Analysis of Transmission Mode of Confirmed Shigellosis in Gyeongju, Korea / 한국역학회지

ABSTRACT

PURPOSE: This study was carried out to investigate the sources of infection and modes of transmission of an 107 (54males, 53 females) confirmed shigellosis in Gyeongju from Sept. 24 to Oct. 24, 1998. METHODS: We reviewed hospital records of all confirmed shigellosis. Thirty-two strains of Shigella sonnei isolated were analyzed in order to trace the source of infections by plasmid profile, antimicrobial drug resistance pattern, biotyping and pulsed-field gel electrophoresis (PFGE). RESULTS: The first source of infection was estimated to be contaminated underground water and simple piped water caused by leakage from the cess pool. Antimicrobial drug resistance pattern showed that all strains were multi-resistant. All isolates had the same XbaI and SfiI PFGE patterns, indicating the epidemiological relationship of the outbreaks strains in this area. The major characteristics of diarrhea were watery (84.2%) in nature. The clinical symptoms among the diarrheal cases included abdominal pain (86.1%), fever (83.2%), headache (78.2%), chill (45.5%) and tenesmus (41.6%). Six cases were asymptomatic. From initial manifestation to admission were 6.2+/-1.6 (median 6) days, so it could be transmitted to others in this infective period. Duration of admission were 5.5 +/-2.4 (median 6) days. We can find familial mean secondary attack rate were 38.5%. CONCLUSION: It's transmission to other areas were certified by contaminated water and contact with shigellosis, and unknown cases were estimated to be transmitted by contacts with inapparent infection. By plasmid profile and PFGE, the epidemiological relationship of the outbreaks strains in this area seemed to be the same micro-organisms.