A systematic review of the data, methods and environmental covariates used to map Aedes-borne arbovirus transmission risk.

BACKGROUND: Aedes (Stegomyia)-borne diseases are an expanding global threat, but gaps in surveillance make comprehensive and comparable risk assessments challenging. Geostatistical models combine data from multiple locations and use links with environmental and socioeconomic factors to make predictive risk maps. Here we systematically review past approaches to map risk for different Aedes-borne arboviruses from local to global scales, identifying differences and similarities in the data types, covariates, and modelling approaches used. METHODS: We searched on-line databases for predictive risk mapping studies for dengue, Zika, chikungunya, and yellow fever with no geographical or date restrictions. We included studies that needed to parameterise or fit their model to real-world epidemiological data and make predictions to new spatial locations of some measure of population-level risk of viral transmission (e.g. incidence, occurrence, suitability, etc.). RESULTS: We found a growing number of arbovirus risk mapping studies across all endemic regions and arboviral diseases, with a total of 176 papers published 2002-2022 with the largest increases shortly following major epidemics. Three dominant use cases emerged: (i) global maps to identify limits of transmission, estimate burden and assess impacts of future global change, (ii) regional models used to predict the spread of major epidemics between countries and (iii) national and sub-national models that use local datasets to better understand transmission dynamics to improve outbreak detection and response. Temperature and rainfall were the most popular choice of covariates (included in 50% and 40% of studies respectively) but variables such as human mobility are increasingly being included. Surprisingly, few studies (22%, 31/144) robustly tested combinations of covariates from different domains (e.g. climatic, sociodemographic, ecological, etc.) and only 49% of studies assessed predictive performance via out-of-sample validation procedures. CONCLUSIONS: Here we show that approaches to map risk for different arboviruses have diversified in response to changing use cases, epidemiology and data availability. We identify key differences in mapping approaches between different arboviral diseases, discuss future research needs and outline specific recommendations for future arbovirus mapping.

Viral shedding patterns of symptomatic SARS-CoV-2 infections by periods of variant predominance and vaccination status in Gyeonggi Province, Korea.

OBJECTIVES: We compared the viral cycle threshold (Ct) values of infected patients to better understand viral kinetics by vaccination status during different periods of variant predominance in Gyeonggi Province, Korea. METHODS: We obtained case-specific data from the coronavirus disease 2019 (COVID-19) surveillance system, Gyeonggi in-depth epidemiological report system, and Health Insurance Review & Assessment Service from January 2020 to January 2022. We defined periods of variant predominance and explored Ct values by analyzing viral sequencing test results. Using a generalized additive model, we performed a nonlinear regression analysis to determine viral kinetics over time. RESULTS: Cases in the Delta variant's period of predominance had higher viral shedding patterns than cases in other periods. The temporal change of viral shedding did not vary by vaccination status in the Omicron-predominant period, but viral shedding decreased in patients who had completed their third vaccination in the Delta-predominant period. During the Delta-predominant and Omicron-predominant periods, the time from symptom onset to peak viral shedding based on the E gene was approximately 2.4 days (95% confidence interval [CI], 2.2 to 2.5) and 2.1 days (95% CI, 2.0 to 2.1), respectively. CONCLUSIONS: In one-time tests conducted to diagnose COVID-19 in a large population, although no adjustment for individual characteristics was conducted, it was confirmed that viral shedding differed by the predominant strain and vaccination history. These results show the value of utilizing hundreds of thousands of test data produced at COVID-19 screening test centers.

Decreased birth weight after prenatal exposure to wildfires on the eastern coast of Korea in 2000.

OBJECTIVES: In April 2000, a series of wildfires occurred simultaneously in five adjacent small cities located on the eastern coast of Korea. These wildfires burned approximately 23,794 hectares of forestland over several days. We investigated the effects of prenatal exposure to the by-products generated by wildfire disasters on birth weight. METHODS: Birth weight data were obtained for 1999-2001 from the birth registration database of the Korean National Statistical Office and matched with the zip code and exposed/unexposed pregnancy week for days of the wildfires. Generalized linear models were then used to assess the associations between birth weight and exposure to wildfires after adjusting for fetal sex, gestational age, parity, maternal age, maternal education, paternal education, and average exposed atmospheric temperature. RESULTS: Compared with unexposed pregnancies before and after the wildfires, mean birth weight decreased by 41.4 g (95% confidence interval [CI], -72.4 to -10.4) after wildfire exposure during the first trimester, 23.2 g (95% CI, -59.3 to 13.0) for exposure during the second trimester, and 27.0 g (95% CI, -63.8 to 9.8) during the third trimester. In the adjusted model for infants exposed in utero during any trimester, the mean birth weight decreased by 32.5 g (95% CI, -53.2 to -11.7). CONCLUSIONS: We observed a 1% reduction in birth weight after wildfire exposure. Thus, exposure to by-products generated during a wildfire disaster during pregnancy may slow fetal growth and cause developmental delays.

Mosquito abundance in relation to extremely high temperatures in urban and rural areas of Incheon Metropolitan City, South Korea from 2015 to 2020: an observational study.

BACKGROUND: Despite concerns regarding increasingly frequent and intense heat waves due to global warming, there is still a lack of information on the effects of extremely high temperatures on the adult abundance of mosquito species that are known to transmit vector-borne diseases. This study aimed to evaluate the effects of extremely high temperatures on the abundance of mosquitoes by analyzing time series data for temperature and mosquito abundance in Incheon Metropolitan City (IMC), Republic of Korea, for the period from 2015 to 2020. METHODS: A generalized linear model with Poisson distribution and overdispersion was used to model the nonlinear association between temperature and mosquito count for the whole study area and for its constituent urban and rural regions. The association parameters were pooled using multivariate meta-regression. The temperature-mosquito abundance curve was estimated from the pooled estimates, and the ambient temperature at which mosquito populations reached maximum abundance (TMA) was estimated using a Monte Carlo simulation method. To quantify the effect of extremely high temperatures on mosquito abundance, we estimated the mosquito abundance ratio (AR) at the 99th temperature percentile (AR99th) against the TMA. RESULTS: Culex pipiens was the most common mosquito species (51.7%) in the urban region of the IMC, while mosquitoes of the genus Aedes (Ochlerotatus) were the most common in the rural region (47.8%). Mosquito abundance reached a maximum at 23.5 °C for Cx. pipiens and 26.4 °C for Aedes vexans. Exposure to extremely high temperatures reduced the abundance of Cx. pipiens mosquitoes {AR99th 0.34 [95% confidence interval (CI) 0.21-0.54]} to a greater extent than that of Anopheles spp. [AR99th 0.64 (95% CI 0.40-1.03)]. When stratified by region, Ae. vexans and Ochlerotatus koreicus mosquitoes showed higher TMA and a smaller reduction in abundance at extreme heat in urban Incheon than in Ganghwa, suggesting that urban mosquitoes can thrive at extremely high temperatures as they adapt to urban thermal environments. CONCLUSIONS: We confirmed that the temperature-related abundance of the adult mosquitoes was species and location specific. Tailoring measures for mosquito prevention and control according to mosquito species and anticipated extreme temperature conditions would help to improve the effectiveness of mosquito-borne disease control programs.

Field-based longitudinal study design for measuring the association between indoor air quality and occupant health status in residential buildings.

There has been a growing interest in the association between indoor air quality (IAQ) with an increase in the time spent at home. However, there is still a lack of evidence on the impact of IAQ on occupants' health and well-being in the long term. This study aimed to develop a field-based longitudinal study design to evaluate the IAQ level and daily symptoms of adults and children living in different types of buildings over one year. We proposed vital principles to be considered when recruiting the study participants so that potential confounders, such as age, underlying diseases, and the geographic area would be either removed in advance or matched between different building types. We suggested collecting exposure and outcome data in three categories: lifestyle and housing environment, IAQ measurement, and occupants' health. We presented web-based survey tools for collecting housing and health data, and the frequency of data collection varied from weekly to six-month intervals. We developed two different models using a generalized mixed model for modeling the association between housing environment, IAQ, and human health. The current study design could be applied for future studies on the association between built environment and health, regardless of the type of buildings.•A real-time indoor air quality monitor was used to monitor indoor air parameters every 5 mins over one year.•A simple web-based survey tool was developed to collect data for occupants' daily symptoms in the long term.•A binomial generalized linear mixed model and a Poisson generalized linear mixed model was developed to evaluate the association between indoor air parameters, and building types and daily symptoms.

Modeling the early temporal dynamics of viral load in respiratory tract specimens of COVID-19 patients in Incheon, the Republic of Korea.

OBJECTIVE: To investigate the duration and peak of severe acute respiratory syndrome coronavirus 2 shedding as infectivity markers for determining the isolation period. METHODS: A total of 2,558 upper respiratory tract (URT) and lower respiratory tract (LRT) specimens from 138 patients with laboratory-confirmed coronavirus disease were analyzed. Measurements of sequential viral loads were aggregated using the cubic spline smoothing function of a generalized additive model. The time to negative conversion was compared between symptom groups using survival analysis. RESULTS: In URT samples, viral RNA levels peaked on day 4 after symptom onset and rapidly decreased until day 10 for both E and RdRp genes, whereas those in LRT samples immediately peaked from symptom onset and decreased until days 15.6 and 15.0 for E and RdRp genes, respectively. Median (interquartile range) time to negative conversion was significantly longer in symptomatic (18.0 [13.0-25.0] days) patients than in asymptomatic (13.0 [9.5-17.5] days) patients. The more types of symptoms a patient had, the longer the time to negative conversion. CONCLUSIONS: The viral load rapidly changes depending on the time after symptom onset; the viral shedding period may be longer with more clinical symptoms. Different isolation policies should be applied depending on disease severity.

Effects of mechanical ventilation on indoor air quality and occupant health status in energy-efficient homes: A longitudinal field study.

Despite the growing interest in energy-efficient homes (EEHs), there is still a lack of evidence regarding whether the mechanical ventilation system of an EEH positively or negatively impacts indoor air quality (IAQ) and the health and wellbeing of occupants. This study aimed to evaluate the IAQ level and daily health symptoms of adults and children living in EEHs compared to conventional buildings over the course of one year. A two-way mixed analysis of variance was conducted to compare the level of IAQ between the two housing types. A binomial generalized linear mixed model (GLMM) and generalized additive mixed model was developed to investigate the association between IAQ and daily risks of symptoms. Differences in the daily prevalence of symptoms between the two housing types were assessed using a Poisson GLMM model. Overall, the indoor concentrations of particulate matter (PM10 and PM2.5), carbon dioxide (CO2), and volatile organic compounds (VOCs) were lower in EEH after controlling for seasonality. The indoor temperature and relative humidity level were relatively constant in the EEH. We also found that an increased level of indoor air quality parameters, particularly CO2, which is closely related to the indoor ventilation rate, was associated with the daily risk of eye fatigue, allergic rhinitis, and atopic dermatitis symptoms. Considering that EEH effectively reduced indoor air pollutants and IAQ improvement was associated with a reduction in the risk of individual symptoms, the IAQ improvement of EEH may have positively impacted occupants' health. Symptoms such as eye fatigue and skin dryness, which have been reported in previous studies as potential side effects of mechanical ventilation, were reported in this study; however, they were not found to be statistically significantly different from those reported in the conventional building.

Population Response to Air Pollution and the Risk of Coronavirus Disease in Chinese Cities during the Early Pandemic Period.

Health behavior is a critical measure in controlling the coronavirus disease 2019 (COVID-19) pandemic. We estimated the effect of health behaviors against air pollution on reducing the risk of COVID-19 during the initial phase of the pandemic. The attack rates of COVID-19 in 159 mainland Chinese cities during the first 2 weeks after the closure of major cities was estimated; air pollution level as a surrogate indicator of the mask-wearing rate. Data on air pollution levels and meteorologic factors 2 weeks prior to the closure were obtained. The attack rate was compared with the level of air pollution using a generalized linear model after adjusting for confounders. When fine particulates (PM2.5) and nitrogen dioxide (NO2) levels increased by one unit of air quality index (AQI), the infection risk decreased by 0.7% and 3.4%, respectively. When PM2.5 levels exceeded 150 (level 4), the infection risk decreased (relative risk, RR = 0.635, 95% confidence interval, CI: 0.442 to 0.912 for level 4; RR = 0.529, 95% CI: 0.337 to 0.830 for level 5; respectively). After controlling for the number of high-speed railway routes, when PM2.5 and NO2 levels increased by one AQI, relative risk for PM2.5 and NO2 was 0.990 (95% CI, 0.984 to 0.997) and 0.946 (95% CI, 0.911 to 0.982), respectively, demonstrating a consistently negative association. It is postulated that, during the early phase of the pandemic, the cities with higher air pollution levels may represent the higher practice of mask-wearing to protect from air pollution, which could have acted as a barrier to the transmission of the virus. This study highlights the importance of health behaviors, including mask-wearing for preventing infections.

Clinical and Psychological Characteristics of Young Men with Military Adaptation Issues Referred for a Psychiatric Evaluation in South Korea: Latent Profile Analysis of Minnesota Multiphasic Personality Inventory-2 and Temperament and Character Inventory.

OBJECTIVE: To investigate clinical and psychological characteristics of young men referred for a psychiatric evaluation due to expected unsuitability for military service and identify their heterogeneous subgroups based on the profiles of MMPI-2 and TCI. METHODS: We conducted a latent profile analysis of 348 men using MMPI-2 and TCI and then a comparative analysis of four latent classes in relation to sociodemographic, clinical, and IQ variables. RESULTS: We identified four classes with distinct clinical and psychological features: Class 1 (nonclinical: n=68), Class 2 (internalized: n=129), Class 3 (externalized: n=60), Class 4 (confused: n=91). Class 1 showed no significant psychiatric symptoms and relatively adaptive temperament and characteristics. Class 2 showed relatively higher harm avoidance and introverted traits indicating vulnerability to internalizing disorder. Class 3 was related to higher novelty seeking, impulsivity, and bipolarity. Class 4 showed the most severe clinical symptoms including psychotic experiences with extremely unstable temperament and immature personality. In total, 50-70% participants reported clinically significant depression, anxiety, and suicidal idea. Participants showed lower processing speed index (M=85.9, SD=16.6) than the general population. CONCLUSION: The results suggest that clinical conceptualization and therapeutic intervention considering distinctive features of young men with adaptive problems related to military service are needed.

A small window into the status of malaria in North Korea: estimation of imported malaria incidence among visitors from South Korea.

OBJECTIVES: This study aimed to develop hypotheses on trends in malaria incidence in North Korea using malaria incidence among South Korean visitors to North Korea. METHODS: The number of South Korean tourists who visited Mount Kumgang from 2000 to 2008 and the number of South Korean employees at the Kaesong Industrial Complex from 2005 to 2015 were obtained from the Korean Statistical Information Service. The number of malaria cases among South Koreans who visited North Korea was obtained from a previous report. The incidence of malaria per 100,000 person-years was calculated using these data and compared with the malaria incidence in North Korea derived from published articles. RESULTS: A high incidence of malaria in 2001 and a sharp decline in the following years were observed in both South and North Korean data. Since then, North Korean data showed a relatively low and stable incidence, but the incidence among South Koreans visiting North Korea increased in 2006. Considering the trends in mass primaquine preventive treatment, floods, and economic growth rate, the incidence of malaria may have increased in North Korea in 2006. Since 2009, the incidence of malaria decreased gradually according to both South and North Korean data. CONCLUSIONS: The trends of malaria incidence in North Korea could be reflected through its incidence among South Koreans who visited North Korea. For future inter-Korean collaboration aiming to eradicate malaria, we propose that a North Korean malaria monitoring system be established applying this method.

Trends of accidental carbon monoxide poisoning in Korea, 1951-2018.

OBJECTIVES: Carbon monoxide (CO) poisoning from coal briquette combustion has been a major public health problem in Korea. In this study, we estimated the time trends of the consumption of anthracite coal and the number of CO poisoning victims over the past 7 decades, in the context of changes in heating facilities. METHODS: Using Population and Housing Census data and energy statistics, we estimated the number of houses using briquettes as heating fuel between 1951 and 2018. After estimating the incidence of CO poisoning in housing units by heating facility type, we determined the ratio of the number of household members who experienced CO poisoning to the overall number of household members. Finally, we estimated the distribution of the victims according to poisoning severity, excluding victims of intentional exposure. RESULTS: We estimated that, overall, over 26 million people experienced CO poisoning between 1951 and 2018 in Korea. The household consumption of anthracite peaked in 1986, but the number of victims of CO poisoning peaked at approximately 1 million people in 1980. From 1951 to 2018, the cumulative number of CO poisoning victims comprised approximately 22,830,000 mild cases, 3,570,000 severe cases, and 65,000 deaths. CONCLUSIONS: The peak in the number of CO poisoning victims occurred 6 years earlier than the peak in the number of people using briquettes for heating. This gap resulted from improvements in briquette heating systems. This finding provides a quantitative basis for epidemiological studies on the health outcomes of CO poisoning in the Korean population.

Malaria Incidence of the Regions Adjacent to the Demilitarized Zone in the Democratic People's Republic of Korea, 2004-2016.

BACKGROUND: Vivax malaria reemerged in the Korean peninsula in 1990s beginning from the western border area and spread across both Koreas rapidly with its peak incidences reported on the early 2000s. There have been few reports on the malaria incidence in the Democratic People's Republic of Korea (North Korea) that provides detailed epidemiological features. The purpose of this study was to describe the time trends and spatial distribution of malaria in North Korea with comparison to those in South Korean regions across the border. METHODS: The incidence of malaria in each province of North Korea from 2004 to 2016 was estimated based on data from domestic and international health authorities. Consistency of the data was evaluated by calculating the ratio of malaria cases in each province to the total cases each year. We also compared the changes in malaria incidence over time in South and North Korea adjacent to the demilitarized zone. RESULTS: In North Korea, the incidence of malaria in the three provinces adjacent to the demilitarized zone was the highest (52.1-315.3 per 100,000), followed by Pyeonganbuk-do (14.7-113.5 per 100,000), where railways and road networks were connected to northern China. The incidence of malaria in each province of North Korea reported after 2011 was more consistent than when compared with previous annual data, and there was also a positive correlation between changes in incidence over time when compared with malaria incidence in South Korea (r = 0.855, r = 0.596). CONCLUSION: The malaria report of North Korea was relatively consistent in its spatiotemporal tendency since 2011, suggesting improvement of the quality of the surveillance data. The strong correlation between North and South Korean malaria incidence at regional level suggests that collaboration between both sides are essential for the successful elimination of malaria in the Korean peninsula.

Systematic review of evidence on public health in the Democratic People's Republic of Korea.

BACKGROUND: Engaging in public health activities in the Democratic People's Republic of Korea (DPRK, also known as North Korea) offers a means to improve population health for its citizens and the wider region. Such an engagement requires an understanding of current and future needs. METHODS: We conducted a systematic search of five English and eight Korean language databases to identify available literature published between 1988 and 2017. A narrative review of evidence was conducted for five major categories (health systems, communicable diseases (CDs), non-communicable diseases (NCDs), injuries, and reproductive, maternal, newborn and child health (RMNCH) and nutrition). FINDINGS: We found 465 publications on the DPRK and public health. Of the 253 articles that addressed major disease categories, we found under-representation of publications relative to proportion of disease burden for the two most significant causes: NCDs (54.5% publications vs 72.6% disability adjusted life years (DALYs)) and injuries (0.4% publications vs 12.1% DALYs), in comparison to publications on the third and fourth largest disease burdens, RMNCH and nutrition (30.4% publications vs 8.6% DALYs) and CDs (14.6% publications vs 6.7% DALYs) which were over-represented. Although most disease category articles were on NCDs, the majority of NCD articles addressed mental health of refugees. Only 165 articles addressed populations within the DPRK and among these, we found publication gaps on social and environmental determinants of health, CDs, and NCDs. CONCLUSION: There are gaps in the public health literature on the DPRK. Future research should focus on under-studied, significant burdens of disease. Moreover, establishing more precise estimates of disease burden and their distribution, as well as analysis on health systems responses aimed at addressing them, can result in improvements in population health.

Job-Seeking Stress, Mental Health Problems, and the Role of Perceived Social Support in University Graduates in Korea.

BACKGROUND: Increases in unemployment and suicide in the young Korean population have recently become major social concerns in the country. The purpose of this study was to examine mental health status in young job seekers and identify sociodemographic factors related to job-seeking stress, depression, and suicidal ideation. We also explored the mediating effect of depression on the relationship between job-seeking stress and suicidal ideation and examined whether social support moderated this effect. METHODS: In total, 124 university graduates completed the Job-Seeking Stress Scale, Beck Depression Inventory-II, Beck Scale for Suicide Ideation, and Multidimensional Scale of Perceived Social Support. Descriptive statistics were calculated for participants' general characteristics, and t-tests or analyses of variance, correlation analysis, simple mediation analysis, and mediated moderation analysis were performed. RESULTS: Of the 124 participants, 39.5% and 15.3% exhibited clinical levels of depression and suicidal ideation, respectively. Sociodemographic factors (i.e., sex, academic major, educational expenses loan, and willingness to accept irregular employment) were associated with job-seeking stress, depression, and suicidal ideation. Women and graduates who were willing to accept irregular employment exhibited high levels of job-seeking stress, depression, and suicidal ideation. Job-seeking stress affected suicidal ideation via depression, and perceived social support moderated the effect of job-seeking stress on depression and the effect of depression on suicidal ideation. CONCLUSION: The results suggest that depression management and interventions are urgently required for young job seekers, and social support should be provided to assist them both emotionally and economically.

An Analysis of Infectious Disease Research Trends in Medical Journals From North Korea.

OBJECTIVES: This study aimed to investigate the current status of infectious disease research in North Korea by analyzing recent trends in medical journals from North Korea in comparison with research from South Korea. METHODS: Three medical journals (Preventive Medicine, Basic Medicine, and Chosun Medicine) were analyzed from 2012 to 2016. Articles on tuberculosis (TB), malaria, and parasitic diseases were selected and classified by their subtopics and study areas. Two medical journals published in the South Korea were selected for a comparative analysis of research trends. RESULTS: Of the 2792 articles that were reviewed, 93 were extracted from North Korea journals. TB research in North Korea was largely focused on multi-drug resistant TB and extrapulmonary TB, whereas research in South Korea more frequently investigated non-tuberculous mycobacteria. Research on parasitic diseases in North Korea was focused on protozoan and intestinal nematodes, while the corresponding South Korea research investigated various species of parasites. Additionally, the studies conducted in North Korea were more likely to investigate the application of traditional medicine to diagnosis and treatment than those conducted in South Korea. CONCLUSIONS: This study presents an analysis of research trends in preventive medicine in North Korea focusing on infectious diseases, in which clear differences were observed between South and North Korea. Trends in research topics suggest a high prevalence of certain parasitic diseases in North Korea that are no longer widespread in South Korea. The large proportion of studies examining traditional medicine implies a lack of affordable medicine in North Korea.

Clinical and sociodemographic correlates of suicidality in patients with major depressive disorder from six Asian countries.

BACKGROUND: East Asian countries have high suicide rates. However, little is known about clinical and sociodemographic factors associated with suicidality in Asian populations. The aim of this study was to evaluate the factors associated with suicidality in patients with major depressive disorder (MDD) from six Asian countries. METHODS: The study cohort consisted of 547 outpatients with MDD. Patients presented to study sites in China (n = 114), South Korea (n = 101), Malaysia (n = 90), Singapore (n = 40), Thailand (n = 103), and Taiwan (n = 99). All patients completed the Mini-International Neuropsychiatric Interview (MINI), the Montgomery-Asberg Depression Rating Scale (MADRS), the Global Severity Index(SCL-90R), the Fatigue Severity Scale, the 36-item short-form health survey, the Sheehan Disability Scale, and the Multidimensional Scale of Perceived Social Support (MSPSS). Patients were classified as showing high suicidality if they scored ≥ 6 on the MINI suicidality module. Multivariate logistic regression analysis was used to examine sociodemographic and clinical factors related to high suicidality. RESULTS: One hundred and twenty-five patients were classed as high suicidality. Unemployed status (adjusted odds ratio [OR] 2.43, p < 0.01), MADRS score (adjusted OR 1.08), p < 0.001, and GSI (SCL-90R) score (adjusted OR 1.06, p < 0.01) were positively related to high suicidality. Hindu (adjusted OR 0.09, p < 0.05) or Muslim (adjusted OR 0.21, p < 0.001) religion and MSPSS score (adjusted OR 0.82, p < 0.05) were protective against high suicidality. CONCLUSIONS: A variety of sociodemographic and clinical factors were associated with high suicidality in Asian patients with MDD. These factors may facilitate the identification of MDD patients at risk of suicide.