Species distribution modeling for wild boar (Sus scropa) in the Republic of Korea using MODIS data

Eu-Tteum Kim,Son-Il Pak 한국예방수의학회 2020 예방수의학회지 Vol.44 No.2

The distribution of wild boar (Sus scropa) in the Republic of Korea was forecasted using environmental factors. A species distribution model was applied with the standard normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), solar zenith angle (SUNZ), daytime land surface temperature (dTemp), and nighttime land surface temperature (nTemp). Understanding wild boar distribution is important for controlling African swine fever (ASF) because the disease could be endemic in wild boar or spread from wild boars to domestic pigs. Among the five predictors, the NDVI was the most influencing factor for the wild boar distribution. The relative contributions of the predictors were 67.4 for NDVI, 16.9 for dTemp, 10.5 for SUNZ, 4.4 for EVI, and 0.8 for nTemp. The area size under the receiver-operating curve of the receiver-operating characteristics for the current model was 0.62, but the real wild boar observation data overlapped with the predicted high-density wild boar distribution area. The wild boar distribution density was relatively higher in Gangwon-do, Gyeongsangbuk-do, Gyeongsangnam-do, and Jeollanam-do. Given the ASF epidemics, contact between ASF-infected animals and ASF-susceptible animals in high-density wild boar distribution areas should be prevented by long-range fencing or active surveillance.

Qualitative risk assessment of introducing Batrachochytrium dendrobatidis to South Korea via the importation of live amphibians

Eu-Tteum Kim,Son-Il Pak,Byong-Youl Cho,Jae-Bum Cho,Jin-Ha Yu 한국예방수의학회(구 한국수의공중보건학회) 2017 예방수의학회지 Vol.42 No.1

The international trade of live amphibian can cause spread of the amphibian fungal disease chytridiomycosis, which has resulted in amphibian population decline worldwide. Introduction of the causal pathogen, Batrachochytrium dendrobatidis (Bd), to South Korea via the importation of live amphibians will have a negative effect on the survival of native amphibian communities. We investigated the likelihood that Bd would be introduced to the captive and wild amphibian population in South Korea by applying standardized risk analysis. We found that the likelihood of entry of Bd into South Korea was high, but that Bd exposure to the captive amphibians had a low impact, while it had a high impact on wild amphibians. Overall, the risk of live amphibian importation for pet trade or zoos was high in wild amphibians, while it was moderate for laboratory or human consumption in wild amphibians. Accordingly, risk management measures to reduce the risks related to live amphibian importation are required.

A descriptive spatial analysis of bovine tuberculosis disease risk in 2015 in Gangwon-do, Republic of Korea

Eu-Tteum Kim,Son-Il Pak 한국예방수의학회(구 한국수의공중보건학회) 2017 예방수의학회지 Vol.42 No.2

In this study, we used a choropleth map to explore the spatial variation of the risk of cattle herds being bovine tuberculosis (BTB) positive in Gangwon-do in 2015. The map shows that the risk of being BTB-positive was lower in provinces located in the middle of Gangwon-do (Wonju, Youngwol, Peongchang, and Kangneung) than in other provinces. In addition, one province located in the north (Goseong) had a low risk of BTB. The estimate for the intercept of the spatial lag model was 0.66, and the spatial autocorrelation coefficient (lambda) was 0.20 (Table 1). The Moran’s I was 0.33 with p-value of 0.02. In 2015, provinces located in the North West (Hwacheon) and East (Donghae) of Gangwon-do had a higher BTB risk. We identified some specific provinces at low BTB-positive risk, information that may prove useful for control of BTB in the study area.

Estimating the basic reproduction number for the 2019/20 African swine fever epidemics in wild boars in the Republic of Korea

Eu-Tteum Kim,Son-Il Pak 한국예방수의학회 2021 예방수의학회지 Vol.45 No.2

Since the first detection of African swine fever (ASF)-infected wild boar in October 2019, the ASF virus has been circulating among wild boars in the Republic of Korea. The priority for ASF control is to understand the epidemic situation correctly. The basic reproduction number (R0) can be used to describe the contagious disease epidemic situation since it can assess the contagiousness of infectious agents by presenting the average number of new cases generated by an infected case. The current study estimated R0 for the 2019/20 ASF epidemics in wild boars in the Republic of Korea using the reported number of ASF cases and a serial interval of the ASF virus. The estimated mean R0 was 2.10 (range: 0.06 – 10.24) for the 2019/20 ASF epidemics, 2.94 (range: 0.43 – 9.89) for the 2019 ASF epidemics, and 2.00 (range: 0.06 – 11.10) for the 2020 ASF epidemics. In addition, the estimated mean R0 was 3.82 (range: 1.16 – 8.78) in winter, 1.39 (range: 0.16 – 6.30) in spring, 4.82 (range: 0.26 – 17.08) in summer, and 2.21 (range: 0.51 – 5.86) in fall. Even though the Korean government has applied ASF control measures, including hunting or fencing, the ASF epidemic situation in wild boars has intensified. For ASF control in wild boars, tailor-made hunting, wild boar management, or active searching for carcasses are required to reduce the ASF virus. For ASF prevention in domestic pigs, no contact between wild boars and domestic pigs and a biosecurity plan by veterinarians are needed to decrease the risk of ASF virus transmission from wild boars to domestic pigs.

Simulation modelling to evaluate the effectiveness of control strategies during the 2010/11 foot-and-mouth disease (FMD) epidemic in the city of Andong, Republic of Korea

Eu Tteum Kim,Son Il Pak 한국예방수의학회 2018 예방수의학회지 Vol.42 No.3

A simulation model of the 2010/11 foot-and-mouth disease (FMD) epidemic in the city of Andong, Republic of Korea was constructed to evaluate the epidemiologic effectiveness of FMD-control strategies. Seven FMD-control strategies were evaluated with respect to a number of epidemiologic indicators relating to the outbreak, including the number of infected animals, number of infected farms, and epidemic duration. The FMD-control strategies in the model consisted of pre-emptive slaughtering, movement restriction, and vaccination; however, levels of each control option differed. The constructed model was not perfectly representative of the 2010/11 FMD epidemic, although it was considered to mimic the actual FMD epidemic in its prediction of two outcomes: the median number of simulated FMD-detected farms was 294 (range 207-515), which was close to the number of farms detected (299) during the actual FMD epidemic (x2=87.239, df=98, p = 0.774); and the simulated epidemic curve was visually similar to the actual epidemic curve of the 2010/11 FMD epidemic. The effectiveness evaluation of simulated FMD-control strategies emphasized the amount the FMD outbreak size could have increased if the radius of the pre-emptive slaughtering area or the duration of movement restriction were decreased.

Sample size and statistical power consideration for diagnostic test research

Kim, Eu Tteum,Park, Choi Kyu,Pak, Son Il The Korean Society of Veterinary Science 2008 大韓獸醫學會誌 Vol.48 No.3

Although power analysis is of important tool of research, investigators in veterinary medicine are unaware of the concepts of the statistical power. Two types of error occur in classical hypothesis testing and, those errors should be avoided, if possible. Since power is highly dependent on the sample size, whenever declaring non-statistically significant result they should consider the potential for committing a Type II error in their studies, which refers to the probability of falsely stating that two treatments are equivalent despite true difference between them. Also, sample size determination is one of the most important tasks facing the researcher when planning a diagnostic study, and provides valuable information on the characteristics of a test performance. This type of analysis forms the basis for proper interpretation of test results. The aim of this article was to re-evaluate some selected studies on diagnostic test reported in the domestic veterinary publications to determine the power and necessary sample size for inequality testing to ensure the desired power. Power calculations were illustrated using real-life examples of comparison of a new test and a reference test for detecting antibodies of various animal diseases. Factors affecting to the power were also discussed.

A descriptive spatial analysis of bovine tuberculosis disease risk in 2015 in Gangwon-do, Republic of Korea

Eu-Tteum Kim,Son-Il Pak 한국예방수의학회 2017 예방수의학회지 Vol.41 No.2

In this study, we used a choropleth map to explore the spatial variation of the risk of cattle herds being bovine tuberculosis (BTB) positive in Gangwon-do in 2015. The map shows that the risk of being BTB-positive was lower in provinces located in the middle of Gangwon-do (Wonju, Youngwol, Peongchang, and Kangneung) than in other provinces. In addition, one province located in the north (Goseong) had a low risk of BTB. The estimate for the intercept of the spatial lag model was 0.66, and the spatial autocorrelation coefficient (lambda) was 0.20 (Table 1). The Moran’s I was 0.33 with p-value of 0.02. In 2015, provinces located in the North West (Hwacheon) and East (Donghae) of Gangwon-do had a higher BTB risk. We identified some specific provinces at low BTB-positive risk, information that may prove useful for control of BTB in the study area

Global and local models of poultry farm vehicle movement contributions to a 2014 highly pathogenic avian influenza epidemic in the Republic of Korea

Eu-Tteum Kim,Son-Il Pak 한국예방수의학회 2019 예방수의학회지 Vol.43 No.4

The goal of the current study was to estimate the contribution of poultry farm vehicle movement frequency to the 2014 highly pathogenic avian influenza (HPAI) epidemic using both global and local regression models. On one hand, the global model did not consider the hypothesis that a relationship between predictors and the outcome variable might vary across the country (spatially homogeneous), while on the other hand, the local model considered that there was spatial heterogeneity within the country. The HPAI outbreak status in each province was used as a dependent variable and the number of poultry farm vehicle movements within each province (within variable), the number of poultry farm vehicle movement from one province to another province (outbound variable), the number of poultry farm vehicle movements from other provinces to one province (inbound variable), and the number of poultry farms in each province were included in the model as independent variables. The results of a global model were as follows: estimated coefficient of the log-transformed within variable was 0.73, that of the log-transformed outbound variable was 2.04, that of the log-transformed inbound variable was 0.74, and that of the number of poultry farms was 1.08. Only the number of poultry farms was a statistically significant variable (p-value < 0.001). The AIC score of the global model was 1397.5. The results of the local model were as follows: estimated median coefficient of the log-transformed within variable was 0.75, that of the log-transformed outbound variable was 2.54, that of the log-transformed inbound variable was 0.60, and that of the number of poultry farms was 0.07. The local model’s AIC score was 1382.2. The results of our study indicate that a local model would provide a better understanding of the relationship between HPAI outbreak status and poultry farm vehicle movements than that provided by a global model.

Epidemiological correlation between biosecurity measures and the 2016/18 highly pathogenic avian influenza epidemics in the Republic of Korea

Eu-Tteum Kim,Son-Il Pak 한국예방수의학회 2022 예방수의학회지 Vol.46 No.2

Evaluation of Reference Intervals of Some Selected Chemistry Parameters Using Bootstrap Technique in Dogs

Eu-Tteum Kim,Son-Il Pak 한국임상수의학회 2007 한국임상수의학회지 Vol.24 No.4

Parametric and nonparametric coupled with bootstrap simulation technique were used to reevaluate previouslydefined reference intervals of serum chemistry parameters. A population-based study was performed in 100 clinicallyhealthy dogs that were retrieved from the medical records of Kangwon National University Animal Hospital during2005-2006. Data were from 52 males and 48 females (1 to 8 years old, 2.2-5.8 kg of body weight). Chemistry parametersexamined were blood urea nitrogen (BUN) (mg/dl), cholesterol (mg/dl), calcium (mg/dl), aspartate aminotransferase(AST) (U/L), alanine aminotransferase (ALT) (U/L), alkaline phosphatase (ALP) (U/L), and total protein (g/dl), andwere measured by Ektachem DT 60 analyzer (Johnson & Johnson). All but calcium were highly skewed distributions.parameters, ranging 5-9% of the samples and the remainingwere only 1-2%. Regardless of distribution type of each analyte, nonparametric methods showed better estimates foruse in clinical chemistry compare to parametric methods. The mean and reference intervals estimated by nonparametricbootstrap methods of BUN, cholesterol, calcium, AST, ALT, ALP, and total protein were 14.7 (7.0-24.2), 227.3 (120.7-480.8), 10.9 (8.1-12.5), 25.4 (11.8-66.6), 25.5 (11.7-68.9), 87.7 (31.1-240.8), and 6.8 (5.6-8.2), respectively. This studyindicates that bootstrap methods could be a useful statistical method to establish population-based reference intervalsIn addition, the results emphasize on the confidence intervals of the analytical parameters showing distribution-relatedvariations.