Waterborne Disease Outbreaks Associated with Splash Pads — United States, 1997–2022

Results

During 1997–2022, public health officials from 23 states and Puerto Rico (Figure 1) reported 60 splash pad–associated outbreaks (Table 1). These 60 outbreaks were associated with exposures in settings where only splash pads were located (n = 39) as well as settings that included splash pads and other venues (e.g., swimming pools and hot tubs) (n = 21). These 60 outbreaks resulted in 10,611 cases, 152 hospitalizations, 99 emergency department visits, and no reported deaths.

The outbreak etiology of waterborne disease was laboratory confirmed for 52 (87%) of the 60 outbreaks (Table 2). Cryptosporidium caused 40 (67%) outbreaks (including one that also was caused by Giardia species and another also caused by Shigella species) that resulted in 9,622 (91%) reported cases, 123 (81%) hospitalizations, and 21 (21%) emergency department visits. More specifically, Cryptosporidium hominis caused 14 (23%) outbreaks that resulted in 7,833 (74%) cases, 97 (64%) hospitalizations, and three (3%) emergency department visits. C. hominis also caused the three largest outbreaks (2,307 cases, 2,050 cases, and 2,000 cases); two of these outbreaks were associated with splash pads only and the remaining outbreak with a splash pad and other venues. Cryptosporidium parvum caused four (7%) outbreaks that resulted in nine (<1%) cases, two (2%) emergency department visits, and no hospitalizations. Cryptosporidium of unknown species caused 17 (28%) outbreaks that resulted in 1,478 (14%) cases, 21 (14%) hospitalizations, and six (6%) emergency department visits. Multiple species of Cryptosporidium caused three (5%) outbreaks that resulted in 199 (2%) cases, 10 (10%) emergency department visits, and one (1%) 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%) outbreaks resulted in 271 (3%) cases of acute gastrointestinal illness, 16 (11%) hospitalizations, and six (6%) 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%) resulted from two outbreaks suspected to be caused by norovirus.

Of the 60 splash pad–associated outbreaks, 57 (95%) were reported during May–August (Figure 2). Approximately one fourth (n = 17; 27%) of the outbreaks were associated with at least one splash pad in a community or municipality setting, followed by 14 outbreaks (23%) 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%) 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%) of the 39 outbreaks. Cryptosporidium caused 25 (64%) of the 39 outbreaks (including one that was also caused by Giardia and another also caused by Shigella) that resulted in 5,111 (95%) of 5,384 cases, nine (11%) of 85 emergency department visits, and 45 (66%) of 68 hospitalizations. More specifically, C. hominis caused nine (23%) outbreaks that resulted in 4,551 (85%) cases, 33 (49%) hospitalizations, and no emergency department visits. C. parvum caused four (10%) outbreaks that resulted in nine (<1%) cases, two (2%) emergency department visits, and no hospitalizations. Cryptosporidium of unknown species caused nine (23%) outbreaks that resulted in 436 (8%) cases, eight (12%) hospitalizations, and no emergency department visits. Multiple species of Cryptosporidium caused one (3%) outbreak that resulted in 22 (<1%) cases, four (5%) 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%) of the 39 outbreaks resulted in 140 (3%) of 5,384 cases of acute gastrointestinal illness, 10 (15%) of 68 hospitalizations, and three (4%) of 85 emergency department visits. Of the 85 emergency department visits reported for outbreaks associated with splash pads only, 72 (85%) 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%), one emergency department visit (1%), and no hospitalizations.

Of the 39 outbreaks associated with splash pads only, 38 (97%) 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%) were associated with splash pads in a community or municipal park setting, followed by 13 outbreaks (33%) associated with a splash pad in a community or municipality setting (Figure 3).

Of the 39 outbreaks associated with splash pads only, 27 (69%) 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.