Parents are advised to take extra precautions in splash zones next year after they have been linked to a rise in illnesses.
More than 10,000 children and adults have become ill after using recreational play areas over the 25 years through 2022, according to a CDC report.
Of those, 152 people were hospitalized while another 99 became so sick that they went to the emergency room. No deaths related to the outbreaks were reported.
CDC scientists said outbreaks were often caused by feces being released from children’s diapers and contaminating water.
Splash pads contain chlorine to prevent breakouts, but it is often sprayed using jets of water, making them less effective.
To prevent the spread of illness to other people, they said families should not visit splash zones for two weeks after a child suffers from diarrhea.
They also suggested taking children to the bathroom regularly while using the splash guards and checking diapers regularly.
Scientists say people who use splash pads may be at higher risk of disease. The image above shows adults and children using a splash pad in Arizona in July 2023 amid a heat wave.
The map above shows the number of splash zone-related outbreaks by state from 1997 to 2022.
According to estimates, there are up to 10,000 splash pads across the United States, and their number has increased in recent years amid attempts to cool off in the summer heat.
And outbreaks linked to recreational areas are not common: The number of reported illnesses (10,000 cases in 25 years), far below the number of people who visit splash zones each year, is estimated in the tens of thousands.
But since 1997, recreational areas have been repeatedly linked to outbreaks of intestinal illness, with symptoms including watery diarrhea, stomach cramps and fever.
For the report, published in CDC’s MMWR, the agency analyzed data on splash zone-related disease outbreaks in 23 states and Puerto Rico from 1997 to 2022.
In total, they detected 60 waterborne disease outbreaks linked to sanitary pads during this time, leading to cases and hospitalizations.
Of the 52 outbreaks with available data, 40 were caused by Cryptosporidium hominis, an easily transmitted single-celled microorganism that thrives in water and can cause prolonged watery diarrhea, stomach cramps and high fever.
The analysis showed it caused 9,622 of the splash pad-related infections, or 91 percent of the total, and 123 hospitalizations, or 81 percent. And it was linked to the three largest outbreaks, which caused 2,307 cases, 2,050 cases and 2,000 cases.
It caused another outbreak this year, when Albuquerque, New Mexico, was forced to close its water parks due to a series of microorganism-related illnesses.
C. hominis causes symptoms such as watery diarrhea and stomach cramps, and illnesses typically clear up within a few days. In severe cases, it can cause life-threatening chronic diarrhea with severe dehydration and muscle atrophy.
The above shows splash pad outbreaks by month they were reported from 1997 to 2022.
There were also five outbreaks caused by Shigella, three by E. coli and one by norovirus, one by salmonella and two other pathogens.
No outbreaks have been linked to the brain-eating amoeba Naegleria fowleri, but in September last year it was reported that a young child in Arkansas had died from the disease after playing in the splash pad at a local country club.
By state, Ohio and Florida reported the most outbreaks during the study period (eight outbreaks each), followed by West Virginia, which reported three outbreaks.
Arizona, California and Idaho each reported three outbreaks, while Utah, Colorado, Texas, Louisiana, Missouri, Tennessee, New York and Massachusetts reported two.
Washington, Kansas, Oklahoma, Illinois, Alabama, Georgia, South Carolina and Pennsylvania each recorded an outbreak.
Outbreaks were most common during the summer months, June through September, when people are also more likely to use splash guards.
Describing how the water became contaminated, the report’s lead author, Hannah Lawinger, an epidemiologist, and others said: “Young children are also less likely to master toileting and hygiene skills, and swim diapers do not prevent fecal contamination of recreational water.
‘Sitting or standing on top of water jets… are behaviors commonly observed in children playing on splash pads. (But) the first behavior results in rinsing diapers or perianal surfaces, which in young children can contain up to 10 grams of feces.
“Therefore, due to their design, splash pads may have a higher risk of contamination with pathogens.”
Regulations require splash pads to maintain chlorine levels at about one part per million, which is the normal threshold for killing off most diseases.
But researchers said spraying water can turn chlorine into an aerosol, lowering its concentration. C. hominis also has some tolerance to the chemical.