ABSTRACT
INTRODUCTION: On 15 June 2020, the National Public Health Organization was informed about the identification of two cases of Escherichia coli Ο157 infection in a small town in the Peloponnese Region in Greece and we suspected an outbreak. METHODS: We asked the local pharmacist to assist us to verify the outbreak by providing the daily number of over-the-counter anti-diarrheal drugs sold from 20 May 2020 onwards. The pharmacist asked customers with gastroenteritis to submit stool samples at the local hospital. Samples were tested for 22 pathogens. We conducted a 1 : 1 case-control study. Cases and controls were retrieved from the pharmacy client list. Chlorination records of the water supply system were retrieved, and water samples were tested for microbiological indicators and viruses. RESULTS: The increased number of sales of anti-diarrheal drugs verified the outbreak. Overall, 58 cases and 57 controls were recruited for the study. Tap water consumption (odds ratio (OR)=10.9, 95% confidence interval (CI)=3.1-38.0, p<0.001) and consumption of ice cubes made from tap water (OR=39.3, 95%CI=10.3-150.9, p<0.001) were independently associated with gastroenteritis occurrence. Eleven stool samples were tested; one was positive for shigatoxin-producing E. coli, one for enteropathogenic E. coli, four for E. coli Ο157 and one for Salmonella spp. Four samples tested negative. Five water samples collected on 18 June tested negative. The residual chlorine on 5 and 14 June ranged from 0.12 mg/L to 0.14 mg/L. CONCLUSION: This was the first investigation of a waterborne outbreak in Greece performed with the collaboration of a local pharmacy. The COVID-19 pandemic favored the use of alternative resources and channels of communication with the local population, which can also be used in the future, especially in remote areas of the country.