Notice to Readers: Revised Recommendations for Responding to
Fecal Accidents in Disinfected Swimming Venues
The 2001 CDC recommendations (1) for responding to fecal accidents in disinfected swimming venues
(e.g., swimming pools) have been revised. Recommendations for
responding to diarrheal fecal accidents, which are thought
to represent a higher infectious-disease transmission risk than formed-stool accidents, are based on the potential presence
of the chlorine-resistant parasitic protozoa of the
genus Cryptosporidium. New data indicate that the recommended
CT inactivation value (or contact time)* is higher than previously published
(2), when inactivation is measured at a
higher pH using an outbreak-associated
Cryptosporidium isolate (3). Based on these data, the CT inactivation value used
in CDC fecal accident recommendations for 99.9% inactivation of
Cryptosporidium has been changed from 9,600
mg-min/L to 15,300 mg-min/L.† This change translates into longer swimming pool closures to ensure inactivation
of Cryptosporidium.
Swimming pool operators should check existing guidelines from local or state regulatory agencies before using
these recommendations, because CDC recommendations
do not replace existing state or local regulations or guidelines.
The CDC revised fecal accident response recommendations
are available at
http://www.cdc.gov/healthyswimming/pdf/fecal_accident_response_recommendations_for_pool_staff.pdf.
Korich DG, Mead JR, Madore MS, Sinclair NA, Sterling CR. Effects of ozone, chlorine dioxide, chlorine, and monochloramine on
Cryptosporidium parvum oocyst viability. Appl Environ Microbiol 1990;56:1423--8.
Shields JM, Arrowood MJ, Hill VR, Beach MJ. Inactivation of
Cryptosporidium parvum under chlorinated recreational water conditions. J
Water Health 2008. In Press.
* The CT number refers to the concentration (C) of free chlorine in milligrams per liter (parts per million) multiplied by time (T) in minutes at a specific pH
and temperature.
† At pH 7.2--7.5, 77°F (25°C).
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