Children under age 5 are banned from public swimming pools in several Utah counties as part of public health's fight against a parasitic outbreak called cryptosporidium.

And if that doesn't clear things up, health officials may close pools entirely for a while.

State health director Dr. David Sundwall said today that officials are trying to use "common sense and a light touch" to end the outbreak, but parents will have to comply with the rules so harsher steps won't be needed.

The state and several local health departments, including Utah County, Salt Lake Valley, Davis, Weber-Morgan and Bear River, have issued restrictions on the littlest swimmers. Other measures will include more frequent hyperchlorination of public pools and public education about the illness. Those counties are home to 98 percent of the public pools in the state.

Meanwhile, officials are trying to figure out what to do about fountains that include wading-pool areas, such as the popular 7 Canyons feature at Liberty Park in Salt Lake City.

There are about 30 cases of cryptosporidium in a normal year across Utah. This year, the state has 422 lab-confirmed cases, and new ones are rolling in daily.

"That's the tip of the iceberg," said Lewis Garret, director of the Davis County Health Department, which has 70 confirmed cases.

Health officials plan to re-evaluate the situation Sept. 10, said state epidemiologist Dr. Robert Rolfs, and decide then whether to lift the ban or possibly close pools.

Cryptosporidium is a tough-to-kill parasite that can cause long-lasting and "often-debilitating" diarrhea. Most cases resolve over time, but the outbreak has created a shortage at area pharmacies of the medication that is used to treat more severe cases, said Dr. Joseph Miner, director of Utah County's health department, where the first signs of the outbreak appeared. Miner said children under 5 are more apt to spread the illness, but they're also among the most vulnerable, so the ban is "protective for them, as well as restrictive."

Those most likely to be severely impacted are young children, pregnant women and anyone with a severely compromised immune system. In those cases, the illness can be life-threatening.

Health officials are asking everyone to refrain from swimming within two weeks of being ill with diarrhea and are emphasizing the need for scrupulous hygiene, including thoroughly washing hands and rear ends before entering a public pool.

In Salt Lake County, 130 cases have been confirmed, with those who became ill between the ages of 8 months and 47 years. The numbers are divided about evenly between those older than 7 and those younger, said SLVHD director Gary Edwards.

Weber-Morgan's numbers show how fast the outbreak can spread, said health officer Gary House. Friday, they had 11 confirmed cases, and by Monday it had jumped to 25. "We anticipate another serious jump today," he said.

The public health officials are speculating that the extremely hot summer, which was a siren call to visit pools in order to cool off, helped fuel the outbreak. House said some seasonal pools are simply closing now instead of in a couple of weeks to help end the outbreak. For those remaining open, "we are asking 100 percent compliance."

Besides hyperchlorinating the pools at least twice a week at 20 parts per million chlorine, an eight-hour process, pools are going to maintain a slightly higher minimum chlorination level at 5 ppm. It won't be harmful, though it might create an "unpleasant aroma," Rolfs said.

Public fountains where kids splash around in pooled water also are subject to the restrictions, according to Salt Lake health officials. Val Pope, director of the Parks Division for Salt Lake City, said he's working with water quality and health department staffers to see what will need to be done, since safety is the biggest priority.

Four Salt Lake-area fountains will be affected by the restrictions, and they have to be certain they can maintain that elevated minimal chlorination or they may be closed temporarily because of the outbreak.

"The 7 Canyons was completely redone three to four years ago with a chlorination system that will meet or exceed any swimming pool in the state. It was designed intentionally that way because it has more demand," Pope said.

But the natural aeration that occurs with the fountain's design may make it hard to maintain the boosted minimum chlorine level. "We'll be assessing those standards to see what we can do," he said.

All four of the affected fountains close for the season in October anyway, he said.

Day care centers are being enlisted to find other activities besides recreational water activities until the crisis passes.