A harmful parasite found in some Anchorage lakes may not be on swimmers’ minds when they take a dip -- but state officials are working to keep them from having it on their bodies when they get out.

Louisa Castrodale, an epidemiologist with the state Department of Health and Social Services, says swimmer’s itch is caused by a parasite found in feces from geese or other birds. Birds and some other mammals are carriers of the parasite.

When people go swimming in a lake with a high concentration of bird waste, they can be infected as the parasite’s larvae burrows into their skin and tries to complete its life cycle -- but can’t, because humans are not carriers of the parasite.

The larvae eventually die, but their presence irritates the human host. There is no time length for a reaction to take place.

Signs have been posted at Jewel Lake noting that people have contracted swimmer’s itch after swimming there in late June and early August. City officials say a single report of swimmer’s itch came in about a week and a half ago from a swimmer at Goose Lake.

Symptoms include tingling, burning itching, small red pimples or blisters. The larvae will eventually die off, leaving sufferers symptom-free; humans can’t become carriers.

Castrodale says there is no treatment for swimmer’s itch. She recommends trying not to scratch or otherwise irritate the bumps.