The itchy rash associated with swimmer's itch looks like reddish pimples or blisters. It may appear within minutes or days after swimming or wading in infested water.

Swimmer's itch usually affects only exposed skin — skin not covered by swimsuits, wet suits or waders. Signs and symptoms of swimmer's itch typically worsen with each exposure to the parasites.

The parasites that cause swimmer's itch live in the blood of waterfowl and in animals that live near ponds and lakes. Examples include:

• Geese
• Ducks
• Gulls
• Beavers
• Muskrats

The parasite's eggs enter the water via their hosts' feces. Before infecting birds, animals or people, the hatched parasites must live for a time within a type of snail. These snails live near the shoreline, which explains why infections occur most often in shallow water.

Swimmer's itch isn't contagious from person to person, so you don't need to worry about catching swimmer's itch from someone who has this itchy rash.

The parasites that cause swimmer's itch live in the blood of waterfowl and in animals that live near ponds and lakes. The more time you spend in infested water, the higher your risk of swimmer's itch. Children may have the highest risk, since they tend to play in shallow water and are less likely to dry off with a towel.

Some people are more sensitive to swimmer's itch than others are. And, your sensitivity can increase each time you're exposed to the parasites that cause swimmer's itch.

Swimmer's itch rarely leads to complications, but your skin can become infected if you scratch too vigorously. Try to avoid scratching the rash.