Guest Column - July/August 2006
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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.