Swimmer's Itch 

Most people who swim outdoors in fresh water have heard of Swimmer’s Itch. Swimmer’s Itch is the common name for Schistosome Cercarial Dermatitis. This is a temporary skin rash caused by a parasitic worm called a Schistosome. Although the rash can be very irritating, and if scratched the skin can become infected, the Schistosomes and the rash are not dangerous and cannot be spread. The rash is caused by an allergic reaction to the Schistosomes when they penetrate skin. People swimming in some lakes are simply in the wrong place at the wrong time.

The normal lifecycle of Schistosome include movement between aquatic birds, such as ducks and geese, and snails (see Schistosomes Life Cycle diagram). When humans are swimming in water that contains Schistosomes the worms accidentally enter human skin instead of the aquatic birds. As humans are not the natural host, the Schistosomes quickly die. Humans have an allergic reaction to the foreign material and the skin becomes swollen, red and itchy for up to fourteen days.

Since the body is having an allergic reaction, each encounter with Schistosomes will cause the reaction and rash to be more severe. The degree of sensitivity a person experiences will depend on his or her immune system, the severity of the infestation, and prior exposure. Anti-itch medications recommended by a doctor or pharmacist, such as lotions and some antihistamines, may help to relieve itchy symptoms.

Protection Tips

• Shower and towel dry vigorously after swimming.
• Don't feed aquatic birds, as this will encourage them to remain on the beach.
• Dispose of food and litter in garbage cans.

Schistosome Life Cycle