CDC warns of swimming pool parasites

The Center for Disease Control and Prevention issued a new report that outbreaks of a parasitic diarrhea-causing infection linked to pools in the United States doubled from 2014 to 2016 according to the Morbidity and Mortality Weekly Report.

“Cryptosporidium is a germ that can make people sick with diarrhea for up to three weeks,” Michele Hlavsa, chief of the CDC’s Healthy Swimming Program, wrote in an email. Nicknamed crypto, this parasite spreads through contact with the feces of an infected person.

In 2016, the CDC received word of 32 outbreaks linked to swimming pools or water playgrounds in the US, compared with just 16 two years earlier.

In Ohio alone, nearly 2,000 people became sick from crypto last year. States are not required to report patient numbers, so the CDC does not collect totals.

There had been a downturn after 20 crypto outbreaks were reported in 2011; just 16 outbreaks were seen in 2012 and 13 in 2013. Symptoms include watery diarrhea, stomach cramps, nausea and vomiting, possibly leading to dehydration.

“Parents can encourage their children not to swallow the water when swimming,” Hlavsa said, adding that swallowing even a single mouthful of contaminated water can cause illness. For this reason, parents should avoid buying pool toys that might encourage swallowing water, such as cups.

“Also, take kids on bathroom breaks every hour, and check diapers in a diaper-changing area and not right next to the pool,” Hlavsa said. “We all share the water we swim in, but we don’t want to share germs, pee or poop.”

In a single bowel movement, millions of cryptosporidium parasites can be released from an infected human or animal, according to the CDC.
Crypto cases in the US have approximately tripled since 2004, said the CDC, though it is unclear whether numbers are rising due to an increase in cases or more awareness and better detection tools.

“Crypto is extremely hard to kill with normal levels of chlorine, which is why it’s important to keep Crypto out of pools in the first place,” Hlavsa wrote. “We can all help do this by not swimming or letting our kids swim if sick with diarrhea.”

“Most people who have healthy immune systems will recover from Crypto without treatment,” she said, though if diarrhea persists for longer than three days, patients should contact their health care provider.

Generally, she said, backyard pools are less of a risk because fewer people swim in them. Still, even in properly treated water, crypto can survive up to 10 days.