Water parasite outbreaks rise

CDC: People getting sick after swallowing pool, water park water

Some icky news just in time for pool season: Reports of diarrhea outbreaks linked to parasites that cause cryptosporidiosis in pools and water parks increased at least twofold in two years, federal health officials reported Thursday.

The cryptosporidium parasite, called crypto for short and spread through human feces, caused at least 32 outbreaks in 24 states in 2016, compared with 16 nationwide in 2014, according to the Centers for Disease Control and Prevention. Final numbers for 2016, along with 2015 numbers, will come in a later report, but “we expect them to go up,” said Michele Hlavsa, head of the CDC’s healthy swimming program.

The increase may be linked to better reporting, but it’s possible the problem is becoming more common, Hlavsa said.

Total cases reported to the CDC increased from about one in 100,000 in the early 1990s to about four in 100,000 in recent years, she said. That means an average of 8,000 people a year suffer through up to three weeks of watery diarrhea, stomach cramps, nausea and vomiting — most often because they swallowed contaminated pool water.

Big outbreaks in 2016 included one in Arizona that sickened an entire Little League team and a cluster in Ohio that started in a water park and spread to nearby pools, contributing to nearly 2,000 cases statewide, adding to details published in the CDC’s Morbidity and Mortality Weekly Report.

Don’t be too quick to blame pool operators, Hlavsa said.

Unlike other bugs that sometimes spread in pools, crypto is not quickly killed by chlorine. It can survive for up to 10 days, even in well-treated pools.

As a result, crypto is the leading cause of illness linked to swimming facilities.

“This is a really tough bug to kill once it gets in the water,” Hlavsa said.

When an outbreak is detected, operators have to close their pools and treat them with levels of chlorine that would not be safe for swimmers.

How does the bug get in the water? It hitches a ride in poop — which is found in a high number of pools, at least half, according to a previous CDC study. A lot of that excrement comes off the bottoms of kids under age 5. One study suggested a park pool with 1,000 unwashed preschoolers could contain 22 pounds of fecal matter, Hlavsa said.