Crypto the biggest waterborne threat this summer: CDC

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The latest CDC report on waterborne illnesses reveals an unexpected villain: Cryptosporidium is a parasite that seems to have been responsible for about one-half of the 90 outbreaks over the two years 2011-12. Simple precautionary measures will help avert illness.

crypto_150_featherIf you ve never heard of the parasite Cryptosporidium, you are not alone. Yet, you might become acquainted with this microorganism in a way you would not wish to be. Crypto, as it s affectionately known in medica/epidemiological circles, has become the nation s leading cause of RWI: recreational water illness.

The most recent CDC/MMWR report, Outbreaks of Illness Associated with Recreational Water United States, 2011 2012, reported on all the 90 known RWIs from 32 states and Puerto Rico in those 2 years, which accounted for almost 1,800 illnesses and one death. Three-quarters of the outbreaks were in pools, ie treated water; the rest were from bathers in the ocean, lakes or rivers. More than half of the cases derived from treated (chlorinated, usually) water were from Crypto; 90 percent of those cases in the summer months were as well.

Crypto can survive in treated water because it is in cystic form, resistant to stomach acid as well as chlorine. Michele Hlavsa, an epidemiologist with the CDC's Healthy Swimming program, told LiveScience:

When people get sick with diarrhea, they often think that something they ate caused the symptoms. But now, "people are realizing it's not necessarily only about where they ate or what they ate. It could be about where they went swimming.

Because Cryptosporidium can't be killed by chlorine and water filters, "we're really asking swimmers to keep Cryptosporidium out of the water in the first place," Hlavsa advised.

To prevent Crypto and other illnesses linked with swimming, the CDC recommends the following measures:

* people not swim if they have diarrhea;

* stay out of the pool for two weeks after their diarrhea stops if they were diagnosed with Crypto;

* shower before swimming;

* take children on frequent bathroom breaks when swimming;

* change diapers in the bathroom rather than by the pool;

* perhaps most importantly: avoid swallowing pool water.

The agency also recommends that water be treated with ultraviolet light or ozone to inactivate Crypto at pools where surveillance data indicates there is an increased risk for transmission of the disease.