Ji-Hyuk Park

Inhalation Toxicity of Humidifier Disinfectants as a Risk Factor of Children's Interstitial Lung Disease in Korea: A Case-Control Study

Background The occurrence of numerous cases of interstitial lung disease in children (chILD) every spring in Korea starting in 2006 raised suspicion about a causal relationship with the use of humidifier disinfectants (HDs). The aim of this study was to evaluate the association between HD use and the risk of chILD. Methods This retrospective, 1∶3 matched case-control study consisted of 16 cases of chILD that had developed between 2010 and 2011. The three groups of parallel controls (patients with acute lobar pneumonia, asthma, and healthy children) were matched by age, gender, and index date. Indoor/outdoor environmental risk factors, including HD use, were investigated by asking the guardians to complete a questionnaire. Results The median age of the affected children (43.8% male) was 26 months (18.25–36.25). The chILD group did not differ significantly from the control groups with respect to socio-demographic and clinical variables. Indoor and outdoor environmental factors were not associated with a risk of chILD. However, the previous use of HDs (OR; 2.73. 95% CI; 1.41–5.90, P = 0.00) were independently associated with an increased risk. Conclusions This study showed that HDs, which are widely used in South Korea in the winter season, independently increased the risk of chILD in spring. Therefore, continuous monitoring and, if needed, changes in policy are essential to prevent and control pediatric diseases caused by toxic chemicals.

Characteristics and Factors Associated with Death among Patients Hospitalized for Severe Fever with Thrombocytopenia Syndrome, South Korea, 2013.

Surveillance for this emerging disease should be expanded to the outpatient setting.

Emerging Pathogens and Vehicles of Food- and Water-borne Disease Outbreaks in Korea, 2007–2012

Objectives Food- and water-borne disease outbreaks (FBDOs) are an important public health problem worldwide. This study investigated the trends in FBDOs in Korea and established emerging causal pathogens and causal vehicles. Methods We analyzed FBDOs in Korea by year, location, causal pathogens, and causal vehicles from 2007 to 2012. Information was collected from the FBDOs database in the Korean Centers for Disease Control and Prevention. Results During 2007–2012, a total of 1794 FBDOs and 48,897 patients were reported. After 2007, FBDOs and patient numbers steadily decreased over the next 2 years and then plateaued until 2011. However, in 2012, FBDOs increased slightly accompanied by a large increase in the number of affected patients. Our results highlight the emergence of norovirus and pathogenic Escherichia coli other than enterohemorrhagic E. coli (EHEC) in schools in 2012. We found that pickled vegetables is an emerging causal vehicle responsible for this problem. Conclusion On the basis of this study we recommend intensified inspections of pickled vegetable manufacturers and the strengthening of laboratory surveillance of relevant pathogens.

Epidemiological Characteristics of Serologically Confirmed Q Fever Cases in South Korea, 2006–2011

Objectives: Q fever has been reported worldwide; however, there was almost no official report of Q fever in Korea. In this study, we describe the current status of human Q fever occurrence in Korea. Methods: Demographic data of Q fever patients were collected from the National Notifiable Diseases Surveillance System from 2006 to 2011. Case investigation reports from regional public health departments were used for additional information, like risk factors and clinical manifestation, of the patients since 2008. Results: There were 65 serologically confirmed cases during the study period. The annual notification rate of Q fever was 0.22 cases per million persons. The majority of cases were men (87.7%), adults (98.5%), and urban inhabitants (67.7%). Relevant exposures to risk factors were identified in 45.7% of patients. The most common symptoms of acute Q fever were fever (89.3%), myalgia (67.9%) and asthenia (53.6%). Two cases with endocarditis were identified in chronic Q fever. Conclusion: This study suggests that Q fever has a low endemicity in Korea. However, management and research at national level is required for prevention of a future epidemic.

Humidifier Disinfectants Are a Cause of Lung Injury among Adults in South Korea: A Community-Based Case-Control Study

Backgrounds An outbreak of lung injury among South Korean adults was examined in a hospital-based case-control study, and the suspected cause was exposure to humidifier disinfectant (HD). However, a case-control study with community-dwelling controls was needed to validate the previous study’s findings, and to confirm the exposure-response relationship between HD and lung injury. Methods Each case of lung injury was matched with four community-dwelling controls, according to age (±3 years), sex, residence, and history of childbirth since 2006 (for women). Environmental risk factors, which included type and use of humidifier and HD, were investigated using a structured questionnaire during August 2011. The exposure to HD was calculated for both cases and controls, and the corresponding risks of lung injury were compared. Results Among 28 eligible cases, 16 patients agreed to participate, and 60 matched controls were considered eligible for this study. The cases were more likely to have been exposed to HD (odds ratio: 116.1, 95% confidence interval: 6.5–2,063.7). All cases were exposed to HDs containing polyhexamethyleneguanidine phosphate, and the risk of lung injury increased with the cumulative exposure, duration of exposure, and exposure per day. Conclusions This study revealed a statistically significant exposure-response relationship between HD and lung injury. Therefore, continuous monitoring and stricter evaluation of environmental chemicals’ safety should be conducted.

Awareness and Work-Related Factors Associated with Scrub Typhus: A Case-Control Study from South Korea

This study aimed to examine the awareness and the work-related factors associated with scrub typhus to provide data essential for evidence-based preventive strategies. A community-based case control study was carried out in the rural areas of Gyeongsangbuk-do, South Korea. Confirmed cases of scrub typhus (n = 57) were based on laboratory tests performed by the Korean Centers for Disease Control and Prevention (KCDC), 114 matched neighborhood controls, age (±6 years), gender and area of residence in the Gyeongsangbuk-do of South Korea. These cases were contracted over the 12-month period of January to December 2015. Overall, 61.4% cases and 79.8% of the control group had heard about scrub typhus. Cases were less aware about the fact that mites are mainly found in the bushes and that long sleeves and full-length pants and boots helped prevent scrub typhus. However, more were aware of the eschar lesion as a characteristic sign of scrub typhus. Work related risk factors such as having a wetland or puddles of water surrounding the house, dry field farming and working in the livestock industry were significantly associated with the scrub typhus. Health promotion strategies, such as creating general awareness, personal protection methods and improving personal hygiene and environmental sanitation in collaboration with relevant sectors, are recommended to reduce the burden of scrub typhus. Further intervention studies on awareness and behavioral and environmental modifications are required to investigate the effectiveness of such interventions.

Seroreactivity and Risk Factors Associated with Coxiella burnetii Infection among Cattle Slaughterhouse Workers in South Korea

Q fever, caused by Coxiella burnetii, is a zoonotic disease that is an occupational hazard to people who work in close contact with animals or their carcasses. A nationwide serologic study among cattle slaughterhouse workers who were presumed to be at risk of having C. burnetii infection in South Korea was performed to investigate the seroreactivity of C. burnetii infection and identify related risk factors. Out of 1017 cattle slaughterhouse workers in South Korea, 923 (90.8%) participated in this cross-sectional study. Samples were tested for immunoglobulin G (IgG) and M (IgM) antibodies against phase II C. burnetii via indirect immunofluorescence assay. The overall seroreactivity, defined as IgG or IgM antibody titer cutoffs ≥1:16, was 9.1% (84/923). Additionally, a significant association was found between the seroreactivity of C. burnetii infection and performing carcass evisceration work (odds ratio, 2.36; 95% confidence interval, 1.39–4.03) in multivariate analysis. To diminish C. burnetii infection, cattle slaughterhouse workers need to take precautions during the evisceration process.