Swimmers escaping the summertime heat face a sharp increase in waterborne diarrheal diseases, the Minnesota Department of Health announced last week.
Already this year, the department has logged 147 cases of people infected by parasites and bacteria found in water parks, pools and lakes. The most common months for these diseases still lie ahead.
"The more people you have in a body of water, the higher the risk," Health Department spokesman Doug Schultz said Friday.
In 2011 there were just 59 recreational water illnesses reported in Minnesota, most between July and October. This year, the number of cases is at a 10-year high. Two major outbreaks in late March were at Edgewater Resort and Water Park in Duluth, with 97 cases, and Paul Bunyan indoor water park in Baxter, with 42. Both closed voluntarily to treat the water and reopened a few days later. No further incidents have been reported.
Both outbreaks are being attributed to Cryptosporidium. The microscopic parasite is protected by a shell that makes it resistant to chlorine disinfection. The illness is spread most commonly in water contaminated by infected human or animal feces.
Symptoms include diarrhea, stomach cramps, dehydration and vomiting. They usually begin two to 10 days after the person swallows contaminated water and becomes infected and can last one to two weeks.
The parasite can be spread even after the symptoms have stopped.
Children, pregnant women and people with compromised immune systems are most at risk of illness or even death, the department said.
Anoka County Recreation Supervisor Lisa LaCasse said swimmers are at risk, even in properly maintained pools. She urged them to use common sense and follow posted rules.
"We require kids who are not potty trained to wear swim diapers. We do request that people take a shower before entering the pool with soap and water, but admittedly that doesn't always happen," she said.
Craig Hedberg, a University of Minnesota environmental health scientist, said that fecal contamination in water can also spread E-coli, shigella, salmonella and norovirus. He said the incidence of these illnesses usually triples during the summer.
Kristian Hernandez • 612-673-4217