Skip Navigation LinksSkip Navigation Links
Centers for Disease Control and Prevention
Safer Healthier People
Blue White
Blue White
bottom curve
CDC Home Search Health Topics A-Z spacer spacer
Blue curve MMWR spacer

Persons using assistive technology might not be able to fully access information in this file. For assistance, please send e-mail to: Type 508 Accommodation and the title of the report in the subject line of e-mail.

Notice to Readers: Recreational Water Illness Prevention Week --- May 23--30, 2005

The first National Recreational Water Illness Prevention Week will be held May 23--30, 2005, at the start of the annual swimming season, to raise awareness of the potential for spread of infectious disease at swimming venues and to help improve prevention efforts. An estimated 8.1 million swimming pools are in residential or public use in the United States (1). Each year, U.S. residents make an estimated 360 million visits to recreational water venues such as swimming pools, spas, lakes, and oceans, making swimming the second-most popular physical activity (walking is first) in the country and the most popular among children (2). However, recreational water use also can be associated with drowning, injury, and the spread of infectious diseases.

Recreational water illnesses (RWIs) are spread by swallowing, breathing, or having contact with contaminated water from swimming pools, spas, lakes, rivers, or oceans (3). 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 from infection with these pathogens. Infection with Cryptosporidium can be life threatening in persons with weakened immune systems (4). Other RWIs can cause various symptoms, including skin, ear, eye, respiratory, and neurologic infections.

A steady increase in reported diarrheal RWI outbreaks during 1984--2002 has resulted in approximately 19,000 illnesses (5). This increase is likely the result of 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 (5), poor pool maintenance (6), and low public awareness of the problem (7). Recommendations for public swimming pools include improved operation, training, and public education to protect swimmers from infectious disease transmission. Additional information for public health professionals, aquatics staff members, and the general public is available at


  1. United States swimming pool market, 2005. Pool and spa marketing reference directory. Markham, Canada: Hubbard Marketing & Publishing Limited; March 2005:19--21.
  2. US Bureau of the Census. Statistical abstract of the United States: 1995. 115th ed. Washington, DC: US Bureau of the Census; 1995.
  3. 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.
  4. Chen XM, Keithly JS, Paya CV, LaRusso NF. Cryptosporidiosis. N Engl J Med 2002;346:1723--31.
  5. Yoder J, Blackburn B, Levy DA, Craun GF, Calderon RL, Beach MJ. Surveillance for waterborne-disease outbreaks associated with recreational water---United States, 2001--2002. In: Surveillance Summaries, October 22, 2004. MMWR 2004:53(No. SS-8):1--22.
  6. CDC. Surveillance data from swimming pool inspections: selected states and counties---United States, May--September 2002. MMWR 2003; 52:513--6.
  7. McClain J, Bernhardt JM, Beach MJ. Assessing parents' perception of children's risk for recreational water illnesses. Emerg Infect Dis 2005; 11:670--6.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

Disclaimer   All MMWR HTML versions of articles are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the electronic PDF version and/or the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to

Date last reviewed: 5/18/2005


Safer, Healthier People

Morbidity and Mortality Weekly Report
Centers for Disease Control and Prevention
1600 Clifton Rd, MailStop E-90, Atlanta, GA 30333, U.S.A


Department of Health
and Human Services