For some whose immune systems are compromised, crypto may lead to life-threatening malnutrition and wasting.
According to the agency, cases of cryptosporidiosis, known as "crypto", are on the rise, and the fecal parasite, which causes diarrhea for up to three weeks, can stay alive in pool waters for up to seven days. At least one child has died, the CDC says. Between 2009 and 2107, there were 444 crypto outbreaks in 40 states and Puerto Rico.
To prevent its spread, the CDC says anyone suffering diarrhea should avoid swimming until at least two weeks after their diarrhea subsides.
Between 2009 and 2017, there were 444 outbreaks across the USA, causing more than 7,000 people to fall ill. Most of those cases were reported during the summer months of July and August when people were most likely to head to the pool. As a result, the CDC warns not to "drink untreated water from lakes, rivers, springs, ponds, streams, or shallow wells".
The number of cases increased by an average of 12.8% annually between 2009 and 2017.
It's also worth noting the one death from cryptosporidiosis came in the sole instance in which the parasite was transmitted in a hospital setting.
Bobbi Pritt, a physician and co-director of Vector-Borne Diseases Lab Services at the Mayo Clinic said the parasite is endemic to the United States and can infect people in swimming pools because the parasite can survive even treated water with its resistance to chlorine and some chemicals.
The parasite is a problem in pools is because an infected swimmer can excrete the parasite at several orders of magnitude higher than the amount necessary to cause infection.
One of the most important precautions to take, according to Michele C. Hlavsa, one of the CDC researchers behind the study, is to keep the water out of you and your loved ones' mouths.
There are preventative measures that can help stem the number of outbreaks, and the CDC is working to educate the public on them.
And if you know anyone who has had diarrhea recently, don't let them in the pool.
Parents are urged to avoid taking their children to the pool if they are sick with diarrhea.
Wash your hands with soap and water after coming in contact with animals or anything in their environment, especially animal poop.
If diagnosed with cryptosporidiosis, do not swim until two weeks after diarrhea completely stops.
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