A seroepidemiological follow-up survey for antibody to Loptospiae 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 aginst 4 strains, which were 1clerohemorrhagiae
lai
and
Canicola canicola Hond Utrecht as standard strains, and 6 P-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 480sera(22.1%) in 1988, and 84 of 328 sera(25.6%) in 1988, and 84 of 328 sera (25.6%) in 1989 turned out to be positive to Leptospirac. The seropositive rates for Leplospirac 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 Leplospiae 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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