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Epidemiologic characteristics of leptospiral infection in healthy population in special service and their neighboring civilians in Korea
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Joung Soon Kim, J.S Kim, Y Heo, H.W Chung, W.Y Lee, Y.C Hahn, H.G Byun, J.D Suh, H.K Chung
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Korean J Epidemiol. 1987;9(2):264-270.
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 Abstract
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Abstract
The specific aim of this study was to provide epidemiologic information on leptospiral infection in healthy population in special service. These are considered to be the most important group in leptospirosis control not only due to the fact that they have frequent chance of exposure to the potentially dangerous environment for leptospiral infection but also the fact that an efficient preventive measure is urgently required for them.
Seven hundred and fifty six service men and 197 their civilian neighbor were subjected for the study. The study included an epidemiologic analysis of the population through interview survey and this was further supported by bacteriologic and serologic confirmatory tests.
Leptospira were isolated from the peripheral blood samples from those cases. The isolation positive rate were 0.5% of service men and 1.3% of the civilians. Percent of sereum antibody positives for microagglutination test (MAT) were varied from 8.3% of service men to 12.1% of the civilians. When the same population were subjected to the bacteridogical and serologic studies following the exposure to the time of harvesting, the percent of positives in both tests were increased 2.5 times comapared to those found in the same population before harvest season. Almost all of the bacteria positives (6/7) were found to be cases of inapparent infection. Only one out of the seven suffered from mild symptoms of leptospirosis complaining fever, conjuctival hemorrhage, headache, and nausea.
More than half (53%) of the serum samples were reacted with L. icterohemorrhagiae serovar lai and 22% with L. irterohemorrhagiae serovar copenhageni. The rests (25%) were reacted with other groups, L. bataviae, L. canicola, L. grippothyposa, L. automnalis, and L. semaranga.
none of the bacteria positives were antibody positives. The seroconversion rate following the expousre (harvest period) were 7.6% in service men and 9.3% in civilians, which were studies on month after the time.
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Summary
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Epidemiologic characteristics of leptospirosis and febrile disease in population in special service at high risk of infection
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Joung Soon Kim, Yong Heo, H.W Chung, W.Y Lee, H.G Byun, J.D Suh, C.M Sung, M.Y Ahn, J.M Choi, S.J Lee, Y.C Hahn
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Korean J Epidemiol. 1987;9(2):278-287.
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Abstract
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Abstract
This is a part of serial works on leptospirosis. In this study, a correct characterization of all of the hemorrhagic disease accompanying high fever which might be caused by various agents such as leptospira, rickettsia, viruses, and others if any was attempted by classifying the symptoms and identifing the etiologic agent which is responsible for the cases. And also serologic studies along with fundamental epidemiologic investigation on the clinical signs of the patients selected from the study area were done to draw a comprehensive conclusion.
The specific aim which is the major focus of this part of study is to find out prevalence rate of true leptospira patients among patients with high fever and to characterize the clinical pictures, such as clinical signs and symptoms, which might be specific for the true cases of leptospiral infection which is confirmed by bacterial isolation from the cases.
One hundred and nineteen patients hospitalized because of high fever (more than 38°C) for more than 24 hours were studied during 10 month (Aug., 1986-May 1987).
The findings are summarized as follows;
1) At the time of admission, leptospira isolation rate was 5.8% (6/103) and this became 13.7% (7/44, average 8.4%) after one week of hospitalization.
2) The serum samples were testeded for the presence of the antibodies specific to 22 different servar in which 3 strains isolated in this laboratory from human blood employing microagglutination tests.
The positive rate was 34.9% when the first blood samples which were collected at the time of admission tested. And it became 50.9% when the second samples were tested one after the first.
The antibody conversion rate within one week was 32.4%. Only one out of 16 cases who were antibody positive at the first test was found to be negatively converted.
When these were grouped by their antibody titer, 83.7% of whole antibody positive samples (64) demonstrated antibody titer 1.400 or lower and only 3.1% of them demonstrated higher than 1:3200.
3) Significantly higher positive rate were found when the sera were tested with the fresh strains isolated from that area.
The majority (32.4%) of the sera from Chullwon area positively reacted with locally isolated L. icterhemorrhagiae lai and 17.1% of sera from Yangoo area with locally isollated L. canicola.
In Chullwon area, 65% of the serum samples were identified belonging to 3 serovars, L. icterohemorrhagiae lai (32.4%), L. canicola (14.7%), and L. ictervhemorrhagiae copenhageni (17.6%).
In Yangoo area, 54% of the scrum samples were positive for 4 serovars, L. icterohemorrhagiae lai (14.6%), L. hebdomadis (12.2%), L. icterohemorrhagiae copenhageni (9.8%) and above mentioned local isolate.
4) among 92 patients with high fever 19 cases (20.2%) were confirmed to be leptospiral infection by the both tests for bacterial isolation and serology. Sixteen cases (16%) were the suspicious cases of leptospirosis. The rest of them, 60 patients (63.8%) were found to be uninfected with the bacteria.
5) When the seasonal changes of incidence of the feverrile disease were comparatively analyzed, the cases belonged to confirmed as leptospirosis occured maily in Autumn whereas the others occured throughout the year except the spring in which time a slight decreased cases were recorded.
The incidence of the confirmed cases were higher in groups which had been exposed to field trainings.
Sore throat, runny nose, hematemesis, and muscle pain were found to be significantly frequent signs complained by the confirmed cases and diastolic blood pressure of the cases was higher.
6) amomg the confirmed cases only 5.3% of them were primarily diagnosed as leptospirosis and majority were diagnosed as fever with unknown reason (47.3%) when they were adimitted because of the high fever. Whereas among the cases confirmed as uninfected 25% was fever with unknown reason and 46.7% for the others. The proportion of cases diagnosed as leptospirosis was 5.0%.
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Summary
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