Over the course of two winters, the significant decline in honey bee populations in Korea has emerged as a major social issue. This phenomenon is expected as attributed to factors such as the failure of pest control due to the pesticide resistance of the Varroa mite. This mite can transmit some viruses that infect honey bees, and these viruses are among the primary causes of the globally occurring colony collapse disorder. Traditional diagnostic methods like (RT-)PCR and ELISA are not ideal for identifying pathogens that are newly emerging or have undergone mutations. To detect any novel or mutated viruses beyond those that have been primarily diagnosed in Korea, we introduced virome analysis technology in the field of honey bees. Employing this method with high-throughput sequencing techniques, we were able to identify all existing viruses within individual or group samples. We discovered that the Lake Sinai virus, which has been reported worldwide but not in Korea, has already significantly spread within the country. Additionally, we were able to confirm the prevalence of viruses previously reported in Korea, such as the recently dominant Black Queen Cell Virus. Through this virome analysis, we can provide foundational data for determining the direction and countermeasures for virus diagnosis.

The purpose of this study was to examine the language and culture of infectious diseases in Korean society through related expressions. Accordingly, four kinds of Korean dictionaries were investigated, and the results were examined by dividing relevant expressions into epidemic-related vocabularies and infectious disease-related case statements. First, examination of epidemic-related vocabulary found that most names of infectious diseases were expressed using Chinese characters and English loanwords. Since each infectious disease name has several synonyms, Koreans have referred to major infectious diseases by a variety of names. The names of infectious diseases were mainly reflect such information as the causes, routes of transmission, and symptoms of infection, as well as attitudes toward how to deal with the diseases. Second, the examination of case statements related to infectious diseases showed that the disease with the most example sentences was COVID-19, which recently started and has not yet ended. Case statements related to infectious diseases can be broadly divided into four categories: the designation of infectious diseases, fear of infectious diseases, patients with infectious diseases, and places of infection. In addition, we found we found that patients with infectious diseases and places of infection generated negative perceptions and expressions.

The epidemiological associations between poultry farm biosecurity measures and the 2016/18 highly pathogenic avian influenza (HPAI) epidemics were evaluated using a multivariate logistic model. In the model, 11 biosecurity measures were used as independent variables in the model: a security fence to keep wild birds out of the farm, a security gate on the farm, a farm signboard, number of footbaths for disinfecting footwear, number of anterooms, U-shaped disinfection farm gate, a tunnel-shaped disinfection farm gate, a high-pressure disinfectant fogging farm gate, disinfectant booth for farm workers and visitors, high-pressure disinfectant sprayer in the farm, and personnel disinfectant sprayer in the farm. Two hundred and eighty-eight poultry farms (144 HPAI-confirmed and 144 non-confirmed) were used as the dependent variable. The numbers of footbaths and anterooms were converted to a categorical measurement format using a general additive model. The likelihood of an HPAI outbreak in a poultry farm with a fence to prevent contact between wild birds and domestic fowl was less than that of farms without a fence (OR: 0.54, P value: 0.01). The Akaike information criterion score of the multivariate model (370.91) was less than that of the univariate logistic model for each biosecurity measure. From an HPAI control perspective, it is recommended for poultry farmers to construct a wild bird-proof fence to decrease the HPAI outbreak risk.

The mallard and spot-billed duck are representative migratory bird species wintering in the Republic of Korea. They can be a highly pathogenic avian influenza (HPAI) virus carrier during their wintering movement. From September 2014 to June 2015, 162 poultry farms were confirmed to have a HPAI infection. The current study estimated the home range of the mallard and spot-billed duck during the 2014/15 HPAI epidemics to explore the relationship between the wintering site of the migratory birds and the geographical locations of HPAI-infected farms. A Brownian bridge movement model was applied to estimate the home ranges of 13 mallards and three spot-billed ducks. As a result, 22 HPAI-infected poultry farms were located geographically in the 99% cumulative probability contour of the home range of the mallard, but no HPAI-infected poultry farm was found in spot-billed duck’s home range. In the case of one spot-billed duck, however, it has two wintering sites: Chungcheongnam-do and Jeollanam-do. Considering that migratory birds can be a major driven factor in HPAI virus transmission from wild birds to poultry farms, it is recommended for poultry farms located within the home range of migratory birds to increase their biosecurity level during wintering season of migratory birds.

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.

The current study explored the epidemiological associations between the 2016/18 highly pathogenic avian influenza (HPAI) epidemics and spatial factors, including the distance from a poultry farm to the closest groundwater source, migratory bird habitat, eco-natural area, and poultry farm altitude. We included 14 spatial factors as independent variables. The variables were used in the original continuous measurement format. In total, 288 poultry farms (144 HPAI-confirmed and 144 non-confirmed) were used as the dependent variable. In addition, the variables’ continuous measurement was converted to a categorical measurement format by using a general additive model. For risk factor analysis based on the continuous measurements of spatial factors, the non-graded eco-natural area distance (odds ratio [OR]: 1.00) and the grade one eco-natural area distance (OR: 0.99) were statistically significant independent variables. However, in the risk factor analysis based on the categorical measurement format of the spatial factors, the non-graded eco-natural area distance (OR: 0.08) and poultry farm altitude (OR: 0.44) were statistically significant independent variables in both a univariate and multiple logistic regression model. In other words, when a poultry farm was located far from the non-graded eco-natural area or in a highland area, the likelihood of an HPAI epidemic would decrease. From an HPAI control perspective, it is recommended that the government apply increased levels of biosecurity measures, such as bird-nets, fences, intensive disinfection of equipment, and regular bird health monitoring, for poultry farms located near non-graded eco-natural areas or in a lowland area.

This study examined the spatial autocorrelation of the 2016 foot and mouth disease (FMD) outbreaks in South Chungcheong to determine the association between the disease epidemics and pig farm vehicle movements. Two spatial autocorrelation testing methods were used: Moran’s I and Getis-Ord G statistics. The Moran’s I statistic for the FMD outbreak areas was -0.239, and its p-value was less than 0.007. The median Getis-Ord G statistic for the FMD outbreak areas was -0.323. The results indicated that the geographical distribution of the FMD outbreak areas was not spatially homogeneous. The spatial autocorrelation of the 2016 FMD epidemics was considered by applying a geographical weighted Poisson regression (GWPR) model in the analysis, in which pig farm vehicle movements were used as risk factors for the 2016 FMD epidemics. The number of FMD-infected farms per second-level administrative province (si or gun) was used as a dependent variable. The number of farm vehicle movements within the province (within variable), from one province to other provinces (outbound variable), or from other provinces to one province (inbound variable), were included as independent variables in the GWPR model. The results of the GWPR model were as follows. The estimated median coefficient of the log-transformed within variable, the log-transformed outbound variable, and log-transformed inbound variable were -0.000, 0.010, and -0.009, respectively. The optimal bandwidth for the GWPR model was 80.49, and the AIC score was 89.35. The results showed that the GWPR model would provide an understanding of the relationship between the 2016 FMD epidemics and pig farm vehicle movements

Since the first HPAI epidemics in 2003, there has been little epidemiological research on the association between HPAI epidemics and vehicle movements around poultry farms. This study examined the relationship between vehicle movements around poultry farms and the 2014/15 HPAI epidemics in the Republic of Korea using two methods: a boosted regression trees (BRT) model and logistic regression of a generalized linear model (GLM). The BRT model considers the non-linearity association between the frequency of vehicle movements around poultry farms and the HPAI outbreak status per province using a machine learning technique. In contrast, a GLM assesses the relationship based on the traditional frequentist method. Among the three types of vehicle movements (outbound, inbound, and within), only the outbound was found to be a risk factor of the 2014/15 HPAI epidemics according to both the BRT model and multivariate logistic regression of GLM. In the BRT model results, the median relative contribution of the log-transformed outbound variable was 53.68 (range: 39.99 – 67.58) in the 2014 epidemics and 49.79 (range: 33.90 – 56.38) in the 2015 epidemics. In the GLM results, the odds ratio of the log-transformed outbound variable was 1.22 for the 2014 HPAI epidemics (p < 0.001) and 2.48 for the 2015 HPAI epidemics (p < 0.001), respectively. The results indicated that intensive disinfection measures on outbound movement were needed to reduce the risk of HPAI spread. The current BRT models are suitable for risk analysis because the median area under the receiver operating characteristic curve was 0.83 (range: 0.74 – 0.91) and 0.85 (range: 0.73 – 0.87) for the 2014 and 2015 epidemics models, respectively. The Akaike information criterion scores for the multivariate logistic regression of GLM were 150.27 and 78.21 for the 2014 and 2015 epidemics models, respectively. These scores were relatively lower than those from the univariate logistic regression of GLM.

Foot-and-mouth disease (FMD) has great potential for causing huge economic loss and was the first disease identified by the World Organisation for Animal Health (OIE) in its official list of free countries and zones. This study examined the governmental expenditures for five FMD epidemics that occurred in the Republic of Korea between 2000 and 2011. The costs of an epidemic ranged from 26 billion Korean won (KRW, approximately 23.6 million US dollars, ) to a maximum of 2,044 billion KRW (US 1.9 billion). For two epidemics in which vaccinations were implemented, the costs were higher than those epidemics without vaccination. The mean cost for an outbreak ranged from 0.5 billion KRW (US 4.5 million) for the 2010/2011 epidemic to 18.2 billion KRW (US 16.5 million) for the 2000 epidemic. Mean costs per infected premises were 7.0 billion KRW for cattle farms (95% CI: 4.72∼9.28), 1.38 billion KRW for pig farms (0.88∼1.87), 0.11 billion KRW for deer farms (0.08∼0.14), and 0.10 billion KRW for goat farms (0.07∼0.13). The highest cost for an outbreak in cattle seemed associated with the number of outbreak cattle farms in two epidemics in which vaccination was implemented.

콩모자이크바이러스병(病)의 방제(防除)를 위(爲)하여 본(本) 바이러스병(病)의 몇가지 발생요인조사(發生要因調査) 및 저항성(抵抗性) 검정(檢定) 결과(結果)는 다음과 같다. 우리나라 각지역(各地域)에서 재배(栽培)되는 대두(大豆)의 콩모자이크바이러스 종자전염율(種子傳染率)은 영주외(榮州外) 14개지역(個地域)의 수집종자(蒐集種子)가 30%이상(以上), 남해외(南海外) 22개지역(個地域)의 수집종자(蒐集種子)는 , 완도외(莞島外) 43개지역(個地域)의 수집종자(蒐集種子)는 이었고 연기용호에는 종자전염주(種子傳染株)가 없었다. 포장(圃場)에서 진딧물발생밀도(發生密度)의 증감(增減) 1개월후(個月後)부터 발병율(發病率)에 차이(差異)가 나타났다. 엽모(葉毛)의 길이가 짧고 조밀(稠密)한 품종(品種)에 가장 매개(媒介)진딧물의 부착(附着) 및 흡즙충수가 적었고, 엽모(葉毛)가 길고 조밀(稠密)한 것에는 시간(時間)의 경과(經過)에 따라 부착충수가 적었으며, 엽모(葉毛)가 길고 엉성한 것에 부착(附着) 및 흡즙충수가 가장 많았다. 감염시기(感染時期)에 따른 종자전염율(種子傳染率)은 6월(月) 20일(日)에 감염(感染)된 대두(大豆)에서 높았고, 7월(月) 20일(日)과 8월(月) 20일(日)에 감염(感染)된 대두(大豆)에서는 아주 낮았다. 대두종자부분(大豆種子部分)의 부위별(部位別) 바이러스전염(傳染) 조사(調査)에서는 배(胚)와 배유(胚乳)에서 바이러스소재(所在)가 확인(確認)되었고, 미숙종자(未熟種子)가 완숙종자(完熟種子)보다는 감염율(感染率)이 높았다. 반문(斑紋)이 있는 종자(種子)는 반문(斑紋)이 없는 종자(種子)보다 다소(多少) 높은 종자전염율(種子傳染率)을 보였으나 반문(斑紋)이 심(甚)하여도 종자전염율(種子傳染率)은 높지 않았다. 그리고 발아율(發芽率)에서는 반문(斑紋)의 영향(影響)이 없었다. 저항성품종(抵抗性品種) 검정(檢定)에서 Columbus외(外) 14품종(品種)이 이병성(罹病性), Chief외(外) 14품종(品種)이 중도저항성(中度抵抗性), 장백(長白)콩외(外) 17품종(品種)이 저항성(抵抗性)인 것으로 나타났다.