Trends in Water- and Foodborne Disease Outbreaks in Korea, 2007-2009

Objectives: In Korea, every outbreak of acute gastroenteritis in two or more patients who are epidemiologically related is investigated by local public health centres to determine causative agents and control the outbreak with the support of the Korean Centers for Disease Control and Prevention. The findings and conclusions of each outbreak investigation have been summarized annually since 2007 to make reports and statistics of water- and foodborne disease outbreaks. Methods: All outbreaks reported to Korean Centers for Disease Control and Prevention from 2007 to 2009 were included in the study. We analysed the trends and epidemiologic aspects of outbreaks by month, year, and location. Results: The total number of outbreaks decreased steadily each year for the period the study covered, whereas the number of patients per outbreak continued to increase resulting from a dramatic increase in the number of patients per outbreak in food service establishments. The outbreaks occurred in the period of June to September, when temperature and humidity are relatively high, which accounted for 44.3% of total outbreaks. The monthly number of outbreaks decreased steadily until November after peaking in May 2009. The most common causative agent was norovirus (16.5%) followed by pathogenic Escherichia coli. The rate of causative agent identification was 60.1%, with higher identification rates in larger outbreaks. Conclusions: Although a decreasing trend of outbreaks by year was observed in the study, the food services in schools and companies require more attention to hygiene and sanitation to prevent large outbreaks. The ability to establish the cause of an outbreak should be further improved.