OBJECTIVESIsolation due to the management of infectious diseases is thought to affect mental health, but the effects are still unknown. We examined the prevalence of anxiety symptoms and anger in persons isolated during the Middle East Respiratory Syndrome (MERS) epidemic both at isolation period and at four to six months after release from isolation. We also determined risk factors associated with these symptoms at four to six months.METHODSOf 14,992 individuals isolated for 2-week due to having contact with MERS patients in 2015, when MERS was introduced to Korea, 1,692 individuals were included in this study. Anxiety symptoms were evaluated with the Generalized Anxiety Disorder 7-item scale and anger was assessed with the State-Trait Anger Expression Inventory at four to six months after release from isolation for MERS.RESULTSOf 1,692 who came in contact with MERS patients, 1,656 were not diagnosed with MERS. Among 1,656, anxiety symptoms showed 7.6% (95% confidence interval [CI], 6.3 to 8.9%) and feelings of anger were present in 16.6% (95% CI, 14.8 to 18.4%) during the isolation period. At four to six months after release from isolation, anxiety symptoms were observed in 3.0% (95%CI, 2.2 to 3.9%). Feelings of anger were present in 6.4% (95% CI, 5.2 to 7.6%). Risk factors for experiencing anxiety symptoms and anger at four to six months after release included symptoms related to MERS during isolation, inadequate supplies (food, clothes, accommodation), social networking activities (email, text, Internet), history of psychiatric illnesses, and financial loss.CONCLUSIONSMental health problems at four to six month after release from isolation might be prevented by providing mental health support to individuals with vulnerable mental health, and providing accurate information as well as appropriate supplies, including food, clothes, and accommodation.

The distinct characteristic of the Middle East Respiratory Syndrome (MERS) outbreak in South Korea is that it not only involves intra-hospital transmission, but it also involves hospital-to-hospital transmission. It has been the largest MERS outbreak outside the Middle East, with 186 confirmed cases and, among them, 36 fatal cases as of July 26, 2015. All confirmed cases are suspected to be hospital-acquired infections except one case of household transmission and two cases still undergoing examination. The Korean health care system has been the major factor shaping the unique characteristics of the outbreak. Taking this as an opportunity, the Korean government should carefully assess the fundamental problems of the vulnerability to hospital infection and make short- as well as long-term plans for countermeasures. In addition, it is hoped that this journal, Epidemiology and Health, becomes a place where various topics regarding MERS can be discussed and shared.

Acute pyelonephritis causes significant morbidity, tends to recur, and can be fatal; however, little is known regarding its epidemiology. In this paper, the authors describe the epidemiology of acute pyelonephritis in South Korea by using nationwide heath insurance claims data from 1997 to 1999. The National Health Insurance System of South Korea covers almost the entire population (99%). The overall average annual incidence rate of pyelonephritis in 1997-1999 was 35.7 per 10,000 population (male, 12.6; female, 59.0). Approximately one of every seven patients was hospitalized (incidence per 10,000: inpatients, 5.5; outpatients, 30.1). Incidence varied with age and was higher in the summer season. Following an initial episode, the risk of a second episode within 12 months was 9.2% for females and 5.7% for males; by contrast, the risk of a fifth episode within a year following a fourth episode was 50.0% for females and 53.0% for males. Female sex (hazard ratio = 1.89, 95% confidence interval: 1.60, 2.23), advancing age, outpatient treatments (hazard ratio = 1.35, 95% confidence interval: 1.14, 1.60), and medical aid (hazard ratio = 1.23, 95% confidence interval: 1.08, 1.40) increased the risk of any recurrence. Pyelonephritis has a clear seasonal pattern and high rate of recurrence. The incidence of hospitalization for pyelonephritis in South Korea is similar to that in the United States and Canada.

Currently, Korea is a low endemicity country for HAV, especially in children. However, recent reports of hepatitis A outbreaks show that there has been a shift of disease incidence to adolescents and young adults, with 2 cases of acute liver failure in one reported outbreak. We need to study the immune status for HAV in order to provide information for the establishment of preventive measures and possible consequences of HAV in Korea. A total of 334 infants, children and adolescents less than 20 years of age living in rural areas of Kyonggi Province, Korea were evaluated for anti-HAV immune status in 1996. Five hundred and eighty-four primary school children living in the same area were separately evaluated for the natural seroconversion rate between 1993 and follow-up samples taken in 1996. Anti-HAV IgG antibody was measured by enzyme immunoassay (HAVAB EIA kit, Abbott Laboratories, Chicago, Illinois, USA). In comparison with previous reports of seroprevalence rates, our data confirmed a dramatic drop in seroprevalence rates among children and adolescents under 20 years of age living in rural areas, from over 63.8% two decades ago to 4.6% in 1996. Natural acquisition of HAV antibody in primary school children rarely occurs, registering only 0.5% during three years. Several outbreaks in young adults during 1996-1998 suggested that immunity against HAV in this population is so low that massive outbreaks are unavoidable. Teenagers and young adults, especially soldiers, who are likely to be exposed to contaminated food or water, would also have a greater risk of hepatitis A. Immunizing children with HAV vaccine as a routine schedule should also be considered in Korea in the future, particularly if the disease burden could be estimated and the cost-effectiveness of the vaccine could be proved.

Ebola virus disease (hereafter Ebola) has a high fatality rate; currently lacks a treatment or vaccine with proven safety and efficacy, and thus many people fear this infection. As of August 13, 2014, 2,127 patients across four West African countries have been infected with the Ebola virus over the past nine months. Among these patients, approximately 1 in 2 has subsequently died from the disease. In response, the World Health Organization has declared the Ebola outbreak in West Africa to be a Public Health Emergency of International Concern. However, Ebola is only transmitted by patients who already present symptoms of the disease, and infection only occurs upon direct contact with the blood or body fluids of an Ebola patient. Consequently, transmission of the outbreak can be contained through careful monitoring for fever among persons who have visited, or come into contact with persons from, the site of the outbreak. Thus, patients suspected of presenting symptoms characteristic of Ebola should be quarantined. To date, South Korea is not equipped with the special containment clinical units and biosafety level 4 facilities required to contain the outbreak of a fatal virus disease, such as Ebola. Therefore, it is necessary for South Korea to make strategies to the outbreak by using present facilities as quickly as possible. It is also imperative that the government establish suitable communication with its citizens to prevent the spread of uninformed fear and anxiety regarding the Ebola outbreak.

Hepatitis B virus (HBV) infection is the major cause of chronic liver disease in Korea. This study investigated the seroprevalence of HBV infection with an emphasis on the coexistence of hepatitis B surface antigen (HBsAg) and antibody (anti-HBs). In all, 290,212 people undergoing health check-up examinations in 29 institutions during 2009 were recruited. The crude seroprevalences of HBsAg and anti-HBs was adjusted by age, sex, and geographic area using the 2009 estimated population of Korea. The adjusted seroprevalences of HBsAg and anti-HBs was 4.0% and 73.5%, respectively. Males showed higher HBsAg positivity and lower anti-HBs positivity than females (P<0.001). HBsAg positivity increased with age from 3.5% in people 20-29 years old to 4.8% in people 40-49 years old, followed by a decrease in people ≥ 50 years old. HBsAg positivity in Southern provinces (4.5%) including Jeju (5.9%), was significantly higher than that in Central provinces (3.6%; P<0.001). Interestingly, HBsAg and anti-HBs coexisted in 0.1% of the total subjects and in 2.9% of the HBsAg-positive group, showing distinct age distribution and higher alanine aminotransferase levels than those of the group positive for only HBsAg. In conclusion, the seroprevalence of HBsAg and anti-HBs in Korea varies significantly by age, sex and geographical location and coexisted in 2.9% of HBsAg-positive subjects. Continuous monitoring of seroepidemiology may facilitate the eventual eradication of HBV infection.

In this study, U-shaped relationship patterns were demonstrated between serum ALT levels and risk for all-cause mortality in adults aged ≥60 years while serum GGT levels showed a linear relationship with risk for all-cause death. Very low levels of serum ALT in elderly patients suggest that they are at high risk of mortality.

R for the nosocomial MERS outbreaks in KSA and South Korea was estimated to be in the range of 2-5, which is significantly higher than the previous estimate of <1. Therefore, more comprehensive countermeasures are needed to address these infections.