Pools, play-in fountains spread diarrheal disease, CDC says
By Elizabeth Weise, USA TODAY Updated 09/26/2011 7:13 PM
That's one lesson from a new report from the Centers for Disease Control and Prevention, which found 134 disease outbreaks associated with recreational water from 2007-2008, the most recent data available. That's a 72% increase from the previous report and the largest number ever reported in a two-year period.
Those outbreaks resulted in at least 13,966 illnesses. Cryptosporidium was responsible for 60 of the 105 outbreaks that health officials were able confirm in a laboratory, and the largest number of victims, 12,137.
Cryptosporidium causes the diarrheal disease cryptosporidiosis. Both the parasite and the disease are commonly known as "crypto." It can cause watery diarrhea and stomach cramps and sometimes dehydration, nausea, vomiting and fever that last about a week. For most people it is unpleasant but not dangerous, but in the very young, the old and those with compromised immune systems it can be more dangerous.
Unlike many illnesses that can be waterborne such as E. coli, norovirus and shigella, cryptosporidium is relatively resistant to chlorine, the most commonly used disinfectant in water.
"Crypto is pretty tolerant of chlorine," says Michele Hlavsa, chief of CDC's Healthy Swimming Program. At the recommended levels for pools, fountains and water parks, 1 to 2 milligrams of chlorine per liter of water, the parasite can live for three to 10 days, she says.
Between 1997-2008, 16 outbreaks linked to fountains were reported to CDC, 11 caused by crypto. t was only in 2005 that the Food and Drug Administration approved a treatment, so prior to that very few people were tested for it. It is spread through fecal transmission. A person will have "a fecal incident" in the water and then another person will swallow water from and get infected. "Crypto usually causes very watery diarrhea, so nobody in the pool will know it's happening," says Hlavsa.
Crypto outbreaks can be very widespread. In 2008 Utah had a statewide outbreak that caused 5,000 illnesses. One infected individual can go on to infect multiple other water sources, sometimes without being aware of it.
There are ways to kill cryptosporidium protozoa, including ultraviolet light and ozone, but they're both much more expensive than chlorine. Recreational water quality is not regulated at the federal level, but by state or local agencies.
Some of the highest-risk places to acquire a cryptosporidium infection are the public sprinklers and fountains that are increasingly popular as play areas for children.
"These are the ones where the kids sit on the nozzles," says Hlavsa. "They're often sitting right on their diapers."
The fountains typically use recirculated water, so "you can see how once that water gets contaminated, a lot of kids could get exposed," she says.
People ill with diarrhea shouldn't swim, and parents should be extra careful if their children are sick. Swim diapers do not necessarily keep the fecal matter from coming into contact with the water.
"And to protect yourself, don't swallow the water. Don't bring toys into the water that encourage drinking water. Make sure you have other drinking options," Hlavsa says.
Finally, everyone should shower or at least rinse off before getting into the water. "Whatever is on your body is going to go into the water that gets on everybody's body."