CEDAR RAPIDS- The cryptosporidiosis case that forced a Cedar Rapids indoor pool to close this week is just one sign of a much larger outbreak in the area.

The city's Bender Pool closed for special cleaning Monday after a child taking swimming lessons was diagnosed with crypto. That's an illness caused by a parasite that infects people swimming in or drinking contaminated water. The symptoms include frequent and watery diarrhea and some conditions that mimic the flu. The pool reopened Wednesday.

The Linn County Public Health Department estimated they've confirmed 50 to 60 cases of the waterborne parasite disease so far this year. But even those numbers might not reflect the size of the outbreak.

Labs at both St. Luke's and Mercy Hospitals did not test for crypto until a doctor specifically ordered a special test. But last April, both labs switched to a new testing system that routinely looks for crypto in samples.

At St. Luke's, the lab confirmed 11 cases in August. To date in September, they've had 37 positive results for crypto. Microbiology lab director Sue Smith said "since April, we'd get a few here and a few there. Since September we've gotten a whole lot more positives so we really are seeing something now."

Health officials say the new lab procedures at the two hospitals may be picking up cases that were always here, but never identified before. However, that doesn't explain the entire increase in crypto cases throughout Iowa.

At the state level, Iowa had 231 confirmed crypto cases in 2006. That was the highest number ever. So far this year, the state has recorded 146. However, that number does not include many cases that are not yet confirmed by county health departments. Health officials say the final numbers in 2007 will probably exceed last year's total.

Healthy children or adults who do contract crypto usual recover in about two weeks. Rules require anyone with crypto to stay out of swimming pools for a full 14 days. Children in daycare with crypto are also not supposed to return until that time has passed.