Epidemiology and Health

Public affairs reporting: Korean Society of Epidemiology; Korean J Epidemiol. 1983;5(1):167-168.

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Board and staff listing: Korean Society of Epidemiology; Korean J Epidemiol. 1983;5(1):166-166.

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List of membership: Korean Society of Epidemiology; Korean J Epidemiol. 1983;5(1):163-166.

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Articles of association: Korean Society of Epidemiology; Korean J Epidemiol. 1983;5(1):161-162.

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General review of family planning and maternal and child health policies and programs in Korea: Sook Bang, Seung Hyun Han; Korean J Epidemiol. 1983;5(1):148-159.

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An epidemiologic investigation to identify source of infection in an epidemic of typhoid fever occurred in W city, 1983: Joung Soon Kim; Korean J Epidemiol. 1983;5(1):140-147.

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An epidemiological investigation was carried out in order to identify the source of infection in an epidemic of typhoid fever, which occurred from February 20 and ended by March 11, 1983 in Wcity of Korea, with population about 140,000. The analysis of confirmed cases and sample survey on the groups of patient’s family and healthy family led the conclusion that the source of infection was the tap water supplied by the second water plant, which supplies 90% of the water for the city, based on the following findings: (1) The incidence rate per 10,000 population was as low as 8.7 involving all ages with the highest rate among children 5~9 years of age and relatively high occurrence among housewives, which is a typical characteristic of water-born epidemic of the disease. (2) The frequency distribution of the cases by the date of onset showed a single peak positively skewed, all cases occurred within the range of one incubation period suggesting one single exposure to the agent. (3) The geographical distribution of the cases showed a strong association with the water supply status from the second water supply plant. (4) The result of the sample survey on patient's family and healthy family showed difference only in source of drinking water; there was no difference between two groups in food markets they utilized and the foods they have eaten during the Lunar New Year Holiday, when was estimated to be the time of exposure. (5) Most of the cases surveyed by interview had a peculiar characteristics such as young children, housewives, and persons with habit enjoying raw water and foods, who all had vulnerability to the exposure and infection for low dose agent.; Summary

A literature review study on mental disorders in Korea: Soon Ja Cho, Joung Soon Kim; Korean J Epidemiol. 1983;5(1):118-139.

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The purpose of this literature review study was carried out to identify epidemiological characteristics of mental disorders occurring frequently among Koreans. It was intended mainly to deal with the prevalence of mental disorders, particularly schizophrenia, manic-depressive reaction, epilepsy, general paresis and a few other cases during the period from 1960 to 1979. In this literature review, all available paper and articles published were carefully reviewed. As a result, some salient features were found as the followings： 1. In 1960’s, the average prevalence of mental disorders was 4.2 persons per 1,000 inhabitants, whereas the average prevalence was 4.9 persons per 1,000 inhabitants in 1970’s. With regard to the prevalence of mental disorder by sexes, the prevalence rate of all mental disorders in male was much higher than the female except the case of schizophrenia, of which prevalence rate was higher than that of male throughout 1960's. On the other hand the prevalence rate in 1970’s was higher for males in all mental disorders for all ages. The modal age of onset of mental disorders was much younger than the modal age at the time of survey. Throughout 1960's and 1970’s, as many as 392 persons out of all the 515 schizophrenic suffered from the disease longer than 4 years. On the other hand, as many as 814 patients comprising 77.7% out of all the 1,047 mental disease patients suffered longer than 4 years from the conditions. The prevalence of mental disorders by educational level showed the tendency that the prevalence rate increased as the educational level became higher. With regard to the area characteristics the average prevalence rate of all mental disorders was 4.1 persons per 1,000 inhabitants in islands and 4.8 persons in the rural areas of the mainloud. The prevalence rate by religion was 5.7 persons per 1,000 persons for Buddhists, and 18.3 persons per 1,000 persons for both Catholic and Protestants. The result showed that the prevalence rate in the people with religion were as high as 8 times than those without religions. 2. Some characteristics of the patients on numerator analysis obstained from the literature were as followings: As many as 167 persons out of the 354 patients were found to have the pre-morbid personality. Almost all of the cases of schizophrenic comprising 55.0%, manic-depressive reaction patients comprising 79.6%, epilepsy patients comprising 38.8% had the tendency of having premorbid personality. With regard to the body-type of the patients, nearly 48.3% out of all the schizophrenics had asthentic types whereas others had diverse body-type unabling to characterize. About one third of the patients had family history of mental disorders. With regard to the marital status, 34.6% of the patients had been leading normal marital life and 46.1% out of all the patients had not been married, while the beleaved and separated patients comprised 10.7%. On the treatment status, 105 persons out of 203 patients never been treated. Only 33 patients(13.6%) made use of various medical facilities, while 38 persons (15.6%) made use of drug stores for medication. Those who relied on herb medicine were 56 patients(23.0%). Only 38 patients(7.1%) had been treated by psychiatric doctors. The frequency of treatement per patient treated was 1.6 times (Kumgu country only). 3. In addition to the community studies, following information was obtained from hospital statistics, SNU hospital and Yonsei University hospital. The proportion of neuropsychiatric patients hospitalized in SNU hospital out of all the inpatients comprised 9.5% during the period from 1964 to 1965, while in the case of outpatients the proportion decreased gradually from the highest 4.5% in 1970~1971 to the lowest 2.2% in 1980. The proportion of patients suffering from schizophrenia was 49.0% in 1968 and 1970, which was 38.8% in 1974. The proportion of those suffering from neurosis showed gradual increase from 16.1% in 1968 to 27.3% in 1971. Likewise the proportion of those suffering from manic-depressive reaction also increased from 3.2% in 1970 to 10.1% in 1975.; Summary

Studies on cancer patients of cancer research hospital (II): J.Y Kim, Y.K Shim, S.Y Choi, T.K Yun, K.B Park, T.W Kang, Y.K Kim, J.O Lee, H.J Ahn, Y.S. Shim, H.J Chang, K.H Lee, U.D Lee, S.H Soe, S.I Chin, J.J Chang; Korean J Epidemiol. 1983;5(1):102-117.

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This study was done on the basis of medical records registered in Cancer Research Hospital for 15 years from the year of 1963 to 1977. All the cancer patients were analyzed in order to obtain available data for future cancer researches. The ICD-O (WHO, 1976) was used for classification of histological types and anatomical sites of cancer. The results of this study were as follows; 1. The total number of the new patients was 106,271 Cases. Among them, patients with, malignant neoplasms were 24.1% and patients with benign neoplasms were 4.1%. The absolute number of malignant neoplasms showed gradual increase by year from 1963 to 1977, however the proportion of cancer patients among all new patients was decreased gradually during the same period. 2) The ratio of cancer patients in male and female was 1 to 1.16. The highest proportion of cancer patients in male and female was seen 55~64, 45~54 age group, rating 29.4, 32.0 percent respectively. The relative frequency of malignant neoplasms increased over 55 ages in male and female by year. 3) The most frequent malignant neoplasms among all cancer patients were stomach, liver, lung, larynx and lymph nodes in male, and cervix uteri, breast, stomach, thyroid gland and liver in female. Integrating various data published by others in Korea, the most frequent primary sites would be stomach in male and cervix uteri in female. 4) 69.5 percent of malignant neoplasams were diagnosed by histological examination. However, there is no autopsy with concurrent or previous history which is the most valid basis of diagnosis of cancer. The proportion of histological examination was decreased whereas the proportion of clinical investigation was increased. The most frequent histological types of the selected malignant neoplasms were adenocarcinoma in stomach, squamous cell carcinoma in cervix uteri and infiltrating duct carcinoma in breast. 5) The proportion of cancer patients who visited CRH without any diagnosis and/or treatment in other institutions was increased by year, whereas that of patients who visted after treating in other institutions was decreased. 6) Among the cases initially diagnosed and/or treated in this hospital, the proportion of malignant neoplasms by the disease was 0.8 per cent for carcinoma-in-situ cases, 60.6% for localized cases, 7.5 percent for regional lymph nodes and 6.9 percent for distant metastasis cases. 7) The highest proportion of the initial treatment method was 49.8% in radiation therapy alone. Among all the cases confirmed malignant neoplasms in CRH, 36.9 percent of the patients never come back to the institute. 8) The proportion of cancer patients traced to death was 3.3 percent out of 610.; Summary

A literature review study of hypertension and salt intake: Joung Ok Kim; Korean J Epidemiol. 1983;5(1):67-101.

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There have been controversial arguments on the relationship between essential hypertension and salt intake for many years. This literature review study have been attemped to consolidate the facts concerning the sodium intake and hypertension relationship by reviewing 241 literatures of the descriptive, analytic and experimental studies published since 1940. The results of this literature review study summarized are as follows. 1. Animal study 1) A positive dose response relationship between blood pressure and sodium intake in animal experiments was established. 2) In Dahl's animal experiment it was found that there were rats responding differently to the salt loading, salt-sensitive and salt-resistant strains. 2. Epidemiologic study 1) A large scale epidemiological studies in many different countries demonstrated strong associations between salt intake and hypertension which suggests strongly that the high dose salt intake may be causally associated with the development of hypertension. 2) In different races, a positive correlation between the degree civilization and salt intake, which is related to the development of essential hypertension, was reported. 3) Only a few studies did not show any correlation between salt intake and hypertension. 3. Human experimental study. 1) In the intervention studies on hospital patients, demonstrated that the rigid low salt intake was effective for the treatment of hypertension. 2) No correlation was identified blood pressure and concentration of neither serum sodium nor serum potassium. 3) In the intervention studies on hopsital patients with various dose of salt loading, a positive correlation was confirmed between blood pressure and salt intake. 4) Many studies also showed a negative correlation between dietary potassium intake and hypertension, the supplementary potassium chloride had been prescribed for the hypertension patients with low salt diet. 5) Accordingly several studies on salt responses among human hypertensives made it possible to separate human beings into salt-sensitive group, suggesting genetic factor involved in susceptibility to excessive salt intake and responsible for essential hypertension. It was concluded from the review study that excessive salt intake plays on important role as a causative factor in developement of essential hypertenion, particularly for the salt sensitive people who may be genetically affected.; Summary

An epidemiologic study of cerebrovascular diseases through stroke registry and case-control study on risk factors in semi-urban and rural communities of about 210,000 population, Korea (I): Joung Soon Kim, M.H Chung, H.S Yoon, I.S Chun, I.S. Lee, B.Y Huh; Korean J Epidemiol. 1983;5(1):55-66.

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This study was carried out in a semi-urban town, Chun-cheon City and a rural area, Chunseong County from November 1982 in order to understand natural history of cerebrovascular diseases and to identify risk factors of the disease occurring in the community. This is the intermediate report on the result obtained for one year period. During the period 205 patients were registered through adminstrative(Ban) and hospital channels. Among those 98 cases have occurred within one year from the time when the research started. These cases were throughly studied by interview, medical examination with chest x-ray, electrocardiogram, blood chemistry, and measurement of height and weight. Each case was matched with one’s neighbour of the same sex and ±3 years of age. These controls were also studied exactly the same as the cases. All the measurements were compared in patient-control pairs by Mc-Nemar’s marginal test. A cross-sectional study was also carried out on one township of the rural community which was followed by a case-control study of hypertension on risk factors; this cross-sectional study was intended to make base-line survey to get ready for a small scale cohort study on the risk factors of cerebrovascular diseases, to estimate registration rate of the cerebrovascular patients, and to differentiate the risk factors of cerebrovascular disease from the risk factors of cerebrovascular disease from the risk factors of hypertension. The matched cerebrovascular patient-control group was 58 pairs and hypertension patient-control group was 98 pairs for the analysis. Despite the small number examined, several factors showed statistically significant association; hypertention, mental stress, duration of cigarette smoking, left ventricular hypertrophy with cerebrovascular disease, hypertension being the most strongly associated. The most of the risk factors of cerebrovascular disease such as mental stress, left ventricular hypertrophy and family history also showed association with hypertension. However, over-weight and high serum triglycerides showed association with only hypertension, and the duration of cigarette smoking with only cerebrovascular disease. Thus the study result strongly suggests that the single most important risk factor of cerebrovascular disease is hypertension, and other factors that showed association with the cerebrovascular disease have operated indirectly through hypertension. A definite conclusion may be derived when the study is completed on the subject. This study was supported by China Medical Board and World Health Organization grant.; Summary

Control measures of Japanese encephalitis in Korea: Chu Won Lee; Korean J Epidemiol. 1983;5(1):47-54.

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Efficacy of vaccination against Japanese encephalitis: Sung Bok Paik; Korean J Epidemiol. 1983;5(1):41-46.

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Ecological studies on the vector of Japanese encephalitis Culex tritaeniorhynchus in Korea: Han Kee Hong; Korean J Epidemiol. 1983;5(1):29-40.

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Ecological studies on JE vector species, C. tritaeniorhynchus, have been carried out at the seven provincial localities for the purpose of monitoring the JE vector mosquitoes from the year of 1980 to 1983. Data on bionomics of the species obtained by author's previous publications are included and reviewed in this paper. The abstracts are given as follows： 1. Culex tritaeniorhynchus showed the first appearance during the mosquito season from the third week of May to third week of October with the highest peak of the population density in Busan city where is the one of seven study areas for monitoring the JE vector population in 1983. The date of first appearance and the peak of the population density of the species at each study area was on the day of one to two weeks after the Busan city shifting toward the northern study areas： Kwangju city, Wanju gun, Daejeon city and Koyang gun respectively. 2. The proportional densities of C. tritaeniorhynchus has been developed consisting of large proportion as a predominant species among the collected species progressing the month of the year, representing 4.7% in June, 34.5% in July, 84.4% in August and 88.0% in September. 3. Parous rate of the female mosquitoes of C. tritaeniorhynchus was estimated as 68.8% in August and no particular age group in physiological age has been collected at certain time period. 4. C. tritaeniorhynchus showed very aggressive biting activities with highest biting peak within two hours after the sundown and another small peak at 06:00 hours in the morning. In the experimental study, 85% of C. tritaeniorhynchus have been escaped to outside the animal shed after blood fed. 5. The main breeding places of C. tritaeniorhynchus were paddy field, parsley field, pond, marsh area and so on. 6. A dispersal experiment on C. tritaeniorhynchus females by a mark-release-recapture method have been obtained resulting the recapture rate of 0.519%, 0.00208 recovery rate, dispersal rates as 77.5% in 0~2 km, 11.7% in 4~6 km, and 5.8% in 6~8 km. The mosquitoes flew 7.5 km in one day and 1.55 km in average of daily mean distances. 7. JE virus were isolated from the infected female of C. tritaeniorhynchus from middle of July to early part of September and the infection rates were given with the highest in August ranging by 0.06%~0.92% in 1982 and 0.1%~0.66% in 1983. 8. The first JE case occurence in the years of 1982 and 1983 were followed, 10~14 days later under the condition obtained that 500 mosquitoes had been collected at a black light trap per night, and after the first isolation of JE virus from infected C. tritaeniorhynchus mosquitoes.; Summary

Epidemiologic characteristics of the 1982 Japanese encephalitis epidemic occurred in Korea: Joung Soon Kim, In Sook Lee, Hyun Sool Lim, Chu Won Lee, Suk Woo Shin; Korean J Epidemiol. 1983;5(1):1-28.

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In 1982, about 2,000 cases of Japanese encephalitis have occurred despite the governmental effort such as the early warning of the increased vector mosquito density, vaccination campaign and other control measures. Japanese encephalitis had been endemic in Korea with small and large epidemics since the JE virus was isolated in 1949; The JE cases had been remarkably reduced to a few hundred cases since 1969 for over a decade, which increased suddely in 1982. In order to identify responsible factors of the epidemic, all reported cases and a part of hospital patients through medical record survey were analysed. Cases suspicious of encephalitis were reported to Ministry of Health and Social Affairs through, national administrative channel and the final confirmation of the disease was based on the HI antiboy titer of which criteria were set up by the government; it was defined as true encephalitis case when the antibody titer was over 1 : 160 and the subsequent tests stowed fourfold increase in case the first test less than 1 : 160. The hospital medical record survey was carried out on 54% of all reported cases. Summary of the study results is as followings: Among 2975 reported cases about 40% of them were confirmed to be true Japanese encephalitis, about 20% were confirmed to be negative serologically, and the rest of the cases reported never been re-test following the first tests that were negative. Accordingly if the same positive rate is applied for the unconfirmed cases, the total true cases of Japanese encephlaitis estimated to be 2,112 cases. When confirmed cases were compared with total reported cases in the date of onset, age and sex specific incidence rate, duration between the first medical attendence and the onset, duration of hospital admission and the type of medical facility utilized, the both groups showed the similar patterns so that it was unable to characterize them separately. Only with the confirmed cases of Japanese encephalitis the incidence rate of the disease was 3.1 per 100,000 population for whole Korean. The incidence rate varied by province from 2.0 in Gangweon to 7.1 in Chungbug Province; in the agricultural rural area the incidence rate was 3 times higher than in metropolitan area being the higher in South-western part of the country than Northeastern part. Also the disease started from the Southwest moving toward the Northeast which coincided with the time of vector mosquito density Peaks. The age specific incidence rates were higher among younger ages between 5 and 15 years and males 1.7 times higher than females. The majority(87%) of the patients had received medical attention within five days from the onset. The duration of hospital admission was 138.5 days. The case fatality rate was 3.3% being Higher among females, and younger children in females and older ages in males. Among total deaths about one third of death occurred within one week and 97% in two weeks. The sero-conversion for the specific antibody by the JE viral infection was found to be so slow that the serological test as the confirmatory evidence was inefficient; The positive conversion occurred in 46% of confirmed cases in one week and 78% in two weeks after the onset of the disease. The human epidemic of Japanese encephalitis showed association with the densities of pigs and vector population when data were comparatively analysed. The medical record survey in which 1692 cases out of 2,975 reported cases were included, showed that only 41% of them were confirmed as true Japanese encephalitis, 5% as non-encephalitis cases and 59% never had follow-up confirmatory test but negative in single serological test. The final diagnosis on discharge varied widely; Japanese encephalitis 32.6%, suspected Japanese encephalitis 6.6%, meningo-encephalitis 6.1%, viral encephalits 3.1%, encephalitis 23.6%, epidemic encephalitis 4.4%, and aseptic meningitis 5.5% which comprised 83% of total cases studied. Also the specific antibody positive rate varied by the final diagnosis ranging from 18% for aseptic meningitis to 62% for epidemic encephalitis. When these diseases were compared with each another in epidemiologic and clinical charateristics, they were very similar except meningo-encephalitis, viral encephalitis and aseptic meningitis that revealed a little differences in many aspects as presented in tables of text. This study was supported by Korean Institute of Population and Health.; Summary

Contents: Editorial department

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