• Clinical and Experimental Pediatrics
• /
• v.50 no.3
• /
• pp.262-267
• /
• 2007

Purpose : The prevalence of hepatitis A virus (HAV) in a certain community reflects that community's living standards and hygienic conditions. And the pattern of HAV infection differs over time and geography. Recently, a shift in prevalence has been observed in cases from chilhood to adulthood. We studied the HAV antibody prevalence in the general population in Busan. Methods : From October 2004 to March 2005, total 472 subjects were tested for HAV antibodies. All samples were collected from patients in Maryknol Hospital. Results : The overall seropositive rate was 22.8% (108/472). The seropositive rates were 1.7% in subjects aged 2-5 years, 1.7% in 6-10 years, 0% in 11-20 years, 40.5% in 21-30 years, 82.1% in 31-40 years, 94.7% in 41-50 years, and 100% in subjects aged over 50 years. There was no significant gap between gender groups. Conclusion : As the socioeconomic conditions in Korea have improved, the HAV seropositive rate in school-aged children has dramatically decreased in the last 20 years. But, the seropositive rate of HAV didn't differ according to gender. The seropositive rate of HAV in the pediatric group was very low, which suggests the increasing possibility of clinical HAV infection in adults in the near future. Therefore, we should actively prevent the spread of hepatits A virus. In order to do that, we need to reorganize our lifestyle and personel hygiene and carry out active and passive immunization to high risk groups.

• Pediatric Infection and Vaccine
• /
• v.15 no.2
• /
• pp.162-166
• /
• 2008

Purpose : It has been previously reported that for patients with Mycoplasma pneumoniae pneumonia was previously recognized that overt illness is unusual under the age of three and the peak incidence of illness occurs in school-aged children. However, a higher incidence of this illness in younger children has been recently noted. Thus we investigated the incidence of M. pneumoniae pneumonia. Methods : The study subjects were 414 children who were diagnosed with M. pneumoniae pneumonia from January 2004 to December 2006 at Myong Ji Hospital were enrolled. The diagnostic criteria consisted of an anti-mycoplasma antibody (AMA) titer greater than 1: 320 or a four-fold rise in the titer at follow up. Results : The age distribution was as follows: before 2 years of age: 58 patients (14%), 2-4 years of age 157 patients (37.9%) and 5-15 years of age 199 patients (48.1%). The yearly incidence for the children before 5 years of age was 52 (44%), 49 (44.6%) and 114 (61.3%), respectively. The distribution according to the antibody titer was as follows; 1: 320 in 130 patients, 1:640 in 63 patients and greater than 1:1,280 in 221 patients. The hospital stay according to the antibody titer was not significant according to either age or the AMA titers. Conclusion : M. pneumoniae pneumonia showed a peak incidence in preschool children with a higher prevalence in children under the age of three than was previously recognized. The emergence of M. pneumoniae pneumonia as a cause of community acquired pneumonia in younger children calls for an epidemiologic study to investigate the changes of the pathogens in this age group and to recommend the proper treatment.

• Clinical and Experimental Pediatrics
• /
• v.45 no.8
• /
• pp.980-986
• /
• 2002

Purpose : Although the number of patients with measles have dramatically decreased since the introduction of measles vaccines in 1965, measles outbreaks have occurred periodically every 4-6 years during the 1990s(1989-1990 and 1993-1994). During 2000-2001, measles prevailed all over the country again. A characteristic of current epidemics is that the majority of affected population was infants and school-aged children. This study was designed to analyze the epidemic and clinical features of measles prevalence during 2000-2001 and to find ways to overcome vaccination failure. Methods : We reviewed the records of 59 patients with mealses admitted in the Pediatric Department of Pusan National University Hospital from January 2000 to October 2001 for patient's age, month of admission, history of vaccination, clinical features and complications. Antibody titers of measles-specific IgM and IgG were measured by enzyme immunoassay. Results : The epidemic show two peaks in the age distribution. Forty three patients(72.9%) were under 2-years of age and 14 patients(23.7%) were over 5-years of age. Outbreaks had high incidence in July to August, 2000 and March to April, 2001, then faded away after July, 2001. Vaccinated group comprised 30.5% and unvaccinated group comprised 69.5% and their mean age was $9.25{\pm}4.27$ years old and $0.95{\pm}0.30$ years old respectively. Positive rate of IgM was 86.7% in vaccinated group and 90.3% in unvaccinated group. This means there was primary vaccine failure; 13 cases of 15 vaccinated patients were positive in IgM antibody. During the prevalence, two patients died with mealses complication. One of them was immunocompromised. Conclusion : To prevent another prevalence of measles in the future, we must enhance revaccination at ages 4-6 and check vaccination status when children enter elementary school. These will produce over 95% of herd immunity, with catch-up MMR vaccination which has been completed already.

• Korean Journal of Poultry Science
• /
• v.39 no.2
• /
• pp.97-104
• /
• 2012

Newcastle disease virus (NDV) infects a variety of birds with a wide range of clinical signs from asymptomatic to severe. During a 10-month period in 2011, a total of 1,024 sera from wild birds including 42 species of birds in 8 orders were collected and the seroprevalence of NDV in wild birds was evaluated by hemagglutination inhibition (HI) test. Evidence of NDV infection was observed in 12.6% (129/1,024) of wild birds with a maximum prevalence reported in Mandarin duck (27.8%, 32/115) followed by Mallard duck (20.8%, 57/274), Spot-billed duck (11.9%, 36/303), Pintail (2.9%, 1/34), Black-tailed gull (2.9%, 1/34), White-fronted goose (1.8%, 1/56) and Common teal (1.4%, 1/69). None of the other 35 species of wild birds were antibody-positive for NDV. Mandarin duck, Mallard duck and Spot-billed duck showed high sero-prevalance of 12.2% to 42% during winter season (November to March). Our results indicate that Mandarin duck, Mallard duck and Spot-billed duck might be natural reservoirs for NDV in Korea and the prevalence of NDV infection in wild birds displayed a seasonal pattern with high prevalence of NDV in winter season (November to March).

• Journal of Life Science
• /
• v.23 no.10
• /
• pp.1267-1272
• /
• 2013

The aim of this study was to determine the prevalence and infection status of Salmonella species (spp.) in 25 conventional pig farms by traditional fecal culture and serological methods to develop a Salmonella control program for Korean pig farms. The individual seroprevalence of Salmonella spp. in pigs reared in the 25 pig farms was 83.1% in sows and 6.4-32% in different aged pig groups, with the total seroprevalence 28.4% (141/848). The seroprevalence of the tested pigs increased in accordance with the decrease in maternal antibody and the rearing period on these farms. Of note, all the 25 pig farms contained at least two or more anti-Salmonella antibody-positive sows. In the fecal cultures Salmonella spp. were isolated only in three (12.0%, 3/25) of 16 serologically Salmonella-suspected farms (64.0%, 16/25), showing the limitation of the fecal culture method and the need for serum assays to understand the exact status of Salmonella infection in swine herds, which likely contain subclinically infected pigs or carriers. The results highlight the need to establish a supply system of Salmonella-free gilts for the promotion of a national Salmonella control program on swine farms in Korea. Further studies will be needed to develop an effective monitoring system for the implementation of a national Salmonella control program.

• Clinical and Experimental Pediatrics
• /
• v.45 no.3
• /
• pp.331-338
• /
• 2002

Purpose : To investigate the feature of the range of measles in 2000, we studied epidemics of the measles in western Kyungnam District. Methods : Among 489 patients under 15 years of age who visited or were admitted to in our hospital from January to December in 2000, we selected 344 patients whose measles IgM antibody was positive. We investigated age, monthly incidence, clinical features, vaccination history, and measles IgG antibody. Results : Patients under 12 months of age occupied the largest proportion(36.9%). Patients firstly occurred in May and geometrically increased from October. Fever, cough and rashes were observed in all patients but conjunctivitis in 54.9%, Koplik spot in 23.8%. The first vaccination ratio was 41.8%. Compared with the number of patients and the first vaccination ratio, the first vaccination ratio was the lowest under 12 months of age. After that age group, the number of patients was decreased as the first vaccination ratio was increased. Among 152 patients sampled for measles IgG antibody, 35 patients had received the first vaccination and 6 patients had received the second vaccination. Among 35 patients who received the first vaccination, 22(62.9%) patients were negative of measles IgG antibody. Among 6 patients who received the second vaccination, 3(50%) patients were negative. Conclusions : Measles patients under 12 months still dominated. Therefore, routine vaccination of single measles vaccine, is currently done at 6 month when measles are prevalent, should be considered. High first vaccination failure suggests problems of vaccines itself, transport and storage rather than vaccination methods. Therefore a thorough investigation should be made.

• Journal of Veterinary Clinics
• /
• v.21 no.3
• /
• pp.229-235
• /
• 2004

To characterize the recent outbreaks of canine distemper (CD) in Korea, we carried out epidemiological investigations by clinical observations, serum neutralizing (SN) antibody titer determination and RT-PCR on the 315 dogs which were clinically suspected as canine distemper virus (CDV) infection. One hundred and sixty two of 315 dogs were infected with CDV. Breed or gender did not seem to have effects on the prevalence of CD. The major part of dogs were in young age from 6 weeks to 18 weeks of age, and were not vaccinated or incompletely vaccinated. Clinical signs of dogs with CD were multi systemic and extremely variable. Dogs died from CD had significantly more ocular signs and neurologic signs than those of dogs survived (p<0.05). The SN titers against CDV of 157 (96.9%) dogs were under 1:16, which is less than protective level. One possible explanation for recent outbreaks of CD in Korea might be low antibody titers against CDV because of vaccination failure. Therefore, to reduce the impact of virulent infection in the dog population, dogs should be vaccinated adequately and prophylactic measures should include isolation of young dogs from the dog population until vaccination can be expected to provide protection.

• Parasites, Hosts and Diseases
• /
• v.33 no.1
• /
• pp.27-36
• /
• 1995

Comparative epidemiological studies on vector reservoir animals of tsutsugamushi disease were carried out in between south coast (the highest endemic) areas and east coast flow endemicl areas in October 1993. Fauna of field rodents and their population densities were not different between two areas. Antibody positive rate of Apodemus agrarius sera was higher in east coast (43.2% in south coast and 63.6% in east coast). High correlation (r = 0.87) was shown between antibody positive rate of A. osrwiur sera and population density of the vector mites (Leptotrombidium scutellare and 1. pnllidunl). L. scutellare was predominant in south coast, showing 110.6 chigger index (74.9% of the total chiggersl , whereas L. pcllidum was predominant in east coast, showing 126.3 chigger index (60.4% of the total). As higher population density of 1. scutellare was found in south coast where the prevalence rate of tsutsugamushi disease is the highest, it is believed that L. scutellare is more important vector species than L. pallidum which may result from more frequent vector-human contact.

• Journal of Veterinary Clinics
• /
• v.33 no.2
• /
• pp.102-106
• /
• 2016

More than 20 years after the first report of porcine reproductive and respiratory syndrome virus (PRRSV) in Korea, the disease is still having major impact on domestic pig health and relevant industries. Although ELISA tests are commonly used by veterinarians to guide herd management, data on diagnostic performance of the test in field settings are very limited. The objective of this study was to evaluate two commercially available PRRSV ELISA (IDEXX PRRS X3 ELISA and Bionote PRRSV ELISA 4.0) to detect antibodies against PRRSV on serum samples. To this end, a total of 1,108 sera were recruited from 35 swine farms located in Gyeonggi province and tested at the Gyeonggi Province Veterinary Service Center. All tests were performed according to the manufacturer's instructions, by laboratory technicians who routinely perform PRRS testing on blood samples. Samples were collected from two sources of swine populations with different PRRS prevalence; 60 samples (5.4%) were originated from breeding farms and the remaining 1,048 samples (94.6%) were from farrow-to-finish farms. We applied Bayesian latent class model (LCM) for two-tests in the two-population when the accuracy of the gold standard is not available. The model estimated that Bionote ELISA was a bit more specific but slightly less sensitive. The estimated sensitivity and specificity of the IDEXX ELISA were 99.8% (95% CI 98.1-100%) and 86.4% (95% CI 81.4-96.5%), respectively. Sensitivity, specificity, positive predictive value and negative predictive value for Bionote kit were 98.7% (95% CI 92.8-100%), 89.8% (95% CI 86.2-93.1%), 93.8% (95% CI 91.5-96.0%), and 97.8% (95% CI 87.1-100%), respectively. Based on the Bayesian 95% credible intervals, the sensitivity and specificity of the two ELISAs were not significantly different each other when assuming that two kits were imperfect, indicating that two kits performed equally well in terms of sensitivity and specificity in our filed setting.

• Korean Journal of Clinical Laboratory Science
• /
• v.54 no.2
• /
• pp.79-94
• /
• 2022

Due to the highly contagious nature and severity of the respiratory diseases caused by COVID-19, economical and accurate tests are required to better monitor and prevent the spread of this contagion. As the structural and molecular properties of SARS-CoV-2 were being revealed during the early stage of the COVID-19 pandemic, many manufacturers of COVID-19 diagnostic kits actively invested in the design, development, validation, verification, and implementation of diagnostic tests. Currently, diagnostic tests for SARS-CoV-2 are the most widely used and validated techniques for rapid antigen, and immuno-serological assays for specific IgG and IgM antibody tests and molecular diagnostic tests. Molecular diagnostic assays are the gold standard for direct detection of viral RNA in individuals suspected to be infected with SARS-CoV-2. Antibody-based serological tests are indirect tests applied to determine COVID-19 prevalence in the community and identify individuals who have obtained immunity. In the future, it is necessary to explore technical problems encountered in the early stages of global or regional outbreaks of pandemics and provide future directions for better diagnostic tests. This article evaluates the commercially available and FDA-approved molecular and immunological diagnostic assays and analyzes their performance characteristics.