Investigation of an Infectious Diarrhea Outbreak Associated with Direct Drinking Water in a High School — Baisha County, Hainan Province, China, November 2024

What is already known about this topic?: (DEC) represents a major causative agent of diarrheal outbreaks in China. Transmission occurs through consumption of contaminated food or drinking water and through person-to-person contact, frequently resulting in clustered infections. What is added by this report?: Between November 6 and 20, 2024, an outbreak of infectious diarrhea affected 344 students at a high school in Baisha County, Hainan Province. Comprehensive field epidemiological and environmental investigations, combined with laboratory testing, identified DEC as the causative agent. This outbreak was primarily attributed to consumption of direct drinking water supplied by substandard water dispensers that inadequately filtered contaminated municipal water. What are the implications for public health practice?: Substandard direct drinking water dispensers equipped only with polypropylene (PP) cotton and activated carbon filters cannot effectively remove microorganisms. When source water is contaminated, the warm water produced by mixing cold and hot water outputs from such dispensers fails to meet required hygienic standards. Ensuring municipal drinking water compliance and strict implementation of quality and safety management regulations for direct drinking water dispensers are therefore essential for drinking water safety. The public and all relevant sectors should be reminded to purchase and use only qualified direct drinking water dispensers, particularly in schools, collective establishments, and public venues.