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Treatment News
Chlorine May Not Protect Against Cryptosporidium In Swimming Pools

By Dan Dunable

August 1999

According to a report from the Centers for Disease Control (CDC) in Atlanta, fecal matter from leaky diapers in swimming pools and water parks dramatically reduces the ability of chlorine to kill the water-borne parasite cryptosporidium.

As reported by the CDC, a test was conducted in which fecal matter was added to water to simulate a common fecal accident in a swimming pool. Results showed that levels of chlorine known to kill the parasite were no longer adequate if there was fecal matter contaminating the water, indicating that the human waste protected the parasite from chlorine inactivation.

With no effective, standard treatment for cryptosporidiosis, the frequent diarrhea, nausea, vomiting, weight loss and dehydration can be very dangerous, especially for those with under 200 CD4 cells.

To prevent outbreaks of the diarrhea, etc., caused by this parasite, the report recommends changes in pool engineering, such as improved filtering and more frequent turnover of the water pumped into the pool. They also suggest changes in pool's policies and urge that staff of and visitors to public pools and water parks be educated about ways to prevent waterborne disease transmission, such as:

  1. staying out of the pool while ill with diarrhea

  2. not swallowing pool water

  3. using safe diaper changing and handwashing practices

  4. giving young children frequent bathroom breaks

  5. encouraging swimmers to shower before entering a pool

To access the full article on-line that the CDC's report was based on, go to

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