Skip Navigation
Skip to contents

PHRP : Osong Public Health and Research Perspectives

OPEN ACCESS
SEARCH
Search

Search

Page Path
HOME > Search
9 "epidemiologic"
Filter
Filter
Article category
Keywords
Publication year
Authors
Original Articles
Early Epidemiological and Clinical Characteristics of 28 Cases of Coronavirus Disease in South Korea
Osong Public Health Res Perspect. 2020;11(1):8-14.   Published online February 28, 2020
DOI: https://doi.org/10.24171/j.phrp.2020.11.1.03
  • 20,057 View
  • 736 Download
  • 79 Citations
AbstractAbstract PDF
Objectives

The first confirmed case of coronavirus disease 2019 (COVID-19) in South Korea was reported in January 2020, with 28 confirmed cases reported as of February 14th, 2020. The epidemiological and clinical characteristics of all 28 cases were analyzed in response to this disease.

Methods

The epidemiological characteristics and early clinical features of the 28 patients from Korea with confirmed COVID-19 were analyzed using COVID-19 reporting and surveillance data and the epidemiological investigation reports prepared by the rapid response team.

Results

There were 16 patients that entered Korea from foreign countries: Wuhan, China (11 patients), Zhuhai, China, (1 patient), Singapore (2 patients), Japan (1 patient), and Thailand (1 patient). The early symptoms were fever, sore throat, cough or sputum production, chills, and muscle ache. Three patients were asymptomatic, however, 18 developed pneumonia. Of the 28 cases, 16 were index cases imported from abroad, with 10 cases of secondary infection originating in Korea, and the route of transmission still under investigation for 2 patients. The 10 patients with secondary infection were infected from contact with family members or acquaintances of primary patients, and the suspected sites of transmission were mostly at home.

Conclusion

COVID-19 in Korea was spread by 16 infected individuals traveling from other countries, leading to second-generation cases. The initial symptoms were mostly minor, but the disease was infectious at this stage, resulting from close contact, particularly at home. Establishing an early detection strategy for COVID-19 is crucial for managing the transmission of the disease.

Characterization of Clostridium difficile Strains Isolated from Patients with C. difficile-associated Disease in Korea
Seung-Hak Cho, Jung-Whan Chon, Kun-Ho Seo, Young Kwon Kim, Jung-Beom Kim, Young-Seok Bak, Woon-Won Jung, Cheorl-Ho Kim, Jong Tae Choi
Osong Public Health Res Perspect. 2017;8(5):325-331.   Published online October 31, 2017
DOI: https://doi.org/10.24171/j.phrp.2017.8.5.06
  • 2,436 View
  • 24 Download
  • 1 Citations
AbstractAbstract PDF
Objectives

Studies on Clostridium difficile are rare in Korea. We investigated the epidemiological characteristics of C. difficile isolates from patients with C. difficile-associated disease (CDAD) in Korea.

Methods

Multiplex polymerase chain reaction was performed to detect the presence of tcdA and tcdB toxin genes. Antimicrobial susceptibility test was carried out by the disk-dilution method. C. difficile strains were subtyped by automated repetitive-element palindromic PCR (rep-PCR).

Results

Among patients with CDAD, 73 (25.8%), 32 (11.3%), 32 (11.3%), and 26 (9.2%) suffered from pneumonia, cancer or neoplasm, diabetes, and colitis, respectively. Of all stool samples, 43 samples (15.2%) were positive for C. difficile strains. We observed two expression patterns of toxin genes: tcdA+/tcdB+ (86% isolates) and tcdA−/tcdB+ (14% isolates), with all isolates expressing tcdB. Furthermore, some isolates were resistant to clindamycin (65%), ampicillin (56%), and cefazolin (40%), but all were susceptible to vancomycin and metronidazole. The tested samples were classified into diverse clusters using automated rep-PCR.

Conclusion

Our findings revealed the characteristics and antibiotic resistance of C. difficile isolates from patients in Korea. The epidemiological data may provide valuable insight into development of treatment strategies for C. difficile infections in Korea.

Comparing Seasonal Pattern of Laboratory Confirmed Cases of Pertussis with Clinically Suspected Cases
Golam Reza Ghorbani, Seyed Mohsen Zahraei, Mahmood Moosazadeh, Mahdi Afshari, Fahimeh Doosti
Osong Public Health Res Perspect. 2016;7(2):131-137.   Published online April 30, 2016
DOI: https://doi.org/10.1016/j.phrp.2016.02.004
  • 1,675 View
  • 18 Download
  • 10 Citations
AbstractAbstract PDF
Objectives
During recent decades, there has been limited attention on the seasonal pattern of pertussis within a high vaccine coverage population. This study aimed to compare the seasonal patterns of clinical suspected pertussis cases with those of laboratory confirmed cases in Iran.
Methods
The current study was conducted using time series methods. Time variables included months and seasons during 2011–2013. The effects of seasons and months on the incidence of pertussis were estimated using analysis of variance or Kruskal–Wallis.
Results
The maximum average incidence of clinically confirmed pertussis was 23.3 in July (p = 0.04), but the maximum incidence of clinical suspected pertussis was 115.7 in May (p = 0.6). The maximum seasonal incidences of confirmed and clinical pertussis cases were reported in summer (average: 12, p = 0.004), and winter (average: 108.1; p = 0.4), respectively.
Conclusion
The present study showed that the seasonal pattern of laboratory confirmed pertussis cases is highly definite and different from the pattern of clinical suspected cases.
Modeling the Spread of Ebola
Tae Sug Do, Young S. Lee
Osong Public Health Res Perspect. 2016;7(1):43-48.   Published online February 28, 2016
DOI: https://doi.org/10.1016/j.phrp.2015.12.012
  • 1,744 View
  • 17 Download
  • 12 Citations
AbstractAbstract PDF
Objectives
This study aims to create a mathematical model to better understand the spread of Ebola, the mathematical dynamics of the disease, and preventative behaviors.
Methods
An epidemiological model is created with a system of nonlinear differential equations, and the model examines the disease transmission dynamics with isolation through stability analysis. All parameters are approximated, and results are also exploited by simulations. Sensitivity analysis is used to discuss the effect of intervention strategies.
Results
The system has only one equilibrium point, which is the disease-free state (S,L,I,R,D) = (N,0,0,0,0). If traditional burials of Ebola victims are allowed, the possible end state is never stable. Provided that safe burial practices with no traditional rituals are followed, the endemic-free state is stable if the basic reproductive number, R0, is less than 1. Model behaviors correspond to empirical facts. The model simulation agrees with the data of the Nigeria outbreak in 2004: 12 recoveries, eight deaths, Ebola free in about 3 months, and an R0 value of about 2.6 initially, which signifies swift spread of the infection. The best way to reduce R0 is achieving the speedy net effect of intervention strategies. One day's delay in full compliance with building rings around the virus with isolation, close observation, and clear education may double the number of infected cases.
Conclusion
The model can predict the total number of infected cases, number of deaths, and duration of outbreaks among others. The model can be used to better understand the spread of Ebola, educate about prophylactic behaviors, and develop strategies that alter environment to achieve a disease-free state. A future work is to incorporate vaccination in the model when the vaccines are developed and the effects of vaccines are known better.
Optimal Implementation of Intervention to Control the Self-harm Epidemic
Byul Nim Kim, M.A. Masud, Yongkuk Kim
Osong Public Health Res Perspect. 2014;5(6):315-323.   Published online December 31, 2014
DOI: https://doi.org/10.1016/j.phrp.2014.10.001
  • 1,663 View
  • 16 Download
  • 3 Citations
AbstractAbstract PDF
Objectives
Deliberate self-harm (DSH) of a young person has been a matter of growing concern to parents and policymakers. Prevention and early eradication are the main interventional techniques among which prevention through reducing peer pressure has a major role in reducing the DSH epidemic. Our aim is to develop an optimal control strategy for minimizing the DSH epidemic and to assess the efficacy of the controls.
Methods
We considered a deterministic compartmental model of the DSH epidemic and two interventional techniques as the control measures. Pontryagin's Maximum Principle was used to mathematically derive the optimal controls. We also simulated the model using the forward-backward sweep method.
Results
Simulation results showed that the controls needed to be used simultaneously to reduce DSH successfully. An optimal control strategy should be adopted, depending on implementation costs for the controls.
Conclusion
The long-term success of the optimum control depends on the implementation cost. If the cost is very high, the control could be used for a short term, even though it fails in the long run. The control strategy, most importantly, should be implemented as early as possible to attack a comparatively fewer number of addicted individuals.
Optimal Implementation of Intervention Strategies for Elderly People with Ludomania
Byul Nim Kim, M.A. Masud, Yongkuk Kim
Osong Public Health Res Perspect. 2014;5(5):266-273.   Published online October 31, 2014
DOI: https://doi.org/10.1016/j.phrp.2014.08.006
  • 1,579 View
  • 18 Download
  • 1 Citations
AbstractAbstract PDF
Objectives
Now-a-days gambling is growing especially fast among older adults. To control the gratuitous growth of gambling, well-analyzed scientific strategies are necessary. We tried to analyze the adequacy of the health of society mathematically through immediate treatment of patients with early prevention.
Methods
The model from Lee and Do was modified and control parameters were introduced. Pontryagin's Maximum Principle was used to obtain an optimal control strategy.
Results
Optimal control can be achieved through simultaneous use of the control parameters, though it varies from society to society. The control corresponding to prevention needed to be implemented in full almost all the time for all types of societies. In the case of the other two controls, the scenario was greatly affected depending on the types of societies.
Conclusion
Prevention and treatment for elderly people with ludomania are the main intervention strategies. We found that optimal timely implementation of the intervention strategies was more effective. The optimal control strategy varied with the initial number of gamblers. However, three intervention strategies were considered, among which, preventing people from engaging in all types of gambling proved to be the most crucial.
Brief Reports
Epidemic Intelligence Service Officers and Field Epidemiology Training Program in Korea
Geun-Yong Kwon, Shinje Moon, Wooseok Kwak, Jin Gwack, Chaeshin Chu, Seung-Ki Youn
Osong Public Health Res Perspect. 2013;4(4):215-221.   Published online August 31, 2013
DOI: https://doi.org/10.1016/j.phrp.2013.07.001
  • 1,900 View
  • 20 Download
  • 9 Citations
AbstractAbstract PDF
Korea has adopted Epidemic Intelligence Service (EIS) officers through the Field Epidemiology Training Program (FETP) since 1999 for systematic control of emerging and re-emerging infectious diseases. Graduates of medical schools in Korea are selected and serve as public health doctors (PHDs) for their mandatory military service. The duration of service is 3 years and PHDs comprise general practitioners and specialists. Some PHDs are selected as EIS officers with 3 weeks basic FETP training and work for central and provincial public health authorities to conduct epidemiological investigations. The total number of EIS officers is 31 as of 2012. The Korea Centers for Disease Control and Prevention (KCDC) has 12 specialists, whereas specialists and each province has one or two EIS officers to administer local epidemiological investigations in 253 public health centers. The Korean EIS officers have successfully responded and prevented infectious diseases, but there is a unique limitation: the number of PHDs in Korea is decreasing and PHDs are not allowed to stay outside Korea, which makes it difficult to cope with overseas infectious diseases. Furthermore, after 3 years service, they quit and their experiences are not accumulated. KCDC has hired full-time EIS officers since 2012 to overcome this limitation.
Epidemiological Characteristics of Imported Shigellosis in Korea, 2010–2011
Hee-Jung Kim, Seung-Ki Youn, Sangwon Lee, Yeon Hwa Choi
Osong Public Health Res Perspect. 2013;4(3):159-165.   Published online June 30, 2013
DOI: https://doi.org/10.1016/j.phrp.2013.02.002
  • 1,892 View
  • 17 Download
  • 5 Citations
AbstractAbstract PDF
Shigellosis is a global disease as food poisoning by infection of Shigella spp (S. dysenteriae, S. flexneri, S. boydii and S. sonnei). In Korea, approximately 500 cases of shigellosis have reported every year since 2004, and imported shigellosis is increasing gradually from 2006 in particular. According to increase of numbers of overseas travelers, the numbers of patients diseased with imported shigellosis is also increasing. We need continuous surveillance studies network (SSN) for control of imported shigellosis. We studied epidemiological characteristic of imported shigellosis by using database of Korea Centers for Disease Control and Prevention (KCDC) from 2010 to 2011. The imported shigellosis is analyzed on correlation with variable factors such as sex, age, symptom, visited country as well as Shigella spp in the database. Total 399 patients diseased with shigellosis have been reported between 2010 and 2011, The 212 patients (53.1%) among them were disease with imported shigellosis and the 205 patients (96.7%) were diagnosed as definite shigellosis. Shigella sonnei (65.6%) and Shigella flexneri (20.3%) were isolated in order. Clinical symptoms of the shigellosis were diarrhea (96.5%), abdominal pain (54.7%), fever (52.8%), chill (31.6%), and weakness (21.7% etc) in order. Duration of diarrhea was 1 to 5 days, the number of diarrhea was mostly more than 10 times, and type of stool was almost yellow stool. Almost shigellosis was occurred in the travelers visited to Asia (98.1%). Particularly, the occurrence rate of shigellosis was highest in traveler visited to Southeast Asia which is India (21.7%), Cambodia (19.8%), Philippines (17.9%), and Vietnam (9.0%) in order. According to increase of traveler to Southeast Asia, imported Shigellosis also increased. We need to strengthen the public health and hygiene, which is infection prevention rules, eating properly-cook food, washing hands, drinking boiled water, for traveler to Asia. The quarantine and surveillance system to control imported shigellosis is need continually in Korea.
Articles
Optimal Control Strategy of Plasmodium vivax Malaria Transmission in Korea
Byul Nim Kim, Kyeongah Nah, Chaeshin Chu, Sang Uk Ryu, Yong Han Kang, Yongkuk Kim
Osong Public Health Res Perspect. 2012;3(3):128-136.   Published online June 30, 2012
DOI: https://doi.org/10.1016/j.phrp.2012.07.005
  • 1,754 View
  • 14 Download
  • 10 Citations
AbstractAbstract PDF
Objective To investigate the optimal control strategy for Plasmodium vivax malaria transmission in Korea.
Methods
A Plasmodium vivax malaria transmission model with optimal control terms using a deterministic system of differential equations is presented, and analyzed mathematically and numerically.
Results
If the cost of reducing the reproduction rate of the mosquito population is more than that of prevention measures to minimize mosquito-human contacts, the control of mosquito-human contacts needs to be taken for a longer time, comparing the other situations. More knowledge about the actual effectiveness and costs of control intervention measures would give more realistic control strategies.
Conclusion
Mathematical model and numerical simulations suggest that the use of mosquito-reduction strategies is more effective than personal protection in some cases but not always.

PHRP : Osong Public Health and Research Perspectives