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.

Pandemic influenza A vaccination and incidence of Guillain-Barré syndrome in Korea.

BACKGROUND: Many studies have investigated the association between Guillain-Barré syndrome (GBS) and vaccinations during the influenza A H1N1 pandemic of 2009 (pH1N1). Based on a nationally representative sample, we estimated the incidence of GBS during the pandemic period in Korea. MATERIALS AND METHODS: All medical records of GBS cases were reviewed in 28 randomly selected hospitals during 2008-2010, and the number of GBS cases at the national level was extrapolated using emergency care utilization data. The GBS rate per 100,000 person-years was estimated in the reference and pandemic periods. RESULTS: The incidence of GBS was 0.63 (95% CI: 0.37-0.89) per 100,000 person-years in the reference period and 0.87 (0.49-1.26) in the pandemic period. During the vaccination season, the pandemic period GBS incidence rate was not significantly higher than the reference period incidence rate (rate ratio: 1.52; 0.99-2.32), but difference was observed among persons aged 20-34 years. Rate of GBS increased after pH1N1 vaccination compared to the reference period (1.46, 1.26-1.68). DISCUSSION: The incidence of GBS increased slightly but not significantly during the pandemic period, although pH1N1 vaccination increased the GBS rate. Therefore, mass influenza vaccination programs should not be precluded on the basis of GBS.

Diarrheal outbreak caused by atypical enteropathogenic Escherichia coli O157:H45 in South Korea.

UNLABELLED: Background: In May 2013, an outbreak of gastroenteritis occurred in a high school in Incheon, South Korea. We investigated the outbreak in order to identify the pathogen and mode of transmission. MATERIALS AND METHODS: A case-control study was performed using standardized questionnaires with a case definition of illness with diarrhea. Stool samples, environmental samples, and samples from preserved food items were collected to test pathogens. Pulsed-field gel electrophoresis (PFGE) was performed on the outbreak-related Escherichia coli strains. RESULTS: Thirty-three people (attack rate: 2.5%) met the case definition, and the pattern of the epidemic curve suggested a point-source outbreak. The common symptoms of cases were diarrhea (100.0%), abdominal pain (75.8%), chills (45.5%), and nausea (39.4%). Cases were found to be 8.26 times more likely to have eaten spicy fish soup with cod (95% confidence interval: 1.05-65.01). Consumption of egg soup with spring onions or braised eggs with razor clam flesh was significantly associated with illness. Atypical enteropathogenic E. coli O157:H45 was isolated from samples of 9 cases (27.3%) and tuna bibimbap. PFGE patterns of all tested isolates of O157 serotype were indistinguishable. CONCLUSIONS: This outbreak was caused by atypical enteropathogenic E. coli O157:H45 and the food vehicle was suspected to be tuna bibimbap. The statistical analysis was not in concordance with the microbiologic tests, probably owing to low pathogenicity of atypical enteropathogenic E. coli O157. This is the first report of an outbreak caused by atypical enteropathogenic E. coli O157.

A cluster of lung injury cases associated with home humidifier use: an epidemiological investigation.

BACKGROUND: In April 2011 a tertiary hospital in Seoul, Korea reported several cases of severe respiratory distress of unknown origin in young adults. METHODS: To find the route of transmission, causative agent and patient risk factors of the outbreak, an investigation of the epidemic was initiated. Clinicopathological conferences led to the suspicion that the cases related to an inhalation injury. An age- and sex-matched case-control study was therefore performed to examine the inhalation exposure of the patients to various agents. RESULTS: Of the 28 confirmed cases, 18 agreed to participate. A total of 121 age- and sex-matched controls with pulmonary, allergic or obstetric disease were selected. All patients and controls completed questionnaires with questions about exposure to various inhalants. The crude ORs for patient exposure to indoor mould, humidifier use, humidifier detergent use and insecticide use were 4.4 (95% CI 1.5 to 13.1), 13.7 (95% CI 1.8 to 106.3), 47.3 (95% CI 6.1 to 369.7) and 3.9 (95% CI 1.3 to 11.7), respectively. However, when considered concurrently, indoor mould and insecticide use lost statistical significance. Moreover, humidifier use was ruled out as the cause because of a lack of biological plausibility and the weak strength of the association. This suggested that humidifier disinfectant was the cause of the outbreak. This information led the Korean government to order the removal of humidifier detergents from the market. In the years following the ban, no additional cases were detected. CONCLUSIONS: Epidemiological evidence strongly suggests that the lung injury outbreak was caused by humidifier detergent use at home.

Humidifier disinfectant-associated children's interstitial lung disease.

RATIONALE: Beginning in 2006, epidemics of a fatal lung injury of unknown cause in children were observed in Korea every spring. A recent study demonstrated that this type of children's interstitial lung disease (chILD) is associated with humidifier disinfectant use. OBJECTIVES: To determine the clinical characteristics of this type of chILD and to assess whether the nationwide suspension of humidifier disinfectant sales in the autumn of 2011 affected its incidence. METHODS: The clinical characteristics of suspected cases between 2006 and 2011 were determined by a nationwide retrospective study. The potential causal relationship with humidifier disinfectants was examined by a prospective surveillance study after humidifier disinfectant sales were suspended. MEASUREMENTS AND MAIN RESULTS: In total, 138 children were diagnosed with this type of chILD, which was characterized by rapid progression, high mortality, predominance in the spring season, and a familial tendency. The annual incidence increased in 2011 and then dropped to zero in 2012. The children were on average 30.4 months old. The most frequent symptoms at admission were cough and dyspnea. As the disease progressed, the typical complication was spontaneous air leak. Eighty children (58%) died. Two years after humidifier disinfectant-sale suspension, no more new cases were found. CONCLUSIONS: This study suggests that humidifier disinfectant inhalation causes an idiopathic type of chILD that is characterized by spontaneous air leak, rapid progression, lack of response to treatment, and high mortality. Further safety studies must be performed on common environmental compounds, particularly those that enter the human body by an unusual route.

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.

Socioeconomic burden of influenza in the Republic of Korea, 2007-2010.

BACKGROUND: Although the socioeconomic burden of 2009 pandemic influenza A (H1N1) was considerable, no reliable estimates have been reported. Our aim was to compared medical costs and socioeconomic burden resulting from pandemic influenza A (H1N1) 2009 with that of previous seasonal influenza. METHODS: We estimated the medical costs and socioeconomic burden of influenza from May 2007 to April 2010. We used representative national data sources(data from the Health Insurance Review Agency, the National Health Insurance Corporation, the Korea Centers for Disease Control and Prevention, and the Korean National Statistics Office) including medical utilization, prescription of antivirals, and vaccination. Uncertainty of data was explored through sensitivity analysis using Monte Carlo simulation. RESULTS: Compared with the seasonal influenza, total medical costs (US$291.7 million) associated with pandemic (H1N1) 2009 increased more than 37-fold. Compared with the 2007-2008 season, outpatient diagnostic costs (US$135.3 million) were 773 times higher in the 2009-2010 season, and the mean diagnostic cost per outpatient visit was 58.8 times higher. Total socioeconomic burden of pandemic (H1N1) 2009 was estimated at US$1581.3 million (10%-90%: US$1436.0-1808.3 million) and those of seasonal influenza was estimated at US$44.7 million (10%-90%: US$32.4-57.9 million) in 2007-2008 season and US$42.3 million (10%-90%: US$31.5-53.8 million) in 2008-2009 season. Indirect costs accounted for 56.0% of total costs in pandemic (H1N1) 2009, and 66.48-68.09% in seasonal influenza. The largest contributors to total burden were productivity losses of caregiver in pandemic (H1N1) 2009, and productivity losses due to morbidity of outpatient in seasonal influenza. CONCLUSIONS: In the Republic of Korea, socioeconomic burden of pandemic (H1N1) 2009 were considerably higher than burden of the previous two influenza seasons, primarily because of high diagnostic costs and longer sick leave.

In-Flight Transmission of Novel Influenza A (H1N1).

The Korea Centers for Disease Control and Prevention confirmed two patients, who had taken the same plane from Los Angeles to Seoul, with novel influenza A (H1N1). Through contact tracing, we concluded that the second patient was infected during the flight.

[National level response to pandemic (H1N1) 2009].

The World Health Organization (WHO) announced the emergence of a novel influenza on April 24, 2009, and they declared pandemic on June 11. In Korea, the proportion of influenza-like illness and the consumption of antiviral agents peaked in early November. The government established the Central Headquarters for Influenza Control and operated the emergency response system. In the quarantine stations, we checked the body temperature and collected quarantine questionnaires from all the arrivals from infected countries. We also isolated the confirmed cases in the national isolation hospitals. However, as the community outbreaks were reported, we changed strategy from containment to mitigation. We changed the antiviral agent prescription guideline so that doctors could prescribe antiviral agents to all patients with acute febrile respiratory illness, without a laboratory diagnosis. Also the 470 designated hospitals were activated to enhance the efficacy of treatment. We vaccinated about 12 million people and manage the adverse event following the immunization management system. In 2010, we will establish additional national isolation wards and support hospitals to establish fever clinics and isolation intensive care unit (ICU) beds. We will also make a computer program for managing the national isolation hospitals and designated hospitals. We will establish isolation rooms and expand the laboratory in quarantine stations and we will construct a bio-safety level 3 laboratory in each province. In addition, we plan to construct a bio-safety level 4 laboratory at a new Korea Centers for Disease Control and Prevention (KCDC) facilities in Ossong.