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A seroepidemiologic study on scrub typhus in Koje island
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Il Suh, Sang Nae Cho, Il Soon Kim, Young Joon Kim, Joon Yong Bang, Eun Cheol Park, Kyung Jong Lee, Ki Hong Jeun, Moon Shik Kim, Dae Kyu Oh
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Korean J Epidemiol. 1988;10(2):230-238.
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Abstract
In order to examine the past infection rate an incidence of Scrub typhus a seroepidemiologi study was performed in Koje County. Paired serums were collected from 518 residents in Sadeung and Koje myun.
Serum were analyzed by ELISA for detection o IgG to R. tsutsugamushi, and were also analyzed by Microscopic Agglutination test for Leptospirosis.
First serum were collected from Aug. 25 to Aug. 31, 1987 and second serum were collected from Jan. 13 to Jan 31, 1988.
The result summarized as follows:
1. One hunderd seventy people(33.9%) had a experience of infection by R. tsutsugamushi： among 501 subjects. The past infection rate was significantly higher in female than that in male and it was increased according to age. By occupation farmers showed the highest infection rate.
2. The incidence rate of Scrub typhus was estimated 4.7%(19 people among 405 subjects) during the study period. The incidence rate was also significantly higher in female than that in male and 40-49 age group showed the highest incidence rate.
3. Two people(0.4%) were reacted to Microscopic Agglutnation test for Leptospirosis. Among 501 sujects and these two people were also reacted to ELISA for Scrub typhus.
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Summary
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A study on the status of reporting typhoid fever cases admitted
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Yoon Goo Kim, Tae Wha Joung, Chul Song, Myung Won Lee, Joung Soon Kim, Dae Kyu Oh
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Korean J Epidemiol. 1985;7(2):240-252.
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Abstract
The objective of this study is to find out current status of reporting and managing one of the most important communicable diseases in Korea, typhoid fever, as well as identifying reasons of poor reporting in order to provide necessary information for an improved reporting system.
This study was carried out on typhoid fever patients who had been admitted to hospitals located in Seoul during the year of 1984. On the reasons and problems associated with poor reporting, the medical staff, both regular and house staff, were surveyed through structured self-recording questionnaire with the help of hospital administration offices.
Information on the hospitalized cases were collected from laboratory and medical records and reported cases from health centers. The summarized results are as followings:
1) The total number of typhoid fever cases reported to the health centers and city government was 403 patients of whom only 103 cases(26%) were bacteriologically confirmed by isolating S. typhi. Eighty percent of these patients were reported by hospitals.
2) On the other hand, the total number of confirmed cases identified in study hospitals were 489 patiens among whom only 16.4% had been reported to the health centers. The reporting rate varied widely ranging from 0% to 57% by medica institute regardless of type of the hospital.
3) The analysis of the patient group revealed that there were more females than males and 56% of the patients belonged to the 20~39 years age group. There was no difference in person characteristics between reported and non-reported cases. The number of cases occurred by month did not show much difference although there was a tendency of clustering more cases in winter season.
4) The average duration of the illness from the onset to the hospital admission was about 12 days and 63% of these patiens had received medical care of some sort before the admission.
Also the average duration of hospitalization was about 12 days. The duration of admission was significantly longer for reported group when compared with that of non-reported group (p<0.001).
5) Follow-up care for the discharged patients was done only for a part of patients (54%), the worst the follow-up stool cultures for only 11% of the patients.
6) The major reasons for not reporting typhoid fever cases stated by the medical doctors were complicated and bothersome administrative process demanded by health center when they report a case(47%) and possibility of misdiagnosis(28%). The most of the medical staff, however, strongly showed their insight or sense of responsibility for reporting communicable diseases.
7) The necessity of nurse epidemiologist employed in hospital for control of hospital infection and reporting communicable diseases was recognized by 62% of the doctors, and 52% of them showed a strong intention to adopt the system. The larger the hospitals the more doctors agreeing the new system, the nurse epidemiologist.
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Summary
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An outbreak of Legionellosis (Pontiac fever) in ICU of K hospital, Korea
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Joung Soon Kim, Sung Woo Lee, Han Soup Shim, Dae Kyu Oh, Min Kee Cho, Hee Bok Oh, Je Hong Woo, Yun Sop Chong
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Korean J Epidemiol. 1985;7(1):44-58.
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Abstract
Early in the morning of July 21，1984 three ICU patients out of eleven died within three hours, and also several medical as well as nursing staff working in ICU of K hospital became seriously ill. The hospital has about 500 beds and located in the middle of Seoul City with good reputation. The hospital started remodeling of the building from the middle of July with an extensive ground excavation to bury cables, particularly around the ICU. The hospital is furnished with central heating/cooling system but for some reason there was a box air-conditioning attached to the window facing to outside where the ground excavation was going on.
An epidemiological investigation was carried out from July 25, 1984 in order to identify the entity of the outbreak by the governmental epidemiology team although the hospital insistingly incriminated the deaths of the ICU patients to their serious conditions and clustered occurrence of the illness among the staff to influenza-like croup.
The epidemiologic investigation consisted of interview and blood collection for the ICU staff, medical record reviews for the deceased, and environmental survey of the hospital including the ICU. Also an additional study was conducted following the initial study from which legionellosis was suspected as the cause of the outbreak; the interview survey was extended to the entire nursing staff of the hospital, medical record review to all ICU patients and specimen collections for the agent isolation such as water collection from tap water, cooling tower of the central cooling system and the box air-conditioning, and dust from the ICU and its vicinities.
Unfortunately, however, any autopsy of the deceased was not performed because they had been hurried already when the investigation started; also the effort of the team to collect blood specimen for the serological test from the ICU patients discharged and the entire nursing staff interviewed failed due to hospital’s reluctance for the additional study.
Therefore the investigation had to rely upon the interview survey on the whole nursing staff in identifying the focus of exposure to the legionella and the serological test results on ICU staff only. In order to confirm the peculiarity of the outbreak to that particular place, ICU of K hospital, the ICU nursing staff of S hospital located in Seoul were also interviewed and serologically tested.
The results of the epidemiological investigation summarized are as followings:
1) The clinical and epidemiological characteristics of the illness that had occurred among the ICU staff were so typical that there was no alternative to consider but non-pneumonic legionellosis (pontiac fever).
2) There were 23 legionellosis patients diagnosed clinically among 26 hospital staff who had been exposed to the ICU environment more than two hours during 32 hour-period between 08 hour of July 19, 1984 and 24 hour of July 20, 1984 ; the attack rate was 88.5%.
3) In serological test by means of IFA test on paired sera against antigens of fourteen serogroups, 14 person’s sera out of 19 reacted positively only against the antigen of L. gormanii. Two out of 14 clinical legionellosis reacted negatively, and two persons out of five healthy staff exposed showed positive results. Accordingly inapparent infection rate among positives of the serological test was 14.3%. The infection rate based on result of serological test among those who were exposed to the ICU during the estimated duration of Legionella contamination and serologically tested (17 persons) was 94% ; one nurse whose serological test revealed negative had serious and typical feature of legionellosis clinically.
4) The most frequent symptoms of the non-pneumonic legionellosis among serologically confirmed cases were fever (100%), malaise (92%), chills (83%), headache (83%), generalized myalgia (83%), and anorexia (83%).
The duration of the illness was 2~3 days in most of the cases.
5) The expired three patients in the early morning, July 21, 1984 with admission diagnosis of bleeding gastric ulcer, liver cirrhosis and acute myocardial infarction had abnormal chest X-ray findings; one with increased density on RLL and two with pulmonary edema before the death. Among seven survivals who had been exposed to the ICU environment during the risk period five patients had revealed abnormal chest X-ray, two of them with definite pneumonia.
6) The duration of exposure to the Legionella contaminated environment estimated from the association between the disease occurrence and the time of exposure was most likely from around midnight of July 19 to that of July 20, 1984.
7) The incubation period that was estimated from the duration of exposure and onset time of the illness ranged from 20 hours to 42 hours.
8) The clinical pathological laboratory results between serology positives and negatives revealed no difference except the CBC; electrolyte, liver and kidney functions were all within normal limits, however, about the half the confirmed cases showed leucocytosis with relative increase of segmented white cells and lymphocytes.
9) The interview survey on clinical manifestation of the illness for all nursing staff of the hospital showed prominant clustering at a point of time only for the ICU staff, which, implies the occurrence of the legionellosis was peculiar to the ICU within the hospital.
The interview and serological survey on the same illness during the same period for the ICU nursing staff of S hospital located in Seoul as a control yielded negative results of serological test against the L. gormanii. One of ten nurses, however, showed 1 : 128 antibody titer to L. pncumophila serogroup 1 suggesting there had been sporadic legionella infection in Korea although this is the first report on legionellosis outbreak in Korea.
10) The effort to isolate the legionella organism from water and dust specimens collected in ICU itself and its vicinities was failed; probably well-planned experiment such as aerosol exposure of guinea pigs with water from box airconditioner and the soil extract from the ground excavated might have produced positive results.
11) It was inferred that the source of ICU contamination by the Legionella could have been the box airconditioner attached to the window outside of which an extensive ground excavation was going on to bury cables; L. gormanii had been aspirated to the airconditioner, multiplied in the water of airconditioner, and aerosol sprayed into the ICU.
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Summary
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Validity of interviewees responses in health interview survey
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Dae Kyu Oh, Han Joong Kim, Kyung Yong Lee
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Korean J Epidemiol. 1984;6(1):70-77.
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The validity of interviewees' responses on the numbers of medical utilization, visits and medication days in a health interview survey were measured. Memory recalls within two weeks and four weeks were also measured. The influences of different types of interviewers and characteristics of respondents were also tested.
The records of requested bills to the heatlth insurance corporation from clinics and hospitals were used as reference information against the validy measurement.
The health interview survey which was used for this study was conducted as a part of a study on impact of health insurance on the medical care utilization in Kangwha county in June 1983.
Followings are summary of the results.
1. As an individual, the agreement rates between two records within two weeks of memory on the numbers of spells, visits and medication days were 98.0%, 68.8% and 46.9% respectively. Within four weeks of memory, the agreement rates were 96.8% 68.4% and 42.1% respectively.
2. As a group, the interviewees’ responses on the numbers of visits and medication days were slightly under-reported to 0.95 within two weeks of memory and 0.20 within 4 weeks of memory.
3. The agreement rates of two different types of interviewers (medical and sociology students) showed no difference.
4. The agreement rates were highest when respondents were head of the household and those of housewife, grand parents, children and kinds were the next in order.
5. The higher the educational level of respondents the higher the agreement rates were seen. Among those respondents who had education of high school and above showed highest agreement rates and even showed over-reporting tendency.
6. There was no difference in agreement rates between male and female respondents.
7. The higher the level of age, the higher the agreement rates were observed.
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Summary
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Study of risk factors for hypertension in a rural adult population
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Il Soon Kim, Il Suh, Hee Chul Oh, Yong Ho Lee, Dae Kyu Oh
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Korean J Epidemiol. 1981;3(1):37-43.
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Arterial blood pressures, height, weight, skinfold thickness, blood pressure, 2 lead ECG, serum cholesterol of 1169 voluntary participants whose age were between 40-64 were examined in a rural community Korea in order to identify risk factors in developing CVD.
The influences of 19 enables on the blood pressure were examined and their independent association with blood pressure was analyzed by means of multiple regression analysis. The most important factors influencing both systolic and diastolic blood pressure were: age, weight, height and cholesterol. The following factors were identified significantly correlated with blood pressure： pulse rate, hemoglobin and triglyceride.
All 19 variables including modified variable from weight, height and age (Ponderal index, Quetelet index, age2, age3, weight2, weight3) could explain 14.4% of total variation of systolic blood pressure and 20.5% of total variation of diastolic blood pressure. Among 25 variables the most important factors influencing systolic blood pressure were: Ponderai index, age, Quetelet index, cholesterol and pulse rate.
With these 5 variables 13% of total variation of systolic blood pressure could be explained. The most important factors influencing diastolic blood pressure were: weight, cholesterol, ponderal index, hemoglobin and triglyceride. With these 5 variables 16% of total variation of diastolic blood pressure could be explained.
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