To date, more than 150 cases of cryptosporidium - a parasite that is chlorine resistant at normal levels used in pools and can be difficult to eliminate - have been reported to the Davis County, Salt Lake Valley, Utah County and Weber/Morgan health departments.

Of particular concern are individuals with compromised immune systems, such as those with HIV or AIDS, cancer, those who have recently had an organ transplant and are taking certain immunosuppressive drugs, and those with inherited diseases that affect the immune system.

The state health department advises people with these conditions to consider avoiding swimming in recreational water sites until the risk has decreased or discuss the risk with their health care provider.

For those who do swim, good hygiene is the best defense. The Centers for Disease Control and Prevention suggests:

* Avoiding swimming when you have diarrhea or for two weeks after recovering from diarrhea.

* Not swallowing any pool, lake or stream water.

* Taking a shower before swimming and washing your hands after using the toilet or changing diapers.

* Taking children on frequent bathroom breaks and check diapers often.

* Changing diapers in a bathroom and not at poolside or near recreational waterways.

* Washing your child thoroughly (especially the rear end) with soap and water before swimming.

For more information about cryptosporidium, visit the Centers for Disease Control and Prevention's Web site at: http://www.cdc.gov/healthyswimming/ or the Utah Department of Health's Web site at: www.health.utah.gov.

lrosetta@sltrib.com