| Shin-Hyeong Cho | 6 Articles |
<sec>
<title>Objectives</title>
<p>Chigger mites are vectors for scrub typhus. This study evaluated the annual fluctuations in chigger mite populations and <italic>Orientia tsutsugamushi</italic> infections in South Korea.</p></sec>
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<title>Methods</title>
<p>During 2006 and 2007, chigger mites were collected monthly from wild rodents in 4 scrub typhus endemic regions of South Korea. The chigger mites were classified based on morphological characteristics, and analyzed using nested PCR for the detection of <italic>Orientia tsutsugamushi</italic>.</p></sec>
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<title>Results</title>
<p>During the surveillance period, the overall trapping rate for wild rodents was 10.8%. In total, 17,457 chigger mites (representing 5 genera and 15 species) were collected, and the average chigger index (representing the number of chigger mites per rodent), was 31.7. The monthly chigger index was consistently high (> 30) in Spring (March to April) and Autumn (October to November). The mite species included <italic>Leptotrombidium pallidum</italic> (43.5%), <italic>L. orientale</italic> (18.9%), <italic>L. scutellare</italic> (18.1%), <italic>L. palpale</italic> (10.6%), and <italic>L. zetum</italic> (3.6%). <italic>L. scutellare</italic> and <italic>L. palpale</italic> populations, were relatively higher in Autumn. Monthly <italic>O. tsutsugamushi</italic> infection rates in wild rodents (average: 4.8%) and chigger mites (average: 0.7%) peaked in Spring and Autumn.</p></sec>
<sec>
<title>Conclusion</title>
<p>The findings demonstrated a bimodal pattern of the incidence of <italic>O. tsutsugamushi</italic> infections. Higher infection rates were observed in both wild rodents and chigger mites, in Spring and Autumn. However, this did not reflect the unimodal incidence of scrub typhus in Autumn. Further studies are needed to identify factors, such as human behavior and harvesting in Autumn that may explain this discordance.</p></sec>
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Objectives
This study aims to develop a high-sensitivity antibody diagnostic kit that will enable a rapid and accurate detection of <i>Cryptospofidium parvum</i> and <i>Giardia lamblia</i> in patients with diarrhea. Methods The cultivated <i>C. parvum</i> oocysts and <i>G. lamblia</i> cysts in each calf and dog were injected to mice to obtain antibodies, which were titrated. Spleen cells of the immunized mouse were separated and blended with myelomas to produce hybrid cell lines that form monoclonal antibodies. Using ELISA method, antibodies that specifically respond to <i>C. parvum</i> and <i>G.lamblia</i> were then selected. The cells were injected into the abdominal cavity of a BALB/c mouse to isolate hydrops abdominis containing high level of antibodies. The IgG antibody was purified using protein G gel. Results The detection limit of monoclonal antibodies for <i>Cryptosporidium parvum</i> and <i>Giardia lamblia</i> was 125 oocysts/mL and 1250 cysts/mL, respectively. In addition, during testing they did not show cross-reactivity to viruses (<i>n</i> = 15), bacteria (<i>n</i> =17), and parasites (<i>n</i> = 9). Conclusion The rapid diagnostic antibody kit developed in this study, which specifically responds to <i>C. parvum</i> and <i>G. lamblia</i>, will be useful in detecting and monitoring diarrheal infections. Citations
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Objectives
To identify the pathogen of the diarrhea outbreak in a village in Jeollabuk province in Korea in April 2010. Methods DNA extraction was performed from the 120 L of collected water, which was centrifuged at 10,000 x g for 30 min. PCR reactions were conducted in a total of 25 ul, which included PCR premix (GenDEPOT, Barker, TX, USA), 2 ul (∼100 ng) of extracted DNA, and 10 pmol of each primer. Results Nine people out of 25 had a symptom of abdominal pain accompanied by diarrhea after they used stored valley water in a water tank as a provisional water supply source without chlorine sterilization. Among them <i>Giardia lamblia</i> was detected in fecal samples of 7 people using the polymerase chain reaction method. Although <i>G. lamblia</i> was also detected from water provided by the provisional water supply system stored in the water tank and used as drinking water, it was not detected in the water tank itself. This water-borne outbreak is considered to have occurred when the provisional water supply tube was destroyed under a building construction and contaminated by <i>G. lamblia</i>, but its precise cause has not been clarified. Conclusion This outbreak resulting from <i>G. lamblia</i> is very meaningful as the first outbreak of an infection by a water-borne parasite in Korea. Citations
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Vivax malaria has reemerged and become endemic in Korea. Our study aimed to analyze by both longitudinal and cross-sectional genetic diversity of this malaria based on the <i>P vivax Merozoite Surface Protein</i> (<i>PvMSP</i>) gene parasites recently found in the Korean peninsula. Methods <i>PvMSP-1</i> gene sequence analysis from <i>P vivax</i> isolates (n = 835) during the 1996-2010 period were longitudinally analyzed and the isolates from the Korean peninsula through South Korea, the demilitarized zone and North Korea collected in 2008-2010 were enrolled in an overall analysis of MSP-1 gene diversity. Results New recombinant subtypes and severe multiple-cloneinfection rates were observed in recent vivax parasites. Regional variation was also observed in the study sites. Conclusion This study revealed the great complexity of genetic variation and rapid dissemination of genes in <i>P vivax.</i> It also showed interesting patterns of diversity depending, on the region in the Korean Peninsula. Understanding the parasiteninsula. Under genetic variation may help to analyze trends and assess the extent of endemic malaria in Korea. Citations
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The prevalence of <i>Clonorchis sinensis</i> infection was investigated among residents of the five major river basins, that is, Hangang, Nakdonggang, Seomjingang, Yeongsangang, and Geumgang River basins in Korea. Methods From January to December 2007, a total of 31,268 stool samples were collected from 29 localities and examined by the formalin-ether sedimentation technique. Results Intestinal parasite eggs and/or protozoan cysts were detected from 2957 (9.5%) inhabitants. Number of residents harbouring helminth eggs in the faeces was 2542 (8.1%) for <i>C. sinensis</i>, 255 (0.8%) for <i>Heterophyes</i> spp., 36 (0.1%) for <i>Echinostoma</i> spp., 30 (0.1%) for <i>Trichuris trichiura</i>, 8 (0.03%) for <i>Ascaris lumbricoides</i>, 7 (0.02%) for <i>Gymnophalloide seoi</i>, and 50 (0.02%) for <i>Trichostrongylus orientalis</i>. Number of residents harbouring protozoan cysts in the faeces was 133 (1.3%) for <i>Entamoeba</i> spp. and 50 (0.2%) for <i>Giardia lamblia.</i> The positive rates of <i>C. sinensis</i> in Nakdonggang, Seomjingang, Yeongsangang, Geumgang, and Hangang River basins were 12.2%, 9.5%, 3.3%, 3.0%, and 1.0%, respectively. The egg positive rate of <i>C. sinensis</i> was higher in male (10.6%) than in female (6.1%), and the age group of 50s had the highest positive rate (10.4%). Conclusion The result of this study revealed little decrease in positive rate of <i>C. sinensis</i> compared with the result of southern endemic areas of Korea in 2006. Citations
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