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Outbreaks of diarrhea-causing parasitic infection linked to swimming pools are on the rise, CDC reports

Waterpark swimming
Crypto gets into swimming pools and other recreational water through contaminated feces from a human or animal.

Outbreaks of cryptosporidiosis — a diarrhea-causing parasitic infection that is often spread through water in swimming pools and waterparks — have doubled in recent years, according to a report published last Friday by the Centers for Disease Control and Prevention (CDC).

At least 32 outbreaks of swimming-pool-linked “crypto” (as the infection is commonly called) were reported in 2016, up from 16 in 2014, the CDC report says.

The increase is troubling — although, as the CDC officials acknowledge, it’s not clear if the rise in outbreaks is the result of more incidents of the infection or to better surveillance and reporting of cases.

With the swimming season about to begin in many areas of the country, however, health officials want everyone to be aware of the risk. They are also urging people — particularly parents — to help reduce the incidence of crypto in their communities.

“To help protect your family and friends from crypto and other diarrhea-causing germs, do not swim or let your kids swim if sick with diarrhea,” said Michele Hlavsa, chief of the CDC’s healthy swimming program, in a released statement. “Protect yourself from getting sick by not swallowing the water in which you swim.”

Hard to kill

Crypto gets into swimming pools and other recreational water through contaminated feces from a human or animal. Even a small amount of feces can contain thousands of the hard-shelled parasites.

Crypto is not easily killed by chlorine and other disinfectants used in swimming pools. Swallowing just a single mouthful of contaminated water can make otherwise healthy people sick, CDC officials stress. The illness causes watery diarrhea, stomach cramps, nausea, vomiting and other symptoms that can last up to three weeks. The symptoms often occur in cycles: You may recover for a day or two, only to have the diarrhea and nausea return.

For individuals with suppressed immune systems, the illness can be life threatening.

Minnesota’s numbers

Crypto is now recognized as one of the most common types of waterborne disease in the United States, and the parasite has been found in every region of the U.S.

The new report focuses on recent large crypto outbreaks in three states:  Alabama, Arizona, and Ohio.

In Arizona, for example, a 2016 outbreak involving 36 Little League players and their family members was traced to a visit to a waterpark. And in one of Ohio’s major outbreaks that same year, 26 members of a university sports team became infected with the parasite after visiting a waterpark.

A 2016 outbreak in Alabama (involving 35 people) was linked to a waterpark that was in full compliance with local standards — a finding that highlights how difficult it is for facilities to keep recreational water crypto-free, even when the pools are carefully run and monitored.

Minnesota was not a specific focus of the CDC report, but state health officials documented 316 cases of crypto in 2015. The infected individuals ranged in age from nine months to 88 years.

From 2006 to 2015, Minnesota had 60 reported outbreaks of crypto, involving 3,148 people. Of those outbreaks, most were traced to either waterborne transmission (22 outbreaks) or person-to-person contact (another 22 outbreaks). The rest were attributed to animal contact or foodborne transmission.

Prevention is key

The CDC recommends you take the following steps to protect yourself and others from crypto at recreational water venues:

  • Don’t swim or let your kids swim if sick with diarrhea.
  • If diarrhea is caused by crypto, wait until two weeks after diarrhea has stopped to go swimming.
  • Don’t swallow the water in which you swim.
  • Rinse off in the shower before getting in the water to help remove any germs on your body that could contaminate the water.
  • Take kids on bathroom breaks often, and check diapers in a diaper-changing area and not right next to the pool.

FMI: The CDC report was published in the agency’s Morbidity and Mortality Weekly Report (MMWR). You can find more information about crypto and other waterborne illnesses at the websites for both the CDC and the Minnesota Department of Health.

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