Swiming pools may look cool and inviting, but all manner of nasty things could be lurking there, not visible to the naked eye. That's why swimming pools are treated with chemicals, like chlorine. They do a pretty good job of killing bacteria. But not all bacteria.
The Centers for Disease Control and Prevention (CDC) has issued a warning to consumers using public swimming pools this summer that there is a heightened risk of a parasitic infection called Crypto.
You may not have heard of Crypto, because until very recently it wasn't much of a threat. Now, however, it is.
32 outbreaks last year
The CDC says it counted 32 outbreaks of Crypto linked to public swimming pools in 2016, twice the number of reports it received in 2014.
Where does crypto come from? There's no delicate way to put this -- when an infected person poops in the pool, they spread the bacteria. The pooping is usually involuntary, since one of the symptoms of Crypto is diarrhea.
The CDC says swallowing just a mouthful of contaminated water is enough to infect a healthy person. It's becoming a bigger problem because the bacteria isn't easily killed by chlorine. It can survive for 10 days, even in water that has otherwise been properly treated.
If you are infected by Crypto, it's not something you get over in a day. You can be sick for up to three weeks, suffering from diarrhea, stomach cramps, nausea, or vomiting.
There's not a lot you can do to avoid it, except avoid public swimming pools this summer. If you do swim, keep your mouth closed.
"To help protect your family and friends from Crypto and other diarrhea-causing germs, do not swim or let your kids swim if sick with diarrhea," said Michele Hlavsa chief of CDC's healthy swimming program. "Protect yourself from getting sick by not swallowing the water in which you swim."
The CDC says one way to control the Crypto threat may be increasing the amount of chlorine used to treat swimming pool water, a process known as hyperchlorination. It says pools should follow a hyperchlorination protocol any time a diarrhea incident is discovered or a Crypto outbreak is reported.