EAST PEORIA — If you swam in a Tazewell County public pool since Aug. 21 and later had multiple bouts of watery diarrhea, you should visit a doctor — you might have cryptosporidium.

“We have one confirmed case, and there are several people that are ill,” said Sara Sparkman, communications manager for the Tazewell County Health Department.

The department declined to name the pool where the suspected transmission took place.

Cryptosporidium is a parasite that can cause diarrhea, cramping, nausea, dehydration, fevers, fatigue and weight loss. Symptoms can last up to two weeks. In most people it will resolve on its own, but treatment may decrease illness and recovery time.

Treatment is especially important in individuals with weakened immune systems.

The health department issued the warning Tuesday afternoon.

“We believe that there are more people out there that are ill, and we want everyone who is ill, who swam in a public pool, to go to a doctor and get tested,” said Sparkman.

Cryptosporidium is not killed by the chlorination processes normally used in swimming pools.

“There has to be a more stringent chlorination process to get rid of it,” Sparkman said.

Even if victims have been ill and recovered, they could still be shedding the parasite, said Sparkman. Infected individuals shed the parasite for up to 60 days.

“We want to make sure other people aren’t being exposed,” she said.

Anyone with diarrheal illness should avoid water activities for at least two weeks.

For more information, contact Taylor Eisele, epidemiologist with the Tazewell County Health Department, 929-0281 or teisele@tchd.net.

Leslie Renken can be reached at 686-3250 or lrenken@pjstar.com. Follow her on Twitter.com/LeslieRenken, and subscribe to her on Facebook.com/leslie.renken.