• Korean Journal of Veterinary Research
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• v.49 no.4
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• pp.309-317
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• 2009

The present study describes an investigation on an epidemic of Tuberculosis (TB) which has been occurred among dairy cattle farms in Jeongeup, Jeollabuk-do since 2007. The investigation was performed in three ways as follows: 1. Collecting information about bovine TB outbreaks using investigation reports, an on-the-spot and tracing-back investigations; 2. Analyzing the outbreak pattern; 3. Establishing hypothesis and performing statistical analysis on potential risk factors. In the early 2000s, TB outbreaks were sporadically reported in beef cattle, and only a small number ($1{\sim}2$) of reactors was confirmed in each of outbreak farms. The number of TB outbreaks has been suddenly increased from 2007, mainly in dairy cattle farms. And these outbreaks were temporarily clustered during the period, from March 2007 to April 2009 (relative risk, RR = 13.7, p < 0.001). And two spatial clusters of which radiuses were 0.3 km (RR = 6.9, p < 0.001) and 0.9 km (RR = 3.6, p < 0.01). The analysis to find risk factors was performed on 99 dairy farms (21 outbreaks), which are located in the most seriously affected village during 2007-2009. Middleman (odds ratio, OR = 47.4, p < 0.05) and raw milk collecting system (OR = 6.9, p < 0.05) were recognized as with the highest association. Considering the fact that all the outbreak farms except one had their own manure composting tank, it might be that the manure containing pathogen was leaked from tank and transmitted to other farms by fomites such as middleman or raw milk collecting system.

• Journal of Life Science
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• v.19 no.9
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• pp.1304-1308
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• 2009

To investigate the infection patterns of porcine epidemic diarrhea virus (PEDV) in Korean pig farms, a total of 4,768 swine sera samples from 159 pig farms were taken twice, in June (n=82) and October (n=77) in 2007. In each farm selected for the survey, 10 samples from breeding pigs and 4 from each of the 5 age groups (30, 60, 90, 120, and 150 days) were taken, and all serum samples were tested for PEDV by the serum neutralization test. The overall seroprevalence was 62.6% (2,983/4,768), with the highest prevalence in breeding pigs (93.5%, 1,485/1,589). The prevalence showed an increasing trend with increasing age (30.8, 27.2, 44.7, 61.6, and 71.2% respectively in the 30, 60, 90, 120, and 150 days age groups) (p<0.0001 for $x^2$ trend test). The association between age and PEDV prevalence was similar in both surveys, indicating that the infection of PEDV seemed to be occurring repeatedly in the farms surveyed. This inference could also be explained by the fact that prevalence in sows was very high despite low vaccination coverage, as they are continuously exposed to PEDV in potentially infected farms for a longer period. Based on the neutralizing antibody levels in sows and growing pigs, the majority of farms (91.8%, n=146 farms) were endemically infected with PEDV, and most of pigs seemed to be intensively infected with PEDV at around early growth (41.8%) and weaning (31.5%). On the other hand, serum neutralizing antibodies were not detected in pigs older than 30 days of age in farms classified as having no PEDV infection (n=13 farms), indicating the level of maternal antibody against PEDV is decreased on a non-detectable level before the piglet is 60 days old in the field situation. The results indicated that most farms surveyed in 2007 were affected with endemic PEDV infection. Therefore, a national monitoring and control program for the endemic type PEDV infection needs further attention.

• Journal of the Korean Data and Information Science Society
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• v.28 no.1
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• pp.153-161
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• 2017

Branching processes which is used for epidemic dispersion as stochastic process model have advantages to estimate parameters by real data. We have to estimate both mean and dispersion parameter in order to use the negative binomial distribution as an offspring distribution on branching processes. In existing studies on biology and epidemiology, it is estimated using maximum-likelihood methods. However, for most of epidemic data, it is hard to get the best precision of maximum-likelihood estimator. We suggest a Bayesian inference that have good properties of statistics for small-sample. After estimating dispersion parameter we modelled the posterior distribution for 2015 Korea MERS cases. As the result, we found that the estimated dispersion parameter is relatively stable no matter how we assume prior distribution. We also computed extinction probabilities on branching processes using estimated dispersion parameters.

• Research in Plant Disease
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• v.10 no.2
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• pp.121-125
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• 2004

An epidemic of target leaf spot of cucumber (Cucumis sativus) occurred in commercial greenhouses in Korea in 2000/2001. The early symptoms on the leaves were small brown spots with yellow halos. These lesions became irregular enlarging in diameter and eventually defoliation resulted. The causal agent was a fungus with morphological characteristics matching Corynespora cassiicola. The sequence of the ITS region of C. cassiicola CM2000-1 was identical to that of an authentic strain of Corynespora cassiicola. Optimal germination of spores and mycelial growth on plate was at 3$0^{\circ}C$. A long dew period on the leaf surface and high temperatures were the main contributing factors for disease development and the greenhouse epidemic. Artificial inoculation of the Korean isolate of C. cassiicola revealed resistance in some Korean cucumber cultivars.

• Korean Journal of Veterinary Research
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• v.48 no.2
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• pp.167-174
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• 2008

Lactic acid bacteria have been reported their beneficial roles on host including reduction of infectious diarrhea problems. In this study, preventive effect of Lactobacillus (L.) reuteri HY25101 and L. johnsonii HY25103 on porcine epidemic diarrhea virus (PEDV) was investigated in suckling piglets. Two groups of one day old PEDV naïve piglets were orally administered L. reuteri HY25101 and L. johnsonii HY25103 for three days respectively before challenge with lethal dose of PEDV. In second experiment, passive immunized one day old piglets using colostrums containing PEDV specific IgA were used. The survival rates of the L. reuteri HY25101 administered group were significantly higher than that of L. johnsonii HY25103 administered group and viral shedding was rapidly diminished in L. reuteri HY25101 administered group. Interestingly piglets born from the sow immunized with attenuated PEDV vaccine were not completely protected from PEDV challenge, however coadministeration of L. reuteri HY25101 and colostrums containing PEDV specific IgA were more effectively prevent PEDV infection. These results suggested that dietary treatment using L. reuteri HY25101 could reduce diarrheal problem and mortality rate caused by PEDV in suckling pigs. In addition, L. reuteri HY25101 could be used as one of effective compensation treatment with attenuated live vaccine for PED.

• Korean Journal of Veterinary Research
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• v.34 no.2
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• pp.321-326
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• 1994

Korean isolate, porcine epidemic diarrhea virus (KPEDV-9) was adapted through serial passages in vero cell. The viral yield reached up to $10^{5-6}$ $TCID_{50}/ml$ at the passage level of 90th. The cell adapted virus was characterized through genetic and morphological examinations. The RNA extracted from virus infected cell revealed the presence of RNA band with molecular size of >20Kb. The electron microscopic examination on purified virus showed the pleomorphic appearance of enveloped particles with 5-10nm surface projections, which fit with the shape of coronavirus. The etiological survey on swine diarrhea by immunofluorescence test(FA) indicated 17.5% positive rate on the PEDV infection. In addition, the incidence were detected both in piglets within two weeks old as well as fattening pigs. Serological survey by ELISA revealed the overall 45% positive result, thus, indicating the PEDV infection are widespread throughout this country.

• Journal of Animal Science and Technology
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• v.57 no.10
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• pp.33.1-33.7
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• 2015

The objective of this study was to evaluate effects of a combined use of extracts of medicinal herbs Taraxaumi mongolicum, Viola yedoensis Makino, Rhizoma coptidis, and Radix isatidis (MYCI) on porcine epidemic diarrhea (PED). Twenty-two 3-day-old piglets received an oral challenge with $3{\times}10^{3.5}$ $TCID_{50}$ of the virulent PED virus (PEDV) in PBS or PBS only and daily oral administration of 60 mg of the MYCI mixture suspended in milk replacer or the vehicle for 7 days in a $2{\times}2$ factorial arrangement of treatments. Average daily gain (ADG) increased (p < 0.05) in response to the MYCI treatment in the PEDV-challenged piglets (-18 vs. 7 g for the vehicle- vs. MYCI-administered group), but not in unchallenged animals (27 vs. 28 g). Diarrhea score and fecal PEDV shedding, however, were not influenced by the MYCI treatment. The PEDV challenge caused severe intestinal villus atrophy and crypt hyperplasia, both of which were alleviated by administration of the MYCI mixture as indicated by an increase in the villus height and a decrease in the crypt depth due to the treatment. Overall, medicinal herb extracts used in this study ameliorated impaired growth performance and intestinal lesion of newborn piglets challenged with the virulent PEDV. Therefore, our results suggest that the MYCI mixture could be used as a prophylactic or therapeutic agent against PED.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.865-875
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• 2008

In this paper, we propose a reliable multicast scheme for the tactical wireless ad hoc network where the members share the situation and operation data. Our scheme consists of two phases to guarantee the reliability. During the dissemination phase, we utilizes an epidemic approach similar to gossip-based ad hoc routing. Then the group members interchange the message reception state information periodically so that they are able to recover missing packets from the other members. We evaluate the performance of our scheme through extensive simulations using the network simulator in comparison with other existing reliable multicast schemes in mobile ad hoc network. Our scheme shows higher packet delivery ratio regardless of the mobility and imposes much lower control overhead to the non-group members compared with the existing schemes.

• Journal of the Korean Data and Information Science Society
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• v.26 no.2
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• pp.301-312
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• 2015

The purpose of this paper is to establish the epidemic model to explain the process of disease spread. The process of disease spread can be classified into two types: deterministic process and stochastic process. Most studies supposed that the process follows the deterministic process and established the model using the ordinary differential equation. In this article, we try to build the disease spread prediction model based on the SIR (Suspectible - Infectious - Recovered) model. we first estimated the model parameters using least squared method and applied to a deterministic model using ordinary differential equation. we also applied to a stochastic model based on Gillespie algorithm. The methods introduced in this paper are applied to the data on the number of cases of malaria every week from January 2001 to March 2003, released by Korea Centers for Disease Control and Prevention. As a result, we conclude that our model explains well the process of disease spread.

• Korean Journal of Veterinary Research
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• v.46 no.3
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• pp.197-206
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• 2006

In March 2003, classical swine fever (CSF) infection was reported in a piggery located at Iksan city, Jeollabuk-do in Korea. Subsequently, a total of 72 infected farms were confirmed between March and December, 2003. Based on epidemiological investigation of the earlier confirmed infected farms, the source of infection was shown to be from a breeding farm. Targeted surveillance of 82 piggeries that had acquired pigs from this breeding farm showed 44 piggeries were infected with CSF virus. CSF virus was introduced into this breeding farm by movement of selected breeder pigs from its 12 contracted farms which were located in areas that had been affected by CSF epidemic in late 2002. CSF had then spread through out the country mainly by direct transmission through the sale and movement of pigs from this breeding farm. Consequently, 47 (62%) among 72 CSF affected farms were associated, directly and indirectly, with this breeding farm. This study showed that inadequate control for breeding farms and transport restriction in CSF outbreak areas resulted in the nationwide spread of CSF and the failure of the eradication campaign that has been underway for several years by the Korean animal hygiene authority as well as the fanners. Improvements of control policy through further research of the 2003 CSF epidemic will be needed to reestablish the Korean CSF eradication program in the future.