WARNING: Parasite 'Crypto' Could Be In Your Swimming Pool, CDC Says

PHILADELPHIA (CBS) -- With the Memorial Day weekend just a day away, and pools opening soon, the CDC is alerting families about a potential danger in some pools.

A bacteria that's difficult to control, even with chlorine.

Summer fun in the pool, but there could be something lurking in the water that can make you really sick.

"You're going to have stomach cramping, diarrhea, vomiting," said Jaima Ballentine, a manager at HML Labs.

Water testing samples from pools usually reveals all sorts of bacteria, even fecal matter, swimming in the water!

That can usually be wiped out with normal levels of chlorine.

But now, the CDC is worried about a parasite called "crypto," and it's harder to kill.

"Bacteria are usually killed within a minute or less of contact with chlorine. Crypto can actually last up to 10 days," Ballentine explained.

Crypto is spread through human feces.

The CDC says outbreaks of crypto have doubled recently, with 32 outbreaks last year linked to swimming pools and water playgrounds.

"If you do have a pool that is infected like the CDC has been finding, you have to super chlorinate the pool and go through some extra procedures," Ballentine said.

The CDC recommends closing a pool and treating the water with high levels of chlorine, called hyperchlorination, when responding to a crypto outbreak.