Background: Dengue fever is considered one of the transfusion-transmissible emerging infectious diseases. Dengue fever has been reported every year by the Korea Disease Control and Prevention Agency (KDCA). Because a blood donor screening assay to detect the dengue virus (DENV) as an agent of dengue fever is not performed, the risk of transfusion-transmitted DENV infection needs to be assessed. Methods: This study collected the data of DENV infected cases from the Infectious Disease Portal of the KDCA, the data of blood donors and blood components from the Blood Information Management System of the Korean Red Cross, and the data of travelers to major dengue outbreak countries from the Korean Tourism Organization.All data were from 2016 to 2018. A risk assessment was performed using European Up-Front Risk Assessment Tool (EUFRAT). Results: The risk of DENV-infected red cells and platelet concentrate was higher than that of plasma and apheresis platelet. Nevertheless, the risk of the DENV infected blood component was shown to be less than one case per year for all kinds of blood components. Conclusion All the DENV infected cases in Korea were overseas travelers. Therefore, the risk of transfusiontransmissible DENV infection is very low. On the other hand, continuous observation and monitoring are required because Aedes albopictus as a vector of DENV is found in Korea, and the increase in reported cases may lead to domestic infections.

Background: Dengue fever is considered one of the transfusion-transmissible emerging infectious diseases. Dengue fever has been reported every year by the Korea Disease Control and Prevention Agency (KDCA). Because a blood donor screening assay to detect the dengue virus (DENV) as an agent of dengue fever is not performed, the risk of transfusion-transmitted DENV infection needs to be assessed. Methods: This study collected the data of DENV infected cases from the Infectious Disease Portal of the KDCA, the data of blood donors and blood components from the Blood Information Management System of the Korean Red Cross, and the data of travelers to major dengue outbreak countries from the Korean Tourism Organization.All data were from 2016 to 2018. A risk assessment was performed using European Up-Front Risk Assessment Tool (EUFRAT). Results: The risk of DENV-infected red cells and platelet concentrate was higher than that of plasma and apheresis platelet. Nevertheless, the risk of the DENV infected blood component was shown to be less than one case per year for all kinds of blood components. Conclusion All the DENV infected cases in Korea were overseas travelers. Therefore, the risk of transfusiontransmissible DENV infection is very low. On the other hand, continuous observation and monitoring are required because Aedes albopictus as a vector of DENV is found in Korea, and the increase in reported cases may lead to domestic infections.

OBJECTIVE: The purpose of this study was to compare the precision of three-dimensional (3D) images acquired using iTero(R) (Align Technology Inc., San Jose, CA, USA) and Trios(R) (3Shape Dental Systems, Copenhagen, Denmark) digital intraoral scanners, and to evaluate the effects of the severity of tooth irregularities and scanning sequence on precision. METHODS: Dental arch models were fabricated with differing degrees of tooth irregularity and divided into 2 groups based on scanning sequence. To assess their precision, images were superimposed and an optimized superimposition algorithm was employed to measure any 3D deviation. The t-test, paired t-test, and one-way ANOVA were performed (p < 0.05) for statistical analysis. RESULTS: The iTero(R) and Trios(R) systems showed no statistically significant difference in precision among models with differing degrees of tooth irregularity. However, there were statistically significant differences in the precision of the 2 scanners when the starting points of scanning were different. The iTero(R) scanner (mean deviation, 29.84 +/- 12.08 microm) proved to be less precise than the Trios(R) scanner (22.17 +/- 4.47 microm). CONCLUSIONS: The precision of 3D images differed according to the degree of tooth irregularity, scanning sequence, and scanner type. However, from a clinical standpoint, both scanners were highly accurate regardless of the degree of tooth irregularity.
Dental Arch ; Imaging, Three-Dimensional* ; Tooth*

Background: The Korean Red Cross adopted HIV NAT for blood donor screening in 2005 using a minipool assay. In June 2012, the NAT system was replaced with the individual assay. This study examined the characteristics of HIV NAT reactive blood donors to determine if there was any difference in their features between 10 years ago and later. Methods: This study analyzed the HIV RNA quantitative values and the distribution of HIV subtypes using 118 HIV NAT positive blood donations (37 in 2007, 20 in 2008, 32 in 2017 and 29 in 2018). Results: No significant variations of the quantitative values of HIV RNA and the distribution of HIV subtypes 10 years ago and later were observed. This study failed to produce quantitative values of three samples due to the low titer. The mean titer of HIV RNA of the remaining 115 samples were 5.14×10 4 IU/mL. The dominant HIV subtype of the HIV NAT reactive donors was B showing 54.2% (64/118). Approximately 5.9% (7/118) of the samples showed the HIV subtype C. Forty-seven samples (39.8%) showed the circulating recombinant form (CRF). Conclusion The rate of HIV subtype B in this study (54.2%) has decreased compared to the results of the past study (95.2%). Some of the cases showing CRF were identified as B in the past study because CRF3, 8, 9, 14, and 15 are recombinant forms, including subtype B.

Analysis of HCV genotypes can help identify infection routes and the development of treatment methods. However, in some samples with a low titer of HCV RNA, it is difficult to analyze their genotypes. In our previous study about HCV genotyping, we could not identify 12 cases among the 175 HCV NAT reactive samples due to their low titer. In this study, we adopted three different kinds of virus concentration methods to identify the genotypes of the 12 unidentified cases and compared their efficacy. The three virus concentration methods were automatic nucleic acid extraction, polyethyleneimine-magnetic bead-based extraction, and sucrose cushion ultracentrifugation. After virus concentration using every three methods, we analyzed HCV RNA genotypes using the concentrated sample of the best efficacy. Among the 12 cases, six were identified as 1b, four as mixed types, and two were unidentified. Here we could validate that the sample concentration method is useful to identify the HCV genotypes, especially in samples with low HCV RNA titers. Furthermore, considering the convenience, high efficacy, and time-saving, automatic nucleic acid extraction is considered the most useful concentration method for samples with titer lower than 50 IU/mL.

There were 10 cases of transfusion-transmitted P. vivax malaria from 1990 to 2021. The Korean Centers for Disease Control and Prevention (KCDC) designated the areas showing a high frequency of malaria as a malaria-endemic area and has restricted whole blood donation from these areas. While the number of malaria infections has declined in recent years, the blood inventory has declined sharply due to the COVID-19 pandemic. Accordingly, the Ministry of Health and Welfare temporarily approved the donation of whole blood from malaria-endemic areas to secure the supply of blood products. In the present study, an anti-malaria screening and nucleic acid amplification test (NAT) was performed on samples collected from the malaria-endemic areas from May 20 to June 30, 2020. A total of 14,741 samples were collected and tested. NAT was performed for 1096 runs to test all the collected samples. The 117 (0.79%) samples showed initial reactive results due to the contamination of abnormal PCR results. Negative results were obtained for the samples showing initial reactive results using a duplicated re-test. From the NAT tests, no sample showed a true positive result. The results of the malaria antibody screening test were reactive in 10 out of the 14,741 samples. The malaria antibody screening needs to be reviewed through further study because of its insufficient sensitivity and specificity. According to this study, excluding the 10 reactive malaria antibodies, additional blood components could be secured from 14,731 blood donors for a stable blood supply.

Background: There have been some domestic and overseas cases of anti-D alloimmunization caused by the transfusion of serologically D-negative blood. However, it is difficult to distinguish between true D-negative and DEL variants using conventional serologic typing. Therefore, we established the RHD genotyping algorithm for the detection of DEL variants and applied this algorithm to serologic D negative donors who voluntarily consented to testing. Methods: From September 2016 to December 2020, 216 RHD negative donors who were C＋ and/or E+ in previous serologic typing were recruited. The screening test was PCR amplification of the RHD exons 4, 7, 10, and a promotor. Based on the results of PCR screening, true D-negative samples and RHD variants (including DEL) were discriminated. When the result was a RHD variant, exon 9 was sequenced to identify the nucleotide changes. Full sequencing was performed if no mutations were detected at exon 9. Results: Among the 216 participants, 39 cases with the C−E−c＋e＋ phenotypes that did not meet the recruitment criteria were excluded from data analysis. Among the remaining 177 samples, 68 cases (38.4%) were RHD total deletions, 35 cases (19.8%) were RHD-CE-D hybrids, and 74 cases (41.8%) were RHD variants. Among the cases of RHD variants, 73 cases (98.6%) had c.1227G＞A substitutions and were confirmed as Asian-type DEL. Conclusion Seventy-four cases of serologic D negative donors were reclassified as RHD variants by RHD genotyping. This is believed to have contributed to the improvement of transfusion safety by lowering the risk of anti-D alloimmunization in D-negative patients.

Analysis of HCV genotypes can help identify infection routes and the development of treatment methods. However, in some samples with a low titer of HCV RNA, it is difficult to analyze their genotypes. In our previous study about HCV genotyping, we could not identify 12 cases among the 175 HCV NAT reactive samples due to their low titer. In this study, we adopted three different kinds of virus concentration methods to identify the genotypes of the 12 unidentified cases and compared their efficacy. The three virus concentration methods were automatic nucleic acid extraction, polyethyleneimine-magnetic bead-based extraction, and sucrose cushion ultracentrifugation. After virus concentration using every three methods, we analyzed HCV RNA genotypes using the concentrated sample of the best efficacy. Among the 12 cases, six were identified as 1b, four as mixed types, and two were unidentified. Here we could validate that the sample concentration method is useful to identify the HCV genotypes, especially in samples with low HCV RNA titers. Furthermore, considering the convenience, high efficacy, and time-saving, automatic nucleic acid extraction is considered the most useful concentration method for samples with titer lower than 50 IU/mL.

There were 10 cases of transfusion-transmitted P. vivax malaria from 1990 to 2021. The Korean Centers for Disease Control and Prevention (KCDC) designated the areas showing a high frequency of malaria as a malaria-endemic area and has restricted whole blood donation from these areas. While the number of malaria infections has declined in recent years, the blood inventory has declined sharply due to the COVID-19 pandemic. Accordingly, the Ministry of Health and Welfare temporarily approved the donation of whole blood from malaria-endemic areas to secure the supply of blood products. In the present study, an anti-malaria screening and nucleic acid amplification test (NAT) was performed on samples collected from the malaria-endemic areas from May 20 to June 30, 2020. A total of 14,741 samples were collected and tested. NAT was performed for 1096 runs to test all the collected samples. The 117 (0.79%) samples showed initial reactive results due to the contamination of abnormal PCR results. Negative results were obtained for the samples showing initial reactive results using a duplicated re-test. From the NAT tests, no sample showed a true positive result. The results of the malaria antibody screening test were reactive in 10 out of the 14,741 samples. The malaria antibody screening needs to be reviewed through further study because of its insufficient sensitivity and specificity. According to this study, excluding the 10 reactive malaria antibodies, additional blood components could be secured from 14,731 blood donors for a stable blood supply.

Background: There have been some domestic and overseas cases of anti-D alloimmunization caused by the transfusion of serologically D-negative blood. However, it is difficult to distinguish between true D-negative and DEL variants using conventional serologic typing. Therefore, we established the RHD genotyping algorithm for the detection of DEL variants and applied this algorithm to serologic D negative donors who voluntarily consented to testing. Methods: From September 2016 to December 2020, 216 RHD negative donors who were C＋ and/or E+ in previous serologic typing were recruited. The screening test was PCR amplification of the RHD exons 4, 7, 10, and a promotor. Based on the results of PCR screening, true D-negative samples and RHD variants (including DEL) were discriminated. When the result was a RHD variant, exon 9 was sequenced to identify the nucleotide changes. Full sequencing was performed if no mutations were detected at exon 9. Results: Among the 216 participants, 39 cases with the C−E−c＋e＋ phenotypes that did not meet the recruitment criteria were excluded from data analysis. Among the remaining 177 samples, 68 cases (38.4%) were RHD total deletions, 35 cases (19.8%) were RHD-CE-D hybrids, and 74 cases (41.8%) were RHD variants. Among the cases of RHD variants, 73 cases (98.6%) had c.1227G＞A substitutions and were confirmed as Asian-type DEL. Conclusion Seventy-four cases of serologic D negative donors were reclassified as RHD variants by RHD genotyping. This is believed to have contributed to the improvement of transfusion safety by lowering the risk of anti-D alloimmunization in D-negative patients.