Splash pads can include single-pass splash pads in which treated tap water is circulated but does not undergo additional treatment within the splash pad.
Recreational waterborne disease outbreaks associated with at least one splash pad can be classified as splash pad–associated outbreaks.
* Results All Splash Pad–Associated Outbreaks During 1997–2022, public health officials from 23 states and Puerto Rico (Figure 1) reported 60 splash pad–associated outbreaks (Table 1).
The 2023 MAHC addresses splash pads in which water is recirculated but not single-pass splash pads.
These two recommendations are more stringent for splash pads because splash pads are at increased risk for contamination by Cryptosporidium.
An introduction.
Splash pads spray or jet water at users; they are also referred to as interactive fountains, water playgrounds, spray parks, and wet decks. Water in the venue plumbing can either be passed once or recirculated. After being sprayed or jetted, the water in recirculating splash pads drains into a tank where it is filtered and cleaned before being sprayed or jetted once more. Only one plumbing cycle occurs in single-pass splash pads before the water drains, usually into a sewer system (1).
Originally introduced in the 1990s, splash pads are made to prevent water from collecting in user-accessible areas (1). While this feature reduces the risk of drowning, splash pads have been linked to chemical or infectious waterborne outbreaks. In some jurisdictions, splash pads may be exempt from public health regulations because they don’t have standing water in areas that users can access. Prior to 2000, only 13 states had splash pad regulations (2). Extra states (e.g. 3. , Oregon) have since passed splash pad-related public health laws, frequently in reaction to outbreaks linked to splash pads (2).
The CDC can receive voluntary reports of epidemiologic, laboratory, and environmental health data gathered by public health officials as they look into outbreaks of waterborne diseases linked to splash pads. Data on splash pad-associated outbreaks reported to the CDC from 1997—the year of the first two documented outbreaks—to 2022—the most recent year for which data are available—are compiled in this report. Although outbreaks linked to splash pads have been documented separately (5) or in a summary of waterborne disease outbreaks (6), this report is the first to include a summary of splash pad-associated waterborne disease outbreaks. The results of this report can be used by aquatics professionals and public health officials to encourage the prevention of outbreaks linked to splash pads (e.g. A. suggested user conduct), and direct the design, use, and maintenance of splash pads.
Techniques.
sources of data.
The Waterborne Disease and Outbreak Surveillance System (WBDOSS) was created by CDC in 1971 to systematically gather information on outbreaks of waterborne diseases using paper forms. Data on outbreaks connected to recreational water were not formally gathered by WBDOSS (e.g. G. lakes and swimming pools) until 1978. Domains (i.e. E. the District of Columbia, the 50 states, the U. A. territories, and states that are freely affiliated) voluntarily submit information on outbreaks of waterborne diseases that affect recreational users. Jurisdictions used a standard paper form to voluntarily report outbreaks to the CDC until 2009.
The National Outbreak Reporting System (NORS), a web-based platform created by CDC in 2009, allows voluntary electronic reporting of data on outbreaks of waterborne and other diseases (i.e. e. environmental factors, foodborne, enteric animal contact, and unclear or unidentified modes of transmission) (https://www . cdc . gov/nors/about/index . html). Since 2009, NORS has been the sole method used to report any waterborne outbreaks. Because of modifications made after the launch, NORS Form 52.12, which was used to report waterborne outbreaks through 2022, does not correspond to the version used to introduce NORS in 2009 (https://www . cdc . gov/nors/pdf/NORS_CDC_5212-form). PDF). Following NORS’s launch, all of the WBDOSS data was combined into NORS. A significant update to NORS was made by CDC in 2023, which included simplifying and updating the data collection process for waterborne disease outbreaks (Form 52.14) (https://www . cdc . gov/nors/pdf/NORS-Form-CDC-52.14_508). in PDF). Every year, the CDC asks jurisdictions for information on waterborne disease outbreaks, then works with health departments to clean and compile the information.
Definitions.
There are two types of recreational water: treated and untreated. Water used for recreational purposes is systematically treated (e.g. A. , filtration, or disinfection) to preserve quality for recreational use, and is usually housed in a enclosed, manufactured structure. Splash pads are treated recreational water areas in addition to pools and hot tubs. Single-pass splash pads are one type of splash pad that circulates treated tap water without undergoing any further treatment. Untreated recreational water is not regularly treated to preserve its quality for recreational purposes. Recreational water sources that are not treated include lakes, rivers, and seas.
An outbreak of recreational waterborne disease occurs when similar illnesses (e.g. G. respiratory or gastrointestinal) in two or more individuals who are epidemiologically connected by the time and place of their exposure to recreational water or by pathogens or chemicals that have been aerosolized or volatilized into the air near the water. Splash pad–associated outbreaks are outbreaks of recreational waterborne diseases linked to at least one splash pad.
variables.
Each outbreak’s data is summarized as follows: exposure jurisdiction (the exposure state is the NORS variable that gathers information on the jurisdiction of outbreak exposure); earliest illness onset date; etiology (confirmed or suspected); venue or venues (at least one splash pad implicated as the outbreak source); setting (the location of the implicated venue or venues [e.g. A. [city park or zoo], contributing factors; and the number of hospitalizations, ED visits, illness cases, and fatalities. These statistics were regularly gathered from 1997 to 2022, with the exception of ED visit counts, which have been gathered since 2009 when NORS was introduced. Multiple-etiology outbreaks were categorized and examined as a single outbreak.
Where the water exposure took place is referred to as the setting. Community or municipal parks, water parks, recreational facilities, and zoos are a few examples of water settings. NORS defines a city, town, or other settlement with a sizable population that lives and works as a community or municipality setting. A park that is owned by a community or municipality is referred to as a community or municipal park setting. The term “water venue” describes the kind of location that is situated near water. Splash pads, pools, and hot tubs are a few types of water venues.
The NORS data for outbreak-causing factors are also compiled in this report (i.e. E. factors that contribute. Using a list of up to 41 factors unique to treated outbreaks of recreational waterborne diseases, jurisdictions can report contributing factors in NORS. Alternatively, they can enter additional contributing factors in a free text field. Contributing factors may be reported as observed, documented, or suspected. If data is obtained through document reviews, in-person observations, or interviews, contributing factors are categorized as documented or observed. If there is no documentation or visible proof of a contributing factor, it is categorized as suspected. The factors that contribute to treated recreational waterborne outbreaks are divided into four categories: facility design, personnel, policy and management, and maintenance.
evaluations.
The splash pad-related outbreaks that were reported and resolved in NORS as of May 1, 2024, are described in this report. The following data were analyzed for each outbreak: jurisdiction, date of illness onset, etiology, water venue, exposure setting, contributing factors, and the number of cases of illnesses, ED visits, hospitalizations, and fatalities. Data on contributing factors were examined for outbreaks that were solely linked to splash pads and not at any other locations. The CDC used R software (version 4.3) to compute descriptive statistics in order to compile information on the features of reported outbreaks linked to splash pads. R Foundation, second). According to CDC policy and applicable federal law, this activity was reviewed and determined not to be research. **.
Results.
All Outbreaks Associated with Splashes.
60 outbreaks linked to splash pads were reported by public health officials from 23 states and Puerto Rico (Figure 1) between 1997 and 2022 (Table 1). These 60 outbreaks were linked to exposures in environments with splash pads alone (n = 39) and environments with splash pads and additional venues (e.g. 3. hot tubs and swimming pools) (n = 21). A total of 10,611 cases, 152 hospitalizations, 99 ED visits, and no recorded fatalities were caused by these 60 outbreaks.
Of the 60 outbreaks, 52 (87%) had laboratory confirmation of the waterborne disease etiology (Table 2). 40 (67 percent) outbreaks caused by Cryptosporidium (including one caused by Shigella and another by Giardia) led to 9,622 (91 percent) reported cases, 123 (81 percent) hospitalizations, and 21 (21 percent) attendances at the emergency room. More precisely, 14 (23 percent) outbreaks caused by Cryptosporidium hominis led to 7,833 (74 percent) cases, 97 (64 percent) hospitalizations, and three (3 percent) ED visits. A. Additionally, hominis was responsible for the three biggest outbreaks (2,307 cases, 2,050 cases, and 2,000 cases); two of these outbreaks were linked solely to splash pads, while the third outbreak involved both a splash pad and other locations. There were four (7 percent) outbreaks of Cryptosporidium parvum, which led to nine (. <1 percent) cases, two (2 percent) emergency department visits, and no hospitalizations. Cryptosporidium of unknown species caused 17 (28 percent) outbreaks that resulted in 1,478 (14 percent) cases, 21 (14 percent) hospitalizations, and six (6 percent) emergency department visits. Multiple species of Cryptosporidium caused three (5 percent) outbreaks that resulted in 199 (2 percent) cases, 10 (10 percent) emergency department visits, and one (1 percent) hospitalization. Shigella caused five outbreaks (including one that was also caused by Cryptosporidium), Escherichia coli O157:H7 caused three, and the following caused one outbreak each: Campylobacter jejuni, Giardia duodenalis (also caused by Cryptosporidium), norovirus, and Salmonella serotype Newport. These 12 (20 percent) outbreaks resulted in 271 (3 percent) cases of acute gastrointestinal illness, 16 (11 percent) hospitalizations, and six (6 percent) emergency department visits. Legionella pneumophila and chloramines were each confirmed to cause one outbreak. Of the 99 emergency department visits reported for all splash pad–associated outbreaks, 72 (73 percent) resulted from two outbreaks suspected to be caused by norovirus. Of the 60 splash pad–associated outbreaks, 57 (95 percent) were reported during May–August (Figure 2). Approximately one fourth (n = 17; 27 percent) of the outbreaks were associated with at least one splash pad in a community or municipality setting, followed by 14 outbreaks (23 percent) in a community or municipal park (Figure 3). Outbreaks Associated with Splash Pads Only Data on outbreaks associated with splash pads only were analyzed separately to evaluate only those etiologic agents and contributing factors associated with splash pads, because these might differ from outbreaks associated with other treated recreational venues (e.g., swimming pools and hot tubs). Of the 60 outbreaks, 39 (65 percent) were associated with splash pads only and resulted in 5,384 cases, 85 emergency department visits, and 68 hospitalizations (Table 3). An outbreak etiology was laboratory confirmed for 33 (85 percent) of the 39 outbreaks. Cryptosporidium caused 25 (64 percent) of the 39 outbreaks (including one that was also caused by Giardia and another also caused by Shigella) that resulted in 5,111 (95 percent) of 5,384 cases, nine (11 percent) of 85 emergency department visits, and 45 (66 percent) of 68 hospitalizations. More specifically, C. hominis caused nine (23 percent) outbreaks that resulted in 4,551 (85 percent) cases, 33 (49 percent) hospitalizations, and no emergency department visits. C. parvum caused four (10 percent) outbreaks that resulted in nine (<1 percent) cases, two (2 percent) emergency department visits, and no hospitalizations. Cryptosporidium of unknown species caused nine (23 percent) outbreaks that resulted in 436 (8 percent) cases, eight (12 percent) hospitalizations, and no emergency department visits. Multiple species of Cryptosporidium caused one (3 percent) outbreak that resulted in 22 (<1 percent) cases, four (5 percent) emergency department visits, and no hospitalizations. Shigella species caused four outbreaks associated with splash pads only (including one that also was caused by Cryptosporidium), E. coli O157:H7 caused two outbreaks, and each of the following etiologic agents caused one outbreak: C. jejuni, G. duodenalis (also caused by Cryptosporidium), norovirus, and Salmonella serotype Newport (Table 3). These 10 (26 percent) of the 39 outbreaks resulted in 140 (3 percent) of 5,384 cases of acute gastrointestinal illness, 10 (15 percent) of 68 hospitalizations, and three (4 percent) of 85 emergency department visits. Of the 85 emergency department visits reported for outbreaks associated with splash pads only, 72 (85 percent) resulted from two outbreaks suspected to be caused by norovirus. Chlorine was suspected to cause one outbreak associated with splash pads only that resulted in 17 cases (<1 percent), one emergency department visit (1 percent), and no hospitalizations. Of the 39 outbreaks associated with splash pads only, 38 (97 percent) were reported during May–August (Figure 2). Puerto Rico reported one outbreak that started in December. Of the 39 outbreaks associated with splash pads only, 14 (36 percent) were associated with splash pads in a community or municipal park setting, followed by 13 outbreaks (33 percent) associated with a splash pad in a community or municipality setting (Figure 3). Of the 39 outbreaks associated with splash pads only, 27 (69 percent) had data on contributing factors reported in NORS (Table 4). Of these 27 outbreaks, a total of 70 documented/observed contributing factors were reported. For outbreaks associated with splash pads only and caused by Cryptosporidium, a person-related contributing factor (i.e., primary intended use of water is by diaper/toddler aged children) and a facility design–related factor (i.e., no supplemental disinfection installed that would have inactivated pathogens [e.g., Cryptosporidium]) were most commonly reported as documented/observed. For outbreaks associated with splash pads only that were caused by a bacterium or virus, a maintenance-related contributing factor (i.e., disinfectant control system malfunctioning, inadequate, or lacking) and a policy and management–related factor (i.e., inadequate water quality monitoring [e.g., inadequate test kit or testing frequency]) were most commonly reported. A person-related contributing factor (i.e., operator error) also was commonly reported as documented/observed for outbreaks caused by Cryptosporidium or by a bacterium or virus. Discussion Cryptosporidium is the most frequently confirmed etiology of splash pad–associated outbreaks reported to CDC. This parasite, like all other laboratory-confirmed infectious etiologies in this report, except L. pneumophila, can be transmitted by ingesting water contaminated with feces from infected persons and cause acute gastrointestinal illness. Jurisdictions most commonly report cases of acute gastrointestinal illness in children aged <5 years, including cases caused by Cryptosporidium (7). Young children also are less likely to have mastered toileting and hygiene skills, and swim diapers do not prevent fecal contamination of recreational water (8). Sitting or standing on top of water jets and wearing diapers or swim diapers are behaviors commonly observed in children playing in splash pads (9,10). The former behavior results in rinsing of diapers or perianal surfaces, which in young children can carry as much as 10 g of feces (11). Thus, because of their design, splash pads can be at increased risk for contamination with pathogens. Because children typically ingest more recreational water than adults (12) and have been commonly observed to place their open mouths on sprayed or jetted water (9,10), children are at increased risk for exposure to pathogens in contaminated splash pad water. Chlorine, a chemical disinfectant, is the primary barrier to pathogen transmission in treated recreational water. Most pathogens (e.g., bacteria and viruses) are inactivated within minutes in water with 1 ppm free chlorine when the pH is 7.2–7.8 and temperature is 77°F (25°C). CDC recommends, and jurisdictions typically require, a minimum of 1 ppm free chlorine in treated recreational water venues open to the public, including splash pads. However, maintaining an adequate free chlorine concentration can be especially difficult in splash pads because spraying or jetting the water aerosolizes free chlorine, which decreases its concentration. Oxidizing organic and nitrogenous compounds introduced from the environment (e.g., on splash pad users’ shoes) or by the splash pad users themselves (e.g., feces and urine) also deplete the free chlorine concentration. An analysis of inspection data from 16 jurisdictions in five states found 10 percent of routine inspections of splash pads identified violations related to improper disinfection levels (i.e., disinfectant concentration was too low or too high) (13). A Tennessee water quality survey of splash pads found samples from five (21 percent) of 24 splash pads had <1 ppm free chlorine (10). Not maintaining an adequate free chlorine concentration increases the risk for transmission of pathogens readily inactivated by free chlorine. In contrast, Cryptosporidium oocysts, the infectious life stage of the parasite, are tolerant to chlorine. Oocysts can survive for > 7 days at 77°F (25°C) and pH 7.2–7.8 in water containing 1 ppm free chlorine (14,15). Hypochlorous acid, also known as free chlorine, is the most active disinfectant form of chlorine. Its concentration is determined by pH in relation to that of hypochlorite ions, which are less effective. A pH between 7 and 7 points strikes a balance between reducing swimmer discomfort and equipment corrosion and optimizing free chlorine. The rate at which pathogens inactivate is determined by temperature. Even in splash pad water with a sufficient concentration of free chlorine, Cryptosporidium can spread due to the oocysts’ exceptional chlorine tolerance, which allows it to cause more widespread outbreaks than pathogens that are easily rendered inactive by free chlorine (16). D. A total of 23% of outbreaks, including those linked to splash pads exclusively, were caused by hominids. Overall, these outbreaks accounted for 74% of cases, with splash pad-specific outbreaks accounting for 85% of cases. The numbers of outbreaks caused by Cryptosporidium of unknown species have increased because of the additional outbreaks caused by this species. There are probably more hominis and ensuing cases. Locating C. The etiology of the outbreak, hominis, suggests a human source of contamination and emphasizes the necessity of involving caregivers of young splash pad users, as other species of Cryptosporidium may indicate animal fecal contamination (e.g. A. birds, raccoons, and squirrels).
For outbreaks linked to splash pads alone, maintenance-related contributing factors—including both documented/observed and suspected factors—were the most commonly reported overall. These factors mostly center on disinfection system failures. However, person-related contributing factors were most commonly reported for Cryptosporidium-only splash pad outbreaks. Improvements in the recommended use of splash pads, particularly for young children, may help lower the frequency of outbreaks linked to splash pads that are brought on by Cryptosporidium, the most prevalent etiological agent, according to this data. Additionally, this evidence supports Cryptosporidium’s tolerance to primary chemical disinfectants (e.g. G. chlorine). Splash pad-associated outbreaks caused by chemically susceptible etiologic agents would be significantly reduced in jurisdictions with code requirements for water quality monitoring and properly designed, maintained, and operated disinfection systems. In contrast, inadequate water quality monitoring and testing policies were the second most commonly reported contributing factor for bacteria and viruses, after disinfectant system failures.
Developed in collaboration with public health officials, aquatics industry representatives, and researchers, the CDC’s 2023 Model Aquatic Health Code (MAHC) is a set of design, construction, operation, and management guidelines to prevent disease and injury linked to publicly accessible treated recreational water venues (https://www . cdc . gov/model-aquatic-health-code/php/our-work/index . html). Splash pads with recirculating water are covered by the 2023 MAHC, but single-pass splash pads are not. The design and construction of MAHC splash pads recommends the use of secondary treatment, which is the reduction of Cryptosporidium oocysts. For instance, ozone (17,18) or UV light is used in splash pads by 3-log10 (99 percent) but only 2-log10 (99 percent) in all other treated recreational water venues (e.g. G. pools) (section 4point 7 of MAHC. 3point 3. (2.1). As a result of “no additional disinfection installed that would have inactivated the pathogen (e.g. 3. Cryptosporidium) Table 4. Cryptosporidium inactivation is referred to as “secondary disinfection” or “supplemental disinfection.”. Additionally, according to MAHC section 4.7, secondary treatment systems should treat all splash pad water, but only a portion of the water in all other treated recreational water venues (up to 100%). 3 point 3. 2point 2). Since splash pads are more likely to become contaminated by Cryptosporidium, these two guidelines are more strict.
Guidelines for MAHC operations at all locations (e.g. A. maintained at least 1 ppm of free chlorine (MAHC section 5.7) in splash pads and pools. 3 point 1. 1.2) between pH 7.0 and 7.8 (MAHC section 5.7). Three-point four. Every two to four hours, the pH and free chlorine concentration are measured (MAHC sections 5.7). 5points 2–7. 5.3), as well as measuring pH and free chlorine concentration using an appropriate test (MAHC sections 4.7). 3 points. 1 and 5 points 7. 3point 6. 1–5 point 7. 3 points (6). 1.1). When splash pad operators follow these guidelines, they can identify issues with disinfection systems. Having a qualified operator on site or instantly available within two hours during operating hours is one of the MAHC splash pad management recommendations (MAHC sections 6.3). One point. 1-point-3. 1-1. 3) in order for locations to be run and maintained in a way that reduces the possibility of disease and harm (e.g. 3. ensuring that the concentration of free chlorine remains sufficient. Operators who have successfully finished training approved by the jurisdiction are considered qualified operators. Pool operation and water quality have been linked to operator training, which also reduces operator errors (13).
