In today's edition of "scrubbing ourselves with bleach," it turns out swimming pools are even grosser than we thought.
Never mind that it's pee, not chlorine, that makes your eyes red after a refreshing dip. Forget that you can get plantar warts and athlete's foot from walking around barefoot. Ignore for a moment that's you're essentially bathing in the dirty bathwater of a room full of strangers.
But now we know that a parasite found in contaminated human faeces is to blame for the majority of pool-related illnesses. And it spreads when you accidentally swallow their poop water.
Cryptosporidium(or "crypto") is a parasite tough enough to survive in even the best-maintained pools, according to a new report from the U.S.'s Centers for Disease Control and Prevention (CDC). And it's nasty.
"Crypto causes 58 percent of outbreaks where a germ was identified linked to pools, hot tubs, and water playgrounds and 89 percent of the illnesses," the CDC said in the report, published in May.
It spreads when someone with the parasite has diarrhoea in the water, and other swimmers swallow it, and kids are particularly vulnerable.
"Swallowing just a mouthful of water with crypto in it can make otherwise healthy kids and adults sick for weeks with watery diarrhoea, stomach cramps, nausea, and vomiting," Michele Hlavsa, R.N., M.P.H., chief of CDC's Healthy Swimming Program, said in a news release.
"Chlorine cannot kill crypto quickly. We need to keep it out of the water in the first place. Don't go into the water, and don't let your kids go into the water, if sick with diarrhoea."
The CDC collected U.S. data from 2000-2014, and found that one-third of swimming-related disease outbreaks happened in hotel pools or hottubs. They tracked 494 outbreaks, 27,219 illnesses, and eight deaths.
Cryptosporidium Outbreak Five Years Ago in Canada
Serious outbreaks are rare, according to Canada's CTV News when reporting on a 2013-2014 outbreak in Nunavik, northern Quebec. It was the first time scientists found an outbreak of the parasite in a remote arctic community.
Ontario had 360 reported cases of cryptosporidiosis in 2014, with the highest incidence rate in children under age five, Public Health Ontario noted.
"... recreational swimming pools (are) a common source of infection among children," Public Health Ontario said.
Hundreds of people in North Battleford, Saskatchewan, became sick after drinking water contaminated with cryptosporidium in 2001, CBC News reported.
In the past several years there have been swimming-related outbreaks in the Niagara region of Ontario, and in Surrey, B.C., according to a 2014 study in Environmental Health Review. The former outbreak occurred at a water park; the latter at a swimming pool and traced back to "two pool-fouling incidents during the exposure period."
"Children may be most affected by cryptosporidium infection as they are the most frequent users of water parks. Furthermore, children may be more susceptible to illness as they generally tend to have a weaker immune system than adults," researchers from the University of Guelph noted in the study.
How to keep your kids safe
Never let your kids swim if they have diarrhoea, the CDC said. And if you know that crypto is the cause of their illness, wait at least two weeks before getting back in the water.
You can check the inspection scores for pools, hot tubs, and water playgrounds, the CDC added, and you can even use your own test strip to check the water's pH, bromine, and chlorine levels.
Take kids on hourly bathroom breaks, and change diapers in an area away from the water, CDC said.
And, for the love of God, try not to swallow the water.