Distribution and Detection of Severe Fever with Thrombocytopenia Syndrome Virus in Ticks Collected from Jeollanam-do, Korea

Severe fever with thrombocytopenia syndrome (SFTS) is firstly reported in China in 2011. Thereafter it is reported an infectious disease in Japan and Korea. It is caused by bunyavirus, called SFTS virus (SFTSV). The main vector of SFTS is Haemaphysalis longicornis tick. We investigated the distribution and detection of SFTSV in ticks collected from the environment using the dragging method and dry ice fogging method from May to November 2014 in Jeollanam-do, Korea. Sampling was taken from the province Suncheon, Gokseong, Boseong, Goheung where patients have occurred in 2013 and Gurye as control. Among the total 3,048 ticks collected, 3,030 ticks were H. longicornis (99.4%) and 18 were Amblyomma testudinarium. H. longicornis was collected 1,330 ticks in Gokseong, 1,188 ticks in Boseong, 240 ticks in Suncheon, 150 ticks in Goheung and 140 ticks in Gurye. Developmental stages by month of H. longicornis were revealed that nymph (92%) was collected from May to June, adult (30%) and nymph (70%) in July, and 93% of larvae from September to October. These results showed the different dominant stage of ticks according to seasons. However, no SFTSV-specific gene was detected in 3,030 ticks of H. longicornis.

Larval Chigger Mites Collected from Small Mammals in 3 Provinces, Korea

A total of 9,281 larval chigger mites were collected from small mammals captured at Hwaseong-gun, Gyeonggi-do (Province) (2,754 mites from 30 small mammals), Asan city, Chungcheongnam-do (3,358 mites from 48 mammals), and Jangseong-gun, Jeollanam-do (3,169 for 62 mammals) from April-November 2009 in the Republic of Korea (= Korea) and were identified to species. Leptotrombidium pallidum was the predominant species in Hwaseong (95.8%) and Asan (61.2%), while Leptotrombidium scutellare was the predominant species collected from Jangseong (80.1%). Overall, larval chigger mite indices decreased from April (27.3) to June (4.9), then increased in September (95.2) and to a high level in November (169.3). These data suggest that L. pallidum and L. scutellare are the primary vectors of scrub typhus throughout their range in Korea. While other species of larval chigger mites were also collected with some implications in the transmission of Orientia tsutsugamushi, they only accounted for 11.2% of all larval chigger mites collected from small mammals.

Intestinal Helminthic Infections in Striped Field Mice, Apodemus agrarius, from Two Southern Regions of Korea

The present study was performed to know the infection status of intestinal helminths in a most common species of field mice, Apodemus agrarius, from 2 southern regions of Korea. Total 133 and 103 mice were collected by the mouse trap in Hapcheon-gun, Gyeongsangnam-do and Gurye-gun, Jeollanam-do, respectively, from July 2005 to June 2006. The small intestine of each mouse was resected and longitudinally opened with a pair of scissors. The intestinal contents were washed with 0.85% saline until the supernatant became clear. Helminths were collected with naked eyes or under a stereomicroscope from the sediment of the intestinal content. More than 11 species of helminths (4 nematode spp., 5 trematode spp., and 2 cestode spp.) were recovered. Among these, heligmosomoid nematodes (97.5%) was the most highly and heavily infected species. As the members of trematodes, Plagiorchis muris, Brachylaima sp., Echinostoma hortense, Echinostoma cinetorchis, and unidentified echinostome larvae were found in the small intestines of 35 (14.8%), 12 (5.1%), 6 (2.5%), 1 (0.4%), and 1 (0.4%) mice respectively. Two species of tapeworms, Hymenolepis nana and Hymenolepis diminuta were also detected in 79 (33.5%) and 21 (8.9%) mice, respectively. Conclusively, heligmosomoid nematodes were the most prevalent (dominant) species among more than 11 helminth species detected, and Brachylaima sp. fluke is newly added in the list of intestinal trematodes in Korea.

Prevalence and Antimicrobial Susceptibility of Campylobacter coli Isolates from Swine

Swine is a common source of Campylobacter coli human gastroenteritis, for the treatment of which erythromycin and fluoroquinolones are recommended. The prevalence of antimicrobial-resistant C. coli differs significantly depending on countries. We investigated the prevalence of C. coli in swine from a farm in Buan-gun, Korea in 2010, and determined antimicrobial susceptibility of the isolates. Rectal swab specimens were used to inoculate Campylobacter Preston media and incubated microaerophilically at 42degrees C for 48 h. The species were identified by phenotypic tests and by detecting hipO and glyA genes. PCR was used to detect mutations of A2074C in 23S rRNA gene, and quinolone resistance-determining region (QRDR) of gyrA, which are associated with high level resistance to erythromycin, and with ciprofloxacin, respectively. Antimicrobial susceptibility was determined by the disk diffusion and agar dilution tests. Of the 100 specimens, 55 (55%) yielded C. coli, and 23 of them (41.8%) had A2074G mutation. A2074G mutated isolates showed the lowest MIC90 of imipenem, while those of ampicillin and clindamycin were relatively low. The majority of both A2074G mutation-positive and -negative isolate were susceptible to ampicillin, cefotaxime, and chloramphenicol. All isolates were resistant to ciprofloxacin, and had mutation in QRDR of gyrA. In conclusion, C. coli was detected in 55% of swine, and A2074G mutation was detected in 41.8% of the isolates. All isolates had gyrA mutation-mediated ciprofloxacin resistance.

Molecular Epidemiological Characteristics of Vibrio parahaemolyticus Isolated from Diarrheal Patients in Jeonnam, Korea

To investigate the occurrence and distribution of serotype, specific virulence genes, and pulse field gel electrophoresis (PFGE) patterns in Vibrio parahaemolyticus isolates from Jeonnam, Korea, we tested 87 strains which were identified with V. parahaemolyticus from diarrheal episode patients in 2005. In this study, 16 different O:K serotype combinations of V. parahaemolyticus were determined. The distributions of O and K serotypes were O4:K68 (51.72%), O1:K70 (18.39%), O3:K6 (5.74%), O1:K68 (4.60%) and O3:K57 (4.60%) respectively. Serotype O4:K68 was the regional dominant specific serotype of V. parahaemolyticus in Sinan of Jeonnam, Korea. For the detection of thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh) gene of V. parahaemolyticus, PCR was performed. The tdh gene was detected in all of the V. parahaemolyticus isolates from diarrheal patients, but trh gene was not detected. Analysis of PFGE patterns of 30 V. parahaemolyticus isolates showed 3 groups and 20 types. Among 14 O4:K68 serotypes which were isolated in Sinan, PFGE patterns of 12 strains were closely related (100%), but 2 strains were related by 58.3% and 45.4%, respectively. Also two strains of O1:K4 serotype in Gurye and two strains of O3:K6 serotype in Yeosu were closely related (100%), respectively. Although serotypes (O1:K4, O1:K70, O3:K6 and O4:K68) were different, PFGE patterns were related for more than 80.9%. Therefore, the epidemiological surveillance of V. parahaemolyticus is required by PFGE typing scheme as a further diagnostic tool.

Retraction: Usefulness of Eschar PCR for Diagnosis of Scrub Typhus

No abstract available.

Retraction: Usefulness of Eschar PCR for Diagnosis of Scrub Typhus

No abstract available.

Herpes Simplex Virus Type 2 Seroprevalence in Korea: Rapid Increase of HSV-2 Seroprevalence in the 30s in the Southern Part

To determine the characteristics of seroprevalence of herpes simplex virus type 2 (HSV-2) infection among Korean people, a cross-sectional study was conducted on three groups in 2004. The three groups consisted of the general public who visited public health centers, commercial sex workers (CSWs), and human immunodeficiency virus (HIV)-infected persons. Among the general public, HSV-2 seroprevalence rates for age under the 20s, in the 20s, 30s, 40s and the above 22.6%, 32.7% and 32.3%, respectively, which showed rapid increase of the rate in the 30s (p<0.0001). In case of the above of 19 yr old, women (28.0%) was higher than men (21.7%) (p<0.0001). The rate of CSWs (81.6%) was about 10 times higher than that of general women. In case of HIV-infected men (47.6%), the figure was about 2-3 times higher than that of general men. The low rate in the teens and the 20s proved that it is essential to develop sexually transmitted infections (STIs) prevention programs of education and publicity for them as a precaution measure. This study is the first major study of its kind on HSV-2 and would provide basic data for prevention of STIs including information about target groups subject to vaccination program.

Scrub Typhus: A Prospective Study of 76 Cases

BACKGROUND: Orientia tsutsugamushi spreads to the entire body through the blood and lymphatics, and it induces vasculitis that results in the patients manifesting symptoms of systemic organ involvement. MATERIALS AND METHODS: We conducted a prospective study to evaluate the clinical manifestations and the change of the laboratory results after instituting treatment for scrub typhus. RESULTS: Most patients presented with fever (100%), malaise (96.1%) and thirst (96.1%). It was remarkable that most patients presented with severe thirst, except for 3 healthy, young patients. This thirst was persistent even after the resolution of fever. The renal and hepatic dysfunction were reversible after the administration of appropriate antibiotics. For the blood testing, it was deteded that the CRP, and LDH were elevated in most patients (95.9% and 100% respectively). DIC could be diagnosed in 95.5% of the patients at the time of admission CONCLUSION: Most patients presented with fever, malaise and severe thirst, and the renal and hepatic dysfunction were reversible after the administration of appropriate antibiotics. DIC was observed in most of our patients, but hemorrhage and infarction were not present. CRP showed a rapid improvement, nonetheless, the LDH and DIC test results improved slowly.

Usefulness of Nested PCR for Diagnosis of Scrub Typhus in Clinical Practice: Prospective study

BACKGROUND: Laboratory studies as diagnostic tools of scrub typhus have shown PCR to be sensitive and specific, but there have been few clinical studies. The aims of this study were to determine the diagnostic accuracy and clinical usefulness of the nested PCR through a prospective comparison of the nested PCR and indirect immunofluorescence assay (IFA). MATERIALS AND METHODS: We conducted a multicenter prospective study of patients with possible scrub typhus. Adult patients who have had fever together with eschar or a maculopapular skin rash and more or equal to two of the following symptoms: headache, malaise, myalgia, coughing, nausea, and abdominal discomfort were enrolled. Each patient was admitted between September, 2004 and December, 2004 to Chosun University Hospital and one of its three community branch hospitals (Haenam General Hospital, Jangheung Hospital, Muan Hospital), which are all located in the southwest of Korea. Whole blood samples were collected for PCR testing and sera were obtained for serology evaluation using the IFA and passive hemagglutination assay (PHA). RESULTS: We enrolled 135 possible scrub typhus patients, and 118 scrub typhus patients were confirmed on the basis of either a single indirect immunofluorescent specific IgM titer against O. tsutsugamushi of > or =1:10 or 4-fold or greater rise in IFA follow up titer. One hundred eighteen patients were confirmed as scrub typhus, 7 patients were undetermined and 10 patients were confirmed as the other diseases. The result of nested PCR assay demonstrated a sensitivity of 82.2% (95% confidence interval 0.74-0.88), a specificity of 100% (95% confidence interval 0.66-1), positive predictive value of 1 (95% confidence interval 0.95-1) and negative predictive value of 0.32 (95% confidence interval 0.17-0.51). 96 patients out of 118 patients were positive for IgM on the admission day. Of 22 patients with negative for IgM antibody at admission, 19 had positive results for nested PCR using buffy coat. CONCLUSION: The nested PCR assay of buffy coat is useful for rapid and reliable test for confirmation of the diagnosis of scrub typhus.

Usefulness of Eschar PCR for Diagnosis of Scrub Typhus

BACKGROUND: We describe a case of scrub typhus, of which the diagnosis was made by PCR using eschar and serologic diagnosis. The patient's attendant insisted that the eschar like crust lesion was caused by minor trauma. In order to find out whether the crust on his head is eschar or not, PCR using eschar was performed. MATERIALS AND METHODS: Informed consent was taken, and then a piece of crust was taken apart. We immerged the crust with about 1 mL of saline bottle. We performed the nested PCR of gene that encodes the 56-kDa specific protein for O. tsutsugamushi. The first serology test for O. tsutsugamushi using indirect immunofluorescent antibody was performed. Then the second serology test & eschar PCR assay were performed at the second week after treatment. RESULTS: 56-kDa protein specific bands were detected in both buffy coat and eschar sample collected at first day of antibiotic administration. However, in the follow up PCR study 7 days after antibiotics administration, 56-kDa protein specific band was detected at only newly formed eschar, not at buffy coat. CONCLUSION: The eschar PCR assay can be useful diagnostic test, even though patient with scrub typhus underwent appropriate antibiotics therapy. The nested PCR method for eschar might be both rapid diagnostic test for scrub typhus in the early acute stage and differential test whether a crust is eschar or not.

Scrub Typhus: A Prospective Study of 76 Cases

BACKGROUND: Orientia tsutsugamushi spreads to the entire body through the blood and lymphatics, and it induces vasculitis that results in the patients manifesting symptoms of systemic organ involvement. MATERIALS AND METHODS: We conducted a prospective study to evaluate the clinical manifestations and the change of the laboratory results after instituting treatment for scrub typhus. RESULTS: Most patients presented with fever (100%), malaise (96.1%) and thirst (96.1%). It was remarkable that most patients presented with severe thirst, except for 3 healthy, young patients. This thirst was persistent even after the resolution of fever. The renal and hepatic dysfunction were reversible after the administration of appropriate antibiotics. For the blood testing, it was deteded that the CRP, and LDH were elevated in most patients (95.9% and 100% respectively). DIC could be diagnosed in 95.5% of the patients at the time of admission CONCLUSION: Most patients presented with fever, malaise and severe thirst, and the renal and hepatic dysfunction were reversible after the administration of appropriate antibiotics. DIC was observed in most of our patients, but hemorrhage and infarction were not present. CRP showed a rapid improvement, nonetheless, the LDH and DIC test results improved slowly.

Usefulness of Nested PCR for Diagnosis of Scrub Typhus in Clinical Practice: Prospective study

BACKGROUND: Laboratory studies as diagnostic tools of scrub typhus have shown PCR to be sensitive and specific, but there have been few clinical studies. The aims of this study were to determine the diagnostic accuracy and clinical usefulness of the nested PCR through a prospective comparison of the nested PCR and indirect immunofluorescence assay (IFA). MATERIALS AND METHODS: We conducted a multicenter prospective study of patients with possible scrub typhus. Adult patients who have had fever together with eschar or a maculopapular skin rash and more or equal to two of the following symptoms: headache, malaise, myalgia, coughing, nausea, and abdominal discomfort were enrolled. Each patient was admitted between September, 2004 and December, 2004 to Chosun University Hospital and one of its three community branch hospitals (Haenam General Hospital, Jangheung Hospital, Muan Hospital), which are all located in the southwest of Korea. Whole blood samples were collected for PCR testing and sera were obtained for serology evaluation using the IFA and passive hemagglutination assay (PHA). RESULTS: We enrolled 135 possible scrub typhus patients, and 118 scrub typhus patients were confirmed on the basis of either a single indirect immunofluorescent specific IgM titer against O. tsutsugamushi of > or =1:10 or 4-fold or greater rise in IFA follow up titer. One hundred eighteen patients were confirmed as scrub typhus, 7 patients were undetermined and 10 patients were confirmed as the other diseases. The result of nested PCR assay demonstrated a sensitivity of 82.2% (95% confidence interval 0.74-0.88), a specificity of 100% (95% confidence interval 0.66-1), positive predictive value of 1 (95% confidence interval 0.95-1) and negative predictive value of 0.32 (95% confidence interval 0.17-0.51). 96 patients out of 118 patients were positive for IgM on the admission day. Of 22 patients with negative for IgM antibody at admission, 19 had positive results for nested PCR using buffy coat. CONCLUSION: The nested PCR assay of buffy coat is useful for rapid and reliable test for confirmation of the diagnosis of scrub typhus.

Usefulness of Eschar PCR for Diagnosis of Scrub Typhus

BACKGROUND: We describe a case of scrub typhus, of which the diagnosis was made by PCR using eschar and serologic diagnosis. The patient's attendant insisted that the eschar like crust lesion was caused by minor trauma. In order to find out whether the crust on his head is eschar or not, PCR using eschar was performed. MATERIALS AND METHODS: Informed consent was taken, and then a piece of crust was taken apart. We immerged the crust with about 1 mL of saline bottle. We performed the nested PCR of gene that encodes the 56-kDa specific protein for O. tsutsugamushi. The first serology test for O. tsutsugamushi using indirect immunofluorescent antibody was performed. Then the second serology test & eschar PCR assay were performed at the second week after treatment. RESULTS: 56-kDa protein specific bands were detected in both buffy coat and eschar sample collected at first day of antibiotic administration. However, in the follow up PCR study 7 days after antibiotics administration, 56-kDa protein specific band was detected at only newly formed eschar, not at buffy coat. CONCLUSION: The eschar PCR assay can be useful diagnostic test, even though patient with scrub typhus underwent appropriate antibiotics therapy. The nested PCR method for eschar might be both rapid diagnostic test for scrub typhus in the early acute stage and differential test whether a crust is eschar or not.

Seroepidemiological Characteristics of Haemorrhagic Fever with Renal Syndrome from 1996 to 2005 in Korea

Haemorrhagic fever with renal syndrome (HFRS) caused by Hantaan viruses has been one of the principal acute febrile disease in Korea. To analysis the sero-epidemiological patterns of HFRS, 4,177 patient sera of acute febrile illness submitted for serological assay to National Institute of Health from Community Health Centers, Institutes of Health and Environment and hospitals from 1996 to 2005 were examined for antibodies against Hantaan virus by indirect immunofluorescent assay (IFA). Serum samples with greater than 1:32 antibody titer were considered positive. The results were analyzed seroepidemiologically by annual, sexual, seasonal, age and regional distribution of HFRS patients. Out of 4,177 serum samples tested, 1,415 samples (33.9%) were positive to Hantaan virus. The ratio of males (48.2%, 682/1,415) to females (38.2%, 541/1,415) was 1.3:1. Seasonal incidence showed that 69.5% (985/1,415) of cases occurred from October to December, resulting with higher prevalence in November (41.3%, 584/1,415). Regionally, seropositive rates of samples collected in Gyenggi, Gangwon and Chungbuk were 39.9% (564/1,415), 19.3% (274/1,415) and 8.5% (120/1,1415), respectively. Age distributions of seropositive of HFRS were detected from 20 to 79 years (78%).

Heterophyid metacercarial infections in brackish water fishes from Jinju-man (Bay), Kyongsangnam-do, Korea

Heterophyid metacercarial infections in brackish water fishes, i.e., perch, shad, mullet, redlip mullet, and goby, of Jinju-man (Bay), Kyongsangnam-do, Korea, were investigated using a digestion technique. Among 45 perch (Lateolabrax japonicus), the metacercariae of Heterophyopsis continua were found in 55.6% (18.5 metacercariae per fish), Stictodora spp. in 28.9% (3.6), and Metagonimus takahashii in 6.7% (17.0). The metacercariae of H. continua were detected in 23 (65.7%) of 35 shad (Konosirus punctatus). Among 15 mullet (Mugil cephalus), the metacercariae of Pygidiopsis summa were found in 100% (105.9 metacercariae per fish), Heterophyes nocens in 40.0% (8.5), H. continua in 13.3%, and Stictodora spp. in 6.7%. Among 12 redlip mullet (Chelon haematocheilus), the metacercariae of P. summa were detected in 91.7% (1,299 metacercariae per fish), H. nocens in 16.7%, and Stictodora spp. in 16.7%. Among 35 gobies (Acanthogobius flavimanus), the metacercariae of Stictodora spp. were found in 82.9% (44.5 metacercariae per fish), and H. continua in 25.7% (2.8). The adult flukes recovered from a cat experimentally infected with metacercariae from perches were compatible with M. takahashii. The results confirm that the estuarine fish in Jinju-man (Bay) are heavily infected with heterophyid metacercariae. Furthermore, it was found for the first time that the perch acts as a second intermediate host for M. takahashii.

Genotypic and Phenotypic Characterization of Enteropathogenic Escherichia coli Isolated from Diarrheal Patients in Gwangju

Enteropathogenic Escherichia coli (EPEC) have been implicated in human diarrhea in several countries. Central to EPEC-mediated disease is its ability to cause intestinal lesions, known as attaching and effacing (A/E) lesion. We investigated 92 EPEC strains isolated from patients with diarrhea in Gwangju for their genotypic and phenotypic characteristics. Sixteen (17.4%) of all strains were found to be typical EPEC because they were bfpA gene positive by PCR. The most of typical EPEC isolates (87.5%) showed a localized adhesion (LA) pattern in Hep-2 cell adherence assay, whereas, only 11 atypical EPEC isolates (14.5%) were adhered to Hep-2 cells in a localized manner. Thirteen of the EPEC strains studied belonged to classical O-serogroups of EPEC and 7 isolates were classified as nonclassical EPEC serogroup and the other isolates could not be serotyped with our antisera. The subtypes of eae, tir, espA and espB genes which are major virulence genes concerned of A/E lesion on chromosome were analyzed by multiplex PCR for finding the original resource. The results showed that the composition of these genes subtypes was homogenous and heterogenous in 12 and 26 isolates, respectively. The others were non-determined type in terms of the gene subtype because of genetic diversity of intimin-coding eae genes. Our findings indicated that EPEC isolates from patients with diarrhea were diverse genetically and phenotypically, which require further study in regard to their virulence and epidemiological significance.

Epidemiological Study of Viral Diarrhea in Gwangju Area During 2000~2002

There are well known infectious diarrheal disease including viral disease such as HuCVs (Human caliciviruses), rotaviruses, enteric adenoviruses and astroviruses. We performed surveillance of infectious diarrheal disease in this study for providing the information for regional prevalence of infectious diarrheal disease and establish basement of diagnostic scheme for these infectious diarrheal disease. For the study, 3,400 stool specimens collected from 10 hospitals in Gwangju from April 2000 to March 2002 were used in investigation for the detection of infectious diarrheal disease. For group A rotaviruses, enteric adenoviruses and astrovirus, we carried out antigen capturing ELISA and RT-PCR with specific primers reacting RNA dependent RNA polymerase gene of HuCVs is used for the detection of RNA of HuCVs. As a results, we detected viral antigen or genome from 537 out of 3,400 specimens (15.8%). 443 out of 537 (82.5%) were confirmed as rotaviruses antigen positively, and 14 (2.6%) and 3 (0.8%) samples were antigen positive to enteric adenoviruses and astroviruses, respectively. We detected HuCV genome from 73 (13.6%) samples by specific amplification. We found that predominantly causative virus is rotavirus in Gwangju but HuCVs take major portion of viral agents causing diarrhea considering the age and seasonal distribution of specimens. Prevalence of adenoviruses and astroviruses are very low compared with worldwide situation. While the infection of rotavirus is limited to young infant under 2 years old, infection of HuCV has wide age distribution. These results suggest that existence of various strains of HuCVs and low rate of cross-protection among distinct antigenic group make it difficult to form immunity in older age. This epidemiological information relating to various diarrheic viruses is first reported in Gwangju, therefore it could provide present prevalence of viral agents causing gastroenteritis and backgrounds to establishment of protection viral diarrhea and development.

Epidemiological Survey of Hantaan Virus Infection of Wild Rodents Trapped in Jeollanam-do, 2003~2004

Hantaan virus (HTNV) is widely distributed in Korea and has been known to cause haemorrhagic fever with renal syndrome (HFRS). Hantaviruses are carried by numerous rodent species throughout the world. Especially, the stripedfield mice, Apodemus agrarius, is the natural host for Hantaan virus in Korea, In this study, a total 117 wild rodents of 2 species (A. agrarius, Crocidura laciura) were trapped from six county (Damyang- gun, Hwasun-gun, Gokseong-gun, Jangheung-gun, Hampyeong-gun and Boseong-gun) in Jeonnam province from Sep. 2003 to Nov. 2004 for epidemiological survey. As determined by the indirect immunofluorescent antibody (IFA) test, IgG antibodies against HTNV were detected in 13.4% (14/103) of A. agrarius captured on above the areas. Serologic evidence for HTNV infection was not found in 14 C. laciura. 5 of A. agrarius were positive of hantaan viral RNA amplication from lung tissue of 14 seropositive A. agrarius by RT-PCR. For isolation of the hantaan virus, the lung tissue homogenate of 14 seropositive A. agrarius inoculated Vero E6 cells, but virus was not isolated.

Infection status of pond smelts, Hypomesus olidus, and other freshwater fishes with trematode metacercariae in 6 large lakes

In order to determine the current infection status of pond smelts, Hypomesus olidus, and other freshwater fishes with trematode metacercariae, a total of 4,861 pond smelts and 18 other freshwater fishes, collected from the Soyang and Uiam Lakes in Gangwon-do, the Unam Lake in Jeollabuk-do, the Jangseong Lake in Jeollanam-do, the Uirim-ji (lake) in Chungcheongbuk-do, and the Andong Lake in Gyeongsangbuk-do, were individually digested with 1% pepsin-HCl and examined under a dissecting microscope. In all pond smelts caught from the 6 lakes, we were unable to detect any known human infectious trematode metacercariae in Korea. However, in other freshwater fishes, such as, Squalidus japonicus coreanus (Unam Lake), and Zacco platypus (Jangseong Lake) and Opsariichthys uncirostris amurensis (Jangseong Lake), metacercariae of human-infecting trematodes, i.e., Clonorchis sinensis and Metagonimus sp. were detected, respectively.