Outbreaks Associated with Untreated Recreational Water — California, Maine, and Minnesota, 2018–2019
Outbreaks associated with fresh or marine (i.e., untreated) recreational water can be caused by pathogens, toxins, or other chemical agents. Public health officials voluntarily report these outbreaks to CDC’s National Outbreak Reporting System (NORS). Reporting to NORS began in 2009; 2017 is the last year for which NORS data have been finalized. Public health officials from 30 states voluntarily reported 98 untreated recreational water–associated outbreaks, which started during 2009–2017 and resulted in at least 4,765 cases. Most of these outbreaks started during June–August (82 [84%]). Enteric pathogens were the leading confirmed outbreak etiologies: Norovirus (17 [17%] outbreaks, 1,753 cases), Shiga toxin–producing Escherichia coli (STEC) (15 [15%] outbreaks, 144 cases), Cryptosporidium (13 [13%], 147 cases), and Shigella (12 [12%] outbreaks, 777 cases). This report highlights three untreated recreational water–associated outbreaks caused by Shigella, norovirus, or STEC during 2018 or 2019. This report also highlights how microbial water quality testing, environmental investigations, microbial source tracking, and health policy and communication can be tools for preventing transmission of enteric pathogens through untreated recreational water.