As the weather warms, schools let out, and people head to pools and water parks, the Centers for Disease Control and Prevention wants to once again warn you of the dangers lurking in those cool, chlorinated waters.
This year, the agency is drawing attention to an uptick in pool-associated outbreaks of Cryptosporidium, aka Crypto. The protozoan parasite is spread by the stool of sick swimmers. A single “fecal release” can unleash tens of millions of hardy oocysts, which can survive in properly chlorinated pool water for up to 10 days. If just a handful of the tiny critters slips into a swimmer's mouth or nose, they can cause stomach cramps, vomiting, and diarrhea.
You might not think that fecal matter is very common in pool water... oh, but it is. As the CDC pointed out in another pool warning from May of 2013, 58 percent of public pools tested positive for fecal bacteria. (A recent Canadian study suggested that large public pools contain an average of about 75 liters of urine, too.)