Under the current African swine fever (ASF) epidemic situation, a science-based ASF-control strategy is required. An ASF transmission mechanistic model can be used to understand the disease transmission dynamics among susceptible epidemiological units and evaluate the effectiveness of an ASF-control strategy by simulating disease spread results with different control options. The force of infection, which is the probability that a susceptible epidemiological unit becomes infected, could be estimated by applying an ASF transmission mechanistic model. The government needs to plan an ASF-control strategy based on an ASF transmission mechanistic model.

Background: African swine fever (ASF) is a hemorrhagic fever occurring in wild boars (Sus scrofa) and domestic pigs. The epidemic situation of ASF in South Korean wild boars has increased the risk of ASF in domestic pig farms. Although basic reproduction number (R0) can be applied for control policies, it is challenging to estimate the R0 for ASF in wild boars due to surveillance bias, lack of wild boar population data, and the effect of ASF-positive wild boar carcass on disease dynamics. Objectives: This study was undertaken to estimate the R0 of ASF in wild boars in South Korea, and subsequently analyze the spatiotemporal heterogeneity. Methods: We detected the local transmission clusters using the spatiotemporal clustering algorithm, which was modified to incorporate the effect of ASF-positive wild boar carcass. With the assumption of exponential growth, R0 was estimated for each cluster. The temporal change of the estimates and its association with the habitat suitability of wild boar were analyzed. Results: Totally, 22 local transmission clusters were detected, showing seasonal patterns occurring in winter and spring. Mean value of R0 of each cluster was 1.54. The estimates showed a temporal increasing trend and positive association with habitat suitability of wild boar. Conclusions The disease dynamics among wild boars seems to have worsened over time. Thus, in areas with a high elevation and suitable for wild boars, practical methods need to be contrived to ratify the control policies for wild boars.

Background: African swine fever (ASF) is a hemorrhagic fever occurring in wild boars (Sus scrofa) and domestic pigs. The epidemic situation of ASF in South Korean wild boars has increased the risk of ASF in domestic pig farms. Although basic reproduction number (R0) can be applied for control policies, it is challenging to estimate the R0 for ASF in wild boars due to surveillance bias, lack of wild boar population data, and the effect of ASF-positive wild boar carcass on disease dynamics. Objectives: This study was undertaken to estimate the R0 of ASF in wild boars in South Korea, and subsequently analyze the spatiotemporal heterogeneity. Methods: We detected the local transmission clusters using the spatiotemporal clustering algorithm, which was modified to incorporate the effect of ASF-positive wild boar carcass. With the assumption of exponential growth, R0 was estimated for each cluster. The temporal change of the estimates and its association with the habitat suitability of wild boar were analyzed. Results: Totally, 22 local transmission clusters were detected, showing seasonal patterns occurring in winter and spring. Mean value of R0 of each cluster was 1.54. The estimates showed a temporal increasing trend and positive association with habitat suitability of wild boar. Conclusions The disease dynamics among wild boars seems to have worsened over time. Thus, in areas with a high elevation and suitable for wild boars, practical methods need to be contrived to ratify the control policies for wild boars.

Purpose: To compare long-term disease-free survival (DFS) between patients receiving tegafur/gimeracil/oteracil (S-1) or capecitabine plus oxaliplatin (CAPOX) adjuvant chemotherapy (AC) for gastric cancer (GC). Materials and Methods: This retrospective multicenter observational study enrolled 983 patients who underwent curative gastrectomy with consecutive AC with S-1 or CAPOX for stage II or III GC at 27 hospitals in Korea between February 2012 and December 2013. We conducted propensity score matching to reduce selection bias. Long-term oncologic outcomes, including DFS rate over 5 years (over-5yr DFS), were analyzed postoperatively. Results: The median and longest follow-up period were 59.0 and 87.6 months, respectively. DFS rate did not differ between patients who received S-1 and CAPOX for pathologic stage II (P=0.677) and stage III (P=0.899) GC. Moreover, hazard ratio (HR) for recurrence did not differ significantly between S-1 and CAPOX (reference) in stage II (HR, 1.846; 95% confidence interval [CI], 0.693–4.919; P=0.220) and stage III (HR, 0.942; 95% CI, 0.664–1.337; P=0.738) GC. After adjustment for significance in multivariate analysis, pT (4 vs. 1) (HR, 11.667; 95% CI, 1.595–85.351; P=0.016), pN stage (0 vs. 3) (HR, 2.788; 95% CI, 1.502–5.174; P=0.001), and completion of planned chemotherapy (HR, 2.213; 95% CI, 1.618–3.028; P<0.001) were determined as independent prognostic factors for DFS. Conclusions S-1 and CAPOX AC regimens did not show significant difference in over-5yr DFS after curative gastrectomy in patients with stage II or III GC. The pT, pN stage, and completion of planned chemotherapy were prognostic factors for GC recurrence.

In epidemiology, the basic reproduction number (R0) is a term that describes the expected number of infections generated by 1 case in a susceptible population. At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, R0 was frequently referenced by the public health community and the wider public. However, this metric is often misused or misinterpreted. Moreover, the complexity of the process of estimating R0 has caused difficulties for a substantial number of researchers. In this article, in order to increase the accessibility of this concept, we address several misconceptions related to the threshold characteristics of R0 and the effective reproduction number (Rt). Moreover, the appropriate interpretation of the metrics is discussed. R0 should be considered as a population-averaged value that pools the contact structure according to a stochastic transmission process. Furthermore, it is necessary to understand the unavoidable time lag for Rt due to the incubation period of the disease.

PURPOSE: To investigate the current status of adjuvant chemotherapy (AC) regimens in Korea and the difference in efficacy of AC administered by surgical and medical oncologists in patients with stage II or III gastric cancers. MATERIALS AND METHODS: We performed a retrospective observational study among 1,049 patients who underwent curative resection and received AC for stage II and III gastric cancers between February 2012 and December 2013 at 29 tertiary referral university hospitals in Korea. To minimize the influence of potential confounders on selection bias, propensity score matching (PSM) was used based on binary logistic regression analysis. The 3-year disease-free survival (DFS) rates were compared between patients who received AC administered by medical oncologists or surgical oncologists. RESULTS: Between February 2012 and December 2013 in Korea, the most commonly prescribed AC by medical oncologists was tegafur/gimeracil/oteracil (S-1, 47.72%), followed by capecitabine with oxaliplatin (XELOX, 16.33%). After performing PSM, surgical oncologists (82.74%) completed AC as planned more often than medical oncologists (75.9%), with statistical significance (P=0.036). No difference in the 3-year DFS rates of stage II (P=0.567) or stage III (P=0.545) gastric cancer was found between the medical and surgical oncologist groups. CONCLUSIONS: S-1 monotherapy and XELOX are a main stay of AC, regardless of whether the prescribing physician is a medical or surgical oncologist. The better compliance with AC by surgical oncologists is a valid reason to advocate that surgical oncologists perform the treatment of AC for stage II or III gastric cancers.
Capecitabine ; Chemotherapy, Adjuvant* ; Compliance ; Disease-Free Survival ; Hospitals, University ; Humans ; Korea* ; Logistic Models ; Observational Study ; Propensity Score ; Referral and Consultation ; Retrospective Studies* ; Selection Bias ; Stomach Neoplasms*

To investigate the transmission pattern of geographical area and temporal trends of the 2010~2011 foot-and-mouth disease (FMD) outbreaks in Korea, and to explore temporal intervals at which spatial clustering of FMD cases space-time analysis based on georeferenced database of 3,575 burial sites, from 30 November 2010 to 23 February 2011, was performed. The cases represent approximately 98.1% of all infected farms (n = 3,644) during the same period. Descriptive maps of spatial patterns of the outbreaks were generated by ArcGIS. Spatial Scan Statistics, using SaTScan software, was applied to investigate geographical clusters of FMD cases across the country. Overall, spatial heterogeneity was identified, and the transmission pattern was different by province. Cattle have more clusters in number but smaller in size, as compared to the swine population. In addition, spatiotemporal analysis and the comparison of clustering patterns between the first 7 days and days 8 to 14 of the outbreak revealed that the strongest spatial clustering was identified at the 7-day interval, although clustering over longer intervals (8~14 days) was also observed. We further discussed the importance of time period elapsed between FMD-suspected notice and the date of confirmation, and emphasized the necessity of region-specific and species-specific control measures.
Animals ; Burial ; Cattle ; Disease Outbreaks ; Foot-and-Mouth Disease ; Geographic Information Systems ; Korea ; Population Characteristics ; Republic of Korea ; Spatial Analysis ; Spatio-Temporal Analysis ; Swine

BACKGROUND: Gallstone is one of the most common cause of acute abdominal pain and is increasingly managed by laparoscopic cholecystectomy. Silent gallstones are usually managed expectantly and are considered for surgery only if the characteristic biliary pain occurs. If predictors of stone-related complications such as acute cholecystitis, pancreatitis, and cholangitis can be identified, patients at high risk can be selectively referred for treatment regardless of symptoms development, while those at lower risk may be safely observed. The purpose of this study was to find out the predictors of stone-related complication or biliary pain in patients with gallbladder stones. METHODS: We collected clinical data retrospectively on patients who were diagnosed with gallstone at Asan Medical Center. Total gallstone number was classified into 1, 2~4, over 5. Diameter of the gallstones were subdivided into 20 mm. Statistical analysis was performed using SAS program (Ver 6.11). RESULTS: 918 patients (432 men and 486 women) were included in the analysis. The mean age was 54.3 years; that of men was 55 years and women was 53.8 years. Stone-related complications developed in 201 patients of acute cholecystitis, 78 patients of acute gallstone pancreatitis and 80 patients of acute cholangitis. Biliary pain was occurred in 568 patients. 658 patients were experienced cholecystectomy (158 patients open cholecystectomy and 500 patiens LLC). 377 patients were experiened ERCP, and 289 persons of that were experienced EST. Acute gallstone pancreatitis and acute cholangitis were significantly more frequent in older age and patients experiencing biliary pain. Their gallstone size was significantly smaller and the number was significantly more numerous in the univariate analysis. But, in the multiple logistic regression analysis, only age and the smallest stone size were independent risk factors. Patients who experiencing biliary pain were older and had significantly smaller and multiple gallstones in the univariate analysis. However in the multiple logistic regression analysis only age and stone number were independent variables. Acute cholecystitis was significantly more frequent in the old age group and patients with biliary pain. CONCLUSION: In the multiple logistic regression analysis, old age and small gallstones were predictors of acute gallstone pancreatitis and acute cholangitis. Old age and multiple gallstones were associated with biliary pain. Old age and biliary pain were predictors of acute cholecystitis, but the gallstone size and number were not associated in this study. We suggest that a well-designed prospective study is necessary in the future.
Abdominal Pain ; Cholangiopancreatography, Endoscopic Retrograde ; Cholangitis ; Cholecystectomy ; Cholecystectomy, Laparoscopic ; Cholecystitis ; Cholecystitis, Acute ; Chungcheongnam-do ; Female ; Gallbladder ; Gallstones* ; Humans ; Logistic Models ; Male ; Pancreatitis ; Retrospective Studies ; Risk Factors

To draw inferences about the sensitivity and specificity of the newly developed ELISA test for bovine paratuberculosis (PTB) diagnosis and posterior distribution on the prevalence of PTB in a province of Korea, we applied Bayesian approach with Gibbs sampler to the data extracted from the prevalence study in 1999. The data were from a single test results without a designated gold test. The prevalence estimates for PTB in study population ranged 3.2~5.3% for conservative and 6.7~7.1% for liberal, depending on the priors used. The simulated specificities of the ELISA close to one another, ranging 84.7~90.6%, whereas the sensitivity was somewhat spread out depending largely on the priors with a range of 46.4~88.2%. Our findings indicate that the ELISA method appeared useful as a screening tool at a minimum level in comparison to other diagnostic tests available for this disease in terms of sensitivity. However, this advantage comes at a cost of having low specificity of the test.
Animals ; Bayes Theorem ; Cattle ; Cattle Diseases/*epidemiology ; Enzyme-Linked Immunosorbent Assay/*methods ; Korea/epidemiology ; Paratuberculosis/*epidemiology ; Prevalence

Although there have been substantial evidences on the usefulness of electrolytes for the diagnosis of disease, the evidences for a direct link between serum sodium and serum potassium in relation to a specific disease are very limited. This study was performed to investigate an association between diseases and Na:K ratios in dogs. From January 1997 to December 1999, a total of 39 cases with an Na:K ratio less than 27 were retrieved from the medical records of Veterinary Medical Teaching Hospital, Seoul National University. Ten dogs (25.6%) had a renal or urinary disease, and six (15.4%) had a parasitism. Other miscellaneous diseases included deep pyoderma, grade III patellar luxation, bacterial pneumonia, diabetes, pancreatitis, and pyometra. The Na:K ratio was significantly lower in dogs with renal failures than those with parasitic diseases (p=0.0735). With the criterion of the Na:K ratio < 27, twenty seven dogs (69.2%) had hyperkalemia, whereas thirteen dogs (33.3%) had hyponatremia. Of 13 dogs with Na:K ratios between 20 and 24, six were diagnosed as a renal or urinary tract disease, two as diabetes, and two as a parasitism. The Na:K ratios of 9 dogs were < 20, being with the most prevalent with the disease of renal failures (55.6%). The serum Na:K ratios were more closely related to serum potassium concentrations (gamma= -0.8710) than serum sodium concentrations (gamma=0.4703). Two dogs with diabetes had an electrolyte pattern of hyperkalemia with normonatremia. Further studies are needed to determine the usefulness of Na:K ratio for diagnosis of hypoadrenocorticism, and to establish a relationship between patellar luxation and electrolyte unbalance.
Animals ; Biological Markers/blood ; Dog Diseases/*blood ; Dogs/*blood ; Hyperkalemia/blood/*veterinary ; Hyponatremia/blood/*veterinary ; Korea ; Potassium/*blood ; Reference Values ; Sodium/*blood ; Water-Electrolyte Balance