• Parasites, Hosts and Diseases
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• v.58 no.1
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• pp.93-97
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• 2020

The cestode Taenia hydatigena uses canids, primarily dogs, as definitive hosts, while the metacestode larval stage cysticercus infects a range of intermediate hosts, including domestic animals such as goats, sheep, and pigs. Cysticercosis due to T. hydatigena has large veterinary and economic drawbacks. Like other taeniids, e.g., Echinococcus, intraspecific variation is found among the members of the genus Taenia. In Africa, few studies are available on the epidemiology and distribution of T. hydatigena, and even fewer studies are available on its genetic variation. In this study, we molecularly identified 11 cysticerci from sheep in Sudan and demonstrated the genetic variation based on the NADH dehydrogenase subunit 1 (nad1) and cytochrome c oxidase subunit 1 (cox1) mitochondrial genes. The isolates were correctly identified as T. hydatigena with more than 99% similarity to those in the GenBank database. Low diversity indices and insignificant neutrality indices were observed, with 3 and 2 haplotypes for the nad1 and cox1 genes, respectively. The results suggest the presence of unique T. hydatigena haplotypes in Sudan, as haplotypes with 100% similarity were not found in the GenBank database. With few available studies on the genetic variation of T. hydatigena in Africa, this report represents the first insights into the genetic variation of T. hydatigena in Sudan and constitutes useful data.

• Korean Journal of Microbiology
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• v.53 no.1
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• pp.1-8
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• 2017

Measles virus is a highly contagious, exanthematic virus, preventable by the use of an effective live-attenuated vaccine. However, measles virus remains endemic in many area of the world causing nearly 200,000 deaths per year and still a major cause of child mortality, mostly in developing countries. In March 2014, Republic of Korea was certified as a 'national measles elimination' by the WHO as a result of a high-quality case-based surveillance system and population immunity, which was achieved by a high vaccination rate (>95.0% since 1996). But, since the beginning of 2014, the Gyeonggi province has experienced a resurgence of measles cases. In this study, we investigated the characteristics of measles viruses isolated from confirmed measles in Gyeonggi province during January 1, 2014 ~ July 31, 2014, 60 isolates were obtained from 72 confirmed measles specimens. Genotypic distributions and genetic diversities of isolated measles virus were analyzed by sequencing of nucleoprotein (N) gene. 58 (96.7%) imported cases were identified. The predominant genotype was B3, which reflects the circulating measles virus in adjacent countries. The sequences of nucleoprotein (N) gene of isolated MeV were showed that the strains characterized showed the highest degree of identity (99%) with the Philippine related strains in 2013-2014. Therefore, infected traveler returning from the Philippines transmitted secondary infection in Korea.

• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.455-459
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• 2017

Norovirus (NoV) is the most common cause of acute gastroenteritis in all age groups worldwide. In this study, prevalence of asymptomatic norovirus infection was investigated in food handler being employed at food catering facilities in South Korea. A total of 2,729 fecal specimens from asymptomatic food handlers were analyzed, and 1.06% of food handlers (29/2,729) had asymptomatic NoV infection. Of these, 17.2% (5/29) were positive for NoV GI and 82.7% (24/29) were positive for NoV GII. Especially, sequencing and phylogenetic analysis showed that GII-4 was the most prevalent genotype and a large number of asymptomatic food handlers were infested with norovirus GII-4 strains. The results of this study show that asymptomatic food handlers may be potential transmission sources for NoV infection. These results emphasize the need for training of food catering employees about norovirus prevention. Asymptomatic norovirus infection should receive more attention.

• Yonsei Medical Journal
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• v.59 no.9
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• pp.1072-1078
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• 2018

Purpose: The Korean society has moved rapidly toward becoming a multicultural society. This study aimed to estimate the seroprevalence of hepatitis viruses and investigate hepatitis B virus (HBV) genotypic diversity in female marriage immigrants. Materials and Methods: Screening program was conducted at support centers for multicultural families in 21 administrative districts in Korea between July 2011 and January 2017. A total of 963 female marriage immigrants were included in this study. Blood samples were tested for hepatitis viral markers and HBV genotype. Results: Subjects' median age was 33 years (20-40 years), and they originated from nine countries including Vietnam (n=422, 43.8%), China (n=311, 32.3%), the Philippines (n=85, 8.8%), Cambodia (n=58, 6.0%), and Japan (n=39, 4.0%). About 30% (n=288) of subjects required hepatitis A vaccination. HBsAg positive rate was 5.4% (n=52). Positive HBsAg results were the highest in subjects from Southeast Asia (6.6%, n=38). Anti-HBs positive rate was 60.4% (n=582). About 34% (n=329) of subjects who were negative for anti-HBs and HBsAg required HBV vaccinations. Genotypes B and C were found in 54.6% (n=12) and 45.4% (n=10) of the 22 subjects with HBV, in whom genotypes were tested. Eight (0.8%) subjects were positive for anti-HCV. Positive anti-HCV results were the highest in subjects from Central Asia (7.9%, n=3). Conclusion: Testing for hepatitis viral marker (hepatitis A virus IgG and HBsAg/anti-HBs) is needed for female marriage immigrants. Especially, HBV genotype B is different from genotype C of Koreans. Therefore, interest and attention to vaccination programs for female marriage immigrants are necessary for both clinicians and public health institutes.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.3
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• pp.217-224
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• 2021

Fluoroquinolone (FQ) resistant gram-negative pathogens have emerged worldwide, and the recent increase in FQ resistant Escherichia coli is of great concern in Korea. This study investigated FQ resistance determinants and the epidemiological relationship of 56 ciprofloxacin-resistant E. coli isolated from a tertiary hospital in Daejeon, South Korea from June to December 2018. Molecular epidemiology was investigated by multilocus sequence typing (MLST). Polymerase chain reaction (PCR) and sequence analysis were performed to identify chromosomal mutations in the quinolone resistance determining regions (QRDR) of gyrA, gyrB, parC, and parE and to describe the occurrence of the following plasmid-mediated quinolone resistance (PMQR) genes: aac(6)-Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD, and qnrS. MLST analysis showed 12 sequence types (STs) and the most prevalent ST was ST131 (31/56, 55.4%), followed by ST1193 (13/56, 23.2%), and ST405 (3/56, 5.4%). In 56 ciprofloxacin-resistant E. coli isolates, Ser83→Leu and Asp87→Asn in gyrA and Ser80→Ile and Glu84→Val in parC (51.8%, 29/56) were the most frequent amino acid substitutions and aac(6)-Ib-cr (33.9%, 19/56) was the most common PMQR gene. These results of FQ resistance determinants were more frequently observed in ST131 compared with other clones. Continuous monitoring of the epidemiological characteristics of ciprofloxacin-resistant E. coli isolates and further investigation of FQ resistance determinants are necessary.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.4
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• pp.342-348
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• 2020

Uropathogenic Escherichia coli (UPEC) is a major cause of urinary tract infections (UTIs), which is one of the most common infectious diseases in humans worldwide. Since UPEC is increasingly gaining resistance to many antimicrobial agents, antibiotic therapy of UTI has recently become a great concern. This study examined the epidemiological relationship, and antimicrobial resistance patterns of 84 UPEC isolates obtained from UTI patients in Daejeon, from March to December 2017. Molecular epidemiology was investigated by multilocus sequence typing (MLST), and an antimicrobial susceptibility test was determined using an E-test. In this study, UTI was more common in females (73.8%) than in males (26.2%), and the highest incidence of UTI was observed in the age group in their 70s. Among the 84 UPEC isolates, 59 isolates (70.2%) were multidrug-resistant (MDR), and the major sequence type was ST131 (44 isolates, 52.4%). Interestingly, the rates of MDR in non-ST131 isolates (72.5%) were higher compared to ST131 isolates (68.2%). These results indicate the possibility of the development and spread of MDR in non-ST131 isolates. Effective surveillance networks and continuous research need to be conducted globally to prevent the emergence and international spread of MDR non-ST131 isolates.

• Clinical and Experimental Pediatrics
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• v.45 no.11
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• pp.1368-1372
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• 2002

Purpose : Group A streptococci have a cell wall which consists of M protein and T protein. T protein is known to be helpful in the understanding of the epidemiology of group A streptococci. To study the epidemiologic characteristics, we serotyped T protein of group A streptococci obtained from patients admitted to hospitals, or who visited OPD in five districts of Seoul the during last three years. Methods : Group A streptococci were obtained in five districts in north, northeast, central, northwest and south Seoul from 1998 through 2000. All isolated group A streptococci were serotyped with T protein antisera(Institute of Sera and Vaccine, Prague, Czech Republic). Results : In 1998, analysis of obtained total number of 92 strains revealed that T12, T4, and NT acounted for 72.2%. Among seven cases of scarlet fever, T12 was isolated in four cases and T4 was found in three cases. Two cases of tonsilar abscess produced T8 and NT. One case of cervical lymphadenitis showed T12. In 1999, 41 cases were studied showing that T12, T4, and T1 contributed 68%. Among five cases of scarlet fever, T12 and T4 make up three case. There were two cases of pneumonia(T4 and T1) and one case of cervical lymphadenitis(T8/25). In 2000, the study was performed in four districts except the central area. Among 83 isolates, T12, T4 and T1 accounted for 63.9%. There were three cases of scarlet fever(T12, T4, T5), one case of tonsillar abscess(T12), one case of pneumonia(NT) and one case of sepsis(T1). Conclusion : Serological analysis of T protein of group A streptococci shows no endemic specificity. The yearly pattern reveals that T12 had been decreasing but T1 had shown the opposite trend.

• Journal of Life Science
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• v.26 no.8
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• pp.911-920
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• 2016

Norovirus is the most common causative agent of acute gastroenteritis. This study was carried out to investigate molecular epidemiology of norovirus infections from outbreaks in Busan from 2012 to 2015. Total of 581 stool specimens were collected from diarrhea patients in outbreaks in Busan, 71 samples were resulted in positive to norovirus. The data were analyzed according to seasonality, patient, age and gender. Noroviruses were detected most frequently during the winter season from November (25.4%) to February (28.2%). The age group from teens was the most susceptible to norovirus infections. To obtain the molecular genetic information of norovirus, we performed sequencing analyses of the strains detected. Norovirus genotypes have been reported to show high genetic diversity. Four kinds of GI genotypes (GI-1, GI-2, GI-3, GI-5) and five kinds of GII genotypes (GII-1, GII-4, GII-5, GII-6, GII-17) were indentified in outbreaks in Busan. Other previous studies have shown that GII-4 is the most predominant circulating in Korea and worldwide. The most prevalent norovirus genotypes of each year were GII-6 in 2012, GII-6 in 2013, GII-4 in 2014 and GII-6 in 2015. Except for 2014, GII-6 genotype was the most prevalent and predominant in Busan. We described the epidemiological analysis of the noroviruses in outbreaks in Busan. The result of this study will contribute to update the epidemiological data and improve hygiene and public health via sustainable surveillance.

• Pediatric Infection and Vaccine
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• v.7 no.1
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• pp.143-151
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• 2000

Purpose : The accuracy of bacteriologic diagnosis of beta-hemolytic streptococcal pharyngotonsillitis depends on the degree of carrier rate in that area where the throat swabs are obtained and the evaluation of serological T typing as an epidemiologic marker is important to understand epidemiology of streptococcal infection. The purpose of this study is to know the carrier rates of group A streptococcus in normal children form four different areas and to find out the epidemiologic characteristic in distribution of the serotypes for 3 years. Method : Throat swabs were obtained from the tonsillar fossa of normal school children in four different areas(Uljin, Seoul, Osan, Kunsan) from March to May 1996, in Uljin in April 1997, and in Uljin in April 1998. The samples were plated on a 5% sheep blood agar plate and incubated overnight at $37^{\circ}C$ before examination for the presence of beta-hemolytic colonies. All isolated beta-hemolytic streptococcus were grouped and serotyped by T agglutination. Results : The carrier rate of beta-hemolytic streptococci and group A streptococci in 1996 were 27.6%, 18.6% at Uljin; 16.4%, 2.7% at Seoul; 33.0%, 26.0% at Osan; 20.0%, 12.3% at Kunsan, respectively. Among 1,192 normal school children from 4 different areas, we obtained 179 strains of group A streptococci. Fifty two percent of the strains were typable by T agglutination in 1996. Common T-type in 1996 were NT, T1, T3, T2 at Uljin; T12, T25 at Seoul; NT, T6, T28 at Osan; T25, T4, NT, T5 at Kunsan, in decreasing order, respectively. At Uljin, T1, T3, T25 accounted for 69% of strains in 1996, T1, T12, T25 accounted for 70% in 1997, and T12, T4 accounted for 88% in 1998. Conclusion : Higher carrier rates were found in Uljin and Osan, where there are a lower population density with scanty of medical facilities compared with another areas. We supposed that low carrier rates is likely to be related to antibiotic abuse or some epidemiologic factor. The periodic and seasonal serotyping analysis is important in monitoring and understanding the epidemiologic patterns of group A streptococci.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.2
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• pp.139-146
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• 2006

Purpose: Human astrovirus (HAstV) is known to be an important etiologic agent of acute gastroenteritis in infants worldwide. However, the prevalence of HAstV infection varies according to geographic region and patient age. The purpose of our study was to investigate the incidence of HAstV infection among hospitalized children at a tertiary hospital in Seoul. Methods: Fecal samples were collected from hospitalized children up to five years of age with acute gastroenteritis. A total of 812 fecal samples were collected from hospitalized children with acute gastroenteritis between February 2004 and January 2005. Fecal specimens were screened for rotavirus, enteric adenovirus and norovirus by enzyme immunoassay (EIA) or reverse transcriptase polymerase chain reaction (RT-PCR). HAstV positive samples were characterized by RT-PCR. Results: Rotavirus was detected in 16.9% (138/812), norovirus in 11.6% (94/812), and adenovirus in 4.0% (33/812) of the study population. HAstV was detected in 4.0% (33/812) samples by RT-PCR. The age distribution of HAstV positive patients was as follows: <12 month old, 82.0% (27/33); 1~2 years old, 6.0% (2/33); 2~5 years old, 12.0% (4/33). The seasonal distribution of HAstV positive samples was as follows; April (3), May (5), June (4), August (12), September (4), October (2), November (2), and December (1). The peak rate of HAstV infection was observed during the summer season, 2004. A mixed infection of viral agents was confirmed in 2.7% (22 /812) of the study population, most commonly with rotavirus and norovirus, and with rotavirus and HAstV. Genotype 1 was the predominant type (91%, 20/22) and genotype 8 was detected in two cases. Conclusion: The prevalence of HAstV infection was 4.0% in hospitalized children with acute gastroenteritis, and was especially high in infants. HAstV can be considered as an important etiologic agent of gastroenteritis in children.