Fine-Scale Spatial Prediction on the Risk of Plasmodium vivax Infection in the Republic of Korea.

BACKGROUND: Malaria elimination strategies in the Republic of Korea (ROK) have decreased malaria incidence but face challenges due to delayed case detection and response. To improve this, machine learning models for predicting malaria, focusing on high-risk areas, have been developed. METHODS: The study targeted the northern region of ROK, near the demilitarized zone, using a 1-km grid to identify areas for prediction. Grid cells without residential buildings were excluded, leaving 8,425 cells. The prediction was based on whether at least one malaria case was reported in each grid cell per month, using spatial data of patient locations. Four algorithms were used: gradient boosted (GBM), generalized linear (GLM), extreme gradient boosted (XGB), and ensemble models, incorporating environmental, sociodemographic, and meteorological data as predictors. The models were trained with data from May to October (2019-2021) and tested with data from May to October 2022. Model performance was evaluated using the area under the receiver operating characteristic curve (AUROC). RESULTS: The AUROC of the prediction models performed excellently (GBM = 0.9243, GLM = 0.9060, XGB = 0.9180, and ensemble model = 0.9301). Previous malaria risk, population size, and meteorological factors influenced the model most in GBM and XGB. CONCLUSION: Machine-learning models with properly preprocessed malaria case data can provide reliable predictions. Additional predictors, such as mosquito density, should be included in future studies to improve the performance of models.

Factors associated with the timely diagnosis of malaria and the utilization of types of healthcare facilities: a retrospective study in the Republic of Korea.

BACKGROUND: This study aimed to analyze trends in the timely diagnosis of malaria cases over the past 10 years in relation to the utilization of different types of healthcare facilities. METHODS: The study included 3,697 confirmed and suspected cases of malaria reported between January 1, 2013, and December 31, 2022, in the national integrative disease and healthcare management system. Some cases lacking a case report or with information missing from the case report were excluded from the analysis. A generalized linear model with a Poisson distribution was constructed to estimate risk ratios and 95% confidence intervals adjusted for other variables, such as distance. RESULTS: When cases involving diagnosis >5 days after symptom onset in confirmed patients (5DD) were examined according to the type of healthcare facility, the risk ratio of 5DD cases was found to be higher for tertiary hospitals than for public health facilities. Specifically, the risk ratio was higher when the diagnosis was established at a tertiary hospital, even after a participant had visited primary or secondary hospitals. In an analysis adjusted for the distance to each participant's healthcare facility, the results did not differ substantially from the results of the crude analysis. CONCLUSION: It is imperative to improve the diagnostic capabilities of public facilities and raise awareness of malaria at primary healthcare facilities for effective prevention and control.

Risk of active tuberculosis development in contacts exposed to infectious tuberculosis in congregate settings in Korea.

Contact investigation is an important and effective active case-finding strategy, but there is a lack of research on congregate settings in countries with an intermediate incidence. This study determined the incidence of and risk factors for tuberculosis (TB) development after exposure in congregate settings. This retrospective cohort study included 116,742 contacts identified during the investigation of 2,609 TB cases diagnosed from January to December 2015. We searched the Korean National Tuberculosis Surveillance System TB registry to identify contacts that developed active TB during follow-up until May 2018. During the mean observation period of 2.9 years, 499 of 116,742 contacts (0.4%) developed new active TB. From these contacts, 404 (81.0%) developed TB within 2 years after exposure. The 2-year Kaplan-Meier cumulative risk for TB was the highest in contacts aged ≥65 years [1%; 95% confidence interval (CI), 0.8-1.3]. Contacts with LTBI who completed chemoprophylaxis exhibited a lower risk of active TB development than those without chemoprophylaxis (adjusted hazard ratio, 0.16; 95% CI, 0.08-0.29). Aggressive contact investigation is effective for the early detection and prevention of TB in congregate settings. The risk of progression to active TB among contacts with LTBI can be minimised by the completion of chemoprophylaxis.

The risk of active tuberculosis among individuals living in tuberculosis-affected households in the Republic of Korea, 2015.

BACKGROUND: In the Republic of Korea (ROK), compared to other high-income countries, tuberculosis (TB) prevalence is relatively high. Active TB and latent TB infection (LTBI) surveillance of individuals living in TB-affected households has been conducted for several years. Although active case finding is an important strategy in low-prevalence, high-income countries, its effectiveness in a high prevalence setting is unclear. This study evaluated the risk of TB in household contact by calculating the incidence of TB among household contacts and comparing it with the general population of the ROK. METHODS: A retrospective cohort study, including 36,133 household-contacts of 17,958 TB patients reported in 2015, was conducted. The data was extracted from the Korean National TB Surveillance System (web-based TB cases notification system, KNTSS). The Cox proportional hazard regression model was used to evaluate risk factors for incidence of TB. A P-value < .05 was considered statistically significant. RESULTS: In this study, 319 (0.9%) of 36,133 household-contacts were reported as having TB within 1 year, which is a higher rate than the rate for the general population in the ROK. The rate of TB reported for contacts that had completed LTBI treatment (0.6%) was lower than for the LTBI group without treatment (4.6%). In multivariate analysis, age older than 65 (p < .001), being a spouse of a TB patient (p = .007), and LTBI without treatment (p = .013) were each a risk factor for TB incidence among contacts. Younger age (p < .001), presence of a cough (p < .001), testing positive for acid-fast bacilli (AFB; p < .001), and cavity on radiograph (p < .001) of the index patient were also statistically significant risk factors. CONCLUSIONS: Individuals living in TB-affected households are at high risk of developing TB in the ROK and active case finding among them is a strategy effective in the early detection and prevention of TB.

A contact investigation after exposure to a child with disseminated tuberculosis mimicking inflammatory bowel disease.

PURPOSE: Tuberculosis (TB) is one of the most important diseases that cause significant mortality and morbidity in young children. Data on TB transmission from an infected child are limited. Herein, we report a case of disseminated TB in a child and conducted a contact investigation among exposed individuals. METHODS: A 4-year-old child without Bacille Calmette-Guérin vaccination was diagnosed as having culture-proven disseminated TB. The child initially presented with symptoms of inflammatory bowel disease, and nosocomial and kindergarten exposures were reported. The exposed individuals to the index case were divided into 3 groups, namely household, nosocomial, or kindergarten contacts. Evaluation was performed following the Korean guidelines for TB. Kindergarten contacts were further divided into close or casual contacts. Chest radiography and tuberculin skin test or interferon-gamma-releasing assay were performed for the contacts. RESULTS: We examined 327 individuals (3 household, 10 nosocomial, and 314 kindergarten contacts), of whom 18 (5.5%), the brother of the index patient, and 17 kindergarten children were diagnosed as having latent TB infection (LTBI). LTBI diagnosis was more frequent in the children who had close kindergarten contact with the index case (17.1% vs. 4.4%, P=0.007). None of the cases had active TB. CONCLUSION: This is the first reported case of TB transmission among young children from a pediatric patient with disseminated TB in Korea. TB should be emphasized as a possible cause of chronic diarrhea and failure to thrive in children. A national TB control policy has been actively applied to identify Korean children with LTBI.

Tuberculosis prevention and care in Korea: Evolution of policy and practice.

Tuberculosis (TB) in Korea remains a serious health problem with an estimated 77 per 100,000 incidence rate for 2016. This makes Korea as the only OECD country with high incidence of TB. The government has increased budgets and strengthened patient management policies since 2011. The management of latent tuberculosis was added to the response with strengthened and extensive contact investigations in the five-year tuberculosis control plan (2013-2017) and implementation was established in 2013. Due to these efforts Korea has achieved an average 5.2% reduction annually in tuberculosis incidence rate between 2011 and 2016. To further expedite the reduction of the TB burden the government has introduced additional measures including mandatory screening of latent tuberculosis infection for community workers in congregate settings including daycare centers for children, kindergarten, and teachers in schools and health care workers in clinics and hospitals to solve the problems identified through contact investigations in 2017. Providing high quality free diagnosis and treatment of active TB including for multidrug resistant TB combined with active contact investigations is the mainstay of the current programmatic response in Korea. However, the limitation of existing tools for LTBI pose challenge including absence of best mechanism for effective communication with professionals and the public, the need for at least 3 months of treatment and the risk of side effects. Developing effective tools will help to overcome these challenges.

Regulatory roles of ganglioside GQ1b in neuronal cell differentiation of mouse embryonic stem cells.

Gangliosides play an important role in neuronal differentiation processes. The regulation of ganglioside levels is related to the induction of neuronal cell differentiation. In this study, the ST8Sia5 gene was transfected into mESCs and then differentiated into neuronal cells. Interestingly, ST8Sia5 gene transfected mESCs expressed GQ1b by HPTLC and immunofluorescence analysis. To investigate the effects of GQ1b over-expression in neurogenesis, neuronal cells were differentiated from GQ1b expressing mESCs in the presence of retinoic acid. In GQ1b expressing mESCs, increased EBs formation was observed. After 4 days, EBs were co-localized with GQ1b and nestin, and GFAP. Moreover, GQ1b co-localized with MAP-2 expressing cells in GQ1b expressing mESCs in 7-day-old EBs. Furthermore, GQ1b expressing mESCs increased the ERK1/2 MAP kinase pathway. These results suggest that the ST8Sia5 gene increases ganglioside GQ1b and improves neuronal differentiation via the ERK1/2 MAP kinase pathway.

A community-based case-control study of behavioral factors associated with scrub typhus during the autumn epidemic season in South Korea.

A community-based, case-control study was carried out to investigate risk factors for scrub typhus in South Korea. Cases (n = 299) were defined as persons who were diagnosed serologically within the past two weeks. Two neighborhood control subjects were selected by matching for sex, age, and occupation. Taking a rest directly on the grass, working in short sleeves, working with bare hands, and squatting to defecate or urinate posed the highest risks, with adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of 1.7 (1.2-2.3), 1.6 (1.1-2.4), 1.7 (1.2-2.4), and 2.0 (1.4-2.9), respectively. Wearing a long-sleeved shirt while working, keeping work clothes off the grass, and always using a mat to rest outdoors showed protective associations, with aORs and 95% CIs of 0.5 (0.3-0.9), 0.6 (0.4-0.9), and 0.7 (0.5-0.9), respectively. These results might be useful in the establishment of a detailed control strategy for scrub typhus.