Strengthening epidemiologic investigation of infectious diseases in Korea: lessons from the Middle East Respiratory Syndrome outbreak / 한국역학회지

The recent outbreak of Middle East Respiratory Syndrome (MERS) coronavirus infection in Korea resulted in large socioeconomic losses. This provoked the Korean government and the general public to recognize the importance of having a well-established system against infectious diseases. Although epidemiologic investigation is one of the most important aspects of prevention, it has been pointed out that much needs to be improved in Korea. We review here the current status of the Korean epidemiologic service and suggest possible supplementation measures. We examine the current national preventive infrastructure, including human resources such as Epidemic Intelligence Service officers, its governmental management, and related policies. In addition, we describe the practical application of these resources to the recent MERS outbreak and the progress in preventive measures. The spread of MERS demonstrated that the general readiness for emerging infectious diseases in Korea is considerably low. We believe that it is essential to increase society's investment in disease prevention. Fostering public health personnel, legislating management policies, and establishing research centers for emerging infectious diseases are potential solutions. Evaluating international preventive systems, developing cooperative measures, and initiating improvements are necessary. We evaluated the Korean epidemiologic investigation system and the public preventive measures against infectious diseases in light of the recent MERS outbreak. We suggest that governmental authorities in Korea enforce preventive policies, foster the development of highly qualified personnel, and increase investment in the public health domain of infectious disease prevention.

MERS epidemiological investigation to detect potential mode of transmission in the 178th MERS confirmed case in Pyeongtaek, Korea / 한국역학회지

Most cases of Middle East Respiratory Syndrome (MERS) infection in Korea (outbreak: May 11-July 4, 2015) occurred in hospital settings, with uncertain transmission modes in some cases. We performed an in-depth investigation epidemiological survey on the 178th case to determine the precise mode of transmission. A 29-year-old man living in Pyeongtaek presented on June 16 with a febrile sensation, chills, and myalgia. Upon confirmatory diagnosis on June 23, he was treated in an isolation room and discharged on July 2 after cure. An epidemiological investigation of all possible infection routes indicated two likely modes of transmission: exposure to MERS in Pyeongtaek St. Mary's Hospital during a visit to his hospitalized father (May 18-29), and infection through frequent contact with his father between the latter's referral to Pyeongtaek Good Samaritan Bagae Hospital for treatment without confirmatory diagnosis until his death (May 29-June 6). Although lack of clear proof or evidence to the contrary does not allow a definitive conclusion, all other possibilities could be excluded by epidemiological inferences. While it is impossible to trace back the modes of transmission of all cases in a large-scale outbreak, case-by-case tracking and isolation of infected individuals and those in close contact with them is important in preventing the spread. Efforts should be made to establish a methodology for rapid tracking of all possible contacts and elimination-based identification of the precise modes of transmission.

Strengthening epidemiologic investigation of infectious diseases in Korea: lessons from the Middle East respiratory syndrome outbreak

The recent outbreak of Middle East respiratory syndrome (MERS) coronavirus infection in Korea resulted in large socioeconomic losses. This provoked the Korean government and the general public to recognize the importance of having a well-established system against infectious diseases. Although epidemiologic investigation is one of the most important aspects of prevention, it has been pointed out that much needs to be improved in Korea. We review here the current status of the Korean epidemiologic service and suggest possible supplementation measures. We examine the current national preventive infrastructure, including human resources such as Epidemic Intelligence Service officers, its governmental management, and related policies. In addition, we describe the practical application of these resources to the recent MERS outbreak and the progress in preventive measures. The spread of MERS demonstrated that the general readiness for emerging infectious diseases in Korea is considerably low. We believe that it is essential to increase society's investment in disease prevention. Fostering public health personnel, legislating management policies, and establishing research centers for emerging infectious diseases are potential solutions. Evaluating international preventive systems, developing cooperative measures, and initiating improvements are necessary. We evaluated the Korean epidemiologic investigation system and the public preventive measures against infectious diseases in light of the recent MERS outbreak. We suggest that governmental authorities in Korea enforce preventive policies, foster the development of highly qualified personnel, and increase investment in the public health domain of infectious disease prevention.

Genetic influence and heritability in mandibular prognathism of Korean families

INTRODUCTION: This study examined the genetic influence of mandibular prognathism epidemiologically in Korean families. MATERIALS AND METHODS: Over a 5-year period from 2005 to 2009, a questionnaire with a pedigree chart was given to 100 (male 51, female 49) probands with skeletal Class III mandibular prognathism, who had undergone orthognathic surgery in Samsung Medical Center. RESULTS: The average age of the probands was 22.1. The average SNA, SNB and ANB angles of the probands were 81.2degrees, 84.1degreesand -2.9degrees, respectively. A total of 2729 (male 1,354, female 1,375) family members were examined, and the affected ratio of the families was 3.5% with no significant difference between genders. 45% of families had at least one member with a Class III malocclusion other than the proband. The affected ratio of the first-degree relatives (10.9%) was significantly higher than those of the second-degree (3.3%) and third-degree (1.9%) relatives. The affected ratio of the total relatives from the male probands (4.2%) was significantly higher than that of the female probands (2.8%). Heritability (h2, Falconer'method) was estimated to be 29.8% (0.298+/-0.059) in first-degree relatives. CONCLUSION: These results showed the significant influence of mandibular prognathism with relatively low heritability in first-degree relatives in Korean families of probands, who had undergone orthognathic surgery to correct a skeletal Class III malocclusion.

Occupational Burden of Cancer in Korea

OBJECTIVES: The extent of the occupational cancer burden has rarely been estimated in Korea. The aim of this study is to provide an estimation of the population attributable fraction (PAF) of occupational cancer in Korea. METHODS: Nine kinds of Group 1 carcinogens addressed by the International Agency for Research on Cancer (IARC) and 7 kinds of cancer were selected for the target carcinogens and diseases, respectively. The prevalence of carcinogen-exposed workers was estimated and correction factors were applied so that the value would be representative of the total population. Data on relative risk (RR) were taken from IARC reports and were compared with the RRs from the studies on Korean workers. The PAF was estimated according to Levin's formula. RESULTS: The proportion of the general Korean population exposed to carcinogens was 9.7%. The PAF of total cancer was 1.1% for incident cancer cases and 1.7% for cancer deaths. The PAFs of lung cancer and leukemia were 7.0% and 4.%, respectively. With the RRs reported from Korean studies, the PAF for lung cancer and leukemia were 3.7% and 3.4%, respectively. CONCLUSION: The PAF in this study (1.1%) was lower than that reported in previous studies (2-4%) from developed countries. Considering that only 9 of the 29 kinds of Group 1 carcinogens were included in this study, the PAF might be underestimated. However, because the process of industrialization in Korea differs from that which occurred in other developed countries, 1.1% of the PAF might be appropriate for Korea.

Occupational Burden of Cancer in Korea

OBJECTIVES: The extent of the occupational cancer burden has rarely been estimated in Korea. The aim of this study is to provide an estimation of the population attributable fraction (PAF) of occupational cancer in Korea. METHODS: Nine kinds of Group 1 carcinogens addressed by the International Agency for Research on Cancer (IARC) and 7 kinds of cancer were selected for the target carcinogens and diseases, respectively. The prevalence of carcinogen-exposed workers was estimated and correction factors were applied so that the value would be representative of the total population. Data on relative risk (RR) were taken from IARC reports and were compared with the RRs from the studies on Korean workers. The PAF was estimated according to Levin's formula. RESULTS: The proportion of the general Korean population exposed to carcinogens was 9.7%. The PAF of total cancer was 1.1% for incident cancer cases and 1.7% for cancer deaths. The PAFs of lung cancer and leukemia were 7.0% and 4.%, respectively. With the RRs reported from Korean studies, the PAF for lung cancer and leukemia were 3.7% and 3.4%, respectively. CONCLUSION: The PAF in this study (1.1%) was lower than that reported in previous studies (2-4%) from developed countries. Considering that only 9 of the 29 kinds of Group 1 carcinogens were included in this study, the PAF might be underestimated. However, because the process of industrialization in Korea differs from that which occurred in other developed countries, 1.1% of the PAF might be appropriate for Korea.

An Epidemiological Investigation of Bacterial Dysentery Outbreak in Busan(Pusan), 1999 / 한국역학회지

BACKGROUND: In March 1999, six children who attended a nursery school became ill with acute gastroenteritis by Shigella sonnei. The majority of the children became sick one day after sharing a snack which was served from one of the children's home. By the time the outbreak of dysentery was recognized, the rest of family members of the children became also sick. The nursery school was located in a crowded residential area. EPIDEMIOLOGIC INVESTIGATION: After active and passive surveillance was established on patients with diarrhea, 438 patients were registered. Among them, 252 patients were considered to have simple diarrhea, but the rest (186 patients) suffered from more than three consecutive diarrheas. Shigella sonnei was isolated from 75 patients. The first attack rate was estimated at 50.0%, the second, 25.6%-34.3% and the third, 13.5%. The epidemic lasted for two months spreading further from person to person in the highly populous area. The active surveillance was implemented after the occurrence of the secondary attack of dysentery among the residents, who had no obvious direct contact with people associated with the nursery school. CONCLUSION: This investigation demonstrates the need for prompt implementation of active surveillance when Shigella infection is recognized in a highly populous city.

Molecular Epidemiology of Methicillin-resistant Staphylococcus aureus Outbreak by Plasmid Restriction Analysis / 대한임상미생물학회지

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a major cause of nosocomial infection and a molecular typing is necessary for proper epidemiologic investigations of sources and moles of spread in an outbreak. An nosocomial outbreak of MRSA in a neonatal intensive care unit at Ewha Womans University Mokdong Hospital was suspected. To investigate the clonality of isolates and control the spread of nosocomial outbreak, we performed plasmid restriction analysis of MRSA isolates from patients and medical staffs. METHODS: We studied 7 MRSA strains (umbilicus 4, blood 1, urine 1 and pus 1) from patients in a neonatal intensive care unit and the MRSA strains from nares and hands surveillance cultures of 26 medical staffs (4 medical doctors and 22 nurses). All MRSA strains were tested for antimicrobial susceptibility and plasmic analysis after EcoRI restriction. We analyzed the plasmid patterns of MRSA isolated from patients and compared with those from medical staffs. RESULTS: Ten MRSA strains (from 7 nares and 3 hands) were isolated from surveillance cultures of 26 medical staffs. Seven out of 10 MRSA strains from medical staffs revealed identical pattern of antibiogram which was the same pattern in all 7 MRSA strains from seven patients. Plasmid restriction patterns were classified 6 groups from A to F showing 2-10 bands. Six out of 7 MRSA strains from the patients showed group A(A1 5, A31) and 5 out of 10 MRSA strains from the medical staffs showed group A(A1 1, A21, A32, A41) and remainders showed different plasmid restriction analysis patterns. CONCLUSIONS: These results suggest that plasmid restriction analysis is a rapid, inexpensive, and good discriminating molecular typing of MRSA outbreak and is useful for the epidemiologic investigation of MRSA outbreaks in the clinical laboratory.

Analysis of Contaminated Ground Water Inducing Methemoglobinemia and Epidemiologic Investigation of Contaminated Ground Water

PURPOSE: Drining of Nitrate-contaminated water has been the most common cause of acquired methemoglobinemia. We had cyanotic infant diagnosed as methemoglobinemia caused by feeding with powdered formula mixed with nitrate-contaminated ground water. METHODS: We had done epidemiologic investigation to identify the cause of an infant's methemoglobinemia. Analysis of ground water and blood test of involved family members and neighbors were performed RESULTS: Analysis of the 8 household ground water revealed high level of nitrate(29837 ppm), indicating contamination of water as the cause of methemoglobinemia. We had done blood tests to evaluate the methemoglobin level of 65 people in the neighborhood ; among them, there was no infant and we could not find another cyanotic case of methemoglobinemia. They had normal blood level of methemoglobinemic concentration. CONCLUSIONS: If ground water will be used for drinking water, especially for formula water, epidemiologic investigation and analysis of ground waters should be recommended.

An Epidemiologic Investigation on an Outbreak of Anthrax Occurred in Kyongju by Eating Dead Cow's Meat / 예방의학회지

This epidemiologic study was carried out to investigate cause and magnitude of food-poisoning like epidemic occurred among inhabitants of a village who have eaten dead cow's meat near Kyonng in February of 1994, around lunar new year. The investigation consisted of interview survey on all inhabitants of 77 households (l11 males and 119 females) and their visitors (40 males and 35 females), skin test with anthraxinum(Russian product), study on clinical characteristics for the patients hospitalized, and microbiologic examination on microbes isolated from cow's meat, patient and soils of dead cow's barn. The results obtained are as followings; 1. The proportion of the inhabitants who ingested the dead cow's meat was 36.4%. The incidence rate of the disease was 65.1% for males, 41.7% for females and the cases were distributed evenly for all age groups. The group ingested raw meat showed higher incidence than the group ingested cooked meat. There was no case among people who did not eat the meat. 2. The most clinical symptoms were significantly more frequent among cases than non-cases; sore throat (57%), nausea (51%), fever(47%), indigestion(43%), cough(41%), anorekia(41%), abdominal distention(41%), and abdominal pain(39%) were the major symptoms among cases. 3. Among 29 cases hospitalized out of total 61 cases, three patients, all old and feeble persons, deceased from the disease resulting in 4.9% fatality rate among total patient and 10.3% among hospitalized. Septicemia and meningitis were the causes of the deaths. 4. Three strains isolated from patients, and three strains from dead cow's meat and soil revealed typical microbiologic characteristics of Bacillus Anthracis, which also proved to be fatal to experimentally infected mice.

Epidemiologic investigation to identify the cause of an infant methemoglobinemia / 예방의학회지

Epidemiologic investigation was conducted on January, 1993 in Seoul to identify the cause of an infant methemoglobinemia. Field investigation of the area of outbreak, survey of household and family members, analysis of ground water, and blood tests of involved family members were performed. Following results were obtained. On analyzing the quality of the ground water on patients's household high levels of nitrate was found indicating contamination of water as the cause of a methemoglobinemia outbreak. On analyzing the quality of the ground waters on seven other places within the neighborhood five were contaminated by nitrate in concentration that exceeded the permissible limit implying presence nearby source of contamination. Sources of contamination were thought to be originating from human waste in conventional bathroom facilities, chicken manure used in nearby orchards and plant fields or fertilizers. But the results of water analysis with presence of bacteria or E.coli, concentration of potassium, phosphate and the past history of diarrhea among family members, chicken manure suggested the most possible source of contamination. To evaluate the health status of members in the neighborhood past history was reviewed revealing no prior existence of patient with cyanosis and 65 people in the neighborhood had normal levels of methemoglobin concentration in their blood. Conclusively, the ground water on patient's household was contaminated with nitrate and despite provision of adequate water supply, family members of the patient along with distrust in the water supply system had used ground water as their source of drinking water resulting of methemoglobinemia. Many suburban area of Seoul and country side thought to be having similar problems concerning contaminated ground water supply and dormant outbreak of patients as a result of the drinking of the contaminated water. Epidemiologic investigation and water analysis of ground waters are advised.