• Korean Journal of Veterinary Research
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• v.41 no.1
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• pp.89-98
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• 2001

This study was conducted to detect the toxoplasma specific-DNA in circulating blood and organs collected from slaughtered pigs at slaughtering house and experimentally infected pigs with Toxoplasma gondii tachyzoites by polymerase chain reaction(PCR), and also PCR was applied to diagnose for acute phase of swine toxoplasmosis as a newly developed diagnostic test. The sensitivity of oligonucleotide primer, T-1 & T-2, designed from toxoplasma B1 gene amplification method was compared with Tp parasite detection by mouse inoculation(MI). On the other hand, latex agglutination test(LAT) was conducted to detect the serum antibodies comparing with the detection of toxoplasma by PCR and MI. The results obtained were summarized as follows. PCR was able to determine at the lowest level of $10^0/ml$ T. gondii in blood samples which were blended with a serial diluted T gondii in vitro. On the other hand, $10^2/5g$ of T gondii could detect from a variety of tissues including lung, diaphragm, liver, heart, spleen and brain in vitro. The primer was proved to specifically determine T gondii in blood and tissues in vitro but it did not detect Neospora caninum used as a negative control. DNA of T. gondii was effectively extracted by freezing, thawing and grinding twice both tissues mixed with T gondii in vitro and in experimentally infected pig's tissues. PCR detected specific DNA in the blood of experimentally infected pigs at 108 hrs and 120 hrs post-infection, it was the same time that the pigs showed fever and parasitaemia. In case of tissue, specific DNA was, however, detected only lung from experimentally infected pigs. Even though the duration of acute phase was from 3 to 7 days post-infection, but the latex agglutination test (LAT) results appeared from 8 days post-infection. A comparison of sensitivity in determining T gondii in blood samples between PCR and MI, PCR positive rate ranged from 25 to 33.3%, but that of MI covered from 75 to 100%.

• Clinical and Experimental Pediatrics
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• v.64 no.12
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• pp.652-660
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• 2021

Background: Viral load and shedding duration are highly associated with the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. However, limited studies have reported on viral load or shedding in children and adolescents infected with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Purpose: This study aimed to investigate the natural course of viral load in asymptomatic or mild pediatric cases. Methods: Thirty-one children (<18 years) with confirmed SARS-CoV-2 infection were hospitalized and enrolled in this study. Viral loads were evaluated in nasopharyngeal swab samples using real-time reverse transcription polymerase chain reaction (E, RdRp, N genes). cycle threshold (Ct) values were measured when patients met the clinical criteria to be released from quarantine. Results: The mean age of the patients was 9.8 years, 18 (58%) had mild disease, and 13 (42%) were asymptomatic. Most children were infected by adult family members, most commonly by their mothers. The most common symptoms were fever and sputum (26%), followed by cough and runny nose. Nine patients (29%) had a high or intermediate viral load (Ct value≤30) when they had no clinical symptoms. Viral load showed no difference between symptomatic and asymptomatic patients. Viral rebounds were found in 15 cases (48%), which contributed to prolonged viral detection. The mean duration of viral detection was 25.6 days. Viral loads were significantly lower in patients with viral rebounds than in those with no rebound (E, P=0.003; RdRp, P=0.01; N, P=0.02). Conclusion: Our study showed that many pediatric patients with coronavirus disease 2019 (COVID-19) experienced viral rebound and showed viral detection for more than 3 weeks. Further studies are needed to investigate the relationship between viral rebound and infectiousness in COVID-19.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.2
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• pp.299-306
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• 2016

Body temperature (BT) monitoring in cattle could be used to early detect fever from infectious disease or physiological events. Various ways to measure BT have been applied at different locations on cattle including rectum, reticulum, milk, subcutis and ear canal. In other to evaluate the temperature stability and reliability of subcutaneous temperature (ST) in highly fluctuating field conditions for continuous BT monitoring, long term ST profiles were collected and analyzed from cattle in autumn/winter and summer season by surgically implanted thermo-logger devices. Purposes of this study were to assess ST in the field condition as a reference BT and to determine any location effect of implantation on ST profile. In results, ST profile in cattle showed a clear circadian rhythm with daily lowest at 05:00 to 07:00 AM and highest around midnight and rather stable temperature readings (mean${\pm}$standard deviation [SD], $37.1^{\circ}C$ to $37.36^{\circ}C{\pm}0.91^{\circ}C$ to $1.02^{\circ}C$). STs are $1.39^{\circ}C$ to $1.65^{\circ}C$ lower than the rectal temperature and sometimes showed an irregular temperature drop below the normal physiologic one: 19.4% or 36.4% of 54,192 readings were below $36.5^{\circ}C$ or $37^{\circ}C$, respectively. Thus, for BT monitoring purposes in a fever-alarming-system, a correction algorithm is necessary to remove the influences of ambient temperature and animal resting behavior especially in winter time. One way to do this is simply discard outlier readings below $36.5^{\circ}C$ or $37^{\circ}C$ resulting in a much improved mean${\pm}$SD of $37.6^{\circ}C{\pm}0.64^{\circ}C$ or $37.8^{\circ}C{\pm}0.55^{\circ}C$, respectively. For location the upper scapula region seems the most reliable and convenient site for implantation of a thermo-sensor tag in terms of relatively low influence by ambient temperature and easy insertion compared to lower scapula or lateral neck.

• Korean Journal of Veterinary Research
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• v.57 no.3
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• pp.169-174
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• 2017

This study was performed to investigate the distribution of ticks and the rate of infection with severe fever with thrombocytopenia syndrome (SFTS) virus in ticks collected at Mt. Gwanak and the Seoul National University campus, Korea. Ticks (n = 273) were collected from May to October and included 76 Haemaphysalis longicornis (4 adult females, 72 nymphs), 49 Haemaphysalis flava (9 adult females, 3 adult males, 37 nymphs), and 148 Haemaphysalis spp. larvae. SFTS virus detection was performed by using one-step RT PCR and nested PCR. The SFTS virus was detected in 7 samples (1 Haemaphysalis longicornis nymph, 3 Haemaphysalis flava nymphs, and 3 Haemaphysalis spp. larva). The overall minimum field infection rate was 2.6%, whereas the minimum field infection rates of adult, nymphal, and larval ticks were 0%, 3.2%, and 2.0%, respectively. For a more accurate indication of the prevalence of SFTS virus in Korea, further in-depth investigations of tick species and SFTS virus occurrence over a larger area and longer period are needed.

• Korean Journal of Veterinary Service
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• v.45 no.2
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• pp.71-77
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• 2022

African swine fever (ASF) is a fatal viral disease in pigs, with a short incubation period and causing immediate death. Few studies exist on the Asian epidemic ASF virus (ASFV) challenge in older pigs, including growing and fattening pigs and sows. We aimed to investigate clinical outcomes, pathomorphological lesions, and viral distribution in organs of 3-month-old growing pigs that were inoculated with the ASFV isolated in Vietnam. The clinical outcomes were recorded daily, and the dead or euthanized pigs immediately underwent necropsy. Viral loads were determined in 10 major organs using quantitative polymerase chain reaction. The average incubation period in growing pigs was more delayed (5.2±0.9 dpi) than that in weaned pigs, and the clinical signs were milder in growing pigs than in weaned pigs. The digestive and respiratory clinical signs in growing pigs showed at the end period of life, but these were observed at an early stage of infection in weaned pigs. The pathomorphological features were severe and nonspecific with hemorrhagic lesions in various organs. The viral loads in organs from growing pigs were higher than those from piglets, and the number of viral copies was related to gross lesions in the tonsil and intestine. In the absence of vaccines against ASF, early clinical detection is important for preventing the spread of the virus. Our findings elucidated that the clinical signs and gross lesions in growing pigs differed from those in weaned pigs, which provide valuable information for diagnosis of pigs with suspected ASF infection.

• Biomedical Science Letters
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• v.3 no.2
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• pp.95-105
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• 1997

Currently, the laboratory diagnosis for lyme disease have been performed with the detection of antibodies against Borrelia burgdorferi. However there might be some difficulties in the interpretation of obtained results due to the usage of foreign isolates as an antigen in the test. Therefore the optimization of serological tests with Korean isolates of B. burgdorferi as an antigen would be needed to establish the standardized diagnostic method for the detection of antibodies against B. burgdorferi infection. In this study, the optimization of ELISA was investigated with experimentally challenged rabbit sera and sonicated B. burgdorferi antigens of Korean isolates. Of 217 human patient's sera with unknown fever, the mean seropositivities in ELISA, done under the optimized conditions obtained in this study, were found to be about 8％ against B. burgdorferi sensu late, showing the highest seropositivity of 14.3％ against B. afzelii. In immunoblotting assay with ELISA-positive human sera, the major reactive bands were 41kDa (flagellin) which might be the indication of early infection, and 27kDa, 31kDa (OspA), 34kDa (OspB) which are the characteristics of late infection. Obtained results in this study might strongly indicate the possibility of B. burgdorferi infections in Korea.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1928-1936
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• 2018

Recently, human infections caused by severe fever with thrombocytopenia syndrome virus (SFTSV), which can lead to fatality, have dramatically increased in East Asia. With the unavailability of vaccines or antiviral drugs to prevent and/or treat SFTSV infection, early rapid diagnosis is critical for prevention and control of the disease. Here, we report the development of a simple, rapid and sensitive portable detection method for SFTSV infection applying reverse transcription-loop mediated isothermal amplification (RT-LAMP) combined with one-pot colorimetric visualization and electro-free reaction platform. This method utilizes a pocket warmer to facilitate diagnosis in a resource-limited setting. Specific primers were designed to target the highly-conserved region of L gene of SFTSV. The detection limit of the RT-LAMP assay was approximately $10^0$ viral genome copies from three different SFTSV strains. This assay exhibited comparable sensitivity to qRT-PCR and 10-fold more sensitivity than conventional RT-PCR, with a rapid detection time of 30 to 60 minutes. The RT-LAMP assay using SFTSV clinical specimens has demonstrated a similar detection rate to qRT-PCR and a higher detection rate compared to conventional RT-PCR. Moreover, there was no observed cross-reactive amplification of other human infectious viruses including Japanese Encephalitis Virus (JEV), Dengue, Enterovirus, Zika, Influenza and Middle East Respiratory Syndrome Coronavirus (MERS-CoV). This highly sensitive, electro- and equipment-free rapid colorimetric visualization method is feasible for resource-limited SFTSV field diagnosis.

• Clinical and Experimental Pediatrics
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• v.57 no.8
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• pp.357-362
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• 2014

Purpose: The incidence of Kawasaki disease (KD) is rare in young infants (less than 3 months of age), who present with only a few symptoms that fulfill the clinical diagnostic criteria. The diagnosis for KD can therefore be delayed, leading to a high risk of cardiac complications. We examined the clinical characteristics and measured the serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) levels of these patients for assessing its value in the early detection of KD. Methods: We retrospectively reviewed the data of young infants diagnosed with KD from 2004 to 2012. The control group included 20 hospitalized febrile patients. Laboratory data, including NT-proBNP were obtained for each patient in both groups. Results: Incomplete KD was observed in 21/24 patients (87.5%). The mean fever duration on admission was $1.36{\pm}1.0$ days in the KD group. Common symptoms included erythema at the site of Bacille Calmette-Guerin inoculation (70.8%), skin rash (50.0%), changes of oropharyngeal mucosa (29.1%), and cervical lymphadenopathy (20.8%). The mean number of major diagnostic criteria fulfilled was $2.8{\pm}1.4$. Five KD patients (20.8%) had only one symptom matching these criteria. The incidence of coronary artery complications was 12.5%. The mean serum NT-proBNP level in the acute phase, in the KD and control groups, were $4,159{\pm}3,714pg/mL$ and $957{\pm}902pg/mL$, respectively, which decreased significantly in the convalescent phase. Conclusion: Incomplete KD was observed in 87.5% patients. Serum NT- proBNP might be a valuable biomarker for the early detection of KD in febrile infants aged <3 months.

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.763-770
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• 1998

Salmonella typhimurium is a causitive agent of diarrhea, fever, gastroenteritis, septicemia and sudden death in piglet. The currently used methods such as IFA, ELISA, DNA hybridization assay is needed a long-time and difficult to detect the organism in carrier animal or contaminated sample with other agents. However, it is important to detect rapidly and sensitively S typhimurium in piglet with other infectious pathogens to minimize an economic loss. Two sets of PCR primer, rfbJ forward primer(5'-AGAATATGTAATTGTCAG-3') and reverse primer(5'-TAACCGTTTCAGTAGTTC-3') were designed to amplify a 882 by fragment of Salmonella serovar type B gene. The target genomic DNA for PCR was extracted from the cultivated materials with various enrichment periods in a nonselective enrichment agar and broth with clinical specimens. The PCR is carried out here made it possible to detect the gene from two hours. Also, the amplified fragment with PCR was cloned into pGEM-T vector and digested with restrict enzyme, and sequenced for the identification of Salmonella serotype B rfbJ gene. Duplicated cultivation agar-broth followed by PCR were performed to develop a rapid and sensitive detection of S typhlmurium based on serovar type. This duplicated cultivation-PCR method provides a sensitive and rapid diagnostic tool to detect Salmonella from infected piglet with improved sensitivity.

• Tuberculosis and Respiratory Diseases
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• v.76 no.5
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• pp.240-244
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• 2014

Pancreaticothoracic fistula is a rare complication of acute or chronic alcoholic pancreatitis. It may present with various symptoms, like dyspnea, abdominal pain, cough, chest pain, fever, back pain, hemoptysis, fatigue, or orthopnea. Pancreaticothoracic fistula can be detected by magnetic resonance cholangiopancreatography (MRCP), endoscopic retrograde cholangiopancreatography (ERCP), or computed tomography. MRCP has high sensitivity and fewer side effects, and thus it has recently been recommended as the first choice for the detection of pancreaticothoracic fistula. On the other hand, ERCP enables the detection and treatment of pancreaticothoracic fistula and allows for stent insertion; for this reason it is a commonly used modality in pancreaticothoracic fistula cases. Herein, the authors describe a case of pancreaticothoracic fistula detected by ERCP and MRCP that manifested only respiratory symptoms, namely hemoptysis and pneumothorax without abdominal pain, which commonly accompanies pancreatitis.