Virginia A. Roberts

Surveillance for waterborne-disease outbreaks associated with recreational water: United States, 2001-2002

Provision of safe water in the United States is vital to protecting public health (1). Public health agencies in the U.S. states and territories* report information on waterborne disease outbreaks to CDC through the National Outbreak Reporting System (NORS) (https://www.cdc.gov/healthywater/surveillance/index.html). During 2013-2014, 42 drinking water-associated† outbreaks were reported, accounting for at least 1,006 cases of illness, 124 hospitalizations, and 13 deaths. Legionella was associated with 57% of these outbreaks and all of the deaths. Sixty-nine percent of the reported illnesses occurred in four outbreaks in which the etiology was determined to be either a chemical or toxin or the parasite Cryptosporidium. Drinking water contamination events can cause disruptions in water service, large impacts on public health, and persistent community concern about drinking water quality. Effective water treatment and regulations can protect public drinking water supplies in the United States, and rapid detection, identification of the cause, and response to illness reports can reduce the transmission of infectious pathogens and harmful chemicals and toxins.

Causes of Outbreaks Associated with Drinking Water in the United States from 1971 to 2006

SUMMARY Since 1971, the CDC, EPA, and Council of State and Territorial Epidemiologists (CSTE) have maintained the collaborative national Waterborne Disease and Outbreak Surveillance System (WBDOSS) to document waterborne disease outbreaks (WBDOs) reported by local, state, and territorial health departments. WBDOs were recently reclassified to better characterize water system deficiencies and risk factors; data were analyzed for trends in outbreak occurrence, etiologies, and deficiencies during 1971 to 2006. A total of 833 WBDOs, 577,991 cases of illness, and 106 deaths were reported during 1971 to 2006. Trends of public health significance include (i) a decrease in the number of reported outbreaks over time and in the annual proportion of outbreaks reported in public water systems, (ii) an increase in the annual proportion of outbreaks reported in individual water systems and in the proportion of outbreaks associated with premise plumbing deficiencies in public water systems, (iii) no change in the annual proportion of outbreaks associated with distribution system deficiencies or the use of untreated and improperly treated groundwater in public water systems, and (iv) the increasing importance of Legionella since its inclusion in WBDOSS in 2001. Data from WBDOSS have helped inform public health and regulatory responses. Additional resources for waterborne disease surveillance and outbreak detection are essential to improve our ability to monitor, detect, and prevent waterborne disease in the United States.

Acute Gastroenteritis Surveillance through the National Outbreak Reporting System, United States

Implemented in 2009, the National Outbreak Reporting System provides surveillance for acute gastroenteritis outbreaks in the United States resulting from any transmission mode. Data from the first 2 years of surveillance highlight the predominant role of norovirus. The pathogen-specific transmission pathways and exposure settings identified can help inform prevention efforts.

Contributing Factors to Disease Outbreaks Associated with Untreated Groundwater

Disease outbreaks associated with drinking water drawn from untreated groundwater sources represent a substantial proportion (30.3%) of the 818 drinking water outbreaks reported to CDCs Waterborne Disease and Outbreak Surveillance System (WBDOSS) during 1971 to 2008. The objectives of this study were to identify underlying contributing factors, suggest improvements for data collection during outbreaks, and inform outbreak prevention efforts. Two researchers independently reviewed all qualifying outbreak reports (1971 to 2008), assigned contributing factors and abstracted additional information (e.g., cases, etiology, and water system attributes). The 248 outbreaks resulted in at least 23,478 cases of illness, 390 hospitalizations, and 13 deaths. The majority of outbreaks had an unidentified etiology (n = 135, 54.4%). When identified, the primary etiologies were hepatitis A virus (n = 21, 8.5%), Shigella spp. (n = 20, 8.1%), and Giardia intestinalis (n = 14, 5.7%). Among the 172 (69.4%) outbreaks with contributing factor data available, the leading contamination sources included human sewage (n = 57, 33.1%), animal contamination (n = 16, 9.3%), and contamination entering via the distribution system (n = 12, 7.0%). Groundwater contamination was most often facilitated by improper design, maintenance or location of the water source or nearby waste water disposal system (i.e., septic tank; n = 116, 67.4%). Other contributing factors included rapid pathogen transport through hydrogeologic formations (e.g., karst limestone; n = 45, 26.2%) and preceding heavy rainfall or flooding (n = 36, 20.9%). This analysis underscores the importance of identifying untreated groundwater system vulnerabilities through frequent inspection and routine maintenance, as recommended by protective regulations such as Environmental Protection Agencys (EPAs) Groundwater Rule, and the need for special consideration of the local hydrogeology.

Foodborne (1973–2013) and Waterborne (1971–2013) Disease Outbreaks — United States

CDC collects data on foodborne and waterborne disease outbreaks reported by all U.S. states and territories through the Foodborne Disease Outbreak Surveillance System (FDOSS) (http://www.cdc.gov/foodsafety/fdoss/surveillance/index.html) and the Waterborne Disease and Outbreak Surveillance System (WBDOSS) http://www.cdc.gov/healthywater/surveillance), respectively. These two systems are the primary source of national data describing the number of reported outbreaks; outbreak-associated illnesses, hospitalizations, and deaths; etiologic agents; water source or implicated foods; settings of exposure; and other factors associated with recognized foodborne and waterborne disease outbreaks in the United States.

Waterborne disease outbreaks associated with environmental and undetermined exposures to water - United States, 2013-2014

Weekly/November 10, 2017/66(44);12221225 Waterborne disease outbreaks in the United States are associated with a wide variety of water exposures and are reported annually to CDC on a voluntary basis by state and territorial health departments through the National Outbreak Reporting System (NORS). A majority of outbreaks arise from exposure to drinking water1 or recreational water,2 whereas others are caused by an environmental exposure to water or an undetermined exposure to water. During 20132014, 15 outbreaks associated with an environmental exposure to water and 12 outbreaks with an undetermined exposure to water were reported, resulting in at least 289 cases of illness, 108 hospitalizations, and 17 deaths. Legionella was responsible for 63% of the outbreaks, 94% of hospitalizations, and all deaths. Outbreaks were also caused by Cryptosporidium, Pseudomonas, and Giardia, including six outbreaks of giardiasis caused by ingestion of water from a river, stream, or spring. Water management programs can effectively prevent outbreaks caused by environmental exposure to water from humanmade water systems, while proper pointofuse treatment of water can prevent outbreaks caused by ingestion of water from natural water systems. CDC analyzed data from waterborne disease outbreaks reported to NORS associated with environmental and undetermined exposures to water during 20132014. Outbreaks with an environmental exposure to water are not associated with a recreational water venue or drinking water system, but rather, are linked to other water types including water from cooling towers, industrial processes, agricultural processes, occupational settings, decorative or display settings (e.g., decorative fountains), and water consumed from natural sources such as backcountry streams.3 Outbreaks involving an undetermined exposure to water could not be definitively linked to a single type of water exposure because of association with multiple suspected or confirmed water types (e.g., both spa and drinking water systems) or because insufficient epidemiologic, laboratory, or environmental evidence was available to identify the exposure. All outbreaks with first illness onset during 20132014 reported by December 31, 2015 are included in this report. NORS defines a waterborne disease outbreak as the occurrence of a similar illness in two or more persons who are linked by time and location to a common water exposure. For each outbreak, data were collected regarding the number of ill persons, hospitalizations, and deaths, along with the sex, age group, symptoms, and duration of illness for persons affected by the outbreak. Results of epidemiologic and laboratory investigations are also reported, including the suspected or confirmed etiologic agent, the type of water to which patients were exposed, and the setting of the water exposure. During the analysis, predominant illness type was assigned, and water type was further categorized as a humanmade or natural water system. Humanmade water systems include infrastructure intended for water storage or recirculation, whereas natural water systems include raw water that might or might not be treated at the point of exposure. Waterborne disease outbreaks associated with environmental and undetermined exposures to water from prior years have been reported previously (https://www.cdc.gov/healthywater/surveillance/environmental/environ-water-surveillance-reports.html).

Waterborne Disease Outbreaks Associated With Environmental and Undetermined Exposures to Water — United States, 2013–2014

Waterborne disease outbreaks in the United States are associated with a wide variety of water exposures and are reported annually to CDC on a voluntary basis by state and territorial health departments through the National Outbreak Reporting System (NORS). A majority of outbreaks arise from exposure to drinking water (1) or recreational water (2), whereas others are caused by an environmental exposure to water or an undetermined exposure to water. During 2013-2014, 15 outbreaks associated with an environmental exposure to water and 12 outbreaks with an undetermined exposure to water were reported, resulting in at least 289 cases of illness, 108 hospitalizations, and 17 deaths. Legionella was responsible for 63% of the outbreaks, 94% of hospitalizations, and all deaths. Outbreaks were also caused by Cryptosporidium, Pseudomonas, and Giardia, including six outbreaks of giardiasis caused by ingestion of water from a river, stream, or spring. Water management programs can effectively prevent outbreaks caused by environmental exposure to water from human-made water systems, while proper point-of-use treatment of water can prevent outbreaks caused by ingestion of water from natural water systems.

Prevention and Control of Youth Camp–Associated Acute Gastroenteritis Outbreaks

Background Approximately 14 million children attend more than 14000 US camps every year. Shared accommodations and activities can facilitate acute gastroenteritis (AGE) outbreaks. Methods We analyzed data from the National Outbreak Reporting System on US youth camp-associated AGE outbreaks that occurred between 2009 and 2016. We also conducted a systematic literature search of youth camp-associated AGE outbreaks that have occurred around the world and a gray literature search for existing recommendations on outbreak prevention and control at camps worldwide. Results Thirty-nine US jurisdictions reported a total of 229 youth camp-associated AGE outbreaks to the National Outbreak Reporting System. Of the 226 outbreaks included in our analyses, 120 (53%) were reported to have resulted from person-to-person transmission, 42 (19%) from an unknown transmission mode, 38 (17%) from foodborne transmission, 19 (8%) from waterborne transmission, 5 (2%) from animal contact, and 2 (<1%) from environmental contamination. Among 170 (75%) outbreaks with a single suspected or confirmed etiology, norovirus (107 [63%] outbreaks), Salmonella spp (16 [9%]), and Shiga-toxin producing Escherichia coli (12 [7%]) were implicated most frequently. We identified 43 additional youth camp-associated AGE outbreaks in the literature that occurred in various countries between 1938 and 2014. Control measures identified through the literature search included camp closure, separation of ill campers, environmental disinfection, and education on food preparation and hand hygiene. Conclusions Youth camp-associated AGE outbreaks are caused by numerous pathogens every year. These outbreaks are facilitated by factors that include improper food preparation, inadequate cleaning and disinfection, shared accommodations, and contact with animals. Health education focused on proper hygiene and preventing disease transmission could help control or prevent these outbreaks.

Outbreaks Associated with Untreated Recreational Water - United States, 2000-2014

1Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, CDC, Atlanta, GA, USA 2Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA 3Environmental Protection Agency, Washington, D.C., USA 4Division of Emergency and Environmental Health Services, National Center for Environmental Health, CDC, Atlanta, GA, USA 5Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases, CDC, Atlanta, GA, USA 6Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, CDC, Atlanta, GA, USA