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A seroepidemiological study on leptospiral infection in a ruralcommunity.
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Soon Jin Lee, Seok Yong Lee, Bo Youl Choi, Ung Ring Ko, Sae Jung Oh, Joung Soon Kim
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Korean J Epidemiol. 1992;14(1):79-90.
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Abstract
A seroepidemiological follow-up survey for antibody to Leptospirae was undertaken twice, the first one in Oct.-Dec. 1988 and the second in Dec. 1989-Mar. 1990 among adult inhabitants of over 20 years of age in Yang-pyeong Gun, Kyeong-ki Do. The sera of 480 persons in 1988 and 328 persons in 1989 were tested for Leptospirae by microscopic agglutination test (MAT) and interview was used for additional inforamtion. The serologic test was performed against 4 strains, which were Icterohemorrhagiae lai and Canicola canicola Hond Utrecht IV as standard strains, and 6P-049-1 and YP-35-1 as strains isolated in 1986 in Korea, in accordance with WHO guideline.
The results of the test showed that 106 of 480 sera(22.1%) in 1988, and 84 of 328 sera(25.6%) in 1989 turned out to be positive to Leptospirae. The seropositive rates for Leptospirae by district in 1988 and 1989 were 12.9~33.3% and 15.0~42.2% respectively and the difference was statistically significant. One district, mainly a commercial area was newly added in 1989. The seropositive rate of that district was 15% and it was significantly low when compared with 32.8% of seropositive rate of the other rural districts. No difference was observed among age groups of 20~30, 40~50 and over 60 years as well as among sexes. The seropositive rate of farmers and non-farmers were 23.0% versus 10.0% in 1988 and 31.1% versus 17.7% in 1989 showing higher rate among farmers. A total of 143 persons were followed up 14 months and it was observed that 37.0% (10/27) of seropositive subjects remained positive, and 31.9%(37/116) of seronegatives were converted to seropositive. The duration of persistent antibody titer over 1 : 80 against Leptospirae that be calculated by formula(prevalence=incidence*duration) was 8.3 months. As for the seropositive reaction with or without febril illness, 29.3% (17/58) of subjects with febrile illness and 24.7 (66/267) of subjects without febrile illness turned out to be positive, showing no significant difference between them.
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Summary
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A follow-up study on the chronological changes of HBV serologicmarkers in a rural community, Korea.
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Bo Youl Choi, Yeong Tae Kim, Ung Ring Ko, Sae Jung Oh, Hung Bae Park
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Korean J Epidemiol. 1991;13(1):6-22.
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Abstract
To estimate incidence rate of HBV infection, prevalence rate of chronic carrier and seroconversion rate of anti-HBs, the chronological changes of HBV serologic markers including HBsAg, Anti-HBs and Anti-HBc were studied using radio-immunoassay(RIA). Two consecutive prevalence surveys were carried out in 14 months ; the first one, from September to December, 1988 and the follow-up, from November, 1989 to March, 1990. Total study subjects were 314 persons(2-85 years in age) who had never been vaccinated against HBV and lived in a typical rural community (Yangpyeong Gun, Gyeong-Gi Do, Korea).
The results are summarized as follows.
1. The HBV serological markers chronologically changed in a wide variety of pattern. Serologic profiles with HBsAg were more variable than the other profiles.
2. The incidence rate of HBV infection was estimated at 10.26% (95% CI ； 5.77-15.38%) and prevalence rate of HBsAg chronic carrier, at 5.40% (95% CI ; 3.18-7.96%). There were no statistically significant differences by age and sex in both the incidence rate of HBV infection and the prevalence rate of chronic carrier.
3. Seroconversion rate of Anti-HBs positives was 9.76% (95% CI ； 4.88-15.45%).
4. The level of HBsAg and Anti-HBs titer at the first prevalence survey had a predictive value in forecasting the chronic carrier state of HBsAg and seroconversion of Anti-HBs positive. Seroconversion rate of only Anti-HBs positives(25.00%) was substantially higher than that of the cases of Anti-HBs and Anti- HBc both positive(6.45%),.
The result suggests that further follow-up study, for a longer period with the more frequent examinations of HBV serologic markers, will be necessary to make a better understanding of the natural course of HBV infection.
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Summary
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A study on the chronological changes of serologic markers of HBV infection among the school children in a rural community of Korea
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Bo Youl Choi, Yeun Ho Lee, Ung Ring Ko
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Korean J Epidemiol. 1990;12(1):81-92.
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Abstract
In Korea, thr reported prevalence of HBsAg in apparently health persons varies as 7.5 to 13.3% in adults and 3.9 to 5.9% in school children. Suggesting, this country belongs to high prevalent area in the world. B hepatitis has been classified into acute and chronic, apparent and inapparent infection, and the prognosis of HBsAg chronic carrier is also variable from complete recovery to fatal outcome such as liver cirrhosis and primary hepatocellular carcinoma. In order to assess the status of infection accurately, the follow-up examination on HBV serologic markers for the considerable period is necessary.
To study the chronological change of serologic markers of HBV infection, authors carried out three successive examinations on HBsAg(by RP-HA) and Anti-HBs(by PHA) of the school children in June, 1985, April 1986 and June 1987. Vaccinees was excluded in the analysis of data.
The results are summarized as follows.
1. HBsAg positive rates in 1985, 1986 and 1987 were 5.89%, 5.67% and 4.29%, and Anti-HBs positive rates 9.68%, 16.75% and 13.50%, repectively.
2. The various chronological changes of serologic markers of HBV infection was observed. All 5 cases who became HBsAg positive in 1986 reversed to be HBsAg negative in 1987, suggesting the newly infected persons in this age group do not ordinarily turn to chronic carrier. Any Anti-HBs positive (58 cases) in 1985 and 1986 did not became HBsAg positives in the next years. So, it is confirmed that Anti-HBs has protective property to HBV infection.
3. Average incidence rate of HBV infection was 7.00(95% C.I.; 4.86-9.34) per 100 person-years. The rate showed a trend of increase as the age increased(5-9yrs; 4.87, 10-14yrs; 5.99, 15-17; 18.87)， and the rate in male(8.80) was higher than in female(5.45). Average loss rate of Anti-HBs was 26.64(95% C.I.; 15.42-39.25) per 100 person-years.
Period prevalence rate of HBsAg chronic carrier was 4.36%(95% C.I.; 2.18-6.85) and no sex difference was observed. The rate was highest(6.42%) in 5-9 years group and lowest(3.13%) in 10-14 years group, though statistically not significant.
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