Swimmers returned to the Hopkins Park pool Thursday – two days after the pool was closed by park district officials for possibly harboring a parasite that causes a diarrheal disease.

Bright yellow DeKalb County Health Department fliers were posted behind the front desk and in both men’s and women’s locker rooms, advising swimmers of an increased incidence of cryptosporidiosis, a diarrheal disease caused by a parasite, in DeKalb County.

The DeKalb Park District voluntarily closed the facility Tuesday to super-chlorinate the pool.

DeKalb County Health Department Administrator Karen Grush said there was no conclusive proof that the pool was the source of the parasite, but health officials ruled the pool was a common link after interviewing several people who became infected with the disease.

The department has identified 10 confirmed and four suspected cases of the disease since Aug. 11, Grush said.

Symptoms of cryptosporidiosis include: diarrhea; loose, watery stool; nausea; stomach cramps; and slight fever. Symptoms usually surface two to 10 days after exposure and can last two weeks.

Grush said there was nothing the park district could have done to prevent the outbreak.

“Chances are an infected swimmer introduced the parasite to the pool,” she said.

The park district was “extremely cooperative” in preventing greater exposure, she said.

Park district Executive Director Dave Mogle said district employees worked Tuesday night until Wednesday morning to bring the Olympic-size pool’s chlorine level to 25 parts per million, about 22 more than average.

Hopkins employees super-chlorinate the pool on a smaller scale two to three times a season, but only bring chlorine levels to 10 to 12 parts per million.

Mogle said the pool needed to be closed for two days to bring chlorine levels back to a safer level. The Illinois Department of Public Health dictates pools must maintain chlorine levels between 1.5 and 3.5 parts per million. These chlorine levels kill common colds and flus, but not a spore like crytosporidium, he said.

“We’re always within that range,” Mogle said. “We check [the pool] four times a day.”

Exposure to high levels of chlorine – like the levels present during the super-chlorination – could have caused irritation to both the skin and eyes, Mogle said.

The Illinois Department of Public Health inspected the pool’s filters on Monday and confirmed that they were functioning properly, Grush said.

Mogle said the kiddie pool was super-chlorinated Monday night.

About 60 swimmers visited the pool Thursday, Mogle said. The pool has averaged 60 visitors a day the last two weeks of the season, he said.

The pool closes on Labor Day.

For more information on cryptosporidiosis, call the DeKalb County Health Department at 758-6673, or visit its Web site at www.dekalbcountyhealthdepartment.com