• Journal of Preventive Medicine and Public Health
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• v.7 no.2
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• pp.403-415
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• 1974

The author has investigated epidemiological features of human cases of epidemic encephalitis (E. E.) in the Republic of Korea and the status of antibody requisition in pre-and post-epidemic time. And virological and serological studies with regarding the relationship of E. E. infection between human and piglet, and field survey against its vector by means of virus isolation from mosquitoes were carried out. Finally, vaccine field trial against human population has also been evaluated in order to confirm its effectiveness. The results of the studies are summarized as follows : 1. The annual incidence of reported cases during the past 25 years (1949-1973) in the Republic of Korea has shown two patterns, one was typical cyclic incidence and the other one was irregular. Annual average morbidity and mortality rate per 100,000 population were 5.7 and 2.1 and fatality rate was 34.6% in typical cyclic years. 2. With regard to the geographical distribution of E. E., the province of Jeolla-Bug-Do illustrated the highest incidence regardless of the epidemic size. 3. The main epidemic period was between mid-August and mid-September (above 90% of the total number of cases). The first case was reported in middle of July and the epidemic ceased in late of October. 4. An analysis of the age distribution of cases of E. E., has shown that above 90% of the total cases occurred in the age groups under 14 years and it was noted that about its 54% were occurred in the age groups between 5-9 years group. 5. Through the Haemagglutination Inhibition (H-I) test for the laboratory diagnosis of E. E., it was found that higher H-I antibody titer was usually detected in the convalescent phase, 15 days after onset. 6. The H-I antibody survey against 563 healthy population by age groups during the pre-epidemic season showed that 422(75%) were less than H-I titer, 1:20 and 122(21.7%) were positive H-I titer, 1:20. Among the 94 American in Seoul who had not been in E. E. endemic area previously only one person had appeared sero-conversion as a H-I titer of 1:80 after post-epidemic season. 7. The E. E. virus could be isolated from the mosquitos pools-C, tritaeniorhyncus which were caught between late July and middle August. 8. E.E. Virus was also isolated from piglet blood on early August and H-I antibody conversion was occurred mostly on middle of August. 9. H-I antibody sero-conversion rate reached to high level when vaccine purified by mouse brain tissue inoculated, showing 98.9%. Higher antibody titer was acquired when booster inoculation was performed, Four fold rise of H-I add N-T antibodies was confirmed with 93.2% and 82.1% respectively.

• Korean Journal of Poultry Science
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• v.8 no.1
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• pp.15-24
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• 1981

A study was conducted to determine whether the vaccination programs for the control of New castle disease (ND) would affect the immune status of birds against the disease. Twenty-six poultry flocks in the epizootic area of ND were surveyed to investigate the level of urn antibody against ND virus and the programs used for the vaccination of birds. The mortality rates and vaccination status of birds during the epizootic of ND were also examined in the infected poultry flocks to elucidate the immune effect against the epizootic with particular regard to various vaccination programs used in the field. The results obtained are summerized as follows: 1. Of 26 poultry flocks investigated, 22 flocks were immunized with live and killed vaccines, their haemagglutination-inhibition (HI) antibody titer being 146 and 50, respectively. Among 22 farms using live and killed vaccines two flocks which showed the lowest HI titer of 10 and 23 had the disease later on. However, no cases of ND were recorded in the killed vaccine groups, although their HI titers were in the range of 38 to 64. 2. Of 14 infected flecks, one flock was not vaccmated against ND while all the remaining 13 flocks were vaccinated against the disease, of which 8 flocks were vaccinated with live vaccine only and the other 5 flocks with both live and killed vaccines. The mortality rate of 8 infected flocks which had been vaccinated with only live vaccine was as high as 32.5% while that of 5 flocks with both live and killed vaccines was as low as 5.1%. 3. It was found that in majority of flocks B$_1$vaccine was used via drinking water and in a few flocks the vaccine was administered via intramuscular route or method of dipping mouth, nose and eye of birds into vaccine solution.