Every year around this time we start to see reports of swimmer's itch around the country. Common lore in the media is that this is caused by "duck fleas" in freshwater and 'sea lice' in salt water; however, this is not correct.

Instead, swimmer's itch is caused by the larvae of a parasite called schistosomes. A number of birds like ducks and gulls and some mammals like beavers can be infected with the parasite in their blood.

Parasitology teacher and author of Parasites: Tales of Humanity's Most Unwelcome Guests, Rosemary Drisdelle joined me to go over the ins-and-outs of swimmer's itch.