The Centers for Disease Control and Prevention (CDC) issued a warning about a rise in cryptosporidium (“crypto”) cases in swimming pools this season.

Crypto is a fecal parasite that can induce “profuse, watery diarrhea” for weeks in adults, with effects potentially more debilitating for pregnant women, children or individuals with weakened immune systems.

While the effects of the parasite are not usually fatal, they can leave you in the hospital. Of the 7,465 people who fell victim to crypto between 2017 and 2019, 287 were hospitalized, according to the CDC. There has only been one death reported since 2009.

How do you contract cryptosporidium?

Crypto can live in a variety of places, including lakes, within animals or even in child care settings. However, one of the most likely places you’ll contract it is in a swimming pool, where it can live for up to seven days.

Pools are especially problematic because victims of the parasite excrete more of it than goes in their body—creating a snowball effect in the water. When other swimmers get infected pool water in their mouths, the cycle continues. Even worse, crypto can live in your pool even if it’s chlorinated properly.

What can you do about it?

Fortunately, if you have a healthy immune system, you likely won’t need treatment if you contract crypto. Just like other forms of diarrhea, you must drink plenty of fluids and eat a well-balanced diet. There are some medications available if needed.

From a preventive standpoint, if you have diarrhea, you should avoid swimming for at least two weeks until it’s subsided. If you don’t, you could be contributing to the parasitic snowball effect.

Likewise, if your child has diarrhea, they should not be placed in child care, according to the CDC. Given the current crypto outbreak, having them there might spread the condition to other children, especially if their illness started after a trip to the pool.

What’s next?

The CDC will continue to educate the public about the dangers of crypto and how to prevent it. Visit to learn more about detection, symptoms, risk factors and more.

Speak with your doctor if you have any concerns. There is medication and treatment available for more severe cases.