Swimmer's Itch

Swimmers Itch Graphic

Illustration: Anthony Ross

While not a persistent, widespread problem, the “Swimmer’s Itch” parasite is believed to be present in lakes Mead and Mohave. While found in warm, shallow waters anywhere from only a few weeks to an entire summer, the parasite is not a life-threatening concern, but one that can cause some discomfort.
“Swimmer’s Itch” is the name given to a condition caused by flatworm larva. The naturally-occurring parasite needs ducks, snails and warm shallow waters to flourish. It is common in lakes in 30 states.

(Illustrated above)
(1)The parasite lives inside ducks and geese and release eggs into lake waters.
(2) These eggs hatch into small larvae that seek out water snails within which to grow.
(3) After incubating in the snails, the flatworm moves out of the snails.
(4) The flatworm swims in search of water fowl. It is during this journey that flatworms can come in contact with humans. It burrows under the skin where it dies because of its incompatibility with humans.

Symptoms include reddening spots which appear within a few hours. Itching, swelling of the skin, and/or red welts may also develop 10 to 15 hours later. Itching may continue for several days, but all symptoms should disappear within a week. Only about a third of people who actually come in contact with this organisms actually develop “Swimmer’s Itch.” Since children swim closer to the shoreline, where the potential is greater to come in contact with the organisms, they are more likely to develop “swimmer’s itch”. Children also tend not to towel down after swimming, which if done would reduce the chance of developing the condition according to the Centers for disease control.

To reduce the risk of developing this condition, briskly towel off immediately upon leaving the water to remove the parasites from your skin; if safe to do so, swim in water away from the immediate shoreline; and avoid swimming during or immediately after an on-shore wind. Remember there are no lifeguards at Lakes Mead and Mohave. Swim at your own risk.

If you experience an unexplained rash and are concerned, please contact your doctor..

Last updated: March 30, 2016

Contact the Park

Mailing Address:

601 Nevada Way
Boulder City, NV 89005


(702) 293-8990

Contact Us