Crypto causes nausea, vomiting and diarrhea that can last for weeks, according to the CDC.
The outbreaks resulted in 7,465 people falling ill.
The CDC says almost 8,000 people in the USA and Puerto Rico have been infected with the parasite since 2009. That's 10 more cases than by the same point in 2017. Outbreaks have increased an average of 13 percent annually between 2009 and 2017, the CDC said.
You can also get crypto by drinking unpasteurized raw apple cider or milk, by touching your mouth with contaminated hands, or by not washing your hands after touching cattle other animals. This time last year, the health department reported eight cases, "but the number for this year is within what could be expected".
Why pools?: The reason the parasite is particularly a problem in pools is because "an infected swimmer can excrete the parasite at several orders of magnitude higher than the amount necessary to cause infection", according to CNN. "And at the CDC recommended levels of greater than one part per million of chlorine in your typical swimming pool-the parasite can still survive for up to a week".More news: Kate Middleton stuns at Wimbledon in classic white dress
More news: Trump denies citizenship question will be cut from 2020 Census
More news: Venezuela charges two intelligence officials over death of detained officer
As you enjoy your long holiday weekend lounging by the pool, be aware that if you're at a public pool there may be a parasite hiding in the water.
There are preventative measures that can help stem the number of outbreaks, and the CDC is working to educate the public on them.
Cryptosporidium lives in the intestines of infected people and animals who shed a form of the parasite in their feces, according to the CDC.
Wash hands with soap and water after swimming or coming into contact with animals.
That last one is most important, as 24% of American say they'd jump in a swimming pool within an hour of having diarrhea, according to a survey released last month by the Water Quality & Health Council. And people who are dealing with a case of diarrhea should abstain from swimming until at least two weeks after diarrhea subsides.