Crypto spreads in pools
In the past two years, outbreaks of cryptosporidiosis, a parasitic disease caused by the bacteria cryptosporidium, have affected hundreds of people.
Every year as the calendar turns to summer, Valley residents hit pools and splash pads to escape the heat. In recent years, some seeking relief from the sweltering conditions were met by a particularly nasty bug.
In the past two years, outbreaks of cryptosporidiosis, a parasitic disease caused by the bacteria cryptosporidium, have affected hundreds of people.
State health department data shows cryptosporidiosis cases tend to peak from July through September, aligning with the height of swim season.
The state health department denied an public records request for reports detailing which pools the sick people visited because communicable disease information is considered confidential under state law. Experts say pinpointing the source of these outbreaks is challenging because the disease can spread to any pool an infected person visits.
While rarely deadly, the bug causes diarrhea, stomach cramps and vomiting that can last two weeks, according to the state health department.
“It starts out typically as a feeling of gastrointestinal discomfort,” said Michael Riggs, a researcher at the University of Arizona. “The initial symptom in some is vomiting, but more commonly it’s diarrhea that gets more severe as the days pass.”
People infected with the virus can easily transfer it to pools and splash pads, especially if they’re dealing with diarrhea.
“As few as one or two organisms will infect 50 percent of people that ingest it,” Riggs said. “That’s unprecedented in terms of acquiring an infection for almost any bug that I’m aware of. So the infectious dose is extremely low.”
The official guidance from health experts is for those with diarrhea to avoid swimming for two weeks after the symptoms clear up. Other stan-
dard safety tips include:
❚ Washing hands, especially after using the bathroom, changing diapers, preparing food or touching farm animals;
❚ Keeping children out of daycare if they have diarrhea;
❚ To avoid swallowing pool or recreational water.
Standard chlorine takes a long time to kill the cryptosporidium bacteria. If one infected person enters the water, chances are the bacteria will live long enough for another person to ingest it.
Pools and splash pads are often vulnerable to the parasite because it’s expensive to treat water in a way that kills it, Riggs said. Public pools, especially municipal pools, are becoming more effective in preventing and responding to crypto outbreaks, he said.
“All of these things are expensive,” Riggs said. “Those that continue to just rely on chlorination are going to be at risk.”
Scottsdale’s municipal pools and recreational water facilities employ periodic hyper-chlorination and UV disinfection to combat crypto, said Ken Shoup, the city’s aquatic maintenance supervisor.
While costly, it’s a necessity for facilities that see thousands of swimmers at peak times, he said.
“To the average pool owner, they’re not going to be exposed to a thousand different people swimming in your pool,” Shoup said. “In a public setting, we have to be very aware of that possibility.”
Water parks also face risk from cryptosporidium. Wet ‘N Wild Phoenix installed UV systems on all its pools and attractions, park spokeswoman Heather Austin said.
Apartment complexes may not have the resources to spend on sophisticated disinfection tools. That’s why the most effective form of prevention starts with raising public awareness, said Jessica Rigler, branch chief for public health preparedness at the Arizona Department of Health Services.
“We are always trying to get awareness out into the general public. And as you can imagine, it’s difficult, especially in the summer when people want to swim whether or not they are feeling OK,” she said. “We’ve continued to do enhanced surveillance ... for crypto and that means that we’re testing a lot more.”
Greg Epperson, managing supervisor for aquatic health and safety at the Maricopa County Environmental Services Department, said education is crucial because pools don’t learn of cryptosporidium outbreaks until after they happen.
“The best thing that a pool operator can do — or just the pool industry in general — is education when it comes to crypto,” he said. “As an operator, you could be operating your pool spot on to what code requirements are as far as chemical levels and cleaning and all that and you could still have an outbreak.”