Epidemiology and Health

An epidemiological characteristic of dysentery outbreak in a rural area: Y.H Kim, S Bang, J.S Kim, Y Heo, H.K Chung, M.Y Ahn, J.K Lee, C.I Ku, H Kim, S.M Kwon, W.H. Chang; Korean J Epidemiol. 1986;8(2):330-336.

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In the middle of August 1986, several people in a small rural village(179 residents) had a similar disease that was characterized by watery diarhea, crampy adominal pain, fever and vomiting. On this outbreaks, local health department collected stool specimens for culture and administered antibiotics prophylactically. From ten stool cultures the Korean National Institute of Health isolated two strains of Shigella flexneri. Even after the massive prophylactic administration of antibiotics, the occurrence of the cases did not show any change. Therefor the community health program of Soonchunhyang medical school and the health department in the area devided to conduct an epidemiological investigation jointly with the team of Seoul National University, in order to find epidemiological characteristics of the outbreak. Followings are the results summarized: 1) Five strains of bacteria isolated and identified independently by three different institutes, two strains in Korea NIH, two strains in Seoul National University and one in local hospital, were all Shigella flexneri, which confirmed the cause of the outbreak being Shigella flexneri. 2) Incidence rate of the bacterial dysentary among 163 population in 41 households was 35%. It was not significantly different by age group and sex. 3) On the study of environmental factors such as water supply, sewer system, struction of privy, and communal dinning and etc. to explore a possible common source of infection, no such factor assciated with the outbreak was found. 4) Familial aggregation statistically examined by binomial distribution revealed strong(p< 0.005) association. Age and sex specific incidence rate of index cases was significantly high in female old aged(over 60 years of age), suggesting that the dysentery primarily spread by grand-mothers visiting around neighbours. Thus it was concluded that this dysentery has spread insidiously in a small rural village through person-to-person transmission by intimate association between neighbours, particularly by old aged females.; Summary

A study on efficiency of culture by type of medium and inoculum, and of identification by culture temperature in Leptospires isolation for epidemiological mass survey: J.S Kim, S.S Lee, Y Heo, H.W Chung; Korean J Epidemiol. 1986;8(2):323-329.

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This study was carried out on 37 febrile patients occurred in the endemic area of Korean hemorrhagic fever during the September 1986. The objective of the study was to explore the most efficient method of leptospiral culture and identification by comparing different type of culture medium and different kind of inoculum as well as different culture temperature for epidemiological survey. Fletcher’s medium containing 8% rabbit serum was compared with the newly developed medium by Lee, YUMC-5050A. This is made of MEM tissue culture medium(GIBCO) with 0.45gm Hepes buffer and 1ml 1.2% pyruvate / 50ml of the medium by adding ultra filtered(0.2μm pore size)urine of healthy person in 1:1 ratio. All media prepared were incubated in 30C incubator for 1-2 weeks to be sure that there was no contamination in the process of preparation. Four different kind of inoculum, whold blood, serum separated solid part of blood(blood cells) and hemolyzed precipitate of blood(5000G centrifugation) were all inoculated to rabbit serum containing Fletcher’s and YUMC-5050A medium in duplicate for comparison. Nine strains of the leptospires isolated were inoculated to the semisolid Fletcher’s medium in quadriplicate, cultured in 30°C incubator until the full grown colonies became recognizable, then the half of the culture were kept in 4°C refrigerator and the other half were kept in 30°C continuously(control) and checked morphological changes of the leptospires every six hours. The results obtained are summarized as followings: 1) Among 37 febrill patients 32 revealed leptospires in blood culture, which suggested that most febrile patients were from the leptospiral infection. 2) The YUMC-5050A medium was more efficient for massive leptospiral culture in terms of its cost and leptospiral growth rate than the Fletcher's medium; the leptospiral culture positive rate regardless of inoculum was significantly higher in the YUMC-5050A than Fletcher, and that the YUMC-5050A was less expensive because the rabbit serum is not only expensive but also sometimes difficult to buy immediately. 3) Leptospiral culture positive rate was the highest(86.5%) when the hemolysed precipitates were inoculated among other inocula; whole blood(21.6%), serum(21.6%), blood cells(18.9%). 4) When the fully grown leptospiral culture were kept in 4°C refrigerator for 36 hours, over 95% of the bacteria formed typical spiral forms whereas the control culture kept in 30°C incubator for the same period of time showed spiral form bacteria in only about 10%.; Summary

An epidemiological study on the occurrence of hepatitis B virus markers in a part of the population of Kwangwon province: In Ho Choo, Don Hee Han, Sung Joo Hwang, Chang Hong Min, Min Kee Cho, Chang Soon Yoon; Korean J Epidemiol. 1986;8(2):314-322.

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The endemic city of hepatitis B virus infection in Asia is strongly correlated with the high incidence of liver cirrhosis and primary hepatocellular carcinoma. Prospective studies in Taiwan and Japan have estimated that the relative risk of HBV carriers developing liver cancer is over 200 times that of other persons. Many serological surveys in the late 1970s and early 1980s carried out in Korea indicated a high prevalence of HBV seropositivicity with the variation of 2.0-12.0% for HBsAg and 33.0-87.8% for anti-HBS, which may be due to insensitive methods available at early days rather than the characteristics of the sample population. Today it is believed that about 10% Koreans are HBV carriers. The nationwide vaccination campaign is currently in implemention by the Health Administration. Most people are therefore aware of need for blood testing to know immune status. Kwangwon Province, which strides on the 38th armistice parallel, has been indicated by some workers as one of geographical areas for high infection, which seems necessary to be confirmed with a more sensitive assay method Radioimmunoassy in order to provide rational estimates of vaccine requirement for the Provincial Health Administration. The authers have carried out this serological study on a total of 575 individual sera with Radioimmunoassay for detection of HBsAg, anti-HBS, HBeAg and anti-HBC. Blood was collected from volunteers at eight county health centers (Chunchon, Chunsong, Hongchon, Inje, Hwachon, Cholwon, Yangu and Samchok) and also at the University Hospital at Chunchon, from March to November 1985. A questionaire form was filled out for each individual by trained interviwers at the time of blood selection. The form was so designed as to include various partmeters affecting HBV infection for computer analysis of risk factors. The findings are as follows： 1) The positive rates for HBV markets ranged 13.3% for HBsAg, 60.0% fir anti-HBS and 62.9% for anti-HBS, and as a result 75.7% of the test sera showed positive for any marker, single or combined, which demonstrates the current of past infection. The positive rate of HBsAg is 2.2 times higher in males than females and other markers had no sex difference. 2) The frequency of HBeAg carrier was 3.8%. The co-occurrence of both HBsAg and anti-HBS together in the same serum was detected in 5.4%. 3) In risk factor analysis, only two variables-eating out and drinking habits were associated with HBV infection, other failed to yield statistical association.; Summary

Field appraisal of the nutritional status of preschool children and their mothers and the investigation of its determinants in rural Korea: Sook Bang, Young Ok Kim, Hae Kyung Chung; Korean J Epidemiol. 1986;8(2):269-313.

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A study on the genetic effect of cadmium on mouse: Hai Won Chung, Jong Kyu Kim, Joung Soon Kim; Korean J Epidemiol. 1986;8(2):260-268.

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This study was carried out in order to evaluate the genetic effect of cadmium on mouse by measuring rates of chromosome aberration and sperm abnormality. The study was done to explore the possibility of utilizing the measurements as an indicator or for the degree of exposure to environmental toxic pollutants. The results of the study summarized are as follows: 1) The frequency of chromosome aberration was increased as the dose of cadmium was increased 2) The frequency of sperm with abnormal head shape also was increased as the dose of cadmium was increased and the frequency of sperm abnormalities was higher in the group autopsized after 4 weeks from the cadmium I.P. injection than the group after 6 weeks 3) The sperm head count in cauda epididymides was decreased as the dose of cadmium was increased. And the density of sperm after 4 weeks from cadmium injection was lower than that after 6 weeks. Different susceptibility in different age of mice to cadmium was not observed for all doses of cadmium except 1mg / kg administered group. The sperm density for the mice given 1mg / kg cadmium injection was lower in 10-week-old mice than that in 32-week old mice. 4) The weight loss of tests was observed as the doses of cadmium was increased 5) Seminiferous necrosis and calcification were observed in the mice to which 3mg / kg and 5mg / kg cadmium were administered. 6) Therefore it was considered that the measurement of chromosome aberration and sperm abnormalities could be useful indicator in measuring genetic effect of environmental toxic pollutants.; Summary

A review on standardized mortality ratio and proportionate mortality ratio: Won Chul Lee, Kwang Ho Meng; Korean J Epidemiol. 1986;8(2):249-259.

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Standardized mortality ratio (SMR) and Proportionate mortality ratio (PMR) are two major indices that are being widely used for studying the risk of death in employed populations because of their simplicities in calculation and their usefullness. Recently, however, these indices have been known to suffer from several methodological defects. This article reviews these criticisms and some alternative approaches for solving the problems.; Summary

A literature review study on the correlation between stomach cancer and dietary factors: Jae Sim Jeong; Korean J Epidemiol. 1986;8(2):233-248.

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In this study 61 papers published locally and outside Korea have been reviewed to study the relationship between stomach cancer occurrence and dietary factors. The results obtained and summarized are as follows: 1) The risky dietary factors associated with the stomach cancer are smoked and salted food, salt, starchy food, and cereals. 2) The protective dietary factors to stomach cancer are fresh vegetables, fruit, milk, and diary products. Among these the fresh vegetables and fruits show the highest correlation to stomach cancer occurrence among the dietary factors. 3) Stomach cancer patient tends to take meals hastly and irregularly. 4) Stomach cancer patient prefers bot food and be verages. 5) Smoking shows association with stomach cancer, but the association has not revealed any does-response relationship. 6) Stomach cancer occurrence is associated with alcohol drinking, especially beer drinking shows strong association.; Summary

A case-control study for risk factors of peptic ulcer: Hee Choul Oh, Il Soon Kim; Korean J Epidemiol. 1986;8(2):221-232.

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A case-control study was conducted to identify risk factors for peptic ulcer with the cases composed of patients who were endoscopically diagnosed from May 1, 1983 to June 30, 1986 in the Kang-wha Community Hospital. A total of 173 duodenal ulcer and a total of 103 benign gastric ulcer cases were studied and the control groups were twice matched by sex and age. Statistically significant variables were screened by X2-test, which were entered to the multiple logistic model to calculate the odds ratios for risk factors. The results were as follows: 1) Odds ratios of three main effects were preference of spicy food 5.6, salty food 5.6, and presence of life event 2.0 for duodenal ulcer respectively. The interaction term between preference of spicy food and salty food was 7.4 whereas odds ratio of drinking alcohol for duodenal ulcer was 0.5. 2) Although preference of spicy food and smoking were statistically significant respectively, their odds ratios could not be determined for benign gastric ulcer because the multiple logistic model was statistically rejected. 3) A multiple logistic analysis showed that the risk factors for duodenal and gastric ulcer were different in composition of risk factors studied here. 4) As in implication for further study, some objective methods to measure preference for spicy and salty food are needed to confirm them to be risk factors of peptic ulcer and new approaches are also needed to understand the effects of stress on peptic ulcer in terms of interactions with stress relieving factors.; Summary

A case-control study for risk factors on primary liver cancer: Soo Yong Choi, Kyung Hee Lee, Taik Koo Yun; Korean J Epidemiol. 1986;8(2):211-220.

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This study is to investigate risk factors in primary liver cancer due to hepatitis B virus(HBV), smoking, drinking and other risk factors by a case-control study. Two hundred and three patients with primary liver cancer and 609 hospital controls were analyzed. The summary of the results are as followings: 1) There were 172(84.7) male cases with a mean age of 50.0 years and the 31(15.3%) female cases had a mean age of 50.7 years. 2) The positive rates of HBsAg for PLC patients, and controls without cancer and with cancer were 70.4%, and 7.1% and 7.9% respectively. 3) Active HBV infection, indicated by positive tests for HBsAg or anti-HBc without anti-HBs was 80.2% in PLC patients and 23.4% in controls(p < 0.001). An estimated relative risk of PLC was 8.9 times of the risk in subject without evidence of active infection. 4) Patients with markers, anti-HBs or anti-HBs and anti-HBc had approximately the same low risk for PLC.(Estimated relative risk:0.8 and 0.7) 5) Three viral markers without HBsAg, anti-HBs and anti-HBc were detected 3.0% of PLC patients and in 20.9% of controls. 6) There was a dose-response relationship between PLC and alcohol. 7) There was no significant association between cigarette smoking and PLC negative for HBsAg. 8) There was no significant positive association between PLC, and history of blood transfusion and history of acupuncture.; Summary

Does air pollution cause lung cancer?: Kwang Ho Meng; Korean J Epidemiol. 1986;8(2):206-210.

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Panel discussion: H.Y. Chung, K.W Choi, K.R Kim, K.H Choi; Korean J Epidemiol. 1986;8(2):200-205.

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Tsutsugamushi disease: Joung-Sang Lee; Korean J Epidemiol. 1986;8(2):193-199.

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Leptospirosis: Woo-Hyun Chang; Korean J Epidemiol. 1986;8(2):191-192.

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Global Distribution and Molecular Biological Characteristics of Hantaviruses: Lee Ho-Wang; Korean J Epidemiol. 1986;8(2):189-190.

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Global distribution and molecular biological characteristics of Hantaviruses: Ho-Wang Lee; Korean J Epidemiol. 1986;8(2):189-190.

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