An Epidemiologic Investigation on the Mode of Transmission of the Lethal Salmonellosis Outbreak in Hamyang County / 한국역학회지

ABSTRACT

An outbreak of Salmonella enteritidis epidemic involving about 200 inpatients of gastroenteritis and 1 death occurred among about 750 participants from Hamyang County who attended 4 wedding lunch parties at one buffet restaurant on April 25, 1999. There were also many patients including 1 death among about 500 participants outside Hamyang County who attended same parties. Person to person interviews made to 155 inpatients revealed that distribution of incubation periods was between 1 to 34 hours with median time, 13-14 hours. A retrospective cohort study was conducted to investigate the mode of transmission. Telephone interviews were made to party participants (except 61 inpatients who already had been interviewed personally) on symptoms and on which they had eaten among 40 served foods including water at the parties and data among 288 persons were available for the analyses. One hundred and ninety one interviewees had more than two symptoms among symptoms of diarrhea(more than 3 times), abdominal pain, and fever, which gave an attack rate of 66.3%(191/288). The relative short incubation period and high attack rate suggested the presence of higher infecting dose in this epidemic. Logistic regression analysis revealed that the probable infective foods were boiled cockle, gamju, boiled midodok, fried rices, eomook, and boiled pig's trotter. Salmonella enteritidis were identified in the specimens of boiled cockle, cooked beef, and uncooked beef. Only boiled cockle was both an epidemiological and microbiological infective food. There might be cross-contaminations between several served foods, which meant presence of many contaminated foods by Salmonella enteritidis with different stage of their multiplications. Efforts to inspect food service areas and educate foodhandlers in good personal hygiene and proper foodhandling practices should be strengthened to reduce the incidences of salmonellosis in Korea.