Water parks studied in outbreak of parasite

BOISE – Nearly 230 Idaho residents have been sickened by a waterborne parasite this year, along with hundreds of others across the Rocky Mountain West, health officials said.

The cryptosporidium outbreak has reached record numbers, Idaho Department of Health and Welfare spokesman Tom Shanahan said, and has federal officials looking at the role water parks and public pools play in spreading the diarrhea-causing parasite.

Since 1995, Idaho has averaged about 23 cryptosporidium cases a year, said Dr. Randall Nett, an epidemic intelligence officer with Idaho’s Health and Welfare Department. But this year, 229 cases have been reported, the vast majority in the Boise and Meridian areas.

Nearby Utah has been even harder hit, with more than 1,600 illnesses attributed to cryptosporidium so far this year, Utah Department of Health epidemiologist Diane Raccasi said.

“It’s a record year by a long way,” said Nett. “There’s probably going to have to be some research done to determine if it was weather, rainfall, runoff or other things contributing to the outbreak.”

Colorado and other Western states have also reported increases, Nett said. However, Montana has seen a decrease. Health officials believe splash parks and other recreational water parks can offer the hardy parasite the opportunity to spread rapidly from person to person.

At splash parks where water is recirculated, the spray can rinse any contamination – whether from diarrhea, vomit or dirt – down into a water holding area and back up through the water spouts, according to the Centers for Disease Control and Prevention.

“Unfortunately, there’s no national pool code to regulate how these splash pads are designed, so the CDC is working with a consortium of scientists to come up with a model pool code,” similar to what the Food and Drug Administration created for food, Nett said.

“To prevent outbreaks of cryptosporidiosis, change is needed in the way we build and operate the nation’s disinfected recreational water facilities,” the CDC wrote in a report earlier this summer. “Key changes call for the inclusion of new supplementary disinfection measures that kill the parasite … and existing chlorine disinfection.”

Cryptosporidium can survive for up to a year in the right conditions, Raccasi said. People infected with the parasite get symptoms ranging from watery diarrhea and abdominal cramps to fever, nausea and vomiting. The illness can last for as long as a month.

An infected person can spread the parasite through water or through contact with changing tables or bathroom fixtures, or during diaper changes, according to the CDC.

Splash parks and pools have been indicated in Utah’s outbreak, Raccasi said, and most of Idaho’s cryptosporidium cases have originated at a Meridian city splash park, Shanahan reported. The splash park in Meridian, like many others, uses chlorine to keep its water clean, but the cryptosporidium parasite has a hard outer shell that allows it to survive even in properly chlorinated water.