HEALTH

Happy Summer: Pool Poop Parasite Outbreaks Are Getting More Common

Annual infections of a hardy bug called crypto have more than tripled since 2004

HEALTH
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May 19, 2017 at 4:11 PM ET

Horrifying as it sounds, pee isn’t the worst thing you could find in your neighborhood pool — there’s also a microscopic parasite called Cryptosporidium spread through poop that can cause you weeks of diarrhea. And according to a new report published this week by the Centers for Disease Control and Prevention, outbreaks of crypto, as it’s often called, are only becoming more common in recent years.

In 2016, the authors found, there were 32 pool-related crypto outbreaks reported to the CDC across 24 states, a number higher than any recorded year previous. One of the largest outbreaks, in Arizona, involved roughly 350 confirmed cases. From 2011 to 2015, though, the median amount of cases in the state was only 46 annually. Overall, since 2004, the annual number of nationally reported cases of crypto infection has more than tripled, making it now the leading cause of pool-related outbreaks. Currently, there are more than 700,000 estimated cases of crypto infection, or cryptosporidiosis, that occur every year, according to the CDC.

Crypto, like other stomach bugs, is largely spread through food and water contaminated via an infected person’s poop. What makes it different is that in its cyst form, crypto can survive the harsh environment of a regularly chlorinated pool for days. That means that even perfectly maintained swimming pools can be a breeding ground. Young kids also seem to be an unknowing ally, since they’re less likely to be hygienic or avoid the pool when they’re sick with the stomach flu.

In 2015, a surveillance system called Cryptonet was set up by the CDC to better track cases based on the exact genetic strain of crypto found. With that, the authors were able to see subtle changes in how we’re interacting with the bug. Many of the outbreaks in 2016 were caused by a subtype called Cryptosporidium hominis, which largely sticks to people, as opposed to Cryptosporidium parvum, which infects a variety of different animal hosts.

What that shift could mean, or why it’s happened, is still a mystery though. One that the researchers don’t think can get solved without further expanding how we track cases. Rather than jump from one large outbreak to the next one, the authors believe public health agencies should be using collected crypto samples to establish a far-reaching system that can track the distribution of crypto strains across the country.

As for us, the best thing we can do to prevent cases from popping up is pretty obvious — and just darn polite.

“Not swimming when ill with diarrhea is key to preventing and controlling aquatic facility–associated cryptosporidiosis outbreaks,” the authors wrote.