Preventing Recreational Water Illness Outbreaks

Association Guest Column: National Swimming Pool Foundation

By Douglas C. Sackett and Thomas M. Lachocki

Every day recreational facility personnel come to work with a commitment to serve the public by creating a fun environment. A New York state park experienced a management nightmare in 2005 (NYS-2005) when a Cryptosporidium (crypto) outbreak at a park splash play area was linked to more than 3,000 illnesses that spread to 36 New York counties, 26 states and two countries. The facility was closed for the remainder of the season, a number of claims have been filed, and individuals are pursuing a class-action lawsuit. This incident is a reminder that all recreational facilities are vulnerable and must focus on both promoting pleasure and preventing pain.

The last decade has seen a dramatic rise in unique and innovative water features including splash play areas, water slides, wave pools, activity pools, leisure rivers and vortex pools. Unique and fun designs are attracting more people and driving additional innovations to satisfy the public's expectations. Aquatic recreational facility managers and health officials must consider the risks these unique designs create and implement controls to prevent illness and injury.

Although emerging facility designs have attracted users, emerging germs (disease-causing microorganisms) increase the risk to those users. The U.S. Centers for Disease Control and Prevention (CDC) publishes biannual reports on Recreational Water Illness (RWI) outbreaks. According to the CDC, outbreaks of diarrhea illness have been increasing for more than a decade, and crypto has been the leading cause of documented RWI.

The most recent CDC report for the two-year period 2001 through 2002 indicates that crypto was implicated in causing illness in 1,469 people. The CDC reported a dramatic rise in RWI at the 2005 World Aquatic Health conference. Approximately 5,000 people contracted RWI in about a dozen outbreaks in 2005 alone. Of those, the NYS-2005 outbreak was responsible for more than 3,000 illnesses due to crypto.

What is crypto?

Crypto is a parasite that causes diarrhea (inflammation of the stomach and intestines). The symptoms include diarrhea, stomach pain, fever, nausea, vomiting, weight loss and dehydration. Although symptoms typically start about two to 10 days after exposure, some people may show no symptoms.

When the crypto "germ" is released in a bowel movement, the parasite is protected by a shell (oocyst) that makes it resistant to chlorine disinfectants. It would take more than eight hours to inactivate crypto if the chlorine was 20 parts per million (ppm) and much longer at normal pool chlorine levels. One accidental fecal release from an infected person can contain one billion germs. Therefore, if an infected person has a fecal release in a 100,000-gallon pool, each fluid ounce of pool water may contain 78 germs (52 germs in 20 mL) after the water is mixed. It takes as few as 10 germs to infect a person. Although current filtration is not particularly effective at removing these germs (which are about 4 to 6 microns), new research funded by the National Swimming Pool Foundation is underway to enhance sand filters' ability to remove crypto.

New York outbreak summary

Many disease outbreaks go undetected and are not documented by health departments. For an outbreak to be detected, studied and documented, health workers or citizens have to notice more than one person being treated for a specific set of symptoms. After the health department is informed, they must be able to recognize a pattern in patients' symptoms and determine their exposure to recreational water. Since it takes two to 10 days for a person exposed to crypto to show symptoms, many victims return home to different geographic locations or contaminate others before they seek treatment. This was observed in the NYS-2005 outbreak.

It was only after many people were affected that the health department was informed about increased numbers of people being ill and a pattern could be established. The post-outbreak investigation showed that people were being exposed and exhibiting symptoms in July. On the weekend of Aug. 12 to 14, the N.Y. State Department of Health received a report of diarrhea at three day-care centers in two counties. On August 15, local and state health officials determined that 47 cases of gastrointestinal illness (GI) were identified, and all had visited the splash play park. Once the splash feature was closed on Aug. 15, the number of people who developed symptoms began to drop while an exhaustive investigation commenced. In an attempt to identify cases and limit spread, alerts were distributed to health-care providers, day-care centers, children's camps, pool managers, HIV/AIDS providers, food-service managers and schools.

Changes to prevent future outbreaks

In response to the NYS-2005 outbreak, the NYS Department of Health accelerated the process to establish new code to include splash play areas since no code was yet finalized for this relatively new type of water feature. The existing "pool" codes did not apply since splash play areas have no "standing water," which is required to be governed by the existing pool code.

The new rules for N.Y. splash play facilities that recycle water require disinfection (chlorine), filtration and an ultraviolet (UV) light disinfection system that delivers energy at least 40 mJ/cm2, which kills all known germs. The code includes specific guidance on filtration to ensure turbidity (water clarity) is maintained at satisfactory levels to not interfere with the UV and the chlorine systems. In addition, existing and new splash play areas will be required to issue a report from a licensed professional engineer that evaluates compliance to the new code prior to opening in 2006. Operator training, design and operation criteria also were implemented. Ozone is being considered as an alternative to UV. However, the ability to contact all the circulation water for a sufficient time remains a challenge. The entire New York state code can be reviewed at

In addition to engineering changes at the facilities, it is also important to implement operational changes and build awareness with consumers. Facility management needs to make sure that restrooms are conveniently located, clean and inviting for use. The general public often does not realize that they contribute to the spread of recreational water illness. Many believe that the water in splash features is drinkable (potable). It is important to educate the public to not swim/splash if they have recently had diarrhea as well as to not swallow water. They must change diapers and clean children in the restroom and practice good hygiene. Fortunately many signs that help convey these messages are available from the CDC at

Preventing outbreaks

Prevention of recreational water illness is far more desirable than dealing with an outbreak and the aftermath. Crypto creates a unique hazard at recreational water facilities since chlorine inactivation is slow and filtration is not particularly effective. As a result, the number of outbreaks is consistently increasing with crypto being the leading cause in recent years. Facility management, operators, designers and owners must thoroughly consider using UV systems as a tool to supplement traditional disinfection and filtration to prevent the spread of illness from crypto. A third leg of protection, like UV, is likely to become the norm in the decade to come, according to CDC. Last but not least, education for staff, management and the swimming public is vital so everyone understands the consequences of emerging germs and emerging defenses to limit their spread.


Douglas C. Sackett is the assistant director of the New York State Department of Health's Bureau of Community Environmental Health and Food Protection. Thomas M. Lachocki, Ph.D., is CEO of the National Swimming Pool Foundation (NSPF), a nonprofit organization committed to improving public health by encouraging healthier living through aquatic education and research. As a recreational water educational provider for operators, managers and health officials through the Certified Pool-Spa Operator (CPO) and Certified Pool-Spa Inspector (CPI) training programs, NSPF also funds research and provides advanced training at the World Aquatic Health Conference, slated this year for Sept. 20 to 21, 2006, in Austin, Texas. For more information, visit

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