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Notice to Readers: Recreational Water Illness Prevention Week --- May 21--27, 2007

The third annual National Recreational Water Illness Prevention Week is scheduled for May 21--27, 2007, at the onset of swimming season, to raise awareness regarding the potential for spread of infectious diseases at swimming venues and the need to improve prevention measures. An estimated 8.1 million swimming pools are available for private or public use in the United States (1). Each year, U.S. residents make an estimated 360 million visits to recreational water venues (e.g., swimming pools, spas, lakes, and oceans), making swimming the second most common physical activity (after walking) in the country and the most common among children (2). The number of waterparks has increased to approximately 1,000 in North America, with another 600 elsewhere around the world. Approximately 73 million visits were made to North American waterparks in 2004, and the number of visits increased by 3%--5% during the preceding 5 years (3). Recreational water illnesses (RWIs) are spread by swallowing, breathing, or having contact with contaminated water from swimming pools, spas, lakes, rivers, or oceans (4). The most commonly reported RWI is diarrhea caused by pathogens such as Cryptosporidium, Giardia, Shigella, and Escherichia coli O157:H7. Children, pregnant women, and persons with compromised immune systems are at greatest risk. Infection with Cryptosporidium can be life threatening to persons with weakened immune systems (5). Other RWIs can cause various ailments, including skin, ear, eye, respiratory, wound, and neurologic infections.

During 1978_2004, a steady increase in RWI outbreaks in the United States resulted in approximately 30,000 illnesses (6). This increase likely can be attributed to a combination of increased water usage, improved outbreak detection, and increased disease transmission. The spread of RWIs is facilitated by emergence of chlorine-resistant pathogens such as Cryptosporidium (6), poor pool maintenance (7), and low public awareness of the problem (8). Recommendations for public swimming pools include improved operation, training, and public education to protect swimmers from infectious-disease transmission.

Public health agencies and officials are encouraged to become involved in Recreational Water Illness Prevention Week by engaging the public, local aquatic operators, and the media in prevention activities. Suggestions for promoting healthy swimming are available at Additional information for public health professionals, aquatics staff members, and the general public is available at and


  1. Pool and spa marketing. United States swimming pool market. Markham, Ontario: Hubbard Marketing and Publishing Ltd.; 2003:20--1.
  2. US Bureau of the Census. Statistical abstract of the United States: 1995. 115th ed. Washington, DC: US Bureau of the Census; 1995.
  3. World Waterpark Association. Waterpark industry general and fun facts. Available at
  4. Castor ML, Beach MJ. Reducing illness transmission from disinfected recreational water venues: swimming, diarrhea, and the emergence of a new public health concern. Pediatr Infect Dis J 2004;23:866--70.
  5. Chen XM, Keithly JS, Paya CV, LaRusso NF. Cryptosporidiosis. N Engl J Med 2002;346:1723--31.
  6. CDC. Surveillance for waterborne disease and outbreaks associated with recreational water -- United States, 2003_2004. MMWR 2006;55(No. SS-12).
  7. CDC. Surveillance data from swimming pool inspections: selected states and counties -- United States, May_September 2002. MMWR 2003; 52:513--6.
  8. McClain J, Bernhardt JM, Beach MJ. Assessing parents' perception of children's risk for recreational water illnesses. Emerg Infect Dis 2005;11:670--6.

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Date last reviewed: 5/17/2007


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