Outbreak of Gastroenteritis Associated With an Interactive Water Fountain at a Beachside Park --- Florida, 1999

Since 1989, approximately 170 outbreaks associated with recreational water venues (e.g., swimming pools, waterparks, fountains, hot tubs and spas, lakes, rivers, and oceans) have been reported, with almost half resulting in gastrointestinal illness (1--5). This report summarizes the investigation of an outbreak of gastroenteritis in Florida during 1999. The findings indicated that Shigella sonnei and Cryptosporidium parvum infections caused illness in persons exposed to an "interactive" water fountain* at a beachside park.

During August 23--27, the Volusia County Health Department (VCHD) received reports of three children with S. sonnei infection whose common exposure was play in an interactive water fountain at a beachside park that had opened August 7. To determine risk factors for gastrointestinal illness, VCHD and the Florida Department of Health (FDH) conducted a case-control study among a convenience sample of park attendees, including 34 members of a teenage group that had attended a beach party near the park on August 14 and 52 family members of persons who had reported illness to VCHD. A case of gastrointestinal illness was defined as abdominal cramps or diarrhea (three or more loose stools within a 24-hour period) in a person who visited the park during August 7--27, with illness onset <12 days after the visit. Study participants were contacted by telephone and interviewed using a standard questionnaire.

Of 86 park visitors interviewed, 38 (44%) had illness that met the case definition. Onsets of illness occurred during August 15--September 2 (Figure 1). The median age of ill persons was 8 years (range: 2--65 years); the median age of well persons was 15 years (range: 5--47 years). Twenty-five (66%) ill persons were male. The most common symptoms reported included diarrhea (97%), abdominal cramps (90%), fever (82%), vomiting (66%), and bloody diarrhea (13%). S. sonnei was isolated by culture of stool specimens from five (36%) of 14 ill persons tested. C. parvum oocysts were identified in stool specimens from two persons by light microscopy using an acid-fast stain. All 38 ill persons, compared with 32 (67%) well persons, had entered the fountain (odds ratio [OR]=undefined; 95% confidence interval [CI]=4.1--undefined). Other associated risk factors for illness included fountain water ingestion (OR=52.5; 95% CI=9.8--377.0) and consumption of food or drink at the interactive fountain (OR=4.7; 95% CI=1.6--14.3). As all ill persons entered the fountain, and all but two ingested fountain water, the independence of these exposures was not established.

On August 27, investigators conducted an environmental assessment of the park, a paved area of approximately 2--3 acres adjacent to the beach in Daytona Beach, which included bathrooms, outdoor showers, vending machines, and the interactive water fountain. The fountain used recirculated water that drained from the wet deck/play area floor (no standing water) into an underground reservoir. The volume of recirculated water was 3380 gallons, and the minimum flow rate through the recirculation system was 115 gallons per minute; the turnover rate was 30 minutes, as required by state code for interactive water features. The recirculated water passed through a hypochlorite tablet chlorination system before being pumped back to the reservoir and then to several high-pressure fountain nozzles at ground level throughout the play area. No filtration system had been installed. Investigators identified several potential opportunities for water contamination. The fountain was popular with diaper- and toddler-aged children who frequently stood directly over the nozzles. Chlorine levels were not monitored, and the hypochlorite tablets that deplete after 7--10 days of use had not been replaced after the park opened August 7.

An estimated 4800 persons attended the park during August 7--27, when the fountain was closed by VCHD. The fountain reopened December 12 after several control measures were implemented. First, a cartridge filtration system was installed, and a chlorine monitor was installed to halt fountain operation automatically when residual chlorine levels fall below 3 ppm. Second, a sign was posted advising visitors to shower before entering the fountain and to avoid fountain water consumption. Third, children in diapers were excluded from entering the fountain. No further illness has been associated with the fountain.

Reported by: P Minshew, Volusia County Health Dept, Daytona Beach; K Ward, MSEH, Z Mulla, MSPH, R Hammond, PhD, D Johnson, MD, S Heber, DrPH, R Hopkins, MD, State Epidemiologist, Florida Dept of Health. Div of Bacterial and Mycotic Diseases and Div of Parasitic Diseases, National Center for Infectious Diseases; Div of Applied Public Health Training, Epidemiology Program Office; and an EIS Officer, CDC.

Editorial Note:

This report documents the second recorded outbreak of gastroenteritis associated with an interactive water fountain (1) and highlights the risk for transmitting diarrheal illness in recreational water activities other than a traditional water-filled pool. Outbreaks of gastroenteritis associated with recreational water exposure are recognized with increased frequency (1). Interactive fountains using recirculating water are new to traditional waterpark amusements (i.e., slides and wave pools). Because these fountains are attractive to diaper- and toddler-aged children, recreational water may be at high risk for contamination by enteric pathogens through overt fecal accidents or rinsing of contaminated bodies in the water.

In this outbreak, S. sonnei and C. parvum were identified in stool specimens from ill persons. Both pathogens have a low infectious dose (6,7), and C. parvum is resistant to chlorine (7); however, removal of pathogens may be enhanced by filtration of fecal material from recirculated water. The recirculated fountain water described in this report was unfiltered and inadequately chlorinated, increasing the risk for contamination and disease transmission. The association between illness with S. sonnei and ingestion of recreational water has been described previously (8,9). The association between illness and consumption of food or drink at the fountain may represent contamination of food and drink by fountain water, or the potential for increased fountain water ingestion among those consuming foods and beverages at the fountain.

Most bacterial outbreaks in recreational water could be prevented if pool and interactive fountain operators maintained mandated chlorine levels at all times and monitored levels more frequently during times of heavy patronage. Although effective chlorination should reduce the risk for S. sonnei transmission, disinfection is not instantaneous, as pathogens may be temporarily sheltered from chlorine when presented as a large bolus of fecal material, resulting in transient contamination. The prevention measures instituted by FDH underscore that water treatment alone does not guarantee illness prevention. The public also should be informed that swimming or playing at recreational water venues is communal bathing and can lead to diarrheal disease transmission when the water becomes contaminated and is swallowed.

To reduce risk for contamination and disease transmission, persons visiting recreational water venues should 1) avoid entering a traditional pool or playing in an interactive fountain if they have diarrhea; 2) avoid swallowing pool or fountain water; 3) practice good hygiene by taking a soap and water shower at home or at the pool, especially after a bowel movement and before entering the water; 4) escort young children to the toilet frequently and clean their bottoms thoroughly before allowing them to resume play; 5) avoid sitting on or over fountain jets because this can increase the risk for water contamination; and 6) take precautions not to contaminate foods or beverages consumed in or near the bathing area with pool or fountain water. Parents should be aware that no diaper (including swim diapers or swim pants) completely prevents stool leakage. If diapered children are to play in waterparks, diapers should be changed immediately after a bowel movement in restrooms where hands and bottoms can be washed thoroughly with soap and water.

Although interactive fountains may not require health department review in some states, waterpark or water attraction operators should recognize that the lack of a pool in these attractions does not necessarily reduce the risk for waterborne disease transmission. States should examine existing regulations for all public recreational water venues and for fountains not intended for interactive water play (10), and should ensure that all public recreational venues and fountains using recirculated water receive appropriate oversight by public health officials. Additional information for bathers, parents, and pool operators on recreational water safety can be obtained on the World-Wide Web at http://www.cdc.gov/ncidod/dpd/parasiticpathways/swimming.htm.

References

1. CDC. Surveillance for waterborne-disease outbreaks---United States, 1997--1998. In: CDC surveillance summaries (May). MMWR 2000;49(no. SS-4).
2. CDC. Surveillance for waterborne-disease outbreaks---United States, 1995--1996. In: CDC surveillance summaries (December). MMWR 1998;47(no. SS-5).
3. CDC. Surveillance for waterborne-disease outbreaks---United States, 1993--1994. In: CDC surveillance summaries (April). MMWR 1996;45(no. SS-1).
4. CDC. Surveillance for waterborne-disease outbreaks---United States, 1991--1992. In: CDC surveillance summaries (November). MMWR 1993;42(no. SS-5).
5. CDC. Surveillance for waterborne-disease outbreaks---United States, 1989--1990. In: CDC surveillance summaries (December). MMWR 1991;40(no. SS-3).
6. Acheson DK, Bennish ML. Shigella and enteroinvasive Escherichia coli. In: Blazer MJ, Smith PD, Ravdin JI, Greenberg HB, Guerrant RL, eds. Infections of the gastrointestinal tract. New York: Raven Press, 1995.
7. Meinhardt PL, Casemore DP, Miller KB. Epidemiologic aspects of human cryptosporidiosis and the role of waterborne transmission. Epidemiol Rev 1996;18:118--36.
8. Keene WE, McAnulty JM, Hoesly FC, et al. A swimming-associated outbreak of hemorrhagic colitis caused by Escherichia coli O157:H7 and Shigella sonnei. N Engl J Med 1994;331:579--84.
9. Rosenberg ML, Hazlet KK, Schaefer J, Wells JG, Pruneda RC. Shigellosis from swimming. J Am Med Assoc 1976;236:1849--52.
10. CDC. Outbreak of cryptosporidiosis associated with a water sprinkler fountain---Minnesota, 1997. MMWR 1998;47:856--60.

* Fountains intended for recreational use, often located at waterparks, as opposed to noninteractive ornamental fountains intended for public display, not recreational use, often located in front of buildings and monuments.

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