Introduction: On June 15 2020, we were informed about the identification of two cases of Escherichia coli Ο:157 infection in a small town and we suspected of an outbreak.
Methods: We asked the local pharmacist to assist us to verify the outbreak by providing us the daily number of over-the-counter anti-diarrheal drugs sold from May 20, 2020 onwards. The pharmacist asked gastroenteritis cases 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 clients’ list of the pharmacy. Chlorination records of the water supply system were retrieved. 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 (OR= 10.9, 95% 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 shiga-toxin producing Escherichia coli, one for enteropathogenic E. coli, four for E. coli O:157 and one for Salmonella spp. Four samples tested negative. Five water samples collected on June 18, tested negative. The residual chlorine on June 5 and 14 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 that can also be used in the future, especially in remote areas of the country.