challenged with C. sinensis metacercariae, then treated with praziquantel and reinfected. Worm recovery rate in reinfected animals was used to estimate resistance to reinfection. The determined resistance rates to reinfection in rats and hamsters were 97.7% and 10.3%, respectively. In rats, cure from the primary infection of C. sinensis increased resistant to reinfection, and the greatert the worm burden and the longer the duration of primary infection, the higher was the resistance rate. For primary infection doses of 10, 40 and 100 metacercariae per rat, the resistance rates were 87.4%, 93.8% and 98.4%, respectively. The resistance rates in rats after 2 or 8-week primary infection were 78.7% and 95.3%, respectively. All worms recovered from reinfected rats were immature. When cured rats were administered with methylprednisolone, resistance to reinfection became impaired. These findings indicate that rats develop a high degree of resistance to reinfection by C. sinensis after cure. The growths and maturations of reinfected worms were also impaired.

• The Journal of the Korean Society for Microbiology
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• v.34 no.5
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• pp.491-500
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• 1999

A recent study showed that comparative sequence analysis of rpoB DNAs could reveal natural relationships in genus Mycobacterium [J Clin Microbial. 37 (6). 1999]. rpoB DNAs showed interspecies variation and intraspecies conservation. Based on these data, we developed polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) protocols which enable species differentiation in genus Mycobacterium. When this assay was applied to 24 clinical isolates identified as M. avium complex (MAC) by biochemical test, these were successfully differentiated into M. avium and M. intracellulare. These results were concordant with those obtained by 16s rDNA analysis. It is the first report that PCR-SSCP analysis of rpoB DNA could be used for species differentiation of MAC strains.

• Parasites, Hosts and Diseases
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• v.44 no.1 s.137
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• pp.1-5
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• 2006

One coastal village in Haenam-gun and two in Yeongam-gun, Jeollanam-do were surveyed for intestinal parasite infections by fecal examination. The egg positive rates of Gymnophalloides seoi were high, $24.1\%$ (14/58) in Haenam-gun and $9.3\%$ (11/118) in Yeongam-gun. The egg positive rates of heterophyids, including Heterophyes nocens, and of Clonorchis sinensis were $10.3\%\;and\;6.9\%$ in Haenam-gun, and $14.4\%\;and\;8.5\%$ in Yeongam-gun, respectively. After praziquantel treatment and purgation, a total of 37,761 fluke specimens were recovered from 17 patients; 11 in Haenam-gun and 6 in Yeongam-gun. Gymnophalloides seoi was the most commonly recovered species, with 37,489 specimens in total (2,205 per person). Other recovered flukes included Heterophyes nocens, Stictodora fuscata, Heterophyopsis continua, Pygidiopsis sUmma, and undetermined species. These results indicate that the areas surveyed are new endemic foci of G. seoi.

• Parasites, Hosts and Diseases
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• v.45 no.1 s.141
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• pp.33-38
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• 2007

To know the prevalence of heterophyid trematodes among inhabitants of a southern coastal village, i.e., Sacho-ri, Gangjin-gun, Jeollanam-do(Province), 82 stool samples were examined on helminth eggs and protozoan cysts using Kato-Katz and formalin-ether sedimentation techniques. Total 33 people(40.2%) were positive for trematodes(Heterophyes nocens; 15 people, Pygidiopsis summa; 3, Metagonimus sp.; 4, Clonorchis sinensis; 7, Gymnophalloides seoi; 6) and/or protozoa(Entamoeba coli; 3). Among intestinal trematode egg positive cases, 17 were treated with praziquantel and their whole diarrheic stools were collected after purgation. Adult flukes of H. nocens(number of specimens=1,294), P. summa(386), Stellantchasmus falcatus(5), Stictodora lari(4), and Heterophyopsis continua(1) were collected using a stereomicroscope. To know the source of human H. nocens infections in this village, metacercarial infections in mullets(10) were examined and most H. nocens metacercariae(101/105, 96.2%) were found in the trunk portion. From above results, the surveyed coastal village has been newly known as an endemic focus of human H. nocens infection and consuming raw mullets was the presumable source of human heterophyid infections.

• Parasites, Hosts and Diseases
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• v.40 no.3
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• pp.157-162
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• 2002

Plasmodium vivax malaria re-emerged in South Korea in 1993, and epidemics continue since then. We examined genetic variation in the region encompassing the apical membrane antigen-1 (PvAMA-1) of the parasites by DNA sequencing of the 22 re-emerging p. vivax isolates. The genotype of the PvAMA-1, which was based on sequence data previously reported for the polymorphic regions, showed that two haplotypes were present at one polymorphic site. Compared with reported data, the two types, SKOR type I and type II, were similar to Chinese CH- l0A and CH-05A isolates, respectively. Thus, the present study showed that two genotypes of AMA-1 genes coexist in the re-emerging Korean P. vivax.

• Parasites, Hosts and Diseases
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• v.38 no.2
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• pp.95-97
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• 2000

A 17 kDa protein from Clonorchis sinensis adults was purified by a procedure including Sephacryl S-200 HR gel filtration and Q-Sepharose anion exchange chromatography. The protein was proved to be a cysteine protease as it showed hydrolytic activity toward Cbz-Phe-Arg-AMC in the presence of dithiothreitol and was inhibited by specific inhibitors such as iodoacetic acid or trans epoxy-succinly-L-leucyl-amido(4 guanidino) butane. The polyclonal antibody raised against the protein reacted to 17 kDa proteins of trematodes such as Paragonimuf westermani, Fasciola hepatica, Opisthorchis viverrini, Gymnophalloides seoi, and Metagonimus yokogawai. The antibody recognized the 17 kDa and 16 kDa cysteine proteases purified from C. sinensis, P. westemani, and G. seoi as well. These results suggest that the 17 kDa protein may be a cysteine protease commonly present in trematodes.