RWIs and Aquatics Staff: Why Be Concerned?
The Centers for Disease Control and Prevention (CDC) has been gathering information from State health authorities on recreational water illness (RWI) outbreaks in the United States since 1978. Diarrhea, which is currently the most frequently reported symptom, is caused by germs such as Crypto (short for Cryptosporidium), E. coli O157:H7 (E. coli), Giardia, and Shigella. Since 1985, the number of outbreaks of diarrhea connected with swimming pools is on the increase. Some of these outbreaks have affected thousands of swimmers. Much of the diarrheal illness reported to health officials, such as that caused by Crypto, occurs during the summer swim season. CDC information from the past few years shows that Crypto is the major germ that causes outbreaks in swimming pools and waterparks, where its high chlorine resistance and small size make it a difficult problem for even the best-equipped and well-maintained pools. Bacteria such as E. coli O157:H7 or Shigella are sensitive to chlorine so outbreaks appear to be a rare occurrence in chlorinated pools.
Approximately 10 diarrheal outbreaks linked to swimming pools are reported each year. However, pool staff need to keep in mind that most diarrheal illnesses are not reported to health care providers and health officials. This means that the number of outbreaks reported is probably only the tip of the iceberg. Because fewer than 10% of people with diarrhea ever go to see a health care provider, public health officials never hear about most cases of illness. Therefore, illness prevention should be a part of every swimming safety program just like the prevention of drowning, injuries, and sunburn.
Even though small or residential pools may have fewer people swimming in them, they still can spread RWIs. Poor maintenance of the pool and the lack of healthy swimming behaviors may lead to low chlorine levels, clogged filters, and contamination of pool water, which may place swimmers at risk for diarrheal illnesses and skin, ear, eye, and upper respiratory infections.
For more detailed information on pool or spa design and operation guidelines visit: http://wwwdev.cdc.gov/healthyswimming/design_and_operation.htm.
For more detailed information on pool or spa disinfection and remediation guidelines visit: http://www.cdc.gov/healthyswimming/disinfection_and_remediation.htm.
For more information on specific germs spread through water visit: http://www.cdc.gov/healthyswimming/water_illness_a_to_z.htm
Division of Parasitic Diseases
National Center for Zoonotic, Vector-borne, and Enteric Diseases
Page last modified: October 20, 2008