Osong Public Health and Research Perspectives

Jung Eun Cho

6 Articles

Comparison of the Epidemiological Aspects of Imported Dengue Cases between Korea and Japan, 2006–2010: Young Eui Jeong, Won-Chang Lee, Jung Eun Cho, Myung-Guk Han, Won-Ja Lee; Osong Public Health Res Perspect. 2016;7(1):71-74. Published online February 28, 2016; DOI: https://doi.org/10.1016/j.phrp.2015.12.001

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Abstract PDF: To compare the epidemiological characteristics of dengue cases imported by travelers or immigration in both Korea and Japan, we determined dengue incidence and related risk factors. During 2006–2010, 367 and 589 imported dengue cases were reported in Korea and Japan, respectively. In Korea, the presumptive origins for the dengue infections were Southeast Asia (82.6%), Southern Asia (13.9%), Eastern Asia (1.1%), South America (0.3%), Central America (0.3%), Africa (0.3%), and other countries (1.6%). In Japan, the origins of the infections were Southeast Asia (69.8%), Southern Asia (20.0%), Eastern Asia (1.7%), South America (2.5%), Central America (1.2%), Africa (1.2%), Oceania (2.4%), and other countries (1.2%). In both countries, more dengue cases were reported for men than for women (p < 0.01), and those aged 20–30 years accounted for > 60% of the total cases. The frequency of imported cases in summer and autumn (∼70% of total cases) was similar in both countries. This study demonstrates that there is a similar pattern of imported dengue cases in Korea and Japan. Therefore, there is a risk of an autochthonous dengue outbreak in Korea, as indicated by the recent outbreak in Japan in 2014.

Comparison of Four Serological Tests for Detecting Antibodies to Japanese Encephalitis Virus after Vaccination in Children: Go Woon Cha, Jung Eun Cho, Young Ran Ju, Young-Jin Hong, Myung Guk Han, Won-Ja Lee, Eui Yul Choi, Young Eui Jeong; Osong Public Health Res Perspect. 2014;5(5):286-291. Published online October 31, 2014; DOI: https://doi.org/10.1016/j.phrp.2014.08.003

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Abstract PDF: Objectives
Several different methods are currently used to detect antibodies to Japanese encephalitis virus (JEV) in serum samples or cerebrospinal fluid. These methods include the plaque reduction neutralization test (PRNT), the hemagglutination inhibition (HI) test, indirect immunofluorescence assay (IFA), and enzyme-linked immunosorbent assay (ELISA). The purpose of this study was to compare the performance of each method in detecting vaccine-induced antibodies to JEV.
Methods
The study included 29 children who had completed a primary immunization schedule with an inactivated vaccine against JEV derived from mouse brain (n = 15) or a live attenuated SA14-14-2 vaccine (n = 14). Serum samples were collected between 3 months and 47 months after the last immunization. The serum samples were tested by performing the PRNT, HI test, in-house IFA, and commercial ELISA. The antibody detection rates were compared between tests.
Results
All 29 serum samples were positive with the PRNT, showing antibody titers from 1:20 to 1:2560. The HI test showed positive rates of 86.7% (13/15) and 71.4% (10/14) in the inactivated and live attenuated vaccine groups, respectively. The results of the IFA for immunoglobulin (Ig)G were positive in 53.3% (8/15) of children in the inactivated vaccine group and 35.7% (5/14) in the live attenuated vaccine group. Neither the IFA nor ELISA detected JEV IgM antibodies in any of the 29 children.
Conclusion
These results show that detection rates of vaccine-induced antibodies to JEV have a wide range (0–100%) depending on the testing method as well as the time since immunization and individual differences between children. These findings are helpful in interpreting serological test results for the diagnosis of Japanese encephalitis in situations where vaccines are widely administered.

Travel-Associated Chikungunya Cases in South Korea during 2009–2010: Go Woon Cha, Jung Eun Cho, Eun Ju Lee, Young Ran Ju, Myung Guk Han, Chan Park, Young Eui Jeong; Osong Public Health Res Perspect. 2013;4(3):170-175. Published online June 30, 2013; DOI: https://doi.org/10.1016/j.phrp.2013.04.008

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Abstract PDF: Objectives
Chikungunya (CHIK) has been classified as a communicable disease group IV in South Korea since late 2010. Based on this, we investigated the extent of imported cases of CHIK in dengue-suspected individuals returning from dengue-endemic regions.
Methods
A total of 486 dengue-suspected serum samples were screened for CHIK by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Further RT-PCR-positive samples were used for the viral culture, and CHIK was subsequently confirmed by sequence analysis of the culture samples.
Results
Five out of 107 dengue-positive samples were found to be positive for CHIK and 15 out of 379 dengue-negative samples were found to be positive for CHIK by immunoglobulin M ELISA. Further, a CHIK virus was isolated from one of the two RT-PCR-positive sera by cell culture and confirmed by sequence analysis.
Conclusion
The present study documents the first evidence of travel-associated CHIK infection in South Korea. Considering the intense international traffic between countries, our finding emphasizes the urgent need for active patient and vector surveillance for timely response to reduce the introduction of CHIK in Korea.

Epidemiologic Features of Animal Bite Cases Occurring in Rabies-Endemic Areas of Korea, 2005 to 2009: Myung Guk Han, Ryou Jung Sang, Young Eui Jeong, Young Ran Ju, Jung Eun Cho, Jun-Sun Park; Osong Public Health Res Perspect. 2012;3(1):14-18. Published online December 31, 2011; DOI: https://doi.org/10.1016/j.phrp.2012.01.002

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Abstract PDF: Objectives
Human rabies is a reemerging infectious disease in Korea. There was no human rabies case for 14 years until the disease had reoccurred in 1999. To prevent occurrence of human rabies, surveillance for animal bite patients in rabies endemic areas in Korea was conducted since 2005 as a part of a human rabies control program. The animal bite cases were analyzed to determine whether patients were treated according to the post-exposure prophylaxis (PEP) guideline of the Korea Centers for Disease Control and Prevention.
Methods
Information of animal bite cases that occurred from 2005 to 2009 in rabies high-risk regions were collected by cooperation with Regional Public Health Centers in 18 cities/districts of rabies endemic areas.
Results
A total of 2458 animal bite cases were reported. Dogs accounted for 86% of animal bites and 67% of the animals were not vaccinated against rabies virus. For PEP, among rabies-vaccinated animals, 92.7% were observed for clinical signs and 1.4% underwent necropsy. Among unvaccinated animals, 72.7% were observed for clinical signs and 4.1% underwent necropsy. The remaining animals were not available for examination. Of the animal bite patients, 32.5% received PEP and 51.6% were treated by first aid or by washing the wound.
Conclusions
Given that no human rabies cases were reported since 2005 and animal rabies was continuously reported in endemic areas of Korea, the human rabies control program implemented in 2005 appears to have a significant role in the prevention and control of human rabies.

Serum MicroRNA Expression Profiling in Mice Infected with Rabies Virus: Myung Guk Han, Jun-Sun Park, Cho Soon Lee, Young Eui Jeong, Jung Sang Ryou, Jung Eun Cho, Young Ran Ju, Kyoung-Ki Lee; Osong Public Health Res Perspect. 2011;2(3):186-191. Published online December 31, 2011; DOI: https://doi.org/10.1016/j.phrp.2011.11.043

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Abstract PDF: Objectives
Serum or plasma microRNAs (miRNAs) are potential biomarkers for the diagnosis for cancer and prenatal diseases. This study was conducted to investigate whether rabies virus causes a change in serum miRNA expression.
Methods
ICR mice were intramuscularly inoculated with rabies virus and were sacrificed weekly to collect serum and brain tissue for 4 weeks postinoculation. Mice were assigned to four groups based on the results of indirect immunofluorescent assays, enzyme-linked immunosorbent assay, and nested reverse transcription-polymerase chain reaction and the expression profiles of serum miRNAs were compared using a commercial mouse miRNA expression profiling assay.
Results
The expression levels of miRNAs changed significantly with the different stages of the disease. The expression level of 94 serum miRNAs in infected mice changed at least twofold. Seven microRNAs of them were significantly upregulated or downregulated in all infected mice regardless of disease status. The number of miRNAs with an expression level change decreased with the progression of the disease. In a hierarchical cluster analysis, infected mice clustered into a group separate from uninfected control mice.
Conclusions
Based on the relationship of miRNAs to gene expression regulation, miRNAs may be candidates for the study of viral pathogenesis and could have potential as biomarkers.

Identification of Dengue Type 1 Virus (DENV-1) in Koreans Traveling Abroad: Young Eui Jeong, Yeon Hee Kim, Jung Eun Cho, Myung Guk Han, Young Ran Ju; Osong Public Health Res Perspect. 2011;2(1):34-40. Published online June 30, 2011; DOI: https://doi.org/10.1016/j.phrp.2011.04.002

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Abstract PDF: Objectives
To date, no indigenous dengue virus (DENV) transmissions have been reported in Korea. However, imported dengue infections have been diagnosed in travelers returning from endemic areas. This study presents the first virological evidence of travel-associated DENV importation into South Korea.
Methods
From January 2004 to June 2006, a total of 278 serum samples from 245 patients with suspected dengue fever were tested using the Panbio Dengue Duo IgM/IgG Rapid Strip Test. We selected 11 of the early symptomatic-phase sera that were negative for IgM and retrospectively studied them by virus isolation and reverse transcription-polymerase chain reaction.
Results
All 11 serum samples were found to be DENV positive by reverse transcription-polymerase chain reaction and viruses were successfully isolated from seven of the 11 serum samples. All the isolates were identified as DENV serotype-1.
Conclusion
We successfully isolated seven DENV serotype-1 strains for the first time in South Korea from imported infections. Considering that the vector mosquito, Aedes albopictus, already exists in South Korea, we propose that a vector surveillance program for dengue is urgently needed.

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