Prevalence of Leptospira interrogans in Wild Rodents in Korea

Leptospirosis has been known as endemic disease in Korea since 1984. Wild rodent, mostly Apodemus agrarius, has been known as an important source of leptospiral infection especially in rainy circumstances in harvest reason of rural area. The infection rates of Leptospira interrogans in field rodents, Apodemus agrarius, was investigated by culture and PCR detection of leptospiral DNA, and compared with previous data. Furthermore, the serogroup and serovar were investigated. Two hundred twenty two Apodemus agrarius were captured during October to December 1996. Spirohaetes were isolated from 22 (9.9%) and leptospiral DNA was detected in an additional six rodents (12.6%). Subsequent cross-agglutinin absorption test, monoclonal antibody reactivity classified 21 cultures among 22 isolates as Leptospira interrogans serogroup Icterohemorrhagiae serovar lai. The above data did not differ from previous survey in 1984 to 1987. There was no significant change of Leptospira interrogans infection in field rodents in Korea.

Epidemiological Characteristics of Salmonella Strains Isolated recently in Korea

No abstract available.

Investigation on the Immunity to Pertussis in the Korea

Acellular pertussis vaccine has been used widely in Korea since 1984. However, because many of the former generations were not inoculated with pertussis vaccine, they may infect infants with pertussis. With this background, we investigated the prevalence of pertussis antibodies in all age groups. Enzyme-linked immunosorbent assay (ELISA) to assess IgG antibodies to pertussis toxin (PT) and filamentous hemagglutinin (FHA) and bacterial agglutination (BA) to assess antibodies to agglutinogen were compared on 842 serum samples which were donated from 11 hospitals in Seoul area. In comparison with age groups under 20 years, antibodies of adults against PT and FHA were maintained. But antibodies against agglutinogen showed no pattem in all age groups. Antibodies to PT were correlated with antibodies to FHA. There was no significant difference in antibody levels between male and female (p<0.05).

Serogroup and Verocytotoxin Productivity of Escherichia coli Isolated from Diarrheal Patients in Korea / 감염

BACKGROUND: Since 1982, many countries has reported outbreaks or sporadic cases caused by enterohaemorrhagic Escherichia coli (EHEC) serogroup strains, mainly E. coli O157:H7 type strain. However, systemic investigation about EHEC agents, including E. coli O157:H7, have not been done in Korea. Therefore, we investigated serogroup and verotoxin productivity of E. coli strains isolated from diarrheal patients and estimated risk of human infection in comparison with the EHEC strains isolated from cow, pig, and food material in Korea. METHODS: Diarrheal patient stool samples were collected and E. coli strains were isolated, according to biochemical characteristics. In order to isolate E. coli O157:H7, D-Sorbitol negative E. coli strains were selected. Serogrouping of the E. coli isolates was done by agglutination test. Verocytotoxin productivity was investigated by polymerase chain reaction (PCR) and reversed passive latex agglutination (RPLA). Human infection risk was estimated in comparison with EHEC strains isolated from cow, pig and food materials in Korea. RESULTS: Twenty-five E. coli strains were isolated from the diarrheal patients who were suspected to be infected with EHEC. However, none of these E. coli strains produced verocytotoxin. Out of 25 E. coli isolates, 16 serogroups of E. coli O1, O6, O8, O15, O20, O25, O26, O28, O29, O44, O86a, O119, O126, O128, O152 and 157:H- were found. In each of the E. coli O157:H- and O25 serogrorps 3 strains were found. CONCLUSION: None of 25 E. coli isolated from diarrheal patients who were suspected of EHEC infection produced verocytotoxin producing E. coli have been reported recently in Korea.

Pulsed-Field Gel Electrophoresis Pattern, Phage Type and Drug Susceptibility of Salmonella typhi Isolates from an Outbreak in Pusan City in 1996 / 감염

BACKGROUND: During the period from April to June 1996, an outbreak of typhoid fever occurred in SuYoung-Ku, Pusan city. We performed the molecular epidemiological analysis and drug susceptibility test for 48 isolates of Salmonella typhi from the outbreak. METHODS: Chromosomal DNA of S. typhi was digested with the restriction endonuclease Spe I and the resulting restriction polymorphism was observed on pulsed field gel electrophoresis (PFGE). Phage typing was performed using Vi-phages, and antimicrobial susceptibility test was done by Disc diffusion method. RESULTS: On phage typing, 2 isolates were M1 phage type, 2 E1 phage type and 44 untypable. The PFGE analysis on 14 to 16 chromosomal DNA restriction fragments ranged from 50 Kb to 1000kb showed 2 different patterns of restriction fragments, divided into group A and B. Forty-seven isolates belonged to group A that were allocated into A1 (42 strains), A2 (1 strain), A3 (3 strains), A4 (1 strain), and one strain was grouped into group B. In the F-value of genetic similarity of the epidemic S. typhi strains, there was low similarity (F value:0.2-0.258) between group A strains and group B strains. However, the subgroup strains (A1-A4) showed high similarity (F value:0.8-0.897) each other. The drug susceptibility test showed susceptibility to ampicillin, carbenicillin, cephalothin, chloramphenicol, tobramycin, gentamicin, kanamycin, nalidixic acid, neomycin, polymyxin B, streptomycin, tetracycline, trimethoprim-sulfamethoxazole, ciprofloxacin and norfloxacin. CONCLUSION: This study showed that phage typing and PFGE were very useful as a tool to investigate molecular analyses of epidemic S. typhi strains this study.

A Study on the Source of Cholera Epidemic of Korea 1995-1996 / 한국역학회지

E1 tor cholera epidemic have been reported eight times in Korea since 1963. Researchers suspected unattempted importation of cholera bacteria from foreign countries or artificial germination by some people. No researchers have made hypotheses of environmental reservoir as the sources of cholera epidemics until in 1991 in Korea. This study focuses on the aquatic reservoir as the potential source of cholera epidemic. A total of 68 cholera patients were noted in 1995 and only two in 1996. Authors argue for aquatic reservoir as the source of 1995, 1996 cholera epidemic and designate sea fishes as the vehicle of cholera infection The national Institute of Health team cultured Vibrio cholera O1, from the samples of sea water from Kangwha county in September 1995. The sporadic Occurrence of cholera patients around the country who have not traveled out of town support aquatic environmental reservoir as the source of 1995, 1996 cholera epidemic in Korea.

An Epidemiologic Investigation on an Outbreak of Anthrax Occurred in Kyongju by Eating Dead Cow's Meat / 예방의학회지

This epidemiologic study was carried out to investigate cause and magnitude of food-poisoning like epidemic occurred among inhabitants of a village who have eaten dead cow's meat near Kyonng in February of 1994, around lunar new year. The investigation consisted of interview survey on all inhabitants of 77 households (l11 males and 119 females) and their visitors (40 males and 35 females), skin test with anthraxinum(Russian product), study on clinical characteristics for the patients hospitalized, and microbiologic examination on microbes isolated from cow's meat, patient and soils of dead cow's barn. The results obtained are as followings; 1. The proportion of the inhabitants who ingested the dead cow's meat was 36.4%. The incidence rate of the disease was 65.1% for males, 41.7% for females and the cases were distributed evenly for all age groups. The group ingested raw meat showed higher incidence than the group ingested cooked meat. There was no case among people who did not eat the meat. 2. The most clinical symptoms were significantly more frequent among cases than non-cases; sore throat (57%), nausea (51%), fever(47%), indigestion(43%), cough(41%), anorekia(41%), abdominal distention(41%), and abdominal pain(39%) were the major symptoms among cases. 3. Among 29 cases hospitalized out of total 61 cases, three patients, all old and feeble persons, deceased from the disease resulting in 4.9% fatality rate among total patient and 10.3% among hospitalized. Septicemia and meningitis were the causes of the deaths. 4. Three strains isolated from patients, and three strains from dead cow's meat and soil revealed typical microbiologic characteristics of Bacillus Anthracis, which also proved to be fatal to experimentally infected mice.